WO2005082263A1

WO2005082263A1 - Device for fixation of femur fractures

Info

Publication number: WO2005082263A1
Application number: PCT/SE2005/000240
Authority: WO
Inventors: Magnus HÖGSTRÖM
Original assignee: Hoegstroem Magnus
Priority date: 2004-02-26
Filing date: 2005-02-22
Publication date: 2005-09-09
Also published as: SE0400470D0; SE526560C2; SE0400470L

Abstract

Device for percutaneous fixation of a first and a second angularly opposing bone parts to each other in case of a bone fracture, comprising an elongated plate (1) with a head (2) angled to the plate (1), the angle of which is chosen in relation to the angle between the bone parts, a means (15) of positioning the plate (1) to rest against the bone part, whereby in the plate (1) is arranged holes (5) for receiving retaining screws (6) to fix the plate (1) to one of the bone parts and a hole (7) to receive a sliding screw (20) for fixing one bone part to the other bone part. Means of positioning comprising an elongated guide and control handle (15) with detachable means (12, 13) of fastening the handle (15) to the plate (1), whereby the said means of positioning (15) in conjunction with the plate (1) offers a guide for applying the said screws (6) to one of the bone parts and a drill for drilling a hole through both bone parts into which a sliding screw (20) is applied.

Description

Device for fixation of femur fractures

The present invention concerns a device for fixation of a hip joint in case of hip fractures as described in the preamble to claim 1. Osteoporotic fractures and in particular hip fractures are a major medical problem that is increasing. Hip fracture is a diagnosis that is currently engaging the largest proportion of bed days and together with stroke is the diagnosis that causes the highest costs within hospital services. The two most common types of fracture, which account for around 95% of hip fractures, are cervical and trochanteric fractures respectively. Cervical fractures are breaks to the neck of the femur, i.e. breaks to the short section joining the head of the femur with the shaft of the femur. Trochanteric fractures are breaks to the transition between the neck of the femur and the femur itself. Trochanteric fractures are a more serious break with more bleeding and are more difficult to rectify but heal better because the fracture surfaces are larger. Present methods of stabilising a fracture are the use of the gamma nail and CHS (Compression Hip Screw). Gamma nails are used for approximately 5% of fractures and involves a nail being inserted through a small incision in the skin and into the bone marrow cavity. A sliding screw is then inserted through the femur and through the neck of the femur and the nail plus two transverse screws, with the help of a special alignment instrument The advantages of this method are that it provides a stable fixation, a short lever arm, little bleeding and minor incisions in skin and muscle. Disadvantages are that it is perceived as difficult by those performing the surgery and that the method has been associated with serious complications such as splitting of the femur when the nail is struck into the marrow cavity of the femur. CHS is a commonly used method with a sliding screw and a plate with a sliding sleeve. Initially, an incision is made in the skin and muscle to the outside of the femur. With the help of an angle guide, a guide pin is drilled in from the femur through the neck of the femur and into the head of the femur. The position of the guide pin is verified through fluoroscopy, e.g. X-ray. A channel is subsequently drilled coaxially to the guide pin and a screw mounted in it. The plate with its sleeve and the sliding screw is the fitted resting against the femur and is screwed onto the femur, after which the fixation is complete. The advantage of this method is that it provides a stable fixation, a dynamic compression of the fracture area and it is a simple procedure to learn. The disadvantage of this method is that when the plate is applied, a relatively large incision must be made in the skin and muscle, around 20 cm long, which can cause extreme bleeding, risk of infection and a longer time required for healing and rehabilitation. The object of the present invention is to relieve these failings with a device and a method that combine the advantages described above and exhibit stable two-point fixation of the plate at an early stage of surgery and the insertion of the plate through a relatively small incision in the skin. This object can be attained with a device exhibiting a plate with guide handle that acts both as a handle for inserting the plate underneath the muscle and an aligning instrument both for the bone screws and for a sliding screw through a relatively small incision in the skin and a detachable sliding sleeve fastened to the plate. One embodiment chosen as an example will be described in the following with reference being made to the attached drawings, of which: fig. 1a shows a plan view of a plate according to the invention, fig. 1 b shows the cross section A-A in figure 1 a viewed from the front, fig. 1c shows the side view of a plate according to figure 1a, fig. 1d shows a sliding screw fig. 2a shows the front elevation of a locking and sliding sleeve, fig. 2b shows the front elevation of the locking and sliding sleeve from figure 2a rotated 90 degrees around its centre axis, fig. 2c shows a plan view of the locking and sliding sleeve from figure 2a and 2b, fig. 3 shows the front elevation of a guiding and aligning handle, fig. 3b shows the guiding handle from behind and fig. 4 shows a plate from figure 1 joined with a handle from figure 3 with lines indicating the direction of the screws, a protective sleeve and a retaining screw. The device shown in figure 1 comprises a means of fixation in the form of an elongated plate 1 of a length greater than its width. On one short side is arranged a means of coupling with a material enlargement in the form of a head 2 angled away from the plate 1. The magnitude of the angle varies between 135° and 150° depending on the angle in question between the patient's femur and the neck of the femur but can naturally be given other angles as well. The other end of the plate 1 in figures 1A and 1C has been given a somewhat tapered shape in the form of a point 3 but in another embodiment can have an abruptly squared-off end, which is indicated by the line denoted X in figures 1A and 1 C. The advantage with a tapered shape is that positioning using fluoroscopy, X-ray for example, is facilitated. The advantage of an abruptly squared-off shape is that the plate can be guided to follow the shaft of the bone in a more certain manner when the plate is inserted under the skin. The plate in both embodiments becomes thinner towards the other end, forming a nose that is easy to insert under the skin between the bone and the muscle. The bottom of the plate 4, i.e. the side intended to rest against the bone, is somewhat dished or arched to follow the shape of the femur when the plate is moved inward/downward through the incision. The plate is provided with a number of through holes

