FR2646596A1 - Femoral prosthesis system - Google Patents

Abstract

The system according to the invention comprises a base prosthesis 1 comprising a tapering cone, a wide shoulder for bearing on the diaphysis and a prosthesis stem 4, and a set of spacers 9 of various sizes which can be inserted and fixed on the stem 4 of the base prosthesis 1, under the seat of the said shoulder, in order to allow the base prosthesis 1 to bear at different levels of the diaphyseal shaft. The prosthesis system can also comprise a claw 19 for fixing the trochanter process in the anatomical position in the case of trochanterotomy. The prosthesis system according to the invention is of advantage for all the complex problems affecting the upper end of the femur.

Description

FEMALE PROSTHESIS SYSTEM
The present invention relates to a femoral prosthesis system and, more particularly, to a prosthesis system for solving all the problems posed by complex cervico-trochanteric, subtrochanteric, or even basi-cervical fractures, as well as all tumor problems or complex resumptions requiring a significant resection of the upper end of the femur.

 The problems are currently very well resolved for all true cervical fractures, for which there are a large number of prostheses called "cephalic prosthesis" simple, totalizable or total.

 On the other hand, for cervico-trochanteric and sub-trochanteric fractures, the only current possibilities are those of osteosynthesis by various systems of which the nail-plate is the most widespread.

 The most common victims of femoral neck fractures are the elderly. For true cervical fractures, the intervention with prosthesis fitting is particularly suitable for the elderly since it allows a resumption of walking quickly, generally around the 48th hour post-operative, fully justifying the risk taken.

 On the other hand, for cervico-trochanteric and sub-trochanteric fractures, osteosynthesis, if it allows rapid mobilization, does not allow walking with support for a month and a half to two months, which goes against the goal surgical risk taking, especially in the elderly.

 An object of the invention therefore consists in providing a prosthesis system making it possible to cope with any fracture situation of the upper end of the femur and allowing the resumption of walking from the 48th hour post-operation.

 Another object of the invention consists in providing a prosthesis system which is integrated into the existing ranges and compatible with "Muller" type material, in order to limit the stocks of material and the costs.

 According to the invention, said system comprises a basic prosthesis comprising a morse cone, a wide shoulder for bearing on the diaphysis and a prosthesis tail, and a set of spacers of various sizes which can be inserted and fixed on the tail of the basic prosthesis, under the base of said shoulder, to allow said basic prosthesis to bear at different levels of the diaphyseal barrel, after cutting according to the fracture or the lesion.

 According to another characteristic of the invention, the tail of the basic prosthesis has a rectangular section, at least in its upper part, as well as the internal hollow of the spacers which are open towards the rear to be inserted from before back on the prosthesis tail.

 According to another characteristic of the invention, the spacers are fixed to the tail of the prosthesis by screws which can be screwed on the anterior side or on the posterior side of the spacer, depending on the laying side or the ease of first intraoperatively.

 According to another characteristic of the invention, the faces of the base of said shoulder of the basic prosthesis are inclined, rising upwards towards the outside, as are the lower and upper faces of the spacers, the angles of inclination of the faces of said base and the angles of inclination of the corresponding lower and upper faces of the spacers being equal.

 According to another characteristic of the invention, the prosthesis tail has a straight profile in an anteroposterior plane.

 According to another characteristic of the invention, at least the lower part of the prosthesis tail has longitudinal grooves.

 According to another characteristic of the invention7 the prosthesis system further comprises a plate-shaped claw with two upper hooks, said plate comprising a hole for receiving a fixing screw intended to enter a tapped hole in the shoulder of the basic prosthesis, said claw serving to fix the trochanteric medallion in anatomical position in the event of a trochanterotomy.

 According to another characteristic of the invention, the prosthesis system is made of titanium.

