Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/38—Joints for elbows or knees
  • A61F2/3836—Special connection between upper and lower leg, e.g. constrained
  • A61F2/384—Special connection between upper and lower leg, e.g. constrained hinged, i.e. with transverse axle restricting the movement
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/38—Joints for elbows or knees
  • A61F2/3836—Special connection between upper and lower leg, e.g. constrained
  • A61F2/384—Special connection between upper and lower leg, e.g. constrained hinged, i.e. with transverse axle restricting the movement
  • A61F2/385—Special connection between upper and lower leg, e.g. constrained hinged, i.e. with transverse axle restricting the movement also provided with condylar bearing surfaces
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
  • A61F2002/30316—The prosthesis having different structural features at different locations within the same prosthesis; Connections between prosthetic parts; Special structural features of bone or joint prostheses not otherwise provided for
  • A61F2002/30535—Special structural features of bone or joint prostheses not otherwise provided for
  • A61F2002/30617—Visible markings for adjusting, locating or measuring
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
  • A61F2002/30621—Features concerning the anatomical functioning or articulation of the prosthetic joint
  • A61F2002/30624—Hinged joint, e.g. with transverse axle restricting the movement
  • A61F2002/30632—Hinged joint, e.g. with transverse axle restricting the movement with rotation-limiting stops, e.g. projections or recesses