5 intended to receive screws 6 for fastening the plate 1 to the bone. The number of holes 5 may vary from two to ten, depending on the length of the plate 1 , and are situated symmetrically at a distance from each other on each side of a plane running through the dish of the plate and an imagined centre axis of a circle that gives the dished shape. Furthermore, the holes are somewhat angled in towards the plane, which make the screws being screwed through the hole and into the bone go through the centre line of the bone or close to its centre line. The head 2 of the plate 1 has a through hole 7 with a shoulder 8 to receive a means of fastening 9 and a locking sleeve 10. The locking sleeve 10 according to figure 2 has a flange-like collar 11 at one end and the head 2 of the plate 1 has a groove 12 inside the through hole of a form corresponding to the collar 11 of the locking sleeve 10, this groove and collar forming a bayonet fastening. The material enlargement of the head gives the through hole a long surface of contact with the sleeve and thereby a high degree of directional stability for the means of fastening that is inserted through the hole and the sleeve. In conjunction with the mouth of the through hole that opens away from the bone is arranged a depression 13 for a locking pin 14. In another embodiment, the plate is intended to be able to take up axial movement of the bone. The plate comprises a first part, which in a longitudinal direction is slide mounted in a second part, i.e. the plate can be lengthened and shortened. The handle 15 shown in figure 3 exhibits a through hole or channel 16 parallel to or coinciding with the longitudinal axis of the handle 15. On one end of the handle is arranged a collar 17 with an inside diameter corresponding to the diameter of the through hole. The outside diameter of the collar has been dimensioned to correspond to the through hole 7 in the head 2 of the plate 1. The transition between the collar and the handle is terminated with a flange 18 with a form and size corresponding to that of the collar 11 of the locking sleeve 10. The handle 15 has a number of holes 19 situated symmetrically along the length of the handle. The number of holes is determined by the number of holes in the plate 1. The holes 19 in the handle are somewhat angled in the same manner as in the plate so they coincide with the direction the screws 6 take through the centre line of the bone. Finally, the handle 15 has a spring-loaded locking pin 14 that is intended to slide into the depression 13 in the plate when the handle and plate are fitted together by means of the bayonet fastening, i.e. the flange on the handle and the groove in the head. When the handle has been fastened to the plate by turning the bayonet fastening as shown in figure 4, the two parts will form an angle corresponding to the angle of the patient's bone. Thanks to the locking pin on the handle and the depression in the plate, the through holes in the handle and plate respectively will be directed towards each other when the handle is turned into position in the head of the plate. The size of the through hole in the handle and the head of the plate is adapted to receive a guide sleeve (not shown) for a guide pin (not shown). The tilt of the handle in relation to the plate and the guide sleeve give the guide pin the desired direction when it is inserted through the handle, plate and bone. The guide pin is used partly to lock the device initially when assembling and partly to guide the drill (not shown) that is used to drill a hole in the bone and neck of the femur to receive the sliding screw 20. The hole is drilled with a stepping drill once the guide pin guide sleeve has been removed, whereby the drill is passed over the guide pin and driven through the bone. The device furthermore comprises a sliding screw 20 that is screwed into the bone.

