ES2371634T3 - SINGLE PREVIOUS CERVICAL PLATE SYSTEM. - Google Patents

Abstract

Plate system adapted for use in the anterior human cervical spine for contact with the anterior protuberance of at least two cervical vertebral bodies, said plate system comprising: a plate (600, 900) having a longitudinal axis and a sufficient length to extend to a disc space and overlap with portions of at least two adjacent vertebral bodies, said plate (600, 900) having a lower surface for placement against the vertebral bodies and an upper surface as opposed to said lower surface ; at least two bone screws (170), each of which has a longitudinal central axis and is adapted to engage each of at least two vertebral bodies, respectively, each of said bone screws (170) having ) a front end for insertion into the vertebral bodies and a rear end (172) opposite to said front end, said rear end (172) having a first surface (178) directed upwards, oriented towards said upper surface of the plate (600, 900), a lower surface opposite to said first surface directed upwardly directed towards said lower surface of said plate (600, 900) and a second surface directed upward, oriented towards said upper surface of said plate (600, 900 ) and disposed between said first surface (178) directed upwards and said lower surface; at least two holes (602, 910, 950) bone screw receptors, which extend through said plate (600, 900) from said upper surface to said lower surface, each of said holes (602, 910) having , 950) bone screw receptors, a central longitudinal axis, at least a first hole of said holes (602, 910, 950) bone screw receptors adapted to be disposed above a first vertebral body, and at least one second of said holes (602, 910, 950) bone screw receptors being adapted to be disposed above a second vertebral body; and a series of locking elements (610) each adapted to block said plate (600, 900) only one of each of said bone screws (170) inserted in each of the holes (602, 910, 950) bone screw receptors, each of said locking elements (610) being coaxially coupled, at least, partially within only one of said holes (602, 910, 950) bone screw receivers to retain said screw for bones (170) in said plate (600, 900), each of said blocking elements (610) having an external perimeter that contacts at least a part of the perimeter of one of said holes (602, 910, 950 ) bone screw recipients, each of said blocking elements (610) having an upper surface configured to cover at least a portion of said at least one surface directed upwards of said bone screw (170) and a surface ie lower as opposed to said upper surface, characterized in that each of said blocking elements (610) has a through hole (306) that crosses said upper surface and said lower surface, said through hole having a central longitudinal axis fixed coaxially with respect to to the central longitudinal axis of one of said holes (602, 910, 950) bone screw receptors and the central longitudinal axis of one of said bone screws (170) when said bone screws (170) and said locking element ( 610) are received in said hole (602, 910, 950) bone screw receiver, the second surface directed upwards of at least one of said bone screws (170) a generally flat contact surface by at least one of said blocking elements (610) when said at least one bone screw (170) and said at least one blocking element (610) they are received in a corresponding hole (602, 910, 950) bone screw receiver, said lower surface of said plate (600, 900) being concave along a substantial part of the longitudinal axis of said plate (600, 900) and each of said holes (602, 910, 950) bone screw receptors being configured to prevent said lower surface of said rear end of said bone screw (170) protruding below said lower surface of said plate (600 , 900).

Description

Single anterior cervical plate locking system 5

1. Technical field of the Invention

The invention relates to a plaque system adapted for use in the human anterior cervical spine to establish contact with the anterior protuberance of at least two cervical vertebral bodies. Therefore, the present invention relates generally to implants and instruments for the fusion of the cervical human spine from the anterior protuberance and, in particular, to plaque systems for aligning and maintaining adjacent cervical vertebrae in a spatial relationship. selected during the vertebral fusion of these vertebrae.

1. Description of related techniques

US-A-5 531 746 (the preamble of claim 1 is based on this document) discloses a posterior cervical implant assembly to keep adjacent immobilized vertebrae by fixation to posterior surfaces thereof, comprising an elongated plate, having at least two through holes arranged in a separate relationship with respect to each other along a longitudinal axis thereof; a series of coupling elements each of which has a hemispherical interior volume and each of said coupling elements being inserted into a corresponding through hole, as well as a series of bone holes, each of said bone screws having a part of the head shape

25 hemispherical and a rod, said rod being insertable through the corresponding through hole into the hole of the vertebra and said hemispherical head being mounted with free rotation capacity within the hemispherical interior volume within the coupling element before insertion and so such that the bone screw shank and the coupling element can be inserted into a corresponding through hole and said bone screw shank can be inserted into the lateral mass at a selected angle within a predetermined range of angles, including angles not perpendicular to the plate and thereby blocking said coupling element and said hemispherical head with said plate at said selected angle when said hemispherical head and said coupling element are forced to advance into said corresponding through hole.

35 It is common practice in this technique to use cervical plate placement systems for the indicated purpose. These systems are essentially composed of plates and screws to align and maintain the vertebrae in desired position with respect to each other. The most primitive of these devices consisted of stainless steel plates and screws and required that the screws pass completely through the vertebrae into the spinal canal in order to attach to the resistant bone tissues (posterior cortex) of the vertebral bodies. This required the ability to observe or visualize this area radiographically, which is not always possible, especially in the part of the lower cervical spine in which the vertebrae can be found radiographically hidden by the action of the shoulders.

In order to form holes in the vertebral bodies for the insertion of each of the screws, it was carried out

45 a drilling operation followed by a threading operation. Each of these operations involved the passage of an instrument completely through the associated vertebral body, passing into the spine. Therefore, these instruments come very close to the spinal cord and dural sac that are very close to the posterior surfaces of the vertebral bodies. Any procedure that introduces an object into the spinal canal presents serious risks that are a concern for the surgeon.

The conventional technique of forming a bone screw receiving hole in vertebral bodies by drilling has a number of significant disadvantages. For example, drilling eliminates bone material, leaving a hole and resulting in a loss of bone material. Drilling also causes microfractures of the bone at the interface between the drill and the bone, and the resulting fracture lines tend to propagate in

55 directions perpendicular to the hole wall. More specifically, the bone material is essentially a type of ceramic that shows a fragile fracture model in its formation and propagation in response to drilling. In addition, drilling generates heat, which can result in thermal necrosis of the bone material, precisely at the interface between the bone and the screw that has been installed next, the necrosis being very harmful. Any bone that experiences necrosis will be subsequently reabsorbed by the body as part of the bone repair process and this can lead to loosening of the screw.

Another problem with drilling is that the drill path is difficult to control and since the drill works by rotation, it can project soft tissue around the associated plate. In addition, except if great care is taken, the drill can be driven significantly beyond the posterior cortex, causing irreparable damage within the spinal canal. Finally, a drill can bend and break inside the vertebral body and

then it can cause serious damage, since the part of the drill that still rotates enters the wound, while the part of the drill that has broken can protrude dangerously from the vertebral body or can break at the level of the upper surface of said body, so that it will be introduced into it irretrievably. In any case, the maneuvers that have to be performed to recover the broken part of the drill will prolong

5 inevitably and will complicate the surgical process.

In the known plate placement systems, problems have arisen due to loosening and failure of the elements used, breakage of the screws and plates and passage of the screws to the throat area of the patient. These events generally require other surgical processes to replace the broken parts of the plates and screws completely, and repair any damage that may have been caused.

Other problems that have arisen with the known systems are the result of the failure of the screws to achieve sufficient introduction into the bone and the disappearance of the thread thread filler.

15 Similarly, the use of known plaque placement systems can result in a loss of lordosis, which is the normal curve in the cervical spine seen laterally.

Known plaque placement systems also experience problems in relation to the procedures in which bone grafts are placed between vertebral bodies to achieve fusion between bodies that is cured by a process called "slow substitution" ("creeping substitution"). In this process the bone of the interface between the graft and the vertebrae is eliminated by a biological process that involves the production of powerful acids and enzymes, as a prelude to the invasion of the interface by living tissue and the deposit or growth of new bone. Although the plates allow the proper alienation of the vertebrae and their rigid fixation, they can therefore, at the same time and unfortunately, retain the separate vertebrae, while in the resorption phase

In the process of slow substitution, interstices are formed in the bone at the site of the fusion, with the result that the desired fusion does not take place. This failure is known as pseudoarthrosis. When this failure occurs, the elements used or hardware are frequently broken or released from the spine, therefore requiring another surgical process to remove the components that have been broken and an additional surgical process to attempt the fusion again.

In response to the problems that have been described, a second generation of plate placement systems has been developed and / or proposed. These comprise the system disclosed in US Pat. Nos.

5,364,399 of Lowery and 5,423,826 of Morscher, as well as the placement systems of the cervical spine and block of SYNTHES Spine, the DANEK ORION plate, the CODMAN SHURTLEFF plate and the SMITH 35 NEPHEW RICHARDS plate, among others . The training elements of the systems of this second generation have a number of common characteristics. All of them are made from a titanium or pure titanium alloy instead of stainless steel, to minimize adverse reactions of the tissues and are also compatible with MRI, which does not happen with stainless steel. The screws and plates have received an additional thickness in order to achieve greater strength. The screws have larger diameters to improve their anchorage without requiring them to fit with the posterior cortex of the vertebral bodies. A smooth longitudinal contour of the plates is used to allow some lordosis, and / or limited transverse contouring to better follow the general curved shape of the front of the vertebral bodies. Mechanisms are used to secure the screws of the vertebral bones to their associated plates, so as to prevent the screws from escaping. While this second generation of plate placement systems represents a significant improvement over the

45 previous systems, some problems still persist, while new ones have been created.

For example, since the screws no longer extend into the posterior cortex, it is common for the threads of the threaded holes for the screws to come off and that the screws do not achieve adequate anchoring. In addition, the breakage of the screw continues to be experienced and takes place in a very habitual way in the union of the screw to the rear profile of the plate. The screws used in both the SYNTHES system and the SMITH NEPHEW RICHARDS system are especially vulnerable to this problem because these screws are hollow to the level at which they are attached to the plate to allow internal reception of the locking screws.

In an attempt to prevent screw breakage at the screw connection to the plate, the most recent screw designs

55 have a larger diameter of the bottom from the tip to the head, which has resulted so far in a smooth and blunt thread, almost unusable, near the screw head with reduced retention power and little tactile feedback to the surgeon to point the termination of the tightening before the screw runs inside the bone. Based on empirical studies to check these prior art screws, it has been observed that it was preferable to use a pre-threaded hole instead of a self-tapping screw to improve the extraction resistance, and therefore these screws have not been self-tapping, so the screw holes must be pre-threaded. Since the thread cutting part of a tap is necessarily sharp and must rotate to perform its work, there is a serious risk of damage to surrounding soft tissues when used. This is combined with the fact that the plates used in these systems do not provide a sufficiently long shaft profile to fully allow lordosis and do not have a

65 Transverse contour sufficient to prevent the edge of the plate around its longitudinal axis, adapting to the anterior shape of the vertebral bodies, so that these plates do not prevent soft tissues from penetrating from the sides and below the holes of the screw thus exposing these tissues to damage by the action of the drill and the tap. Although it is possible, at the time of surgery, to make certain changes in the shape profile of these plates, this is generally limited to the contour of the longitudinal axis and very

5 frequently causes distortion of the bone screw holes in the plate and the screw holes in the plate joints, such that it has an adverse effect on the screw and plate coupling. The lack of proper contouring prevents these plates from having an optimally low profile with respect to the spine.

10 In some second generation cervical plate placement systems, cases of screw leakage continue to occur, because these plates have not been designed to allow locking of all screws. Specifically, although the designers of these plates have recognized the importance of fixing the bone screws to the plates, they have been unable to block all the screws and have had to settle for leaving some of the screws unblocked.

15 In addition, some of these second generation systems use small and delicate pieces of “watchmaking” to achieve interconnection. These pieces are characterized by the need to attach them with especially delicate small screwdrivers. These interconnection components become easily ineffective by any effort to alter the contours of a plate during surgery.

