JP3722438B2 - Internal fixation member for femoral neck fracture treatment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal fixation member used for a fracture involving a pulverized fracture and a high degree of osteoporosis, particularly when a femoral neck fractures.
[0002]
[Prior art]
When reducing a femoral neck fracture and fixing the fracture site, osteosynthesis is performed using an internal fixation member comprising a plate and a plurality of screws that pass through the plate. This conventional inner fixing member is shown in FIG. The conventional inner fixing member 101 has a plate 102, a main screw 103, a sub screw 104, and a plurality of bone screws 105. The plate 102 is fixed along the diaphysis with the bone screw 105, so that it is attached to the straight portion 102a of the plate. Has a plurality of bone screw guide holes 102c, a main screw guide hole 102d at the base of the refracting portion 102b of the plate, and a sub screw guide hole 102e at the top.
[0003]
A screw fixing tube 106 having an inclination angle α (α = 125 ° to 135 °) with respect to the straight portion 102a is projected on the inner surface of the plate of the main screw guide hole 102d. It was fixedly inserted along the inclination angle α. On the other hand, the sub screw guide hole 102e has a slightly larger shape with respect to the screw diameter so that the insertion angle of the sub screw 104 can be adjusted. In this case, it can be freely adjusted within a range of β ≦ 20 degrees.
[0004]
When bone repair is performed using such an internal fixation member, the position of the fractured bone may change as the bone hardens, so that the bone can be hardened sufficiently. It was undesirable to attach the screw firmly to the bone. When the screw was fixedly attached, the end of the screw could penetrate the femoral head during hardening. Therefore, the main screw 103 in the conventional inner fixing member 101 is slidably accommodated in the main screw guide hole 102d and the screw fixing tube 106, and the sliding force is applied by the sliding, and the load is transmitted to the fracture surface. It was expected to promote bone fusion.
[0005]
[Problems to be solved by the invention]
However, in fractures with pulverized fractures or severe osteoporosis, there is a risk of excessive axial movement of the screw due to the pressure applied to the postoperative fracture, and there is a risk of re-breaking the fracture or crushing the fracture surface. there were. In addition, when a screw fixing tube is present, a large hole for insertion is made in the outer bone cortex at the upper part of the diaphysis, and this portion may be broken in a bone having strong osteoporosis.
[0006]
The present invention has been made to solve the above-mentioned problems of the conventional internal fixation member, and may cause excessive axial movement of the screw even in a fracture with a pulverized fracture or a high degree of osteoporosis. In addition, there is no risk of re-fracture of the fractured part or crushing of the fractured surface, and internal fixation that can be expected to promote bone fusion by transmitting appropriate load to the fractured surface by allowing appropriate sliding and applying appropriate compression force The object is to provide a member.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, an internal fixation member of the present invention is used for the treatment of a femoral neck fracture, a plate that is fixed along a diaphysis by a diaphysis fixing screw, and a sub drilled in an upper portion of the plate. In an internal fixation member having a main screw and a subhead for fixing a bone head inserted through the screw guide hole and the main screw guide hole from the upper part of the diaphysis, respectively, the plate is attached to the upper part of the diaphysis A flat plate that does not protrude from the screw fixing tube, the main screw has a base portion that encircles a groove having the same pitch as the tip screw portion, and the main screw guide hole is formed on the back surface of the plate. A stopper piece that engages with the tip screw portion and the groove and is elastically deformable in the screw shaft direction is provided on the side.
[0008]
For the main and sub screws, select the appropriate length to insert the screw tip to the optimal position of the bone head. The tip of the stopper piece protrudes into the main screw guide hole, and the protruding length is a length that can be accommodated in the screw portion and the groove.
[0009]
If the stopper piece engages with the thread when the main screw is inserted, the screw is fed while rotating. When the stopper piece exceeds the tip screw portion, it comes into contact with a smooth main screw intermediate shaft portion. However, since the stopper piece is elastically deformable, it can be fed into the inner portion of the main screw.
[0010]
Even when the groove provided on the base beyond the main screw intermediate shaft engages with the stopper piece, the screw is fed while rotating, and then the main screw is moved to a predetermined depth while sliding the stopper piece that is elastically deformed against the base head. Insert.
[0011]
After the operation, the sliding force of the screw is applied and the fracture portion is shortened and healed. The slidable length of the main screw is the distance from the initial insertion position until the stopper piece engages with the groove.
[0012]
