CN100500110C - Anti-rotating self-locking bone fracture internal fixing device - Google Patents

Abstract

An anti-rotation self-locking fracture internal fixer, which is composed of a screw, a sleeve and a bolt. The front part of the screw has a helical edge, and the end of the rear part of the screw has a connection structure connected with one end of the bolt. The rear part of the screw is inserted at least close to the end. The outer diameter of the part is smaller than the inner diameter of the front end of the sleeve that is in contact with the screw; the bolt is placed in the sleeve to connect the screw and the sleeve; the outer surface of the bolt is provided with external threads, and the corresponding part of the inner surface of the sleeve is provided with internal threads. threads; the outer surface of the end portion of the sleeve away from the distal end of the screw rod has a sheet-shaped wing; the rear section of the screw rod and the sleeve are provided with a rotation limiting structure. When in use, after the bolt is tightened, the retainer is placed in a "locked" state, and the wings on the sleeve have a reliable anti-rotation effect, which limits the loosening and withdrawal of the retainer. The fixer has the advantages of simple operation, short operation time, reduced bone mass loss, and favorable fracture healing, and is especially suitable for the treatment of osteoporotic femoral neck fracture patients.

Description

Anti-rotation self-locking fracture internal fixator

Technical field:

The invention relates to an anti-rotation self-locking fracture internal fixer, in particular to a fracture internal fixer with a helical blade and a winged sleeve, which can be automatically locked and anti-rotation.

Background technique:

Fracture internal fixation is an effective means of fracture treatment. Most of the internal fixators currently used are screws, and several screws are often used to fix them. Moreover, the screw is easy to gradually loosen or partially withdraw after being driven into the bone. Among the patients who are prone to fracture, most of them are osteoporotic patients, whose cancellous bone has less holding force on the thread, so the phenomenon of screw rotation or loosening is more prominent.

For example, for a fracture of the femoral neck, the maximum anti-rotational stability can only be obtained if three screws are inserted and arranged in a "pin" shape, and neither one nor two screws can provide firm fixation. Therefore, in the internal fixation of femoral neck fractures, closed reduction and three half-threaded cannulated screws have become the "gold standard", but this method has some unavoidable shortcomings:

First of all, three screws with a diameter of 6-8 mm are driven into the small femoral neck, which not only reduces the bone contact area at the fracture end, but also requires repeated insertion of positioning guide pins to keep the three screws from touching each other during operation. , have certain difficulties, and have adverse effects on fracture healing;

Secondly, during the drilling process before each screw is inserted, there will be different degrees of loss of cancellous bone mass. For many elderly patients with osteoporosis, the hollow screw is easy to gradually loosen or partially withdraw during the fracture healing process, and needs to be taken out again.

Therefore, for the technical requirements of the fracture internal fixator, it is extremely important to prevent rotation, self-locking, no loosening, and reduce the loss of cancellous bone.

The Swiss Association for Internal Fixation (AO) introduced the anti-rotation proximal femoral intramedullary nail to treat intertrochanteric fractures. This intramedullary nail has a helical blade and plays a certain role in anti-rotation. However, this technique is not currently applicable to fractures of the femoral neck or other parts.

Invention content:

The purpose of the present invention is to provide an anti-rotation self-locking fracture internal fixator.

The anti-rotation self-locking fracture internal fixer provided by the present invention is composed of a screw rod, a sleeve and a bolt, and is characterized in that:

The screw consists of two sections, the front section of the screw and the rear section of the screw. The front section of the screw has a helical edge, and the end of the rear section of the screw has a connection structure connected to one end of the bolt. The inner diameter of the front end of the sleeve that is in contact; the bolt is placed in the sleeve to connect the screw and the sleeve; the outer surface of the contact part of the bolt and the sleeve is provided with external threads, and the corresponding part of the inner surface of the sleeve is provided with bolts The external thread matches the internal thread; the other end of the bolt is provided with a tapered hole; the outer surface of the end part of the sleeve away from the distal end of the screw has a sheet-shaped wing; the rear section of the screw and the sleeve are provided with a rotating limit structure.

The connection structure includes a hollow cylindrical end at the rear section of the screw, a T-shaped notch at the end, and an annular groove on the inner surface of the hollow cylinder, and the bolt has a cylindrical head that matches the annular groove and Neck, the size of the T-shaped notch is suitable for the head and neck to enter the hollow cylinder.

The rotation limiting structure can be in two ways: one is that the rear section of the screw is provided with a protruding part with a diameter larger than the outer diameter of the front end of the sleeve, and the protruding part has a ring of teeth, and the front end of the sleeve has a corresponding Ring tooth pattern.