20 Despite the improvement of these second-generation plate placement systems with respect to the first mentioned problems, the problems still persist, the most important of which is pseudoarthrosis, and particularly pseudoarthroses distraction (“pseudoarthroses distraction”) . While these second generation plates have clearly led to an increase in the melting rate, when the failure in the

25 generation of fusion, this is generally accompanied by a reabsorption of the bone along a line at the junction of the graft to the vertebra, which can be seen on an x-ray.

In the case of the first generation weak plates and screws, the plates can retain the separate vertebrae, preventing fusion, but only until the mechanical or hardware elements break, overcoming

30 the deviation and then allowing the merger to take place. Second-generation plaque systems are too resistant to allow this to occur, therefore requiring other surgical processes for the correction of pseudoarthrosis.

Compression plates are well known and widely used in orthopedic surgery for stabilization.

35 of the tubular bones and in some cases also of the flat bones. These plates can be based on certain external compression means or they can be of the self-compression type, based on the ability of the screw head to slide into a ramp groove, such that the tightening of the bone screws with intermediate of the handle imparts a linear movement perpendicular to the axes of the screws. US Patent No.

5,180,381 discloses an attempt to use this mechanism in relation to the anterior spinal fixation.

40 However, it has been observed that all of the self-compression type plate systems that have been proposed have in common the need for a screw that fits both the proximal cortex and the distal cortex, (bone envelope of a very bone material dense), in order to anchor the screw tip in a way that allows the plate to move relative to the screw when tightening is done instead of allowing the plate

45 Move the screw out of the shaft. However, as explained earlier in this description, when a screw has to fit in the posterior cortex of the vertebral body, it is necessary that the drill and the tapping screw that forms the screw hole, as well as the tip of the screw, enter the spinal canal, thereby exposing the spinal cord to damage.

50 Although the system disclosed in US Patent No. 5,180,381 avoids this danger by attaching the end plate of the vertebral body instead of the cortex of the posterior vertebral body, the screw path is necessarily very short, so that there is very little opportunity for the screw to be threaded to achieve additional anchorage within a vertebral body. It seemed, therefore, that to the extent that the device disclosed in US Patent No. 5,180,380 is capable of achieving the stated objectives, it would make traction of the

The frontal part of the spine to a greater extent than the posterior part and would not appear to compress the posterior part of the vertebral bodies at all, thus producing an undesirable iatrogenic loss of normal cervical lordosis. This situation alters the normal biomechanics of the cervical spine and is potentially very dangerous.

60 The creation of compression between adjacent vertebrae would offer a number of advantages, including a reduced deviation pseudoarthrosis, increased surface area of contact between the graft and the vertebrae when slightly unrelated surfaces are forced against each other, greater osteogenic stimulation, since compression loads stimulate bone formation, and increased fusion grafting, as well as greater stability of the spinal segment.

Among the new problems created by these second-generation systems is the tendency for the small pieces of “watchmaking” used to block the bone screws to the plates from falling off the screwdriver used for fixing them or falling off the legs associated and lost in the wound. In addition, these small pieces are very fragile and require additional specialized instruments for insertion and / or handling. In addition, improper placement of a bone screw with respect to the axis of the plate hole may make the screw locking mechanism impracticable or may cause the formation of sharp titanium chips when a locking screw is inserted in contact with a screw for bones that have been improperly coupled. The means for establishing the alignment of the bone screw with the hole of the plate and its preparation are unreliable. In addition, most of these second generation systems have no means

10 effective and reliable for positioning and retaining the plate during coupling.

Specific characteristics of different prior art systems will be summarized below.

The system disclosed in U.S.A. No. 5,364,399 and No. 5,423,826, which have been cited

Previously in this description, it comprises a thin stainless steel plate that allows the placement of a bicortical screw displaced from side to side, whose plate has a combination of holes and grooves for the screws.

The Acromed system comprises a titanium plate and screws that require bicortical screw placement. This system does not include locking means for bone screws.

The system disclosed in U.S.A. No. 5,180,381 comprises an "H" shaped plate having a combination of ramp grooves and a hole that requires bicortical placement of a screw with an angle of 45 ° with respect to the plane of the plate. This patent discloses that this angular positioning is intended for

25 goal of producing compression.

The SYNTHES Morscher plate system uses hollow screw heads with grooves. The screws are placed unicortically, so that the heads, when properly aligned, rest on top of the holes in the plate. The top of each screw is internally threaded to receive a small screw

30 which is threaded into the head of the bone screw, in order to increase the mounting with interference between the head of the bone screw and the hole wall of the associated plate.

In the system disclosed in U.S.A. No. 5,364,399 and No. 5,423,826, pairs of unicortical bone screws are used that can be locked in place by both ends of the associated plate, 35 by locking screws having a small diameter shank and a large head. At each end of a plate, two bone screws can be locked in position by a single locking screw that is located between the bone screws. In general, the plate is provided, between its two ends, with a slot or diagonal grooves to receive one or more additional screws, each of the additional screws being fixed in a bone graft or a corresponding vertebra, which is tensioned by the plate. There is no screw

40 lock associated with these intermediate bone screws to lock the bone screws to the plate.

The Codman Shurtleff plate system uses the side of a previously assembled rivet that has a rotating head to press against the side of the head of a bone screw, in order to fix said screw to the plate. The plates of this system are also equipped with holes for receiving intermediate screws, but these screws are not

45 are associated with no blocking means.

While the designers of the aforementioned systems have recognized the importance of locking bone screws in position on the associated plates, they have not provided locking of the intermediate type bone screws in their associated holes.

50 In an initial version of the Codman Shurtleff system, the locking system was a pivoting lever around a rod that passes completely through the plate, and then flares for the purpose of retaining the rod within the plate. The lever was subject to rotation after the bone screw had been inserted to attach the head of the bone screw and thus fix the bone screw to the plate.

55 Based on a consideration of the characteristics of all known cervical plate placement systems, it follows that there remains a need for an improved system having the following combination of characteristics:

60 1) The plate must be strong enough to perform the intended function without mechanical failure; 2) The plate must be preformed in three dimensions, in order to adapt anatomically both in the longitudinal plane and in the transverse plane to the anterior cervical spine; 3) The plate must be constructed so that all bone screws are, in general, perpendicular to the plate when viewed from the side, but the screw pairs are highly convergent corresponding to any vertebral level when viewed from the lower part or from the end; 4) Each pair of screws is coupled in the corresponding vertebrae and the high convergence of screws in a pair allows the length of the screws that attach the bone to be longer, still remaining

5 within the vertebra, and providing a safer and stronger coupling with the vertebrae; 5) The system must include bone screws capable of achieving greater anchorage within the bone of the vertebral body, and without the need to penetrate the posterior vertebral cortex and enter the vertebral canal; 6) A self-tapping screw should be used, thus eliminating the need for separate threading stages; 7) A reliable means must be provided for coupling and maneuvering the plate during installation; 8) The plate must be attachable with an instrument that can reliably produce holes for the bone screws that are coaxial with the holes for the plate screws; 9) It must be possible to prepare the vertebral bone to receive the bone screws, in order to produce

15 a stronger connection and a lower danger of thread pasting by means of a pilot hole punch that creates a pilot hole for bone screws; 10) Alternatively to the use of a punch for a pilot hole, a drill bit of relatively small diameter (compared to the overall bottom diameter of the screw) should be used, in order to create the pilot hole; 11) Means must be provided for locking each and every bone screw in relative position with respect to the plate, and the locking means must be of sufficient strength and dimensions to perform the intended functions; 12) The bone screw locking means must preferably be retained by the plate before the bone screw is inserted or must be reliably attachable to a

25 screwdriver to prevent small parts from loosening in the wound; and 13) The system must be able to carry out the compression of the vertebral segments to be fused, simultaneously maintaining and restoring lordosis.

OBJECTIVES OF THE INVENTION

It is an objective of the present invention to disclose an improved anterior cervical plaque system that has the characteristics described above and avoids many of the drawbacks of the previously known systems.

Another objective of the invention is to provide a system of anterior cervical plaque that allows intersegmental compression of the vertebral segment (compression of adjacent vertebrae and fusion graft in the disc space between adjacent vertebrae) in case of lordosis , and similarly, if desired, in multi-segment compression.

Another object of the invention is to disclose a plate constructed to reliably engage an instrument to form all screw holes for coaxial bones with the holes formed in the plate, the instrument having integral depth limiting means that completely limit the danger of perforation of the posterior vertebral wall or entry into the vertebral canal.

Another objective of the invention is to provide a system in which the bone screws and the locking mechanisms, once installed, have a low profile.

The stated objectives, as well as other objectives and features of the invention will be more clearly understood from the following description of preferred embodiments of the invention, which is given with reference to the accompanying drawings showing embodiments of the invention only by way of non-limiting example. .

CHARACTERISTICS OF THE INVENTION

The present invention discloses a plate system having the characteristics of claim 1. Other embodiments of the invention are described in the dependent claims.

The plate system of the invention comprises a plate that is of sufficient length to cover a disc space and overlap, at least in part, at least two adjacent cervical vertebrae, being a substantial part of the lower surface of the plate preferably biconcave, that is, concavely curved along a substantial part of the longitudinal axis of the plate and concavely curved along a substantial part of the transverse axis of the plate. The lower surface of the plate may also be textured and / or treated to induce bone growth along the lower surface of the plate that makes contact with the cervical vertebrae. The plate is provided with a series of bone screw receiving holes that cross the plate, from the upper surface to the lower surface thereof, and at least one locking element is associated with the bone screw receiving hole . The plate and its component parts may be

made from any implant quality material suitable for use in the human body, and the associated plate and components can be made of a bioabsorbable material.

The bone screws are insertable, each of them, into the respective receiving holes for the

5 bone screws, for the purpose of coupling the plate to a vertebra. A blocking element can be coupled to a receiver recess of the blocking element and has a head formed for blocking bone screws in the plate.

In the present invention, a blocking element is engaged within a corresponding hole receiving a

10 bone screw, to lock a corresponding bone screw in place. According to this second embodiment of the invention, each of the bone screws is locked in the plate by means of an individual locking element that contacts at least a part of the bone screw. Since it is not necessary to form other holes in the plate to fix the locking elements in the plate, the plate is very strong.

The locking elements can take multiple forms to achieve the desired objective such as, without limitation, screws, threaded caps, rivets, captive screws, protruding elements and the like.

20 Likewise, a new bone screw is disclosed to prevent the exit or removal of the screw during use. This is achieved by a design that includes a screw in which the external diameter or diameter of the thread crests remains substantially constant along the entire length of the bone screw axis, from below the head to the tip, in which thread fillets with a smaller external diameter facilitate insertion. The screw tip has a groove at its distal end to make it

25 self-tapping The thread also has an extremely thin and sharp profile for cutting the bone material of the spine, while retaining its integrity.

The plate placement system does not require that the head of the bone screw be hollow, or that additional holes be placed through the plate in addition to those arranged for the passage of the bone screws. Be

30 will observe that the bone screws weaken when their heads are hollow and that the plates weaken when they are provided with additional holes.

Additionally, the plate of the systems indicated above allows proper alignment of the holes in the plate for the bone screws and so that the plate is easily applied to the vertebrae in an action of

35 compression The plates comprise appropriate grooves and coupling means for coupling compression instruments, which are described in detail below, to apply a compression force between adjacent vertebrae to which the plate is coupled, easily and reliably.

An improved locking screw drive device is disclosed. The drive device provides

40 a wedge interference with a recess in the head of the bone screws and the head of the locking elements. The same drive device can be used for both bone screws and locking elements. The drive device ensures that the blocking element cannot fall from the drive device, losing itself in the wound. The drive device has a conical end to facilitate insertion into the complementary recess in the screw head and is used to couple and collect the elements of

45 lock. Alternatively, the reception housing can be conical with the same objective.

