RU2525739C1 - Method of osteosynthesis of femoral neck fracture and device for its realisation - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: reposition of the fracture is performed, and a device for fixation of the femoral neck fractures is introduced under X-ray control through a zone, located directly at an obtuse angle to the fracture plane, open outwards and downwards, with the maximal distance from the lower point of contact of the bone fragments. The device for fixation of the femoral neck fractures contains a fixing element in the form of a rod, a spring, a support cup for the spring with an external thread, a spring fixer and a locknut for fixation of the spring fixer position. An internal end of the rod has the quill sharpening and three-four coils of self-tapping thread of a screw-type. The ccutting edge of the thread coil, closest to the sharpened rod end, is made toothed. The thread and two rows of transverse cuts are made on an external rod end on 2/3 of its length.

EFFECT: group of inventions makes it possible to ensure stable fixation of fragments, increases reliability of the device fixation in the femoral head with different strength characteristics of bone tissue and dimensions of the proximal part of the hip.

2 cl, 14 dwg

Description

The invention relates to medicine, namely to traumatology, and is intended for the treatment of fractures of the femoral neck, based on the principle of active fixation by contraction.

Let us explain the origin of the new term - active fixation by contraction. Fixation of bone fragments with the known methods of osteosynthesis of femoral neck fractures is carried out in accordance with two principles of mechanics: splinting and simultaneous interfragment compression.

When splinting osteosynthesis, an implant (device) is inserted into the bone fragments, which is a support for them and prevents displacement by its rigidity, reaction forces arising in response to the functional load of the limb (Figure 1). Splinting - reducing the mobility of fragments of fractures by connecting with a rigid body. The tire can be external (gypsum, external fixative) or internal (plate for internal fixation, intramedullary nail) [1 p.112].

Known methods of osteosynthesis, based on the principle of simultaneous inter-fragment compression, which is carried out, for example, with a screw (Figure 2).

However, as is known, such compression acts for a short time, until the first episode of overload with minimal destruction of the ends of the bone fragments [2], and in the future, fracture fixation is provided on the basis of splinting. Therefore, simultaneous inter-fragment compression cannot be considered as an independent fixation mechanism.

Known methods of osteosynthesis, in which the duration of the simultaneous inter-fragment compression was increased using implants (devices) equipped with springs [3,4] - (Figure 3).

However, these methods, based on the principle of continuous inter-fragment compression, did not lead to improved treatment results and refused to use such implants (devices).

Thus, currently used methods of osteosynthesis of femoral neck fractures, which are based only on fixation by splinting. There are many options for splinting. At the same time, researchers give splinting a low rating as a fixation mechanism: splinting reduces, but does not prevent, the mobility of bone fragments; splinting is not intended for stable fixation; small implants (devices) do not provide stability, and massive ones destroy bone fragments and their blood supply system [1,5,6]. A.Seppo gave the most fundamental assessment [7]: “The insoluble contradiction of the applied methods of osteosynthesis is that for all known fixators, the voltage in the area of contact of the bone with the metal is greater than its crushing resistance ..., there can be no question of stability or long-term firm fixation ". The number of complications after osteosynthesis reaches 49% [8.9].

Along with splinting in clinical practice, methods of osteosynthesis are widely used, based on the principle of mechanics called "fixation by contraction." They were introduced by F.Pauwels for osteosynthesis of fractures of those segments of the musculoskeletal system, which are affected by eccentric functional load. The femur, humerus, radius, and ulna are subjected to such loads, as described in the manual on internal osteosynthesis of Mueller E.M. et al. [1]. Under the action of an eccentric load, the bone bends - stretching its convex side and compression - on the concave. Therefore, at first, the fracture gap opens from the extension. The essence of fixation by pulling is to neutralize the resulting stretching of the bone, compensating for the unfolding moment of the applied load using a prestressed structure (Figure 4).

However, despite the fact that eccentric loads are applied to the upper thigh, fixation by contraction during osteosynthesis of femoral neck fractures was not used.

5, 6 schematically shows how the principle of fixation by constriction during osteosynthesis of femoral neck fractures is realized by a fixation device supporting the load, namely, the reversal of bone fragments is prevented. As a prestressed fixing device, a device supporting the load (force F) by means of a spring is used. Moreover, due to the anatomical features of the femoral neck zone, the device is not located on the bone, but intraosseous.