Definitions

• the invention is framed within the field of medicine, and more particularly within the field of knee prostheses.
• the object of the invention is a novel knee prosthesis that allows to regulate the angle of rotation allowed without the need for external devices or the replacement of the prosthesis, even total knee arthrodesis can be achieved.
• knee arthrodesis surgical procedure that aims to complete and definitive fixation of the knee joint, as the only alternative to resolve the serious complications that may arise during these complex procedures, although it should be always the last option to achieve the absence of pain and stability at the expense of nullifying mobility.
• knee arthrodesis surgical procedure that aims to complete and definitive fixation of the knee joint
• knee prosthesis models are used primarily in primary replacement surgery (in cases of severe antomicofunctional joint deterioration), and more often in revision surgery after the failure of an arthroplasty previously implanted
• the first type which is the most widely used, is generically called a "rotational hinge", and seeks to achieve joint stabilization through central mechanisms that join the femoral and tibial component, allowing both flexion-extension and rotational movement in the axial leg plane.
• the second type is usually called "pure hinge”, and has a single transverse axis that only allows knee flexion extension.
• joint replacement implants in addition to pain control with an adequate range of mobility, is to partially replace the bone loss of the epiphyseometaphyseal regions and compensate for the insufficiencies of the capsuloligamentary structures responsible for joint stability, elements often incompetent because of the pathological process itself by which primary arthroplasty was indicated and that will continue to deteriorate in a way inevitable in successive surgical rescue interventions.
• arthrodesis complete and definitive fixation of the knee joint
• current techniques require the removal of implanted prosthetic components (which undoubtedly involves adding another major surgical gesture to the patient) as a prior step to the arthrodesis procedure itself, which is usually based in the implantation of another endomedular device or an osteotax (the latter is also always provisional, therefore requiring another surgical intervention for its removal once bone fusion is achieved). Therefore, as stated above, the clinical scenario shown by a patient with severe knee arthropathy or after a previous failed knee arthroplasty is often complex:
• Arthrodesis In general, a rescue prosthesis constrains the patient's knee movements more than the previous prosthesis. Sometimes a situation can be reached in which it is necessary to completely immobilize the patient's knee with the leg fully extended, thus preventing any type of flexoextension. This situation of joint stiffness is called arthrodesis.
• the possibility of dispensing with external immobilizers that are currently used during the first days or weeks of convalescence after the installation of a prosthesis is opened.
• the surgeon may initially set the prosthesis as an arthrodesis, and subsequently expand the angle of rotation allowed during the following days or weeks. In this way, the duration of time that the patient must spend in bed is reduced, which is of great importance in very elderly patients (most in this type of operations).
• An adjustable knee prosthesis according to the invention basically comprises:
• a base piece adapted for fixing to the upper end of the tibia of a patient, and which is rotatably attachable to the ball joint by means of a transverse axis, where the maximum angle of rotation allowed between the ball joint piece and the base piece is adjustable.
• this regulation establishes lower and upper configurable limit angles between which the knee can move freely.
• the lower limit angle is 0 or , that is, a position equivalent to an arthrodesis in which the leg is fully extended, the upper limit angle can be configured at will.
• the transverse axis is non-rotatably coupled to the base piece, for example using means known in the art, and at least one end of said transverse axis comprises first means of limiting rotation of the ball piece.
• the non-rotating coupling between the regulating bushing and the lateral channel of the ball joint preferably allows the coupling of the regulating bushing according to different turning positions, thus allowing greater flexibility in the configuration of the minimum and maximum angles of spin allowed. More preferably, it comprises an external longitudinal teeth of the regulating sleeve (protruding or "male” teeth) and a complementary internal longitudinal teeth (incoming or "female” teeth) of the lateral channel of the ball joint.
• the first turning limitation means are radial projections projecting outwardly from at least one end of the transverse axis
• the second turning limiting means are radial projections protruding internally from the inner hole of the regulating bushing.
• the second projections are in the form of radial sectors, so that the position of the regulating shells and the angular amplitude of said second projections determine the lower limit and the upper limit of the maximum permitted angle of rotation.
• This configuration shown in greater detail in Figs. 5 and 6 attached, requires the replacement of a regulating bushing with a different one in order to vary the permitted angle of rotation.
• the regulating bushing has internal longitudinal radial projections comprising at least one removable part and a fixed part, the removable part being connectable in different radial positions of the internal orifice of the regulating bushing to modify the angle of rotation. permitted.
• This configuration which is shown in greater detail in the attached Fig. 7, allows a single regulating bushing to be used, varying the angle of rotation permitted by changing the position of the second turning limitation means.
• Fig. 1 shows an exploded view of a knee prosthesis according to the prior art.
• Figs. 2 and 3 show two profile views of the knee prosthesis of the prior art of Fig. 1.
• Fig. 4 shows an exploded view of a first example of knee prosthesis in accordance with the present invention.
• Figs. 5a and 5b respectively show a profile view of the prosthesis and a detail of the rotation limitation zone of the prosthesis of Fig. 4 according to the invention with the leg stretched.
• Figs. 6a and 6b respectively show a profile view of the prosthesis and a detail of the rotation limitation zone of the prosthesis of Fig. 4 according to the invention with the leg rotated 30 °.
• Fig. 7 shows a detail of a second embodiment of regulating bushing (5) according to the invention where the internal longitudinal radial projections are formed by a fixed part and a removable part ..
• a support piece (115) provided with a curved surface is coupled to the base piece (105), introducing a projection (1 16) through a transverse hole (117) of the central channel (11) and through a transverse hole (18) of the shaft (104), thus preventing rotation of said shaft (104) when it is mounted.
• the curved surface of the support piece (1 15) serves as support for the front area of the ball joint (102) to allow the prosthesis (100) to have some lateral play.
• This prosthesis (100) therefore, belongs to the type of "rotational hinge".