Alternatively, a combination of the bone screw and the locking screw drive device is disclosed in which the bone screw drive passes through a longitudinal opening in the locking screw drive device, so that the bone screw and the locking screw

50 can be loaded before inserting the bone screw and both can be tightened with an instrument without removing it from its position.

In addition, instruments for forming pilot holes to aid in the ease and accuracy of bone screws and to create a compression force between adjacent vertebrae during the installation of the instrument are disclosed.

55 plate and to retain the plate during installation.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments, according to Figures 1-46, 60-62, 70-79, 83-84E are not part of the invention.

Figure 1 is a perspective view, from the top, of a first embodiment of a multiple locking plate of the spine in the cervical part. Figure 2 is a top plan view of the multiple locking plate of the cervical spine shown in Figure 1.

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Figure 3 is a side elevational view of the multiple locking plate of the cervical spine shown in figure 1. Figure 4 is a view from one end of the multiple locking plate of the cervical spine shown in figure 1. Figure 5 is a bottom plan view of the multiple locking plate of the cervical spine shown in figure 1. Figure 6 is a top plan view of the multiple locking plate of the cervical spine shown in Figures 1-5, with locking elements mounted in an open configuration. Figure 7 is a top plan view of a modification of the plate of Figures 1-6 with an element of four-bolt lock for placed bones. Figure 8 is a top plan view of another embodiment of a cervical locking plate, according to Figure 1, with an elongated central groove for greater compression capacity. Figure 9 is a top plan view of a locking element that is not part of the invention, a use with the plates in figures 1-6. Figure 10 is a top plan view of a block element to be used with the central opening of the plate of figures 7 and 22. Figure 11 is a top plan view of a locking cap for use in openings extremes shown in figures 1, 6 and 7. Figure 12 is a side elevation view of the locking element of Figure 16. Figure 13 is a side elevational view of another embodiment of the locking element of Figure 16. Fig. 14 is a top perspective view of an alternative embodiment of multiple lock plate of cervical spine to use with locking rivets. Figure 15 is a bottom plan view of the multiple locking plate of the cervical spine of the figure 14. Figure 16 is a top plan view of a two bone screw locking element. Fig. 17 is a top plan view of an alterative embodiment of a blocking element of four bone screws that have grooves in the heads for greater flexibility of the fins of blocking. Figure 18 is a top plan view of a rivet-type locking element to be used with the central opening of the plate of figure 14. Figure 19 is a side elevation view of a rivet locking element that does not correspond to the present invention Figure 20 is a top perspective view of the bottom of the rivet head of Figure 19, view from lines 20-20. Figure 21 is a top perspective view of the head part of a three locking element. bone screws Figure 22 is a top perspective view of a third embodiment of the multiple lock plate of the cervical spine using locking elements in the form of threaded caps. Figure 23 is a side elevational view of a locking element that does not correspond to the present invention, to be used with the plate of figure 22. Figure 24A is a side elevational view of a bone screw according to the present invention. Figure 24B is a side elevation view, on a larger scale, of a bone screw of Figure 24A. Figure 25 is a side elevational view of an alternative embodiment of a bone screw according to with the present invention. Figure 26 is a bottom end view of the bone screw shown in Figure 24A. Figure 27 is an extreme top view of the bone screw shown in Figure 24A. Figure 28 is a top perspective view of a fourth embodiment of multiple block plate for cervical spine. Figure 29 is a top perspective view of a locking element to be used with the plate of Figure

28. Figure 30 is a partial side sectional view of the plate of Figure 28, along lines 30-30, with a bone screw placed. Figure 31 is a top perspective view of the plate of Figure 1, positioned against the previous profile of three successive vertebral bodies in the cervical spine, a plaque support and an instrument for formation of bone screw receptor holes in the vertebral bodies. Figure 32 is a cross-sectional view of a part of the bone formation device, shown in figure 31, according to lines 32-32. Figure 33 is a side elevational view, in partial cross section, showing a tool of a compression post and a compression post coupled thereto for insertion into a vertebral body. Figure 34 is a side elevational view in partial section of the tool of the compression post coupled for disassembly of the compression post with respect to the vertebral body. Figure 35 is an end view of the lower part of the tool of the compression post of Figure 34. Figure 36 is a side elevational view of a coupling hook to a plate for use with the compression apparatus shown in figure 38.

60 E03028963 11-14-2011

Figure 37 is a sectional view of the plate of an alternative shaped hole forming instrument of a drill and drill guide for use during the plate installation process. Figure 38 is a side elevation view showing the intersegmental compression of the spine and a compression apparatus Figure 39 is a view similar to that of Figure 38 showing the compression apparatus at another stage of the plate installation process. Figure 40 is a top perspective view showing the blockage of the bone screws of the license plate. Figure 41 is a partial side sectional view of a locking element attached to an instrument of placement. Figure 42 is a partial sectional side view of another embodiment of the locking element fixed to the placement instrument. Figure 43 is a partial sectional view showing a cervical plate, locking element and screws for bones according to lines 43-43 of figure 40. Figure 44 is an enlarged part of a detail along line 44 of Figure 43. Figure 45 is a partial sectional side view of a plate holder fixed to a plate. Figure 46 is a partial cross-sectional side view of another plate support fixed to a plate. Figure 47 is a top perspective view of a first embodiment of an individual locking plate. Figure 48 is a top plan view of the plate shown in Figure 47. Figure 49 is a side elevational view of the plate shown in Figure 47. Figure 50 is a view from one end of the plate shown in Figure 47. Figure 51 is a bottom view of the plate shown in Figure 47. Figure 52 is a top plan view of the plate shown in Figure 47 with locking elements in its place. Figure 53 is a side elevation view of a bone screw used with the plate shown in the figure

47 Figure 54 is a top plan view of the bone screw shown in Figure 53. Figure 55 is a view of the lower end of the bone screw of Figure 53. Figure 56 is a top plan view of a locking cap for use with a plate individual lock according to figure 47. Figure 57 is a side elevational view of the locking cap shown in Figure 56. Figure 58 is a bottom plan view of the locking cap shown in Figures 56 and 57. Figure 59 is a bottom perspective view of the locking cap of Figures 56-58. Figure 60 is a top perspective view of the individual lock plate of Figure 47 shown in its retention by the support of the plate against three vertebral bodies, with the instrument of formation of the hole for punching a pilot hole in the vertebral bodies to receive a bone screw. Figure 61 is a side elevational view with partial section of the threaded hole forming instrument. to a receiving hole for a bone screw. Figure 62 is a side sectional perspective view of the drill bit and drill guide threadedly coupled to the plate for drilling a hole in the insertion of a bone screw. Figure 63 is a top perspective view of an individual lock plate installed along a segment of the spine with two locking caps installed in two receiving holes of bone screws Figure 64 is a side elevational view, with partial section, of a locking cap coupled to a drive device to install the locking cap. Figure 65 is a partial sectional view of the plate, bone screws and locking caps, according to the line 65-65 of figure 63. Figure 66 is a partial view on a larger scale of the area 66 of Figure 65. Figure 67 is a perspective view of a cervical block plate retained by an instrument of Alternative plate support. Figure 68 is an end sectional view showing a support of the plate of Figure 67 coupled to a license plate. Figure 69A is a sectional view of one end of an alternative embodiment of the plate holder. Figure 69B is a sectional view of one end of another alternative embodiment of the plate holder. Figure 70 is a support instrument for the plate with a displaced and detachable handle. Figure 71 is a top perspective view of a second embodiment of an individual locking plate Cervical with individual locking elements to block each bone screw. Figure 72 is a top perspective view of a threaded locking element for use with the Individual cervical block plate of Figure 71. Figure 73 is a partial side sectional view of the plate of Figure 71 seen along the lines 73-73 with the locking element of Figure 72 is its place to retain a bone screw, but not completely tense. Figure 74 is a top perspective view of an alternative locking element for use by a first modification of the individual cervical block plate of Figure 71.

Figure 75 is a side sectional view of the first modification of the plate of Figure 71 with the blocking element of figure 74. Figure 76 is a perspective view of an alternative locking element for use with the first modification of the plate of figure 71.

5 Figure 77 is a partial side sectional view of the first modification of the plate of Figure 71 with the locking element of Figure 76 in place. Fig. 78 is a top perspective view of another alternative locking element in the form of a rivet for use with a second modification of the locking plate of Fig. 71. Fig. 79 is a partial side sectional view in detail of the plate of figure 71 modified to use

10 a locking element, according to figure 78, shown in its place. Figure 80 is a partial sectional view of a bone plate and screw, showing the end of a tool for use in the insertion of bone screws and locking caps. Figure 81 is a side elevational view of another embodiment of the tool of Figure 80. Figure 83 is a further embodiment of a multiple locking plate of the cervical spine to be used

15 in the stabilization of multiple segments of the spine. Figures 84A-84E are several embodiments of multiple locking plates of the cervical spine to be used in stabilizing a single segment of the spine.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention will first be described in association with a plate system, in which a series of bone screws are locked in place with a locking element. This is what is referred to as a multiple lock plate system. The multiple locking plates will be described, then the blocking elements to block the bone screws in the plate, then the associated bone screws

25 with the multiple locking plates and finally the instrumentation and mounting method of the multiple locking plates. After that, the plate systems in which a single locking element will block a single bone screw will be described. This is what is designated as an individual plate locking system. The locking elements of the bone screws, instruments and installation method associated with the individual locking plate will be explained below.

1. Multiple locking plate system (not part of the invention)

The preferred embodiment of the anterior cervical locking plate 2, multiple locking, according to the present invention (shown by way of example for use in level two of fusion (three adjacent vertebrae)) is shown in Figures 1-5. . The plate 2 is generally elongated in shape, whose contour moves away from the rectangular one due to the presence of lateral lobes or projections 4 in the corners and in the center of the sides of the plate 2. Each lobe 4 has a rounded profile and contains a hole receiver 6 of the respective circular bone screw. Two additional holes 8 of the intermediate circular bone screw are located inside the sides of the plate 2 and are centered on the longitudinal axis of the plate 2. The lobes 4 provide the plate 2 with additional resistance in the

40 area surrounding each receiving hole 6 of the bone screw. It is recognized that other shapes can be used for plate 2.

The receiving holes 8 of the bone screw, intermediate rigged, are used for fusion of level two (three vertebrae). The intermediate receiving holes 8 of the bone screw can be dispensed with at a single fusion level 45 (two vertebrae), or said additional intermediate receiving holes 8 of the bone screw can be added if the additional levels are to be fused.

The plate 2 is further provided with three holes 12 of blocking element, each of which is internally threaded 3 in the preferred embodiment and each of which is surrounded by a slightly embedded zone 14

50 deep. As will be described in more detail below in the preferred embodiment, the bone screws are inserted into the bone screw receiving holes and a single pre-installed locking element, associated with each of the holes 12 of the locking element , block a series of bone screws 30 in one position at a time.

55 The number of screw holes for mated bones corresponds in general to the number of vertebrae to be fused. A plate for a melting level could, however, have a single blocking element hole 12, while plates for fusion of more than two levels (three vertebrae), could have additional intermediate blocking element holes 12 corresponding to the additional screw holes for the bone screw. In the embodiment shown in Figures 1-6, each of the end locking elements 20

60 will lock the three bone screws 30 in the proper place, while the locking screw 21 of the central locking hole 12 locks the two bone screws 30 in place. As shown in Figure 7, the central locking element 25 can also be configured so that four bone screws 30 are locked in one go.