Another rotation limiting structure is that a ring of teeth is provided on the end surface of the rear end of the screw, and a ring of teeth is correspondingly provided on the inner surface of the middle part of the sleeve.

In the above two kinds of rotation limiting structures, the number of tooth lines on the rear section of the screw rod and the sleeve is equal, and the size and shape of the concave and convex are matched, so that they can engage with each other. The first design is preferred because it is easier to manufacture.

The connection method of the screw, the sleeve and the bolt is as follows: after the head and neck of the bolt are inserted into the end of the rear section of the screw from the connecting mechanism, they are inserted into the sleeve, and the threads on the outer surface of the bolt body placed in the sleeve are connected with the sleeve. The threads on the inner surface of the barrel contact, the bolt is rotated, and the bolt connects both the screw and the sleeve within the sleeve. When the built-in connecting bolt is tightened, the teeth are fully engaged, so that the sleeve and the screw rod are tightly connected as a whole.

When the connecting bolt is not fully tightened, the retainer is "unlocked", that is, the screw can rotate freely in the sleeve. Once the bolt and the sleeve are fully tightened, the fixer is placed in a "locked" state, that is, the screw, the sleeve and the connecting bolt become a whole, so that the screw cannot do any rotation in the sleeve.

During the operation, the fixer in the unlocked state (that is, the screw rod, the sleeve and the connecting bolt are assembled, but the bolt is not fully tightened) is driven into the fracture end, and then the connecting bolt is tightened to make the fixator become locked. At the same time, the flake-shaped wings on the sleeve have a reliable anti-rotation effect. After the bolt is tightened, the fixer has a self-locking function, which limits its looseness and withdrawal in the bone.

There can be 3 to 4 helical blades on the screw;

The end of the spiral blade is in the shape of a spiral cone, which is called a "blade" structure by industry insiders, so as to facilitate penetration into cancellous bone.

The thickness of the screw rod can be different at both ends and in the middle, and should be changed accordingly according to the situation of the fracture site. When used for femoral neck bone fixation, the screw rod is thicker at the part with the helical blade, and the rear part of the screw rod is thinner, so as to occupy the smallest fracture area when driving into the femoral neck or other parts.

The wings of the sleeve are in the shape of flat sheets, preferably 1 to 3, and the wings can play a reliable anti-rotation role in the bone;

The screw and the bolt can be hollow tubular, and can be driven into the fixer under perspective along the positioning guide pin, which has the characteristics of minimally invasive operation, and saves materials, making the whole fixer lighter in weight;

The material of the anti-rotation self-locking fracture internal fixer provided by the present invention can be selected from metal materials such as stainless steel or titanium alloy.

The anti-rotation self-locking fracture internal fixator can be used for fixing metaphyseal fractures rich in cancellous bone, and is especially suitable for femoral neck fractures.

Technical effect of the present invention:

Since the helical blade is driven into the bone and is placed in a locked state, the fixer must be rotated in reverse to withdraw, and the axially running flat wings of the sleeve part restrict the fixer from rotating, making it impossible to withdraw;

The sleeve part can only be loosened or withdrawn when it moves straight in the axial direction, and the helical blade part can only rotate and walk after the overall lock, and it is impossible to move straight in the axial direction, so the sleeve part cannot be withdrawn. This anti-rotation self-locking function makes the fracture Internal fixators greatly reduce the chance of loosening or withdrawal.

Because there are 3 to 4 helical blades on the screw, and the cross-section of the helical blade part of the screw is close to triangular or quadrilateral, it has a certain degree of rotation stability. When treating fractures, only one fixator can play a role. The fixing function played by 3 semi-threaded hollow screws makes the operation easier.

During the femoral neck fracture treatment operation, one piece of this anti-rotation self-locking fracture internal fixator can be inserted directly along the indwelling guide wire at the proximal end of the femur to achieve a firm fixation effect. The operation is simple and the effect is clear. The chance of screw loosening and backing out is significantly reduced by the self-locking feature.

Advantages of the present invention are summarized as follows:

1. The fracture internal fixator will not rotate in the bone

After the helical blade in the fracture internal fixator of the present invention is combined with the wings on the sleeve, it has a more reliable anti-rotation effect than the prior art product with only the helical blade;

2. Fracture internal fixator has self-locking function

Once the screw rod and the sleeve are tightly connected with bolts, they have a self-locking function. The combination of anti-rotation and self-locking functions limits the loosening and withdrawal of the fixator, which is especially suitable for fracture treatment of osteoporosis patients;

3. Reduce bone loss and facilitate fracture healing

The step of drilling is omitted during the insertion process, which greatly reduces the loss of bone mass; the contact area of the fracture end is larger when only one fixer is driven than three screws; and after implantation of the internal fixator, the compaction The surrounding bone is equivalent to increasing the local bone density, which is conducive to fracture healing;

4. Simple operation and short operation time

In the internal fixation of clinical fractures, only one fixator needs to be inserted simply along the positioning guide pin, which can not only achieve the fixation effect of the original three screws, but also shorten the operation time.