The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, made in relation to the accompanying drawings, among which:
Fig. 1 is a side view of a basic prosthesis according to the invention,
Fig. 2 is a front view of the basic prosthesis of FIG. 1,
Fig. 3 is a perspective view of a spacer according to the invention,
Fig. 4 is a top view of the spacer of FIG. 3,
Figs. 5a to 7a are respectively front views of spacers of different sizes according to the invention, and Figs. 5b to 7b are respectively sectional views along lines XX of Figs. 5a to 7a,
Fig. 8 is a top view of a claw for fixing the trochanteric medallion according to the invention,
Fig. 9 is a sectional view of the claw along the line IX-IX of FIG. 8,
Fig. 10 is a front view of the claw of FIGS. 8 and 9,
Fig. 11 is a schematic view showing the basic prosthesis of FIGS. 1 and 2 placed in a femur with conservation in place of the greater trochanter, and
Fig. 12 is a schematic view similar to FIG. 11, but showing the basic prosthesis, with spacers and a claw for fixing the trochanteric medallion, in place in a fully sectioned femur below the greater trochanter.

The basic prosthesis 1, shown alone in Figs. 1 and 2, conventionally comprises a morse cone 2, a shoulder 3 and a prosthesis tail 4. In practice, the morse cone 2 is a universal morse cone which has the advantage of allowing the use of several systems of head. It also allows mounting as
Moore without totalization, respecting the diameter of the anatomical head, as well as a totalization in one step, or secondary, without retouching the femoral part.

 The shoulder 3 has a base which clearly protrudes from the front faces and the lateral faces of the prosthesis tail 4. In the following description, the lateral sides of the prosthesis will also be called anterior side and posterior side due to their anatomical position. As for the rear face of the shoulder 3, it is practically in alignment with the rear face of the prosthesis tail 4.

 The front and lateral lower faces of the base of the shoulder 3 form inclined faces, respectively 5, 6 and 7, in a downward slope towards the prosthesis tail 4. In the embodiment shown, the lateral or anterior sides and posterior 6 and 7 are narrower than the front panel 5. They are therefore slightly more inclined than the front panel 5. Their angle of inclination with respect to the horizontal is satisfactorily about 220 while the angle of inclination of the front face is approximately 150. The inclination of the base of the shoulder 3 has a double advantage: it ensures better impaction, better centering and progressive support of the prosthesis on the diaphyseal barrel, with good adaptation whatever the diameter of the diaphyseal barrel. It also contributes to better adaptation and greater mechanical strength of the spacers which are placed below the shoulder, as will be seen below.

 In the upper part of its rear face, the shoulder 3 comprises an inclined tapped hole 8, oriented forward in the median plane of the prosthesis 1. The tapped hole 8 is intended to receive a fixing screw for an annex element of the prosthesis system, namely a claw for fixing the trochanteric medallion which will be described later.

 The prosthesis tail 4 has an upper part 4a intended to optionally admit one or more spacers, described below, and a lower part 4b intended for anchoring in the femoral barrel.

 The upper part 4a is rectilinear and has a uniform rectangular section. In a satisfactory embodiment, its length is approximately 6 cm, but it can of course be longer or shorter.

 The lower part 4b of the prosthesis tail 4 has a section which is also rectangular, but which decreases downwards. The projection of part 4b in an anteroposterior plane is rectilinear, while in a lateral plane, it has a slightly curved shape, or anatomical shape, which recalls the curvature of the medullary canal of the femur. Thus, the same basic prosthesis can be used both for a right femur and for a left femur. Preferably, the lower part 4b has longitudinal grooves, not shown in the drawings, in order to avoid rotation in the diaphyseal barrel. Optionally, said grooves may extend over the upper part 4a of the prosthesis tail.

 The spacers 9 are shown in Figs. 3, 4, Sa at 7a and 5b at 7b. They have a general rider or U shape, with a front part 10 and two wings 11 and 12. As shown better in FIG. 4, the spacers 9 define between their front part 10 and their wings 11 and 12 a hollow, the retangular profile of which, seen from above, has the same dimensions as the section of the upper part 4a of the prosthesis tail 4.