As specifically shown in Figures 3, 4 and 5, the plate 2 is shaped so that its bottom surface 27 (surface that will be in contact with the vertebral bodies) has biconcave curvature, being concave both in the longitudinal plane (corresponding to its length) as in the transverse plane to it, corresponding to its width. The concave curvature in the longitudinal plane forms the appropriate shape

5 of the anterior profile of the spine with the vertebra aligned in the appropriate lordosis. The longitudinal curve is an arc along the circumference of a circle (referred to in this description as "radius of curvature") of 15.0 cm to 30.0 cm radius and more preferably 20.0-25 , 0 cm radius. According to a view from one end in Figure 4, the plate 2 has a radius of curvature of a circle of 15-25 mm radius, preferably 19-21 mm radius. Although the plate 2 may have a thickness between 2 and 3 mm, a thickness between 2.25 mm and 2.5 mm is preferred.

10 Being the bottom surface 27 of the plate 2 contoured so that it is able to remain at the same level against the associated vertebral bodies is in contrast to conventional plates that have larger radii of curvature that establish contact with the vertebral bodies only at along the longitudinal axis of the plate, thus allowing oscillation from side to side of the plate with respect to the vertebral bodies. He

The contour of the plate of the present invention provides an effective resistance to the oscillation of the plate 2, with respect to the vertebral bodies on the longitudinal axis of the plate, thereby reducing the tension in the plate 2 and the screws of bone 30, preventing soft tissues from re-coupling below the plate.

Other advantages produced by the aforementioned curvature are that the plate 2 will be shaped more

20 approximate to the surface of the opposite bone; plate 2 will extend from the spine over a reduced distance; soft tissues will be prevented from sliding below the edges of plate 2, where damage could occur; and the angle of the bone screws 30, perpendicular to the plate when viewed from the side, when installed, will be a substantially convergent angle, holding the vertebral bone between the bone screws 30, and therefore anchoring the bone more firmly. Plaque to the spine.

25 As seen in Figure 5, the bottom surface 27 of the plate 2 preferably has a porous, rough and / or textured surface layer and can be coated with, impregnated with or comprising substances that promote fusion (such as morphogenetic proteins for bones) in order to increase bone growth along the lower side of plate 2, between vertebra and vertebra. The textured bottom surface 27 also has a

30 means for retaining substances that promote fusion with which the lower surface layer 27 can be impregnated before installation. The lower surface 27 of the plate 2 may be provided with the desired porous textured form by means of coarse blasting or other conventional technology, such as, for example, chemical attack, plasma spraying, sintering and molding. If it is porous, the bottom surface 27 is formed so that it has a porosity or pore dimensions of the order of 50-500 microns, and preferably 100-300 microns. Between

The substances that promote fusion, with which the porous textured bottom surface 27 is impregnated include, without limitation, morphogenetic bone proteins, hydroxyapatite, or tricalcium hydroxyapatite phosphate. The plate 2 can comprise, at least in part, a resorbable material that can be additionally impregnated with the bone growth material so that the plate 2 is resorbed by the patient's body, the bone growth material is released, acting at as much as a release mechanism by

40 timing When the plate 2 is formed from a material that is reabsorbable and that has a material that promotes bone growth in mind, the vertebrae are allowed to be fused more naturally since the plate is progressively less load-bearing, preventing this mode a later protection by effort of the spine.

As further shown in Figures 4 and 5, at least one end of the plate 2 has a recess 18 that can cooperate with the compression apparatus, described in detail below, referring to Figures 36 and 38.

Figure 6 is a top plan view of the plate 2 of Figure 1, with the locking elements 20, 21

50 inserted in the receiving holes of the blocking element. In a preferred embodiment, the locking elements 20, 21 are in the form of screws that cooperate with the threaded interior 3 of the locking holes 12. Each of these locking elements 20, 21 is shown in its initial open orientation, in the that the orientation of the cuts 22 in the head 23 of each locking element 20, 21 is directed so as to allow the introduction of the bone screws 30 into the receiving holes 6, 8 of the adjacent bone screw, without interference

55 through the head 23 of the locking elements 20, 21. It will be noted that other configurations of the head 23 are possible in order to allow the introduction of bone screws into the receiving holes of adjacent bone screws without interference by the head 23 .

Figure 8 is a plan view of another embodiment of plate 2 of Figures 1-5, and is generally referred to as

60 plate 120. The plate 120 is provided with an elongated groove 122 that extends longitudinally along its longitudinal axis that overlaps the intermediate locking hole 12. The elongated groove 122 allows additional relative movement between the plate 120 and a compression post 54 associated with a compression tool during the compression procedure, as described above.

Referring to FIGS. 14 and 15, an alternative embodiment of a multiple locking plate is shown, referred to with numeral 70. The plate 70 is provided, instead of the threaded locking hole 12, with a central opening 200 to receive a detachable rivet 202, of the type shown in Figures 17-20. Figure 15 is a bottom plan view of the plate 70 shown in Figure 14. The outline of the plate 70 is the

5 same as plate 2 shown in Figures 1-5. The rivet 202 is removable and fits into the threadless opening 200, comparable to the locking hole 12 and the slot 122 described above. Other embodiments may use a rivet that is not removable, but is manufactured as part of the plate 70, as would be used in the end locking holes 19 of Figures 14 and 15.

Referring to Figure 22, another alternative embodiment of a multiple lock plate is shown, referred to with numeral 230. Plate 230 uses threaded caps, such as cap 300 shown in Figures 9 and 23, for a blocking element, or preferably one having cuts such as described with the appearance in a top view similar to the blocking element of Figures 10-11, for example. The central locking hole 602 has an elongate groove 234 to provide greater compression capacity, such as

15 will be described further below.

Referring to Figures 10-13, a first embodiment of a locking element 20, 21, 25 is shown in the form of locking screws, according to the present invention, for use with the plate 2. Figure 10 is a top plan view showing the head 23 of the central locking element 25, shown in the figure

7. The stem 46 of the locking element 25 is threaded 47 to coincide with the threaded 3 within the associated locking hole 12 of the plate 2. As seen in Figure 21, each segment 49 on each side of the cuts 22 of the blocking element 21 has a support surface 48 formed in the lower surface of the head 23 of the blocking element. As shown in Figure 16, the head 23 of the locking element may be provided with two slots 42 to grant flexibility to the head 23 of the blocking element, to assist

25 to the blocking element in its ability to move over the top of the head 32 of the bone screw during the support action when the blocking element is rotated. Alternatively, it is noted that the support surface can be inclined, wedge or cam. The characteristics of inclination, wedge shape

or cam can also be used with other locking elements described in this document.

Referring to Figures 6 and 10-13, it will be noted that, when the locking elements 20, 21 are turned clockwise with respect to Figure 6, a respective support surface 48 will be directed towards the surface curved upper 39 of the respective bone screw head 32, in order to effectively lock the associated bone screws 30 and the locking elements 20, 21 in place.

Alternatively, as shown in Figure 21, instead of a support surface 44, a wedge or ramp-shaped surface 44 can be used to increase the force applied to the head 32 of the bone screw. When in the locked position, the leading end of the inclined part of the blocking element should be lower than the projection of the head 32 of the bone screw, so that more force is necessary to lift the blocking element and loosen it. the necessary one so that the blocking element remains firm and locked. However, the heads 23 of the locking element do not require having grooves, having a cam shape or having an inclined surface to get the bone screw lock 30 in place. Pressure, friction, interference or other coupling elements capable of preventing the blocking element from being displaced from its blocking position can be used.

The rivet 202, shown in figures 17-20, is intended for use in association with the plate 70 shown in figures 14-15, being shown in detail in section, in figures 19 and 20. The rivet 202 has a head 204, a rod 206 and an elongated lower segment 208 for engagement within the corresponding opening 200 of the plate 70. The lower surface 210 of the head 204 of the rivet 202 has an irregular surface that can have a cam structure, such as in the lower part of the locking element 20, 21, for coupling with the upper surface 39 of the head 32 of the bone screw. For use in the locking holes 19 of the end, the upper surface of the elongated lower segment 208 may have an irregular surface to cooperate with the irregular surface of the lower part of the plate 70, to retain the rivet 202 in the locked position against the head 32 of the bone screw, as shown in Figure 15. While the rivet of Figure 18 is a separate and removable component with respect to the plate, the rivets, and

55 particularly those intended for use with the end locking holes, may be formed as part of the plate during the plate manufacturing process, and the rivet may be non-detachable.

Each of the aforementioned embodiments provides a firm coupling of the locking element with respect to the bone screw 30 and the corresponding plate.

In the alternative embodiment of the multiple locking plate 23, shown in Figure 22, the locking element may take the form of a threaded locking cap 300, which is shown in Figure 23. The threaded locking cap 300 has a thread 302 in its outer circumference, corresponding to the thread 303 of the inner circumference of the recesses 304 of the locking element in the upper part of the plate 230, shown in 65 in Figure 22. The locking cap 300 is relatively thin, especially in Comparison with its width.

The upper part 305 of the locking cap 300 is provided with a non-circular through hole 306 to receive a drive tool having the same configuration.

Referring to Figures 28, 29 and 30, another embodiment of the multiple lock plate has been shown,

5 indicated, generally, with the numeral 400, and a blocking element in the form of a thin blocking element 412. The plate 400 has an opening in its upper surface for the insertion of the blocking element of reduced thickness 412, a recess 402 associated with each of the holes 408 bone screw receptors 408 and a groove 410 in the side wall of the holes 408 bone screw receptors to allow the shallow locking element 412, which has a series of thin overhangs or 414 blades, thinner

10 than slot 410, which give this locking element 412 an appearance similar to a propeller. The blocking element 412 of reduced thickness is capable of being rotated inside the plate, so as not to cover the holes of the bone screws, thus allowing said blocking element 412 of low thickness to be pre-installed, prior to assembly of the screws, by the surgeon. The limited rotation of the shallow locking element 412 allows the blades 414 to protrude through the groove 410 and cover a part of the upper area of

15 the associated bone screws 30. The blades 414 of said low thickness locking element 412 are flexible and, when subjected to rotation, slide over the upper surface 39 of the head of the bone screw 32 to block said screw 30 in its place. As with the other embodiments that have been explained, each of the embodiments of the blocking element is capable of blocking more than one bone screw 30. It will be noted that the different multiple blocking plates and combinations of blocking elements are capable of

20 block up to four bone screws simultaneously, but they are equally effective in blocking a smaller or no number, that is, producing their own fixation to the plate.

It will be noted that a characteristic, of each of the embodiments of blocking elements described above, consists in having a coupling means for its actuation or drive, in these cases, by

For example, a recess 24 as large as the recess 34 of the bone screws 30, so that the same tool can be used for the rotation of the screws 30 and the locking elements. Also, the blocking elements are strong enough and have sufficient mass to withstand their blocking without breakage.

All examples shown of multiple locking elements, which have a series of lowered areas or

30 cuts, have an arch with a radius greater than the head of the bone screw. In addition, the head 23 of each of the locking elements 20, 21 is provided in its central part with a non-circular recess 24, such as that shown in Figure 9, which can be coupled by a manipulation tool appropriate, such as that shown in Figures 40-42. In the embodiment of the head 23 shown in Figure 9, the associated tool would have a hexagonal head, but other forms of head recesses can be used

35 23. The thread of each locking hole 12 and each locking element 20, 21 has a narrow tolerance, so that it will reliably retain its orientations, allowing the introduction of bone screws 30 into the holes 6 , 8 bone screw receptors, without interference.

It will be appreciated that, although several forms of blocking elements have been disclosed, taking into account the

40 description, other equivalent elements may be used in order to lock in place the bone screws 30. In Fig. 83, an alternative multi-type locking plate 990 is shown having intermediate holes receiving additional bone screws 980 and associated locking elements 960 for locking the bone locking screws 30 in place. The 990 plate allows a separation with greater proximity and a number of holes for bone screws greater than the number of vertebrae to be coupled.