Description of drawings:

Figures 1 to 8 are anti-rotation self-locking fracture internal fixators for the treatment of femoral neck fractures with serrations on the back section of the screw rod and the end surface of the sleeve, wherein: Figure 1 is a three-dimensional schematic diagram of the screw rod; Figure 2 and Figure 3 are built-in connecting bolts Figure 4, Figure 5 and Figure 6 are respectively a perspective view, a longitudinal sectional view and a left view of a sleeve with three wings; Figure 7 is a perspective view of the retainer in a locked state; Figure 8 is a A three-dimensional schematic diagram of the fixer in an unlocked state;

Figure 9 and Figure 10 are the X-ray films during and after the operation of "three hollow nails fixing femoral neck fracture" in the prior art, wherein: Figure 9 shows that the three hollow nails were placed in the normal position during the operation; Figure 10 shows the first section of the operation After a period of time, the hollow nail loosens and exits;

Figure 11 and Figure 12 are the anti-rotation self-locking fracture internal fixator for the treatment of femoral neck fractures with tooth lines on the end surface of the rear end of the screw rod and the inner surface of the sleeve, wherein: Figure 11 is the operation, the fixator is in the unlocked state Drive into the fracture site; Figure 12 shows that the fixer is in a locked state after the built-in bolt is tightened, and the fracture site is fixed.

Detailed ways:

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. What the embodiment provides are two kinds of anti-rotation self-locking fracture internal fixators for the treatment of femoral neck fractures.

Example 1 An anti-rotation self-locking fracture internal fixator with tooth patterns on the rear part of the screw rod and the end surface of the sleeve

Fixer structure:

See attached drawings 1 to 8. The structure of the internal fixator for anti-rotation self-locking fractures consists of the screw rod shown in Fig. 1, the built-in connecting bolt shown in Fig. 2 and Fig. 3, and the three-winged internal fixator shown in Fig. It consists of a sleeve, and the three parts are hollow structures.

The screw part has three helical blades 1, which are used to drive into the femoral head. The head end of the blade is in the shape of a spiral cone to facilitate penetration into the cancellous bone. The linear length of the helical blade part is between 15mm and 30mm; The front part with the helical blade is thicker, and the middle part of the rear part of the screw is thinner, so as to occupy the smallest fracture area when driving into the femoral neck. The diameter of the tail section of the rear section of the screw is just enough to be inserted into the sleeve without any gap, and in the unlocked state, the tail section of the rear section of the screw can rotate freely in the sleeve.

The hollow built-in connecting bolt is used to connect the screw rod and the sleeve, and the bolt is divided into three parts: a head 4, a neck 5 with a slightly thinner diameter and a threaded bolt body. The connecting bolt is hollow, and the tail end surface is a hexagonal tapered hole 6 for inserting a hexagonal screwdriver.

There is a "T"-shaped notch 3 at the end of the rear section of the screw, which is used to insert the head 4 and neck 5 of the built-in connecting bolt through the notch, and a groove is designed on the inner peripheral surface of the screw here to connect the bolt head. The neck fits right into it, and the bolt can turn, but not come out. After the bolt head and neck are placed in the end of the rear section of the screw, the threads on the surface of the bolt body are used to tighten with the internal threads of the sleeve to connect the screw and the sleeve.

There is also a circle of teeth 2 on the screw rod rear section, and the end face of the wingless end of the sleeve also has a circle of teeth 9, the number of teeth of the two is equal, and its size and concave-convex shape match. When the screw rod is inserted into the sleeve, once the built-in connecting bolt is tightened, the tooth pattern further makes the sleeve and the screw rod fully engage, and the two parts cannot rotate with each other, so that the sleeve and the screw rod are tightly connected to form a whole. The three axially running flat wings 7 on the sleeve can be embedded in the cancellous bone and/or cortical bone of the femoral trochanter to play a certain anti-rotation role. The smooth curved shape of the two ends of the wing 7 facilitates its entry and extraction in the bone.

2) Surgical operation process

1. Assemble the holder in the unlocked state

Select an anti-rotation self-locking fracture internal fixator with a suitable length, put the head 4 and neck 5 of the bolt into the T-shaped notch 3 of the screw rod, insert the sleeve, and rotate the bolt through the tail end of the sleeve to make the sleeve The thread on the surface of the bolt body inside the barrel is in contact with the internal thread of the sleeve, but the bolt is not fully tightened, see Figure 8. The bolt is now in the sleeve.