 On the other hand, the upper face 13 of the front part 10 of each spacer has the same inclination and the same width as the front face 5 of the base of the shoulder 3. Similarly, the upper faces 14 and 15 of the wings 11 and 12 have the same inclinations and the same widths as the side panels 6 and 7 of the shoulder 3. The lower face of the front part 10 is parallel to its upper face 13 and the lower faces of the wings II and 12 are parallel to their upper face, respectively 14 and 15. All the other faces of the front part 10 and of the wings 11 and 12 are vertical, and the end faces 16 and 17 of the wings 11 and 12 are in the same plane, perpendicular to said wings 11 and 12.

 As shown in Figs. Sa to 7a and 5b to 7b, the spacers 9 form a set of three different sizes. In a satisfactory embodiment, the heights hl, h2 and h3 of the vertical faces of the different spacers are respectively 1 cm, 2 cm and 3 cm.

 The spacers 9 are mounted on the upper part 4a of the prosthesis tail 4, their front face being placed under the front panel 5 of the shoulder 3. They are fixed by means of screws which are engaged in tapped holes 18 in the wings 11 and 12 of the spacers, and the ends of which are forcibly supported on the lateral faces of the part 4a, or penetrate into receiving recesses provided for this purpose - in said lateral faces. Preferably, the holes 18 in the wings 11 and 12 are inclined. In practice, they are parallel to the upper and lower faces of the wing 11 or 12 in which they are located. In the embodiments shown, the small spacers have a single hole 18 in each wing, FIG. 5b, the intermediate dimension spacers two superimposed holes 18 FIG. 6b, and the large spacers three superimposed holes 18, FIG. 7b. As the two wings of each spacer 9 have holes 18, there is the possibility of screwing on the anterior side or on the posterior side of the spacer, depending on the laying side or the ease of operation first.

 It thus appears, as shown in FIG. 11, that one or more spacers can be placed under the base of the shoulder 3, ie two spacers in FIG. 11. The upper front and side faces of the upper strut fit under the inclined faces 5, 6 and 7 of the shoulder 3, while the upper faces of the lower strut fit under the lower faces of the upper spacer. The length of the wings 11 and 12 of the spacers 9 is such that their rear edge is in the plane of the rear face of the prosthesis tail 4. Thus, the lower faces of the lowest spacer on the prosthesis tail 4 reproduce the inclined sections of the shoulder 3 which are conducive to good support of the prosthesis on the femoral barrel, FIG. 11.Using various combinations of spacers of different sizes, you can lower the base of the shoulder 3 by 1, 2, 3, 4, 5 or 6 cm and thus respond to all cases of fracture or injury to the part superior of the femur. As already mentioned, the inclination of the faces of the base of the shoulder 3 and of the lower and upper faces of the spacers 9 ensures better adaptation and greater mechanical strength of the spacers 9 which are put in place.

The fixing claw 19 shown in FIGS. 8 to 10 is in the form of a curved plate 20, of general shape in an isosceles triangle, the base of which has a notch 21 between two legs 22a and 22b whose free ends form hooks 23a and 23b directed outwards from the concave face of the plate 20. The top of the triangle opposite the notch 21 also forms a hook 24 oriented like the hooks 23a and 23b. On the other hand, the plate 20 has a substantially central hole 25 allowing the passage of a fixing screw ~ received in the threaded hole 18 of the shoulder 3. The claw 19 is used to hold in place the trochanteric medallion in case of operation with trochanterotomy, as shown in
Fig. 12, the hooks 23a and 23b being positioned upwards and the hook 24 downwards. It will be noted that embodiments of the claw 19 can be designed without the hook 24, the latter not being absolutely essential, although that advantageous in practice.
It will also be noted that the claw 19 can be used on its own for isolated trochanter fractures. A conventional bone screw will then be used to fix the claw 19, the hole 25 in the plate 20 being provided for this dual use.