If the bone into which the screw is screwed is hard, it may be necessary to thread it first using a screw tap (not shown). The threaded part of the screw is shorter than the shaft 21. The shaft is cylindrical but has ground flats on two sides. The locking sleeve has been given an opening 22 the shape of which corresponds to the shaft of the screw in order to prevent it from turning but still allow it to move axially. One end of the locking sleeve has a rounded bevelled edge 23 for easy entry into the hole drilled into the bone. The other end of the locking sleeve has a threaded section 24 to suit a tool (not shown) for the insertion of the locking sleeve into the bone and for turning the sleeve to position the bayonet fastening. In another embodiment, a nail with extendable wings or flaps is struck into the hole drilled in the bone, whereby the wings or flaps are extended to prevent the nail from sliding out of the hole in the bone. The shaft of the nail is designed in the same manner as the screw, which allows for an axial movement of the nail in the locking sleeve. The aforesaid bayonet fastenings can be replaced with threaded connections or with another means that will prevent rotation. The arrangement works as follows: the angle of the femur in relation to the neck of the femur is determined through fluoroscopy. A plate is chosen with a head that has an angle corresponding to the angle of the neck of the femur. The fracture is repositioned with the fracture surfaces matching each other, after which the leg is fixed with a frame. A handle adapted to the head angle of the selected plate is placed against the head of the plate. The collar of the handle is inserted into the through hole in the head of the plate and pressed in place. When the collar stops against the shoulder inside the hole, the handle is turned around its longitudinal axis, whereby the flange on the handle will move inside the head of the plate. When the rotation continues, the locking pin will slide towards the depression in the plate until it finally slides into the depression. When the spring-loaded pin is in the depression, the handle is locked to the plate as shown in figure 4. An incision the same size as the cross section of the plate or somewhat larger than the cross section is made in the skin and muscle of the patient's thigh level with the bone fracture. The free end of the plate is inserted into the incision through the skin and muscle by means of the handle to a position where the end of the plate meets the bone. The plate is then pressed downward using the handle so that its free end slides along the bone shaft, femur, and the plate is angled increasingly in towards the bone to finally rest completely against the shaft of the bone with the dished side facing the bone. The dished shape of the plate and the bevelled nose mean the plate can be moved behind the muscle in a simple manner and in this way located between the shaft of the bone and the muscle tissue. Once the plate has been located in this way, its position can be verified in relation to the bone through fluoroscopy. The position can be adjusted as necessary by moving the handle appropriately. Once the desired position has been attained, the guide sleeve for the guide pin is placed in the handle. The guide pin is drilled into the shaft of the bone all the way through the neck and head of the bone. The guide pin is subsequently locked in the handle with a means of locking (not shown). At this stage, the distance the guide pin has entered the bone is measured using a measuring rod and determines how long the drill should be. The plate is now locked in the longitudinal direction of the bone. Another small incision is then made in the skin and muscle at the same level as the hole that is closest to the free end of the handle. A protective sleeve 25 in the form of a pipe is inserted, viewed from the outside and in toward the bone, through the hole in the handle, through the skin and muscle, and against the plate. The sleeve 25 when inserted has an inner part that tapers to a point to facilitate its passage through the muscle tissue. Thanks to the holes in the handle and the plate being adapted to correspond to each other, the protective sleeve will meet the holes in the plate when the sleeve is inserted through the handle. After pilot drilling through the adapted sleeve 25, after the sleeve has been taken out, a screw 6, which can be self-tapping, is screwed in using a screw driving device such as a screwdriver through the protective sleeve and into the shaft of the bone. Alternatively, a screw tap and standard screw can be used. This drilling and threading is done through the protective sleeve. The protective sleeve prevents the screw threads coming in contact with skin and tissue to avoid damage