The use of a device supporting the load by means of a spring for clamping is mandatory, since its voltage without a spring will be insufficient, the voltage of a conventional device will disappear after the first episode of overload with minimal destruction of bone tissue, and fracture fixation will continue only on the basis of splinting (by analogy with simultaneous inter-fragment compression). Therefore, the generally accepted definition of “clamping by pulling” when using clamping devices supporting the load with a spring should be supplemented with the specification “active”, i.e. acting regardless of the applied functional load. Therefore, in the description of the invention we use the term - active fixation by contraction.

Fig. 5,6 shows that when implementing the principle of active fixation by contraction, the stabilizing moment of the spring force of the fixation device exceeds the uncoupling moment of the limb functional load, and in this case, the resulting force of the fixation device and limb functional load passes through the fracture plane and crosses it. If this condition is met, the turn of the femoral head is excluded and, accordingly, contact between the surfaces of the bone fragments and the action of friction forces that prevent the displacement of bone fragments across the width are maintained.

Known devices for fixing Charnley and J.N. Rodin [3,4], which support inter-fragment compression by springs, but, based on the design features, they can be carried out only along the axis of the femoral neck. Therefore, the resulting spring force of these fixation devices and the functional load of the limb passes outside the fracture plane, i.e. does not prevent the head of the femur from separating the surfaces of bone fragments, which is accompanied by the disappearance of the friction forces, which is the reason for their inefficiency for stable fixation (Figure 3).

Closest to the proposed method is a method for osteosynthesis of femoral neck fractures (RF patent No. 2350293, 2009), using fixators (devices for fixation) supporting inter-fragment compression, including radiometry, introduction of a device for fixation, measurement of the magnitude of the pulling force that can withstand one device without removing from the femoral head, determining the magnitude of the compression force and the number of devices for fixation, while using the construction on the x-ray: determine the place entered I lock - just below the upper contour of the femoral neck.

The disadvantage of this method is the need to use several devices for fixation, since only one of them can be carried out directly under the upper contour of the femoral neck, and the rest, due to lack of space, is carried out distally - parallel to the device already inserted, or closer to the vertical (along the axis of the neck hips). And if in the first case the effectiveness of the spring force of the device decreases (the shoulder of its stabilizing moment decreases), in the second case its resulting from addition with the functional load of the limb does not actually prevent the head of the thigh from turning and, as a result, the principle of active fixation by contraction is combined with the compression principle bone fragments, as shown in Fig.3. In addition, there are difficulties associated with the need for X-ray diffraction, determining the magnitude of the pulling force that a single device can withstand without removing from the femoral head and calculating the required number of devices, which complicates the operation and lengthens its execution time.

A device for fixing fractures of the neck of the femur (RF patent 2280416, 2006), comprising a spring, a locking element with a distal end for the spring, a spring retainer, a support cup for the spring and keys for working with the device. The locking element can be made in the form of a self-locking needle or screw.

However, not in all cases of femoral neck fractures, the self-locking device spokes are securely fixed in the femoral head with a pulling force due to insufficient bending of its fixing element in the form of an elastic lobe when interacting with bone tissue having different strength characteristics. This leads to the need to determine the magnitude of the pulling force for each device and conduct x-ray to assess the stability of a particular fracture, which complicates the operation and increases its duration. The fixing element, made in the form of a screw, although it can be firmly fixed in the femoral head, it is necessary to use several devices to ensure stable fixation, for example, for basal femoral neck fractures, a force of 27-30 kgf is required, which cannot be provided with one device.

The technical task is to simplify the operation and reduce its execution time, ensure stable fixation of fragments, through the use of the principle of active fixation by tightening bone fragments and increase the reliability of securing the device in the femoral head for various strength characteristics of the bone tissue and the size of the proximal femur.

The problem is solved as follows.

In the method for osteosynthesis of femoral neck fractures comprising reposition of the fracture, fixation of fragments by a load-supporting device, according to the invention, a device for fixing fragments is carried out to the femoral head through an area located directly below the point of transition of the greater trochanter to the femoral neck, at an obtuse angle to the fracture plane, open outward and down at the maximum distance from the lower point of contact of the bone fragments, while to fix the fragments using one device for active fixation by pulling.