In Figures 84A-84E, several 700a-g plates used for single-level fusion have been shown. Each of these 700a-g plates is designed to extend to a segment of the spine, consisting of the space of a disc and two adjacent vertebrae (which contain the bone graft), and have bone screws inserted into the end of the vertebrae through the 6 screw receptor holes associated with the two vertebrae

50 adjacent and locked, then in place. As shown in Figures 84A-84E, a locking element 710 or two locking elements can be used to lock four bone screws in place. In Figures 84A-84E, each of the plates 700a-e has been shown with the locking elements in their open orientation, before their rotation to block the bone screws.

Each of the plates described above can have the same contour, generally biconcave, that has already been described to adapt to the anterior aspect of the spine.

Figures 24A and 24B provide a side view of an embodiment of a bone screw 30. Figure 27 is a top view of the bone screw 30. In the center of the head 32 of the bone screw is a

60 profiled recess 34 which may have the same shape as recess 24 of each of the blocking elements 20, 21, in which case it can be rotated with the same tool used for the rotation of said blocking elements 20, 21. It will be noted that the coupling part of the drive element of the bone screw 30 could have a groove, and could be of male or female structure (as shown).

In the embodiment of the bone screw 30 shown in Figures 24A and 24B, the head 32 of the screw is staggered, with the first part 35 of the lower head disposed adjacent to the screw shank 33, having a further diameter smaller than the top of head 32 of the bone screw. When this embodiment of the bone screw 30 is used, each of the holes 6, 8 screw recipients of the plate 2 has

5 a recessed area 14 that adapts to the diameter of the upper part of the head 32 of the bone screw and that is sized for an interference coupling. The lower part 35 of the head 32 of the bone screw is sized so as to achieve a coupling with interference with its associated part of the receiving holes for screws 6, 8. The upper part of larger diameter of the head 32 of the bone screw ensures that the bone screw 30 cannot be completely displaced by the holes 6, 8 bone screw recipients of the plate 2. The bone screw 30 completely passes through the upper surface of the plate 2, without engaging with the upper surface in any way.

As shown in Figure 44, the head 32 of the screw 30 passes unobstructed through the upper surface of the plate, until the lower surface of the enlarged screw head 32 engages with the upper face 15 of the receiving part of the narrowest bone screw in the middle part or under the middle part of the plate. This arrangement is considered optimal to allow greater stability of the screw with respect to the plate, even in the absence of blocking, against all forces except those inverse to the insertion path, while providing the greatest resistance of the plate below the head 23 of the bone screw. That is to say, since the plate is only, in general, 2-3 mm thick, a purely circumferential and vertical wall is the one with the greatest capacity to restrict the movement of a screw, if the head is similarly configured and there is a reduced tolerance between both elements. Placing the head support near the average thickness of the plate, it is preferred since this allows the head to be large to receive the recess for the screwdriver or tool without undermining, simultaneously placing the head support away from the surface top of the plate to allow the screw head to remain

25 placed deep inside the plate. The placement of the head support approximately half the thickness of the plate ensures a significant amount of the plate material below the head for support purposes, simultaneously providing the appropriate length of the head above and below the point of contact to prevent the contact point from acting as a fulcrum by providing suitable lever arms to prevent unwanted movement.

In the alternative embodiment of the bone screw 30 ', shown in Figure 25, the head 32' of the bone screw is inclined in the direction from the top of the head 32 'of the bone screw towards the tip of the screw 36' . Also in this case, the head 32 ’of the bone screw is sized to achieve interference coupling in the hole 6, 8 associated bone screw receiver when said bone screw 30’ has been completely assembled. When this embodiment of the bone screw 30 ’is used, it is not necessary that the holes 6, 8 bone screw receptors be provided with the recessed area

Four.

In each of the previous embodiments of the bone screws, the bone screws 30 and 30 'have a unique combination of a conical screw rod 33 and helical thread 31. The diameter of the screw rod 33 generally increases from a distal part of the rod near the tip 36 of the screw towards the proximal part of the rod, near the head 32 of the screw. In the preferred embodiment, the diameter increase rate is also higher near the head 32 of the bone screw. This conformation avoids areas of increased effort and provides greater resistance in the screw-plate joint, in which it is required to a greater extent.

45 The taper of the screw shank 33 may have a concave shape, as shown in Figure 24A, or it may be linear. The distal part of the screw shank 33 can adopt a constant diameter.

Referring again to Figures 24A and 24B, the thread 31 of the bone screw 30 has a substantially constant outside diameter "d" or crest, from the proximal part of the stem below the head 32 of the bone screw to the distal part of the stem near the tip 36 of the bone screw. At the tip 36 of the screw, the crest diameter of the thread 31 can preferably be reduced by one or two turns to facilitate the insertion and penetration of the bone screw 30 into the bone.

In the preferred embodiment, the thread 31 of each bone screw 30 has a slightly outer diameter

55 smaller than the diameter of the lower part 35 of the head 32 of the bone screw that is adjacent to the rear or upper end of the associated thread 31. In addition, the thread 31 is relatively thin, in the direction of the longitudinal axis of the screw , and conicity outwards and has a triangular cross section.

An example of the dimensions of a bone screw to be used in surgery of the human anterior cervical spine for insertion into the vertebrae is as follows: the threaded part of the screw has a length between approximately 10 mm and 22 mm (preferably 12 -18 mm) and a head length of approximately 1 mm to 3 mm (preferably 2-2.5 mm). The threaded part must have a maximum outside diameter between approximately 3.6 and 5.2 mm (preferably 3.8-4.5 mm) and the head has a diameter approximately between 3.8 mm and 6 mm (preferably 4 -5.5 mm). The thread pitch is approximately between about 1.25 mm and 2.5 mm (preferably 1.5-2.0 mm) and has a profile of

Thin and sharp thread. The vertex of the two sides of the filleting forms an angle less than about 21 degrees (preferably 15 degrees) and the base of the fillet is less than about 0.60 mm thick (preferably 0.25 mm-0.35 mm). The screw has a diameter at the base that increases approximately above the tip of the stem, along the longitudinal axis to approximately below the part of the

5 screw head. Preferably, the screw tip is grooved, at a minimum, by a recessed area in order to make the screw self-tapping.

Although the fillet 31 of the bone screw 30 has a thin profile, the thread fillet will, however, be stronger than the bone in which it is inserted, so that the thread fillet will effectively cut a thin helical groove in bone tissue The volume of bone that will be displaced by the thickness of the thread fillet is minimal by the thin form of the thread fillet, however, the substantial diameter of the screw thread crest maximizes the surface area of the fillets in contact with bone. While enlarging the diameter of the rod 33 of the screw near the head 32 of the bone screw increases its resistance, if necessary, reducing the diameter of the rod 33 of the screw from the head 32 of the screw where it is not required

15 said resistance, allows to achieve the maximum coupling area for filleting 31 with respect to the bone.

In the preferred embodiment, as shown in Figures 24A and 26, the tip 36 of the bone screw is provided with cutting slots 38, to make the bone screw 30 self-tapping. Unlike bone screws of the previously known type, used for spine surgery of the anterior cervical part, which are not self-tapping, the screw thread form of the present invention is more similar to that of a tapping screw. than a conventional screw because of the fact that the thread steaks are sharp and grooved. Additional embodiments of the bone screws 30 have been shown in Figures 53-55.

As an example, plates are shown for the fusion of three adjacent vertebrae (two intermediate spaces or two

25 dorsal segments). Each set of bone screw receiving holes, associated with a vertebra, is considered to be a segment of the plate such that, for example, in Figure 1 three segments have been shown: an upper segment, a central segment and a lower segment Although the present description is related to plates to be used in the fusion of three vertebrae with two intermediate spaces, it should be understood that longer and shorter plates are provided that have the appropriate number and the appropriate location of bone screw receptor holes corresponding to the number of vertebrae to be fused, and would take the form of the plates shown with a greater or lesser number of intermediate segments, such as the segment along line 9 of Figure 1, or the intermediate segments of the plates shown in figures 82-84F.

Referring to Figures 31-42, an explanation of the steps of the method is shown below.

35 to install the plates. This explanation is followed by a detailed description of the instrumentation and method for the installation of the multiple locking plate.

Stage 1

Once the fusions between bodies are finished, the surgeon removes any protruding points or irregularities located along the front of the spine of the area to be fused.

Stage 2

45 The correct length plate is selected by the surgeon, measuring the distance on the spine by means of a gauge, ruler, template or similar. The plate will be of sufficient length to cover the distance of the spine to be fused and partially overlap a part of each of the extreme vertebrae to be fused.

Stage 3

Using a plate support, it is placed inside the wound and positioned to confirm the positioning, length and alignment of screw holes with respect to the segments of the spine to be fused.

Stage 4

55 As shown in Figure 31, with the plate positioned in this way and held firmly, the plate can be coupled to any of the vertebrae to be fused (only by way of example, the upper vertebrae have been shown) .

Sub-stage 4A

The pilot punch 60 (guide) of the hole is fixed to the plate 2, as shown in Figure 32, or alternatively, although not preferably, the drilling guide can be used as indicated in Figure 37. In In any case, the pilot hole formation means are rigidly aligned with the wall of the receiver hole of the

65 bone screw of the plate, being caught by it.

Sub-stage 4B

The pilot hole is then formed by impact of the pilot hole punch of Figure 32 or by drilling

5 with the drill of Fig. 37. In an alternative embodiment, which is not preferred, the formation of the pilot hole can be dispensed with and the correct screw selected can be inserted directly so as to have a length less than the distance along from its trajectory to the posterior vertebral cortex.

The appropriate screw length is determined by measuring or applying an X-ray template, 10 MRI or CT scans, or is determined directly by measuring the depth of the disc space.

Stage 5

Next, the correct screw is attached to the screwdriver which, regardless of the specific shape of the

15 screwdriver coupling means, is designed so that it has a mounting with interference in order to remain firmly coupled to the screwdriver during transport to the insertion site. Figures 41, 42, 63, 64, 80 and 81 show various ways of achieving said coupling between the screwdriver and the screw. In addition to the screw and screwdriver interface wedging, clips and springs are well known as well as other means for temporary and reversible fixing of the screw to the screwdriver, as shown in the

Figure 80, in which a grooved bushing with spring features inwards retains a peripherally threaded cap until, when threaded into the plate, it is automatically pushed back releasing the threaded cap.

Once a first bone screw has been fully inserted into a vertebra through the plate, it is preferred to insert the other of the transverse pair in the manner already described with respect to Figure 33.

Similarly, it is possible to insert the remaining bone screws, according to the surgeon's preference, into each of the vertebrae to be included in the fusion, exactly the extreme vertebrae of the fusion assembly or construct, or additionally place screws in the grafts of fusion.

However, as shown in Figures 33, 34, 38 and 39, it is possible with the present invention, at the option of the surgeon, to place any part or all of the fusion construct under compression and proceed in this way intersegmental manner or along the entire length of the fusion construct, even when it has a multi-segment structure.

It will be appreciated that the same procedure could be used in general for any of the plate systems of the present invention.

As shown in Figure 31, the vertebrae 50a-c are separated from each other by graft blocks of

Fusion 51 that have previously been mounted in the disc space of the spine between adjacent vertebrae 50, forming a bone graft construct for fusion. Plate 2 is shown in Figure 31 with the locking elements 20, 21 removed, in order to simplify the illustration. It will be understood, however, that in the preferred embodiment the blocking elements 20, 21 can be and, preferably are, pre-installed in the positions shown in Figure 6, before positioning the plate 2 on the vertebral bodies of the vertebrae

45 50, saving the surgeon time and problems.

The plate 2 can be held in position in any support means of the plate, but preferably by the retention tools shown in Figures 45, 46 or 47 by means of the grooves 142 on the sides of the compression arms 104, 130 of a 100 vertebral compression tool, as shown in the

Figure 39, or as an additional alternative, for the unit plate holder, similar to the design of Figure 70.