and to facilitate the fitting of the screw into the hole in the plate, as the plate is under the skin and not visible from outside. Once this has been carried out, the plate, and thereby the handle, will also be locked transversely. With this, a stable drill rig has been attained for the preparation of drilling for the sliding screw. To further stabilise the device, the remaining screws are screwed in through the plate and bone in the manner described above with the help of protective sleeves. The guide pin is subsequently removed from the handle together with the guide sleeve and a stepping drill of standard type is inserted into the handle. The stepping drill has two diameters, one smaller with its free end adapted to suit the dimension of the screw, and one larger at the other end that is fastened in the drilling machine and is adapted to the plate's locking sleeve and can be adapted to different lengths of sliding screw. Once the necessary drilling depth, which was determined through measurement, has been attained, the drill is removed and the sliding screw screwed in using a screwdriver especially adapted for the purpose. When the screw has reached the bottom of the hole, the handle is removed and the locking sleeve subsequently fitted using a spanner with a threaded section that suits the threaded section of the sleeve. Once the sleeve has been fastened with its bayonet fastening using the spanner, the screw can slide in an axial direction but is prevented from turning. The spanner is removed once the sleeve has been locked, after which the process is completed by suturing the incision that was made in the skin and muscle for inserting the various components. The device described above refers to the fixation of a fracture to the neck of the femur, a cervical fracture, a fracture to the join between the femur and the neck of the femur, a trochanteric fracture, or even a subtrochanteric fracture, i.e. a fracture to the transition between the join and the neck of the femur. The device can also be used to stabilise and fixate a fracture of the bone in conjunction with the knee joint, a suprachondylar fracture to the knee. The angle between the plate and the head of the plate has been changed to about 95°. The application of the plate when used for this purpose is done in the manner described above. The locking between the head of the plate and the locking sleeve and handle respectively can be designed in a number of different ways. A bayonet fastening has been described for the embodiments described above, whereby the parts are screwed together with a groove and a flange. It should be understood that other means of fastening can be used, for example threads in both parts for joining them together, and also a lock washer or other sprung locking ring can be used. In the above description, a sliding screw mounted in a sleeve is used to allow the fracture surfaces to move in relation to each other. In certain cases, a compression screw can be used that is screwed into the end of the sliding screw and rests against the tube sleeve, whereby both parts of the fracture are pressed together by the force of the screw pulling the loose part of the bone against the part on which the plate is fastened. The plate can be made with an extension that passes the head of the plate in a longitudinal direction. This type of plate can be used if the connection between the neck of the femur and the femur itself, trochanter major, has splintered, e.g. in a complicated fracture. When fastening the plate to the femur, this type of plate provides further support for the top of the femur, i.e. the part above the neck of the femur viewed in the longitudinal direction of the bone. A further modification of the plate can comprise an additional screw hole in the head of the plate. This screw hole is intended to prevent rotation of the parts of the bone. Since the plate normally comprises just one hole in the centre of the head of the plate, both parts of bone can gyrate in relation to each other due to the relatively high torque that arises when screwing in the sliding screw. The bone parts are usually locked to prevent rotation with the help of the rough fracture surfaces. However, the rotation stability of, for example, a fracture at the neck of the femur can be too weak to prevent the bone parts from rotation relative to each other. This can be prevented by screwing in a screw parallel to the centre screw, preferably a screw of smaller dimension than the sliding screw, after which the sliding screw can be screwed in. The present invention is not limited to the above description and as illustrated in the drawings but can be changed and modified in a number of different ways within the framework of the idea of invention specified in the following claims.