A device for fixing fractures of the femoral neck, comprising a spring, a locking element, a spring retainer, a support cup for a spring, according to the invention, the device is additionally equipped with a lock nut for securing the position of the spring retainer, the locking element is made in the form of a rod, the inner end of which has feather sharpening and threads of self-cutting threads type of screw, and the cutting edge of the thread turn closest to the sharpened end of the rod is sawtooth, and the outer end of the rod is 2/3 of the length of the rod with a thread and two and a number of transverse notches, the support cup under the spring is made with an external thread.

Using the principle of active fixation by contraction during osteosynthesis of femoral neck fractures and the introduction of a device for fixation at the maximum distance from the lower contact point of bone fragments through the area located directly below the junction of the greater trochanter to the femoral neck, at an obtuse angle to the fracture plane, is open outwards and downwards. use only one device of the proposed design to fix the fragments, supporting the load, with a pull of at least 27 kgf pulling it from the femoral head. Accordingly, this simplifies the operation and reduces its execution time, since there is no need, in comparison with the prototype, to use x-ray and to determine the magnitude of the force of the drawing device for fixing.

Carrying out a device for fixing fragments that supports the load “immediately below the point of transition of the greater trochanter to the thigh neck at an obtuse angle to the fracture plane, open outward and downward” is an important addition, in comparison with the prototype, the effect of which increases with increasing angle of inclination of the fracture plane, her approximation to the vertical. We illustrate this statement with the diagrams shown in Figs. 7, 8, 9. Points O indicate the lower contact points of bone fragments, the beginning of fracture planes, inclined at angles B relative to the horizon plane. The vectors of the spring force F when combined with the vectors of the functional load P forms the resulting M. The influence of this resulting determines the effectiveness of osteosynthesis. The nature of the effect of the resulting is determined by its decomposition relative to the plane of the fracture into normal N and tangential T components [10]. Obviously, the normal components prevent the head of the femur from turning, cause compression of the bone fragments, stabilizing the position of the bone fragments, and tangential ones, on the contrary, act to displace the bone fragments in width. It follows that the effectiveness of osteosynthesis depends on the ratio between the normal and tangential components of the resulting M. In turn, the ratio between the normal and tangential components is determined by the angle a, “open outward and downward” relative to the fracture plane, under which the implant supporting load. At a dull angle a, the resulting angle passes at an angle C relative to the plane of the fracture, at which its normal components are greater than the tangential ones (Figs. 7, 8). And, on the contrary, with acute angle a, the tangential component is larger than normal (Fig. 9). As follows from the presented diagrams, for small angles of inclination of the fracture plane in the implant, carried out along the upper contour of the femoral neck, according to the prototype of the method, by default it will be located at an obtuse angle a “open outward and downward” and, accordingly, the normal component of the resulting load will exceed tangential component, which will ensure stable fixation of the fracture. However, when the device is held along the upper contour of the femoral neck, as the angle of inclination of the fracture plane B increases, the obtuse angle a will decrease to acute, the ratio between the components will change, and the biasing tangential component will become more stabilizing normal. These data prove the need to withstand obtuse angle a when performing osteosynthesis. It is also clear that to position the device at an obtuse angle to the plane of the fracture at the maximum distance from the lower contact point of the bone fragments is possible only when it passes through the area located "directly under the junction of the greater trochanter to the femoral neck." Holding the device “directly under the upper contour of the femoral neck”, as indicated in the prototype of the method, when the inclination of the fracture plane to the horizontal is more than 60 °, it is not possible to position the device at an obtuse angle to the fracture plane at the maximum distance from the lower contact point of the bone fragments (Figure 10, eleven).

The implementation in the device for fixing fractures of the femoral neck of the fixing element in the form of a rod, the inner end of which has a feather sharpening and a self-tapping screw type thread, consisting of turns, with a sawtooth cutting edge of the turn closest to the sharpened end of the rod, provides a minimum force for screwing it into the head of the thigh, which eliminates the possibility of a fracture of the rod, in addition, increases the reliability of fixing the inner end of the rod in the femoral head.

The reliability of fixing in the bone of the cup for the spring, actually fixing the second end of the locking element, is enhanced by the external thread located on the wall of the cup for the spring. Reliable fastening of the ends of the device allows the use of a powerful spring. To exclude the spring opening, due to the possible self-loosening of the nut (spring retainer) during the treatment, the device is equipped with a lock nut. The implementation of two rows of transverse notches on the outer end of the locking element allows you to easily shorten the rod to the desired length.