As shown in Figure 45, the support 870 of the plate has a hollow tubular casing 872, with a central rod 874 with a thread 878 at one end for the coupling of one of the threaded locking holes 12 in the plate 2. The bottom end of the housing 872 has protrusions 880, 882 which is

55 extend outward and then downward to engage in the holes 8 recipients of the bone screws of the plate 2, preventing the housing 872 from rotating. The central rod 874 is located in the housing 872 so that it can be forced to rotate by causing the rotation of a handle (not shown) that is fixed to the central rod 874 at its upper end.

60 An alternative embodiment of the plate holder 890 is shown in Figure 46. A single solid element 890 has a threaded boss 894 at its lower end for coupling to the threaded central locking hole 12 of the plate. The lower surface of the support 890 of this embodiment is shaped so as to adapt to the contour of the upper surface of the plate adjacent to the locking hole 12, shown in the form of a recess or depression 14.

65 Referring to Figures 67-68, an embodiment of a plate holder for retaining any of the plates arranged on vertebrae has been shown and generally referenced with the numeral 800. The plate holder 800 has a hollow tubular housing 802 with a central rod 804 having a handle 806 at one end and a thread 808 at the other end for engagement with one of the threaded locking holes 12 on the plate 600. The

5 lower end of the enclosure body 802 has projections 810, 812 extending outwardly and then downwardly 814, 816, engaging along the side edge of the plate 2 between the end and intermediate lobes 4, preventing the enclosing body 802 can rotate. The central rod 804 is located in the enclosure body 802, so that it can rotate by rotation of the handle 806, which is fixed to the central rod 804 at its upper end. This central rod 804 can also be fixed to the body 802, so that it can move up and down to some extent in a series of conventional ways, for example, by making the central rod 804 have an annular recess with an approximate length of 3-5 mm, and an adjustment screw protruding inwards from the housing to engage the central rod 804. Once the plate 600 is in the appropriate place and the plate is fixed to one of the vertebrae by the bone screws 30, the central rod 804 is disconnected from the opening in the plate 600 and the support 800 is removed.

Figure 69A is an alternative embodiment of the plate holder 850. A single solid element 852 has a threaded shoulder 854 at its lower end for attachment to the central threaded locking hole 12 of the plate. The solid element 852 could also be threaded into a hole 6 receiving the bone screw. The bottom surface of the support 850 of this embodiment is shaped such that it engages the contours of the upper surface of the plate adjacent to the locking hole 12, shown as recess 14.

Figure 69B is another embodiment of support 850 'of the plate. An enveloping body 851 ’that has an end 853’ configured to engage a hole 6 receiving a bone screw, contains a rod 855 ’that has an irregular diameter and is provided with a threaded area 857’. By turning rod 855 ’by a handle similar to handle 806

25 shown in Figure 68, the rod 855 ’is threaded into the shell 851’ on the conjugated thread fillets 858 ’. By inserting the end of rod 855 ’, it extends parts 859a’ and 859b ’(859c’ and 859d ’not shown) by wedging plate holder 850’ into a hole in the receiving plate of a bone screw. The 850 ’plate holder is best used with non-threaded bone screw receiving holes, but it works for all types of bone screw receiving holes.

Referring to Fig. 70, an alternative embodiment of the plate support referred to with the numeral 800 'has been shown, in which there is a detachable handle 860' which is used to first fix the support 800 'from the plate to the plate itself, by turning the rod 804 and then retaining the support 800' to the side by the extension 864, during the fixing process, reducing the interface of the support 800

35 of the plate with the surgical process.

Referring to Figure 38, a compression tool 100 is shown with a toothed bar 102 having a first compression arm 104 fixed to its free end. The compression arm 104 has, at its distal end, a hole 106 for detachably retaining a coupling element 108 with a plate, which is shown in Figure 36, which has a hook 110 at an end for coupling a recess or depression or slot 18 at the end of the plate 2, or to detachably retain a compression element 54 shown in Figures 33-34. As shown in Figure 36, the coupling element 108 with the plate comprises the rod 112 that will be inserted into the corresponding hole 106 of the compression arm 104, and a flange 115 for resting against the bottom or bottom face of the hole 106 to limit

45 precisely the insertion depth of the plate coupling element 108 into the hole 106. An annular spring 128, preferably metal, is located in an annular recess of the shaft 112, to retain the plate coupling element 108 in hole 106.

Referring to Figures 38-39, the compression tool 100 comprises a second movable compression arm 130 movable along the toothed bar 102 parallel to the first compression arm 104. The distal end or away from the second compression arm 130 it also has a hole 132, the same as hole 106, which can receive a detachable rod 134. The holes 106 and 132 are the same, so that any of the compression arms 104, 130 can be used to retain the detachable rod 134, allowing compression tool 100 to be used in any orientation. By allowing element 108 of

55 coupling with the plate and the compression rod 54 rotate both and slide into the holes 106, 132 of the two compression arms 104, 130, with the coupling hook 110 with the plate capable of operating even at a certain angle with respect to the plate, it is possible that the apparatus is easily attachable to the spine through the compression rod 54 and the plate.

The compression arm 130 has a drive assembly consisting of a gear wheel (not visible) that is coupled with the gear wheel 138 of the gear bar 102 and that is connected to the compression arm 130 so that said compression arm 130 it is movable according to the length of the sprocket 102 by means of the rotation of the handle 140, which is connected to the sprocket. When the handle 140 is rotated in the direction of the arrow shown in Figure 38, the compression arm 130 is moved towards the compression arm 104. The drive assembly has a self-locking release mechanism so that he

movement of the two compression arms 104, 130, moving away from each other, is prevented, without the activation of disassembly or release. At the internal distal end of each of the compression arms, on opposite sides of each other, there is a groove 142 or recess for retaining the plate 2 along its sides between the central lobes 4 and the end lobes 4, such as shown in figure 37.

5 While the toothed bar 102 and the compression arms 104, 130 have been described in a straight way, it is possible that the toothed bar 102 and the compression arms 104, 130 are arcuate or otherwise shaped, for the purpose of induce lordosis in the vertebrae, if desired.

As shown in Figure 31, in the case where the compression tool 100 is used to retain the plate 2, the ends 144 of the compression arms 104, 130 will be located in line with the element

or fusion graft construct 51, which has been placed in the disc space when the plate 2 is properly positioned. An interstitium will be produced between the plate 2 and each of said fusion graft elements 51, providing a space to receive the free ends of the arms 104, 130, in case

15 extend beyond the bottom surface of the plate 2. As will be described later, the same compression tool 100 has also been used for the compression of a series of vertebral bodies of the cervical part with bone grafts interposed during the coupling of plate 2 to vertebrae 50.

Referring to Figure 31, the plate 2 is retained by a suitable support, in the case shown in the form of compression arms 104, 130. Once the plate 2 of the appropriate length has been positioned, so that the holes 6 Bone screw receptors are aligned with each of the corresponding vertebrae 50a-ca to fuse, the next step is the formation of the 6 holes for the bone screws before mounting the bone screws 30 themselves in the vertebrae 50th While the procedure has been described by firstly fixing the plate 2 to the upper vertebrae 50a, the plate 2 can be fixed to any of the vertebrae in any order. Plates of different dimensions are used so that, as indicated above, the physician will select the plate of the appropriate dimension in which the holes 6, 8 bone screw receptors are aligned with the three adjacent vertebrae 50a, 50b and 50c. Pilot holes are formed by an apparatus 60 for forming them, as shown in Figures 31 and 32. Unlike the prior art and the screw coating systems, the bone screws 30 can be inserted without the prior formation of an opening in the vertebrae, since the bone screws 30 are preferably constituted with a sharp tip, and with self-tapping characteristics, and have a decreasing main diameter at the tip to aid in the screw entry and penetration in the bone However, although a hole may be formed in the bone of the vertebrae before screw insertion, it is preferred that the hole has a smaller diameter than the diameter of the screw base and for a purpose

35 different than in the prior art. In the prior art, the drilled hole had to have an equal diameter but preferably greater than the diameter of the (smaller) base of the screw, since the screws are not self-tapping. It is desirable to create pilot holes to ensure that a proper path is maintained for bone screws 30, and also to prevent damage to the bones of the vertebrae during the insertion of said bone screws 30. In addition, the hole forming apparatus 60 Pilot creates a more compact vertebral bone mass to receive the self-tapping bone screw 30 used in this insert.

As shown in Figures 31 and 32, the apparatus 60 for the formation of the pilot holes comprises a hollow cylindrical housing 62 having its bottom endowed with a through hole 63. The housing 62 comprises a central axis 64 which is extends through the through hole 63 of the bottom of the housing 62. The front end 66 of the shaft 64 forms a gradual taper to a sharp point 65. The shaft 64 is provided with an annular element 73 having a diameter that corresponds intimately to the diameter internal of the housing 62 to guide the movement of the shaft 64 within the housing or housing 62. A compression spring 67 is interposed between the annular element 73 and the bottom of the housing 62. The compression spring 67 provides an antagonistic force that normally it forces the sharp tip 65 to a retracted position within the enclosure 62. The upper end of the stem 64 has a head of greater d imensions 68 extending outwardly from the enveloping body 62, which is intended for manual pressing or beating by means of a percussion instrument, in order to drive the sharp point 65 outwardly from the enveloping body 62, passing into the vertebral body 50a . The shaft 64 has a length, taking into account the length that the spring 67 will have once fully compressed, to determine the maximum depth of the pilot hole

55 formed in the vertebral body. The depth is selected to ensure that the pilot hole does not reach the posterior cortex of the vertebral body, which borders the spinal canal.

Certain structural features of the hole-forming apparatus 60 are shown in more detail in Figure 32. In particular, it can be seen that the lower end of the housing 62 has a projecting portion 69 sized to engage precisely in the hole 6 or 8 bone screw receiver of the plate 2. The bottom 71 of the protruding part 69 is flat in a plane perpendicular to the axis of the enclosure 62. When the protrusion portion 69 of the enclosure 62 is intimately inserted into a bore 6, 8 receiver of a bone screw and the flat bottom 71 is positioned flush against the upper surface of the plate 2, it is ensured that the front end 66 of the shaft 64 will form a pilot hole in the vertebral bone that has its perpendicular axis 65 to the plane of the associated part of the plate 2, thus ensuring that the bone screw 30

it will then be installed so that its axis is also perpendicular to the plane that is parallel to the upper and lower surfaces of the associated part of the plate 2.

When a plate having a threaded hole is used to receive a screw, the lower end of the apparatus 60

5 for the formation of pilot holes is threaded in order to engage with the thread of the hole 6, 8 receiver of the bone screws, thereby fixing the plate and the pilot hole formation apparatus with each other, ensuring a stable coupling between the pilot orifice formation apparatus and the plate 2. It should be noted that the diameter of the front end 66 of the stem 64 is small since it has to be engaged within the reduced space between the internal walls of the pilot orifice formation apparatus. Since only one pilot hole is formed for a self-tapping bone screw 30, the reduced diameter is satisfactory.

Referring to Figure 37, if for any reason it is desired to form the pilot hole in the vertebral body 50 by drilling, instead of using the pilot hole formation apparatus 60, a guide 80 can be used for

15, which has a lower end as shown in Figure 37. The drill guide 80 consists of a tubular element 82 and a lower end of small diameter 84 that is sized to achieve a coupling with precise interference in the hole 6, 8 associated bone screw receptor of the plate 2. Along the lower end 84 of small diameter, the drill guide 80 has an axial end surface in a plane perpendicular to the longitudinal axis of the drill guide 80 , so that when the part 84 of reduced diameter is engaged within the hole 6 receiving the bone hole and the surface surrounding said part 84 of small diameter is flush with respect to the upper surface of the plate 2, the axis of the drill guide hole 86 on the drill guide 80 for the drill will be precisely perpendicular to the upper and lower surfaces of the associated part of the plate 2. As in the case where described above, the lower end of the guide 80 for the drill can be threaded to engage the threaded opening of the plate 2.