2. Positioning

When the femoral neck fracture is closed and reduced satisfactorily, a positioning guide pin is driven into the lower and posterior part of the femoral neck axis, and an anti-rotation guide pin is driven in parallel above it, so that the internal fixator for anti-rotation self-locking fracture can be fixed. Prevent femoral head rotation and displacement during insertion.

3. Drive into the unlocked fixator at the fracture site

Make a 1cm-long incision on the skin, and drive the above-assembled unlocking fixture along the direction of the helical blade along the positioning guide pin to an appropriate depth, that is, the head of the helical blade is located slightly below the articular surface, with wings 7 The caudal end of the sleeve portion is left just a little outside the cortex of the tuberosity.

4. Lock the fixator in the bone

Insert a hexagonal screwdriver into the hexagonal taper hole at the end of the connecting bolt assembled with the sleeve, tighten the built-in connecting bolt, and tighten the thread of the connecting bolt body with the internal thread 8 of the sleeve. During this process, a certain compression effect on the fractured end can be produced. After the connecting bolts are tightened, the tooth pattern on the head end surface of the sleeve part and the tooth pattern on the outer end surface of the inner rod of the helical blade part will bite together, and the anti-rotation self-locking fracture internal fixator as a whole will change from an unlocked state to a locked state, that is, the helical blade part It can no longer be rotated and the sleeve part can no longer move axially.

5. Remove the positioning guide pin and complete the operation.

Example 2 An anti-rotation self-locking fracture internal fixator with tooth patterns on the end surface of the rear end of the screw rod and the inner surface of the sleeve

Except that the end surface of the rear section of the screw and the end surface of the sleeve do not have tooth lines, and the tooth lines are on the end surface of the end of the rear section of the screw rod and the inner surface of the sleeve, the rest of the structure is the same as that of Embodiment 1.

During the operation, the fixers in the unlocked state and locked state are shown in Fig. 11 and Fig. 12 respectively. Since the teeth are inside the sleeve, they are not shown in the figure.

Claims (9)

1. An anti-rotation self-locking internal fixator for fractures, consisting of a screw rod, a sleeve and a bolt, is characterized in that: the screw rod comprises two sections, the front section of the screw rod and the rear section of the screw rod, the front section of the screw rod has a helical edge, and the end of the rear section of the screw rod has a In the connection structure connected to one end of the bolt, the outer diameter of the inserted part of the rear section of the screw at least near the end is smaller than the inner diameter of the front end of the sleeve in contact with the screw; the bolt is placed in the sleeve to connect the screw and the sleeve as a whole; The outer surface of the contact part between the bolt and the sleeve is provided with an external thread, and the corresponding part of the inner surface of the sleeve is provided with an internal thread matching the external thread of the bolt; the other end of the bolt is provided with a tapered hole; the sleeve is far away from the far end of the screw rod The outer surface of the end portion of the screw has a sheet-shaped wing; the rear section of the screw and the sleeve are provided with a rotation limiting structure. 2. The anti-rotation self-locking fracture internal fixer according to claim 1, characterized in that the connection structure includes a hollow cylindrical end in the rear section of the screw rod, a T-shaped notch in the end, and a hollow cylindrical inner surface with An annular groove, the bolt has a cylindrical head and a neck matching the annular groove, and the size of the T-shaped notch is suitable for the head and neck to enter the hollow cylinder. 3. The anti-rotation self-locking fracture internal fixer according to claim 1 or 2, characterized in that the rotation limiting structure is that a protruding part with a diameter larger than the outer diameter of the front end of the sleeve is provided on the rear section of the screw rod, and the The protruding part has a ring of teeth, and the end surface of the front end of the sleeve has a ring of teeth correspondingly. 4. The anti-rotation self-locking fracture internal fixer according to claim 1 or 2, characterized in that the rotation limiting structure is that a ring of tooth lines is provided on the end surface of the rear end of the screw rod, and the inner surface of the middle part of the sleeve Correspondingly, there is a circle of teeth. 5. The anti-rotation self-locking fracture internal fixer according to claim 1 or 2, characterized in that there are 3-4 helical blades on the screw rod. 6. The anti-rotation self-locking fracture internal fixator according to claim 1 or 2, characterized in that the sleeve has 1-3 wings. 7. The anti-rotation self-locking fracture internal fixator according to claim 1 or 2, characterized in that the screw rod and the bolt are hollow structures. 8. The anti-rotation self-locking fracture internal fixer according to claim 1 or 2, whose material is stainless steel or titanium alloy. 9. The anti-rotation self-locking fracture internal fixer according to claim 1 is used for fixation of femoral neck fracture.

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