Thus, the implementation of the osteosynthesis of femoral neck fractures using the device of the proposed design allows using the principle of active fixation by tightening bone fragments to ensure stable and reliable fixation of bone fragments while simplifying the operation and shortening its execution time.

The proposed method for osteosynthesis of femoral neck fractures is as follows.

The fracture is repositioned and, under X-ray control (or with the help of the image intensifier tube), the Kirschner needle is passed through the zone located directly under the junction of the greater trochanter to the femoral neck at an obtuse angle to the fracture plane, open outwards and downwards, at the maximum distance from the bone bone fragments' contact point. Visually assess the compliance of the position of the spokes with the listed requirements and, if they are followed, introduce a device for fixing fragments, fix its spring in a fully compressed position, shorten the outer end of the fixing element directly at the bone and end the operation by applying 2 sutures to the wound.

Stable fixation of any fractures of the femoral neck during osteosynthesis based on active fixation by contraction provides the device of the proposed design. On Fig presents the device Assembly; Fig.13 is a locking element; on Fig - support cup under the spring, spring, spring retainer (nut) and locknut.

The device for fixing fragments contains a locking element in the form of a rod (1), a spring (2), a support cup (3) for a spring, a nut (4) (spring retainer), a lock nut (5). The necessary tools for installing the device are: standard Kirschner knitting needles and a cannulated drill (for large cancellous screws) for provisional fixation, as x-ray marks, a conductor, for making a channel in the bone for the fixing element, a cannulated countersink for making a channel in the bone for a glass, a screwdriver for the insertion of the fixing element, keys for the cup, for the nut and for the lock nut, a breaker for the outer end of the shaft.

The locking element is a rod (1), the inner end of which has feather sharpening (6) and three to four turns (7) of high self-tapping thread with a large pitch, such as a screw, and the thread height increases from 1 mm to a maximum at the nearest to the sharpened end of the rod to the thread thread, the cutting edge of this thread is serrated, a metric thread (8) and two rows of transverse notches (9) are applied on the outer 2/3 of the shaft lengths on opposite sides, with an interval of 5 mm, a groove is made at the end of the outer end of the fixing element (10) under screwdriver. The support cup (3) for the spring is made with a hole in the bottom for the rod, with a shoulder (11) on the opposite edge and an external thread (12) on the wall for fixing in the bone, with two grooves in the shoulder for the key of the glass. The spring (2) of the device is a calibrated cylindrical compression spring. The nut (4) (spring retainer) is made in the form of a cylindrical sleeve with an internal metric thread for the thread of the outer end of the fixing element, the diameter of the cylindrical part of the sleeve allows it to fit in a glass, the wall of the external part of the sleeve is made in the form of a hexagon for a nut wrench, a channel in the external part The bushings have an extension for the locknut. The lock nut (5) is made in the form of a cylindrical sleeve with an internal thread for the thread of the locking element and with two grooves on the outer end for the lock nut key. To make a canal in the bone for a glass, a cannulated countersink is used, which has the form of a sleeve with a through hole for a cannulated drill, with cutting elements at the end and lateral surfaces of the working end, with a hexagon for the handle at the opposite end. The key for the cup is a cylindrical sleeve with a through hole for the locking element, with two protrusions for the grooves of the cup and a centralizer of the cup on the working end, with an external hexagon for the handle on the opposite end. Wrench for the nut - a cylindrical sleeve with a through hole for the locking element and for the key of the lock nut, has an internal hexagon for a nut at the working end, an external hexagon for the handle at the opposite end, is equipped with a removable wrench. The key for the lock nut is a cylindrical sleeve with a through hole for the locking element, with two protrusions for the lock nut grooves on the working end, with an external hexagon for the handle on the opposite end. The breaker of the outer end of the locking element is made in the form of a cylindrical sleeve.

A device for fixing fractures of the femoral neck works as follows. After reposition of the fracture under the control of the image intensifier (or X-ray control), 2-3 Kirschner spokes are carried out for reference and provisional fixation. A soft tissue incision is made up to 1.5 cm long in a correctly located knitting needle. On the selected spoke cannulated drill using a drill perform a bone channel to the fracture line. Using a cannulated drill as a conductor, a channel for a glass is made with a countersink. The cannulated drill and the countersink are removed, and the fixing element of the device is introduced into the femoral head through the channels made. On it, as in a conductor, a glass key is screwed into a bone canal prepared for it. At the outer end of the locking element, a spring is placed in the glass, which is fully compressed and its position is locked with a lock nut. A breaker is put on the outer end of the locking element, the protruding end is bent several times and breaks off, shortening along the notch closest to the outer edge of the locknut. End the intervention by applying two sutures to the skin.