Claims

Claims 1. Device for percutaneous fixation of a first and a second angularly opposed bone parts to each other in case of a bone fracture comprising an elongated plate (1) with a head (2) angled to the plate (1 ), the angle of which is chosen in relation to the angle between the bone parts, a means (15) of positioning the plate (1 ) to rest against the bone part, whereby in the plate (1 ) is arranged holes (5) for receiving retaining screws (6) to fix the plate (1) to one of the bone parts and a hole (7) to receive a sliding screw (20) for fixing one bone part to the other bone part, c h a r a c t e r i s e d in that the means of positioning (15) comprises a continuous guide and control handle with a means (12, 13) of detachable fastening of the guide handle to the plate (1 ) whereby the said means of positioning (15) in conjunction with the plate (1) offers a guide for applying the said screws (6) to one of the bone parts and a drill for drilling a hole through both bone parts into which a sliding screw (20) is applied.

2. Device according to claim 1 , whereby the guide handle (15) comprises holes (19) situated along its length that are angled in relation to the longitudinal axis of the guide handle (15) for guiding the retaining screws (6) essentially at right angles to one bone part through the guide handle (15) and the plate (1).

3. Device according to claim 1 , whereby the guide handle (15) is arranged with a channel (16) that is parallel to the longitudinal axis of the handle (15) and intended to receive an elongated guide pin and a drill for drilling the hole into which the sliding screw (20) is screwed.

4. Device according to claim 3, whereby the drill is inserted coaxially with the guide pin when drilling the hole.

5. Device according to any one of the previous claims, whereby the drill comprises a stepped bit with a first diameter adapted to the sliding screw (20) and a second diameter larger than the sliding screw (20).

6. Device according to claim 3, whereby a detachable locking part can be fastened to the guide handle's channel for fixing the guide pin in a longitudinal direction.

7. Device according to any one of the previous claims, whereby a detachable means of sliding and locking (10) can be fastened to the head (2) of the plate (1) to prevent the rotation of a shaft (21) arranged on the sliding screw (20) but allows an axial movement of the sliding screw (20).

8. Device according to claim 7, whereby the means of sliding and locking (10) comprises a sleeve with an opening (22) through which the shaft of the screw (21 ) can run.

9. Device according to any one of the previous claims, whereby the means of sliding and locking (10) with the guide handle (15) and the head of the plate (2) respectively are arranged with detachable means (11, 12) of fastening one to the other.

10. Device according to any one of the previous claims, whereby the means comprises a flange (11 , 18) and a groove (12) respectively arranged on the means of sliding and locking (10) with the guide handle (15) and the head of the plate (2) respectively to provide a rotary lock of one with the other.

11. Device according to any one of the previous claims, whereby at least one guide sleeve (25) can be inserted into the hole (19) in the guide handle (15) to guide the plate's (1) retaining screws.

12. Device according to any one of the previous claims, whereby the side of the plate (4) facing one of the bone parts is adapted to the shape of that bone part.

13. Device according to any one of the previous claims, whereby the side of the plate (4) facing one of the bone parts is concave.

14. Device according to any one of the previous claims, whereby the guide handle (15) and the head of the plate (2) respectively comprise a means of locking (13, 14) that prevents the guide handle (15) from rotating after it is mounted in the head (2) of the plate (1 ).

15. Device according to any one of the previous claims, whereby the guide handle (15) comprises means of adjusting the angle between the guide handle (15) and the plate

(1 ).

16. Device according to any one of the previous claims, whereby the plate (1) comprises means of adjusting the angle between the guide handle (15) and the plate (1 ).

17. Device according to any one of the previous claims, whereby the material at one end of the plate (1) tapers off into a point (3).

18. Device according to any one of the claims 1 - 14, whereby the material at one end of the plate (1) thins to an abruptly squared-off end to form a nose.

19. Device according to any one of the following claims, whereby the head (2) of the plate comprises an additional hole intended to receive a screw for locking the relative rotation of the bone parts.

20. Device according to any one of the previous claims, whereby the plate (1) extends past the head (2) in a longitudinal direction on either side of the head (2).