25 After having formed the holes 6, 8 bone screw receptors in the vertebral body 50a through the two upper holes 6 for fixing bone screws of the plate 2 by means of said hole forming apparatus 60 or of the guide 80 for the drill bit, the bone screws 30 are threaded into the vertebrae 50 while simultaneously holding the plate 2 firmly against the vertebrae 50 with the compression tool 100 or the plate holder 800. This blocks the plate to the 50th vertebrae.

Then, it is possible, if desired, to compress the fusion graft into the following adjacent vertebrae 50b, before coupling the bone screws 30 to adjacent vertebrae 50b through the central holes, bone screw receptors, of the plate 2. Once the initial bone screws are

35 found in place in the vertebrae 50a, the support 100 or 800 of the plate can be disassembled from the plate 2. The compression of the fusion element or construct between the two adjacent vertebrae 50a and 50b is achieved in the manner indicated by continuation:

The compression rod 54 is driven through the central locking hole 12 of the plate 2 by means of the insertion tool 90, shown in Figures 33, 34 and 35, passing into the vertebral bone of the vertebra 50b, where it will be used in a next stage to apply a compression force between the vertebrae 50a and 50b. The compression rod 54 consists of an axis 56 having a sharp tip 57 at its lower end, a central collar of larger dimensions 58 that serves as a depth stop, and a circumferential groove 59 in the vicinity of its upper end, defining a enlarged head 55.

The compression tool 90 for inserting the compression rod comprises a shaft 92 having a hollow and closed part 94 at its lower end 96 to receive the compression rod 54 and an enlarged percussion cap 98 at the other end. The compression tool 90 for inserting the compression rod also comprises, at its lower end 96, a second opening 95 having a recess 99 in its inner wall to allow coupling of the enlarged head 55 on the compression rod 54 within the depression or recess 97. The second opening 95 is in communication with the hollow part 94 of the insertion tool 90, as shown in Figure 35.

Referring to Figure 38, the hole 132 of the second compression arm 130 of the tool

The compression 100 is applied to the compression rod 54 in the vertebrae 50b, and the coupling element 108 with the plate is inserted into the hole 106 of the first compression arm 104 of the compression tool 100. The hook 110 of the element 108 Coupling with the plate, shown in Figure 36, is mounted inside the groove 18 at the end of the plate 2 which is fixed by the bone screws 30 in the vertebra 50a, as shown in the Figure 38. However, as indicated above, the compression tool 100 may be forced to rotate so that the first compression arm 104 is, in this case, at the bottom and is capable of engaging on the rod compression 54 in vertebra 50c.

Since the plate is coupled to the vertebrae 50a by means of the bone screws 30 and the compression rod 64 is fixed to the adjacent vertebrae 50b, the movement of the first and second arms of

Compression 104 and 130 in the direction of the vertebrae 50a, by rotation of the handle 140, results in the compression of the bone graft element or construct 51 between adjacent vertebrae 50a and 50b. The distance of several millimeters is sufficient for the compression of the bone graft element or construct 51. Once the desired compression has been obtained, the pilot holes for bone screws can be formed in the vertebral body 50b by means of the pilot hole formation apparatus 60, as described

5 above, for the insertion of the bone screws 30 into the receiving holes 8 of the bone screw of the bone plate 2, fixing the plate 2 to the adjacent vertebrae 50b. The compression tool 100 can then be removed by activating the release element.

Figure 39 shows the use of the compression tool 100 to induce compression between the two lower vertebral bodies 50b and 50c after the bone screws 30 have been installed in the middle vertebral body 50b, as just described. As shown in Figure 39, the compression rod 54 remains in place, in the middle vertebral body 50b, and an additional compression rod 54 is driven into the lower vertebral body 50c by means of the tool 60 formation of the pilot orifice, distal to the plate itself, in the recess located at the end projections 4 to allow the lower compression stem 64 to be displaced towards the vertebrae 50b in an upward direction, as shown. The original compression rod 64 is inserted into the hole 106 of the first compression arm 104 and the additional compression rod 54 is inserted into the hole 132 of the second compression arm 130 of the compression tool 100. Again, as has been explained above, the rotation of the handle 140 results in the two compression arms 104, 130 moving towards each other, with the result that the compression rod 54 in the vertebra 50c moves towards the upper compression rod 54 of the vertebra 50b, again compressing the fusion graft element or construct 51 between the vertebrae 50b and 50c. The upper compression rod 54 of the vertebra 50b cannot be displaced since the vertebra 50b has been fixed to the plate by inserting the bone screws 30 into the holes 8 of the plate 2, bone screw receptors. Therefore, only the lower compression rod 54 and the vertebra can be displaced

25 50c. As before, the pilot holes associated with the vertebra 50c are formed and the bone screws 30 are inserted through the holes 6 receiving the bone screws. Then, the compression tool 100 is disassembled. The compression rod 54 is then removed from the vertebra by inserting it into the second opening 95 of the compression rod insertion / disassembly tool 90, so that it engages with the enlarged head 55 of the end of the compression rod 54 by the depression 57, as shown in figure 34.

It will be noted that other variants can be used for compression purposes. For example, during compression of the fusion element or construct 51 between the vertebrae 50b and 50c, the hook 110 of the compression tool 100 may contact the groove 18 at the end of the plate 2, and the other arm 35 Compression of the compression tool 100 can be coupled to the compression rod 54 in the third adjacent vertebra 50c. It should also be noted that the plate 2 has a cut-out part in the form of an extreme recess, between the lobes, at the end of the plate for insertion of the compression rod 54 into the vertebra. Otherwise, there may be no space below the end of plate 2 for compression rod insertion

54

It will be noted that the process described above has been carried out with the bone screws 30 fully inserted in the vertebral bodies 50a, 50b and 50c, and the lordosis is maintained during compression of the construct

or bone graft element 51.

As indicated above, the process for coupling plate 2 to vertebrae 50a, 50b and 50c has been shown without locking screws 20, 21, instead, on plate 2. Figure 40 is a perspective view showing the plate 2 of Figures 1-5, at a stage of a surgical process, when the bone screws 30 have been completely installed in three adjacent vertebrae 50a, 50b and 50c and the locking screws 20 , 21 have been forced to rotate at an angle of about 90 ° to lock, instead, three bone screws 30; so that the left locking screw 20, as shown, has been forced to rotate at an angle of about 60 ° to lock three bone screws 30 in place, and the central locking screw 21 has been forced to rotate at an angle of about 90 ° to lock two other bone screws 30 in place. At this time, one of the cam surfaces 44 of each of the locking screws 20, 21 rests on the top of the head 32 of the screw of the corresponding bone screw 30.

55 The mounting of the locking cap 300 can also be carried out with a tool 220, as shown in Figures 41 and 42, with an appropriately shaped tip 222 with a length that depends on the depth of the hole 306 in a locking cap 300. The end 222 of the tool 220 is flared in the vicinity of the most distal end, such that it creates a snap coupling with the cap 300 of the screw to facilitate handling, and prevents the cap 300 of the screw detach from tool 200.

Figure 43 is a sectional view, along the plane of the axis of the two holes 6 for end locking screws of the plate 2, with two bone screws 30 in their mounting positions and the locking element 21 in its position of blocking. Figure 44 is an enlarged view of one of the bone screws 30 on the plate 2 of 65 Figure 43. In a preferred embodiment, the axis of each screw 30 is, in general, perpendicular to the tangents a

the upper and lower surfaces of the plate 2, at points that are cut by the longitudinal axis of the associated bone screw 30. Therefore, because of the curvature of the plate 2 in the plane of Figure 18, the screws for Bones 30 can be directed so that they converge towards each other, according to the desired angle. The axis of the two bone screws 30 shown in Figure 18 can form an angle of about 45 °. Alternatively, the

The curvature of the plate from one side to the other can be such that it adapts to the surface of the anterior profile of the cervical spine of an adult human, and the axis of the paired screw holes can deviate from the perpendicularity to the plate , when viewed from the end, achieving optimal convergence.

Since the bone screws 30, once inserted, are locked to the plate, a "claw" is obtained with a rigid triangular structure in each pair of bone screws 30, such that the coupling of the plate 2 to the Vertebral bodies 50a, 50b and 50c would be very safe due to the retention of a wedged mass of bone material between the triangle formed by the bone screws, even if there was a thread run. The "claw" can be additionally formed by three angled bone screws, in a tripod configuration or by four bone screws in a four-sided claw configuration.

A coating system, according to any of the above embodiments, can be mounted in the same manner as described, and using the same instruments and tools, as shown and described above with respect to the first embodiment. In the case of the embodiment shown in Figure 22, the compression operations would be carried out by means of the slot 604, instead of the intermediate hole 12 for a locking screw.

b.) Single lock plate systems

The single locking plate system will be described below. Figures 47-52 are views of a first

25 realization of a single plate locking system. The outline of the plate 600 is the same as that of the plate 2 shown in Figures 1-5. The plate 600 contains holes 602 bone screw receptors that are internally threaded 603 to receive the corresponding locking elements in the form of a locking cap 610 shown in Figures 56-59. For example, in the plate 600, the hole 602 for the bone screw has an external diameter of approximately 5 mm with a preferred range of 4-6 mm and a threaded internal diameter of approximately 4.8 mm with a range of 3, 5-5.8 mm for this use. Fixing means other than threads can be used such as bayonet type fasteners.

The bottom of each hole 602 receiving a bone screw has a stepped portion in dimensions appropriately selected to retain an associated bone screw 170, as has been

35 shown in Figures 53-55. As described below in detail in this embodiment, a single locking element in the form of a locking cap 610 with thread fillets 608 shown in Figures 56-59 is associated with each of the screw receiving holes 602 for bones.

The difference between the bone screw 170 used in the realization of the single locking plate with respect to the bone screw used in association with the multiple locking plate is essentially due to the fact that, while in the realization of the plate multiple locking, the locking elements slide on a part of the upper part 39 of the screw head 32, in the embodiment of a single locking plate, the locking cap 610 is coupled on the head 172 of the bone screw 170. By therefore, the head 172 of the bone screw 170 of the present embodiment does not need to be smooth. This allows head 172 of this embodiment of

45 bone screw 170 is thicker and more resistant.

Figure 63 shows two bone screws 170 and the associated threaded locking caps 610 in their complete installation positions. In these positions, the head parts 174 and 176 of each of the bone screws 170 form an interference coupling with corresponding parts of a hole 602 receiving a bone screw. The flange 612 of each threaded locking cap 610 forms an interference coupling with the top 178 of the head of its associated bone screw 170. Since the thread 608 of each locking cap 610 precisely engages with the thread internal of a receiving hole 602 of a bone screw, each threaded locking cap 610 is additionally subjected to a fixing force between the part 178 of the associated head and the internal thread fillets 603 of the receiving hole 602

55 of the associated bone screw. The rounded head 614 of each threaded locking cap 610 ensures that the upper surface of a mounted plate system will be free of sharp or protruding edges.

Referring to Figures 80 and 81, they have been shown useful for use in the insertion of the bone screws and the locking cap on a single type lock plate 600. In the first embodiment of the drive tool 1000 shown in the Figure 80, said tool 1000 has a tubular casing body 1002. Inside the casing body 1002 is a hexagonal drive element or "torks" 1004 having a projecting end 1006 corresponding to the recess 306 in the cap 610 for coupling with said cap 610. As indicated above, the drive device 1004 is configured such that it constitutes a firm fixation for the lock cap 610 to retain said lock cap 610 65 firmly with respect to the drive device. Hexagonal drive device 1004 is hollow to have

ability of the shaft 1010 of a Phillips or "torks" screwdriver to be coupled by the hollow part 1012 for coupling by the tip 1012 with the corresponding recess 1080 of the bone screw 170 for coupling by the end 1006 of the drive device 1004. The rod 1010 and the drive device 1000 is longer than the tubular body and the drive device 1004 has an upper end (not shown)

5 which extends from the upper end of the tubular body 1002, so that it can be forced to rotate by means of the handle.