When the stopper piece engages with the groove, no further sliding is possible, but the groove and the tip screw are formed at the same pitch, so it can be easily removed by rotating the main screw in the direction of removal. Can do.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view of an internal fixation member used for the treatment of a femoral neck fracture according to the present invention. The inner fixing member 1 has a plate 2, a main screw 3, a sub screw 4, and a plurality of bone screws 5. The plate 2 is a flat plate body composed of a straight portion 2a that can be attached as it is to the upper portion of the femoral shaft (not shown) and a refracting portion 2b that is bent at a predetermined angle, and the tube for fixing the main screw does not protrude. The tube is not provided in order to avoid making a large hole (diameter 14 to 15 mm) in the diaphysis. This is because if such a hole is present in a bone having strong osteoporosis, this portion may be broken and excessive telescoping may occur.
[0014]
A plurality of bone screw guide holes 2c are formed in the straight portion 2a, a main screw guide hole 2d is provided in the base of the refracting portion 2b, and a sub screw guide hole 2e is provided in the upper part thereof. The main screw guide hole 2d has an inclination angle of approximately 135 ° with respect to the linear portion 2a, and the main screw 3 is inserted along this inclination angle.
[0015]
The main screw 3 has a base portion 3c having the same outer diameter for screwing a groove 3b having the same pitch as the tip screw portion 3a, and the main screw guide hole 2d is engaged with the tip screw portion 3a and the groove 3b on the back side of the plate. A stopper piece 6 that is elastically deformable in the direction of the screw shaft is projected.
[0016]
When attaching the internal fixation member, first reduce the fracture, and insert the guide pin for the main screw to the level of the femoral head subchondral bone using a 135 ° angle guide under fluoroscopy. With this guide pin inserted, a depth gauge is inserted into the femoral cortex and the length of the main screw used is measured. Next, reaming is performed by inserting a reamer along the guide pins, and then the plate is attached to the femur. At this time, hydroxyapatite granules are packed with fibrin glue and filled up to the neck. This improves the interfacial rigidity between the screw and the bone to increase the screw torque, gain higher initial fixation, and enable early post-operative loading even for cervical fractures with advanced osteoporosis It is.
[0017]
The main screw 3 of the measured size is inserted and fixed along the guide pin, and the guide pin is removed. Thereafter, the plate 2 is fixed to the diaphysis with a bone screw 5, and finally the sub screw 4 is inserted in parallel with the main screw 3. Since the main screw 3 and the sub screw 4 distribute the load, the risk of perforation of the head is reduced.
[0018]
The main screw 3 is moved in the axial direction by a load acting on the bone head after the operation, but when it slides to the position shown in FIG. 2, the stopper piece 6 engages with the groove 3b and stops. This slide distance can be arbitrarily set between approximately 10 mm and approximately 15 mm in consideration of the shortened length required for healing of the fractured portion. Since the groove 3b is formed for one round, the stopper piece 6 is always engaged when sliding, and since it has the same pitch as the tip screw portion 3a, it can be easily removed by rotating the main screw 3 in the extraction direction.
[0019]
【The invention's effect】
As described above, the inner fixing member of the present invention uses a flat plate that does not protrude a screw fixing tube, and a groove having the same pitch as that of the tip thread portion is screwed around the base portion of the main screw to make a main screw guide. A stopper piece that protrudes elastically deforms in the axial direction of the screw and engages with the tip screw part and groove on the back side of the plate of the hole, so that even if the main screw slides due to the load acting on the bone head after surgery, the stopper piece does not Engage with the groove and stop. Therefore, there is no risk of excessive axial movement of the screw or shortening of the neck, even for pulverized fractures or fractures with a high degree of osteoporosis. There is no fear. In addition, since moderate sliding is allowed, an appropriate compression force can be applied to transmit the load to the fracture surface, thereby promoting bone fusion.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an inner fixing member.
FIG. 2 is a cross-sectional view of an inner fixing member when a main screw slides.
FIG. 3 is a cross-sectional view of a conventional inner fixing member.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inner fixing member 2 Plate 2c Bone screw guide hole 2d Main screw guide hole 2e Sub screw guide hole 3 Main screw 3a End screw part 3b Groove 3c Base part 4 Sub screw 5 Bone screw 6 Stopper piece

Claims (1)

Used for the treatment of femoral neck fractures, a plate that is fixed along the diaphysis by a diaphysis fixing screw, and a sub-screw guide hole and a main screw guide hole that are drilled in the upper part of the plate are inserted into the diaphysis. In an internal fixation member having a sub head and a main screw for fixing a bone head inserted from the upper part toward the bone head, the plate has a back surface attached to the upper part of the diaphysis and does not protrude a screw fixing tube. The main screw has a base portion for threading a groove having the same pitch as that of the tip screw portion, and the main screw guide hole engages with the tip screw portion and the groove on the plate back surface side in the screw axial direction. An inner fixing member characterized in that an elastically deformable stopper piece projects.

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