• this known prosthesis (100) is mechanically simple, as seen in Figs. 2 and 3.
• the kneecap piece (102) can rotate around the axis (104), despite said axis (104) being immobilized, due to to that the lateral channels (103) slide around the shaft (104) (and / or the plastic bushings (1 12) surrounding the ends of the shaft (104) to minimize friction).
• This prosthesis (100) therefore, in principle does not pose limitation to the patient's knee rotation.
• Fig. 4 shows a perspective view of a prosthesis (1) according to the invention, where reference numbers similar to those of Fig. 1 denote similar parts. It is appreciated how the prosthesis (1) of the invention has essentially the same parts as that belonging to the prior art of Fig. 1, although only those that are relevant for the operation of the prosthesis (1) of the invention have been numbered , such as the ball joint (2) for coupling to the femur of a patient that is provided with lateral channels (3) to allow the passage of the transverse shaft (4) and a base piece (5) for coupling to the tibia of the patient.
• the ball joint (2) for coupling to the femur of a patient that is provided with lateral channels (3) to allow the passage of the transverse shaft (4) and a base piece (5) for coupling to the tibia of the patient.
• base piece (5) only the upper part of a larger group of pieces (equivalent to 105, 113, 1 14, 115 in Fig. 1), said term It is intended to refer to the part or pieces that connect the patient's tibia and the transverse axis of rotation, regardless of the way in which said connection is made, or the number of intermediate pieces used.
• the prosthesis (1) of the invention comprises, in addition to the above parts, at least one regulating bushing (6) designed to be non-rotatably coupled to the side channels (3) of the ball joint (2).
• This regulating bushing (6) can be considered as a new part, or as a modification of the plastic bushings (112) shown in Fig. 1.
• the non-rotating coupling between the side channels (3) and the regulating bushing ( 6) it can be carried out in different ways, such as by means of a key or the like, although in this example the regulating bushing (6) has an external longitudinal teeth (7) complementary to an internal longitudinal teeth (8) of the side channels (3).
• the bushing (6) can be inserted by moving it according to a lateral or transverse direction of the prosthesis (1), so that when inserted into said lateral channel (3) it is integral with the ball joint (2).
• the regulating bushing (6) also has a central longitudinal hole provided with a second means (9) for limiting rotation, which in this example are internal longitudinal radial projections in the shape of a circumferential sector that protrude into said hole.
• the transverse axis (4) has, at least at its ends, first turning limit means (10), which in this example are specifically four external longitudinal projections covering at least a length approximately equal to that of the side channels (3) of the ball joint (2).
• the internal longitudinal radial projections (9) of the bushing (6) cooperate with the internal longitudinal radial projections (10) of the shaft ends (4) to limit the rotation of the bushing ( 6), and therefore of the ball joint (2), at an angle that is determined by the shape of said projections (9, 10).
• the internal longitudinal radial projections (9) cover a certain angle by another different regulating bushing (6) where they cover a different angle.
• the total knee arthrodesis of the patient could be achieved.
• Fig. 5a shows a position in which the patient has the leg fully extended, the lower connecting rod to the tibia and the upper connecting rod to the femur being parallel.
• one side of each of the four internal longitudinal radial projections (9) of the regulating bushing (6) is supported on a corresponding surface of each of the four projections radial (10) external longitudinal axis (4), thus being limited the angle of rotation of said bushing (6), which in turn is integral with the ball joint (2), according to that direction of rotation.
• the other side of said internal longitudinal radial projections (9) has a space or play that allows a certain angle of rotation in the opposite direction, in this example of about 30 °.
• FIG. 6a shows the prosthesis (1) after turning the entire angle allowed by this particular regulating bushing (6), in this example 30 °. This is best seen in the detail of Fig. 6b, where a black tooth (7) serves as a reference to check the rotation of the bushing (6). It can be clearly seen how the inner radial projections (9) of the bushing (6) have rotated until they hit the other side of the outer radial projections (10) of the shaft (4), which prevent said bushing (6) from rotating more than 30 °.
• This concrete example of prostheses (1) has four radial longitudinal protrusions (10) and four radial longitudinal protrusions (9) in order to distribute the tensions as much as possible.
• this limits the maximum angle of rotation of the prosthesis which in this case will necessarily be somewhat less than 90 °. It is understood, however, that other designs would be possible where the number of radial projections (9, 10) was smaller, for example three or even two, thus achieving a greater range of angles of rotation.
• this example also shows external longitudinal radial projections (10) that only cover a part of the length of the shaft ends (4), specifically that which will be housed within the side channels (3) of the part ball joint (2).
• these radial longitudinal projections (10) it is also understood that it would be possible for these radial longitudinal projections (10) to be continuous along the entire axis (4).
• a suitable regulating bushing (6) would be one in which the angular amplitude of the inner radial projections (9) was greater than in the example of the figures, being between interior projections (9) and others a space equivalent to the width of the radial longitudinal projections (10) of the external axis (4). Subsequently, once the surgeon considers that e!
• FIG. 7 shows a second embodiment of adjustable bushing (5 ') comprising inner longitudinal radial projections having a fixed part (9a') and a removable part (9b ').
• the fixing of the removable part (9b ') is achieved by means of a series of essentially radial grooves (9c') arranged in the longitudinal hole of the bushing (6 '), each of which corresponds to a specific turning angle.
• the removable part (9b ') of the internal longitudinal radial projections is essentially in the form of a parallelepiped from which a sheet that is inserted into said grooves (9c') protrudes in the desired position.

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• Health & Medical Sciences (AREA)
• Orthopedic Medicine & Surgery (AREA)
• Physical Education & Sports Medicine (AREA)
• Cardiology (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Transplantation (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Vascular Medicine (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Prostheses (AREA)

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Citations (6)

• 2012
  • 2012-03-29 ES ES201230481A patent/ES2429390B1/es not_active Expired - Fee Related
• 2013
  • 2013-03-21 WO PCT/ES2013/000080 patent/WO2013144392A1/fr not_active Ceased

Patent Citations (6)

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