The casing body 1002 has a diameter that allows the locking cap 610 to be retained within the inner end of said tubular body 1002 by friction coupling or by the drive device 1004. It will be noted that other methods can be used for the retention of the locking cap 610 inside the end of the tubular housing 1000.

As shown in Figure 80, the operation of the bone screw and the actuation device 1000 of the locking element is as follows: the cap 610 is inserted over the end of the device

15 actuation 1004 of the hood and then said actuation device 1004 of the hood with the stem 1010 of the bone screw actuator passing through the central longitudinal opening of the hood actuator. As shown, the stem 1010 of the bone screw drive device passes through the recess 306 of the cap 610 and engages with the recess 180 of the head of the bone screw 170. The bone screw 170 has been shown mounted in a bone screw receiving hole in the plate 600. The handle (not shown) of the bone screw actuator is forced to rotate, thereby screwing the bone screw 170 in place. Since the diameter of the bone screw drive device is smaller than the width of the recess 306 of the cap 610, the bone screw drive device 1010 can rotate without rotation of the cap 610.

25 The hollow tubular casing body 1002 rests on the upper surface of the plate 600 and aids in the alignment of the stem 1010 in relation to the plate. Once the bone screw 170 has been inserted, the drive device 1004 of the cap is driven until the thread fillets 608 outside the cap 610 are coupled with the thread fillets 603 of the bone screw receiving hole . Then, the hood drive device 1004 is forced to rotate until the hood 610 is securely in place.

In Fig. 81, an alternative embodiment of the combination of the bone screw and the locking cap drive device is shown. In this embodiment, no enveloping body is used. Instead, the hood drive device 1010 retains the hood 610 by friction and the handle 620 for the

35 1010 bone screw actuation device is forced to rotate. A spring and ball assembly 622 keeps the cap drive device 1002 at the top until the bone screw has been screwed into the receiving hole thereof. The drive device 1010 has an elongated portion that, once the bone screw has been assembled, the spring and ball assembly 622 is pressed, and the handle 624 associated with the capper drive device can descend for rotation. of the cap 610. A tubular shell can be used to aid in the alignment of the cap 610 in the receiving hole of the bone screw, as indicated above.

The drive elements, shown in Figures 80 and 81, simplify the procedure and reduce the number of instruments that need to be used during the assembly process. The process is fast and reliable,

45 providing the doctor with greater assurance that small parts will not be lost or will be difficult to handle.

Figure 52 is a top plan view of the plate 600, partially assembled, with threaded locking caps 600 mounted in holes 602 bone screw receptors.

Figures 54-56 show a bone screw 170 for use with the single locking plate system according to the invention. The bone screw 170 differs from the bone screw 30 described above in detail, only as regards the stepped configuration of the head 172. Preferably, the bone screw 170 includes a bottom 174 which is continuous to the screw shank, and has a reduced diameter equal

55 to the maximum diameter of the rod 176. The part 178 of the head 172 also has a smaller diameter than the lower part 174. The thread 182 has the same configuration as in the bone screw 30 explained above. However, any embodiment of bone screws with any of the plates can be used.

As in the case of a multi-plate locking system described above, the bone screws 170 for use in a single locking plate system are preferably solid, so that the screws reach the surface of the lower plate, in which situation, the screws used with prior art plates have the greatest tendency to break, being the only recess in the heads for the coupling of the tip 222 of the operating tool 220 and the recess being found by above the critical area. 65 Therefore, these bone screws 170 remain robust. The screw heads are not

grooved deeply by dividing them into parts, and the locking caps do not exert a radial external force on the associated bone screw heads, so that the screw heads do not open deforming and weakening.

5 Referring to Figures 71, 73 and 75, another alternative embodiment of the single locking plate system of the present invention has been shown, reference being made thereto with the numeral 500. The plate 500 has the same contour as the plate 2 of Figures 1 to 5, but associated with each of the openings 502 for the bone screws are threaded openings 524 displaced from the openings 502 of the bone screws to receive the locking element 506-508 shown in the Figures 72 and 74 as a game of

10 threaded locking screws or 506 cap or 508 screw.

It will be noted that other unique lock plate configurations can be used. Referring to Fig. 82, a single locking plate 900 has been shown in which a pair of bone screw receiving holes 910 is seen at its ends 930 and a series of bone screw receiving holes 950 along

15 of the longitudinal axis of the plate 900. The additional holes 950 bone screw receptors allow a single plate to be aligned with a series of disc spaces of vertebrae of different dimensions and bone fusion grafts. As indicated above, the plate of the present invention shown in Figures 1-5 requires the selection of a properly sized plate by the surgeon, so that each pair of bone screw receiving holes 6-8 are aligned with the

20 appropriate vertebrae. This requires having a series of plates of different dimensions for optimal coupling of the bone screw receiving holes to each of the vertebrae. With the plate 900 of Figure 82, the reduced separation and increased number of central openings allow the surgeon to place at least one appropriate opening aligned with each of the intermediate vertebrae and / or bone grafts.

The procedure for mounting single type locking plates is substantially the same as described in detail for multiple type locking plates. The longitudinal central groove 670 of the single type locking plates is used for the compression process. The same instrumentation is used to create the hole of the plate by means of a punch or a drill. Figures 60-69 show the different stages in the assembly procedure of the single-type locking plates, comparable with the stages used in the

30 mounting of multiple type locking plates.

Referring to Figures 76-79, heads 507 and 526 of locking elements 508 and 522 have a recess 510 and 524 corresponding to the radius of openings 502 and 528 for bone screws, such that locking element 508 and 522 can be mounted in place before the insertion of the bone screw 170 in

35 hole 502 and 528 intended to receive said screws. When the locking elements 508 and 522 are forced to rotate, a part of their head extends over the top of the head of the bone screw 170 blocking in place. As in the previous embodiments, the lower surface of the locking screws 508 and 522 may have an eccentric configuration and another, for engagement with the upper surface 39 of the associated bone screw 170.

40 Although the instrumentation of the plates and their procedure have been described, in relation to the fixation of a plate to the vertebrae of the spine, it should be noted that the plates can be adopted for application to other parts of the body. However, the dimensions of the plate, the specific contour of the plate, and the placement of the receiving holes of the bone screws would have to be modified.

45 Similarly, the bone screws described in this application can be used in other parts of the body, which would also have to be modified to serve the intended purpose, depending on the dimensions of the part of the body in which they have to be mounted.

Claims (13)

1. Plaque system adapted for use in the anterior human cervical spine for contact with the anterior protuberance of at least two cervical vertebral bodies, said 5-plate system comprising: a plate (600, 900) having a longitudinal axis and a length sufficient to extend to a disc space and overlap with portions of at least two adjacent vertebral bodies, said plate (600, 900) having a lower surface for placement against the vertebral bodies and a superior surface in opposition to said 10 lower surface; at least two bone screws (170), each of which has a longitudinal central axis and is adapted to engage each of at least two vertebral bodies, respectively, each of said bone screws (170) having ) a leading end for insertion into the vertebral bodies and 15 a rear end (172) opposite said front end, said rear end (172) having a first surface (178) directed upwards, oriented towards said upper surface of the plate (600, 900), a lower surface opposite to said first surface directed upwards towards said lower surface of said plate (600, 900) and a second surface directed upwards, oriented towards said upper surface of said plate (600, 900) and disposed between said first surface (178) directed towards above and said lower surface; At least two holes (602, 910, 950) bone screw receptors, which extend through said plate (600, 900) from said upper surface to said lower surface, each of said holes (602, 910, 950) bone screw receptors, a central longitudinal axis, at least a first hole of said holes (602, 910, 950) bone screw receptors adapted to be arranged by 25 on top of a first vertebral body, and at least one second of said holes (602, 910, 950) bone screw receptors being adapted, to be arranged above a second vertebral body; Y a series of blocking elements (610) each adapted to block said plate (600, 900) only one of each of said bone screws (170) inserted in each of the holes (602, 910, 30 950) bone screw receptors, each of said locking elements (610) being coaxially coupled, at least, partially within only one of said holes (602, 910, 950) bone screw receivers to retain said screw for bones (170) in said plate (600, 900), each of said blocking elements (610) having an external perimeter that contacts at least a part of the perimeter of one of said holes (602, 910, 950 ) bone screw recipients, each having Said blocking elements (610) an upper surface configured to cover at least a portion of said at least an upwardly directed surface of said bone screw (170) and a lower surface as opposed to said upper surface, characterized because each of said blocking elements (610) has a through hole (306) that crosses said surface 40 upper and said lower surface, said through hole having a central longitudinal axis fixed coaxially with respect to the central longitudinal axis of one of said holes (602, 910, 950) bone screw receptors and the central longitudinal axis of one of said screws for bones (170) when said bone screws (170) and said locking element (610) are received in said hole (602, 910, 950) bone screw receiver, the second surface being directed upwards of at least , one of said bone screws (170) a 45 generally flat contact surface below at least one of said blocking elements (610) when said at least one bone screw (170) and said at least one locking element (610) are received in a corresponding hole (602, 910, 950) bone screw receiver, said lower surface of said plate (600, 900) being concave along a substantial part of the longitudinal axis of said plate (600, 900) and each of said holes (602, 910, 950) being screw receptors for bones for 50 preventing said lower surface of said rear end of said bone screw (170) from protruding below said lower surface of said plate (600, 900). 2. Plate system according to claim 1, wherein said lower surface of said plate (600, 900) is concave, at least, in a transverse part with respect to the longitudinal axis of said plate (600, 900). 55

3.

 Plate system according to any one of claims 1 or 2, wherein said lower surface of said plate (600, 900) is flat, at least in part transversely to the longitudinal axis of said plate (600, 900).

Four.

 Plate system according to any one of the preceding claims, wherein at least one of said

60 blocking elements have a generally circular shape and the central longitudinal axis of said blocking element is the axis of rotation of said blocking element, the axis of rotation being coaxial with the longitudinal axis cetnral of one of said bone screw receiving holes when said blocking element is inserted into said bone screw receiving hole. 5. Plate system according to any of the preceding claims, wherein at least one of said locking elements (610) comprises at least one screw and a cap. 6. Plate system according to any one of claims 1 to 5, wherein at least one of said 5 locking elements (610) comprises a threaded part (608). 7. Pallet system according to any of the preceding claims, wherein the rear end of at least one of said bone screws (170) is configured to cooperate with one of said locking elements (610) to block said bone screw (170) to said plate (600, 900).

8.

 Pallet system, according to any of the preceding claims, wherein at least one of said holes (602, 910, 950) bone screw receptors is threaded.

9.

 Plate system according to any one of claims 1 to 8, wherein at least one of said holes

15 (602, 910, 950) bone screw receptors is configured to constitute a socket with interference with one of said bone screws (170). 10. Plate system according to any of the preceding claims, in combination with a bone graft. 11. Plate system according to any of the preceding claims, in combination with a bone growth building material. 12. Plate system according to claim 11, wherein said bone growth promoting material It comprises at least one of bone, bone morphogenic protein, hydroxyapatite and tricalcium phosphate of hydroxyapatite. 13. Plate system according to any of the preceding claims, wherein at least a part of one of said plates (600, 900), said locking elements (610) and said bone screws (170) is of a bioabsorbable material. 14. Plate system according to any of the preceding claims, wherein at least one of said holes (602, 910, 950) bone screw recipients has a reduced dimension in the vicinity of said lower surface of said plate (600, 900) to form a seat, said seat having a surface that is at least flat and adapted to make contact with said lower surface of said end 35 back of said bone screws (170).