Thus, the proposed method for the osteosynthesis of femoral neck fractures using the device of the proposed design allows for stable osteosynthesis in accordance with the principle of active fixation by contraction, which simplifies the operation and reduces the duration of its implementation, while increasing the reliability of fixing the device in the femoral head.

Information sources

1. Muller EM, Allgover M., Schneider R., Willinger X. Guide to internal osteosynthesis. Ad Marginem, 1996.

2. Barraud G.W., (1982) De la stabilite des osteotomies spiroiddes in vitro fixees par differennts vissages avec ou sans plaque de protection. Inaugural dissertation, University of Bern.

3. Charnley I.I. I Bone Joint Surg 1956; 38-B: 772.

4. Rodin Ya.N., Kositsina A.M., Reshetnikov N.P. Our method of surgical treatment of medial femoral neck fractures using compression osteosynthesis. Materials of the 1st congress of traumatol. and orthopedist. USSR, Moscow: 1963, p. 158 - 159.

5. Stetsula V.I., Staheev V.I. The role of contact and pressure in reparative bone regeneration. Questions restored. surgery, traumatol. and orthopedist. Sverdlovsk Research Institute of Injuries, and Orthopedics., Vol. 9, 1964, p. 488 - 450.

6. Kovalenko T.N., Sysenko Yu.M., Kaminsky A.V. Devices for osteosynthesis of fractures of the proximal femur (review of patent literature). The genius of orthopedics 2001; 4: 124-128.

7. Seppo A. Metallic osteosynthesis of bone fractures based on exact clinical and technical sciences. Tallinn: Periodicals, 1978.

8. Voitovich A.V., Shubnyakov I.I., Parfenov S.G. et al. A review of the treatment of patients with fractures of the proximal femur. Thes. Report of the VI Congress of Traumatologists and Orthopedists of Russia - N. Novgorod, 1997. - P.370.

9. Rogmark S.S., Carlsson E., Johnell O., Sernbo I. A prospective randomized trial of internal fixation versus arthroplasty for displaced fractures of the neck of the femur. Functional outcome 450 patients at two years. J Bone Joint Surg [Br] 2002; 84-B; 183-8.

10. Mityushov E.A., Berestova S.A. Theoretical Mechanics: Statics. Kinematics. \\ Lecture notes. - Yekaterinburg, 2003 ″ Ed. UMTS UPI ″ 79 s.

11. Patent for invention No. 2350293 of the Russian Federation MCP A61B 17/56. The method of osteosynthesis of femoral neck fractures / G.B. Shugol, S.L. Demakov (RF) Decl. 04/18/2006; Publ. 03/27/2009. Bull. No. 9.

12. Patent for invention No. 2280416 for the invention of the Russian Federation IPC 7 A61B 17/56. A device for fixing fractures of the femoral neck / G.B. Shugol, S.L. Demakov, S.I. Fominykh, Yu.S. Shilov (RF). - Declared. 03/24/2004; Publ. 07/27/2006. Bull. No. 21.

Claims (2)

1. The method of osteosynthesis of femoral neck fractures, including reposition of the fracture, fixation of fragments by a device for fixing femoral neck fractures that supports the load, characterized in that the device for osteosynthesis of femoral neck fractures according to claim 2, so that when introduced, the fixing element is located under the junction a large spit in the femoral neck, at an obtuse angle to the plane of the fracture, open outwards and downwards, at the maximum distance from the lower contact point of the bone fragments, providing active fixation of the contraction eat. 2. A device for fixing fractures of the femoral neck, containing a spring, a locking element, a spring retainer, a support cup under the spring, characterized in that the device is equipped with a lock nut to fix the position of the spring retainer, the locking element is made in the form of a rod, the inner end of which has feather sharpening and three to four turns of a self-tapping screw-type thread, the cutting edge of the thread turning closest to the sharpened end of the rod being serrated, and the outer end of the rod 2/3 of the length of the rod has a thread and two rows transverse notches, the support cup under the spring is made with an external thread.

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