 The main indication of the prosthesis system of the invention is the per-trochanteric fracture, or short oblique sub-trochanteric fracture, or multi-fracture, and it can be used for fracture lines up to about 10 cm from the summit of the lesser trochanter.

 The other indications are tumor affections of the upper extremity of the femur requiring diaphyseal resections and complex resumptions of fractures associated with a cephalic prosthesis or a major problem of osteoporosis, for example.

 To place such a prosthesis, we first study the measurements, on a radio of the pelvis showing the two femoral diaphyses, in order to have an idea of the fractured diaphyseal length that will have to be replaced. A reference point - extreme point of the fracture, for example - is transferred to the healthy side and makes it possible to take the measurement.

Then, in lateral decubitus, by posterior external route, with approach to the posterior joint according to
Moore or others, we remove all the fractured cephalic and cervical elements after arthrotomy, keeping as much of the capsule as possible on the acetabulum.

If the type of fracture allows, it is best to keep the greater trochanter in place, as shown in Fig. 11. Otherwise, we do a trochanterotomy using more or less the existing fracture lines, and preserving the muscle continuity as much as possible: vast external - gluteus medius (trochanteric medallion).

 The measurement noted previously on the diaphysis makes it possible to predict the level of diaphyseal cutting, the number and the height of the spacers 9 to be used. The diaphyseal cut, perpendicular to the barrel, is made in the conventional way with an oscillating saw. It is followed by a rasp bore until you can admit the prosthesis tail 4. You can prepare the acetabulum if you need to total the prosthesis, and put it in place by sealing, screwing or impacting it .

 After the gesture on the acetabulum if necessary, or directly after the diaphyseal cut and the rasp bore in the other cases, the prosthesis tail 4 is put in place with the spacer or the number of spacers required 9 to make up for the length.

We then proceed to integration into the acetabulum with a test head to find the length of the neck required. In general, there is a choice between a short collar, a medium collar or a long collar. Once the choice of the collar is made, we seal the prosthesis with cement 26,
Figs. l1 and 12, respecting a fairly marked anteversion
It then remains to carry out the positioning of the chosen head, the reintegration into the natural or artificial acetabulum, the repositioning, if necessary, of the greater trochanter using the claw 19 provided for this purpose, then the closure on suction drain, generally of the Redon type. Charging can take place from the 48th hour, after a radio control.

 If this type of prosthesis system is proposed mainly for pertrochanteric and subtrochanteric fractures, it can also be used in oncology (reconstruction prosthesis), and when all these cases are complicated by hip osteoarthritis, be totaled.

It is therefore of interest for all complex problems of the upper end of the femur.

 The advantages of such a prosthesis system are manifold. First, the principle of a fracture replacement prosthesis allows the resumption of walking with support from the 48th hour in most cases. On the other hand, this system allows to answer all the problems with a very limited stock the basic prosthesis is unique and is the same for a right or left femur. A basic prosthesis and a set of three spacers therefore makes it possible to cope with all types of fracture, the cephalic or coeyloid part being found in all totalizable prosthesis systems and therefore in the basic stock of any hospital or clinic. In addition, the ancillaries necessary for fitting this prosthesis system are simple: a diaphyseal rasp, Moore type or equivalent; sometimes reamers, Muller type; an impactor for fitting the prosthesis; a single hexagonal screwdriver for screwing the spacers and the trochanter retaining claw; a material for preparing the classic acetabulum if necessary, and the material for installing the artificial acetabulum chosen if there is totalization.

 Preferably, the prosthesis of the invention is made of titanium, a metal which combines mechanical qualities of resistance, elasticity, solidity with great lightness and remarkable biological tolerance.

Claims (9)

 1) Femoral prosthesis system, characterized in that it comprises  - a basic prosthesis (1) comprising a Morse taper  (2), a wide shoulder (3) to rest on  the diaphysis, and a prosthesis tail (4), and  - a set of spacers (9) of various sizes which can  insert and attach to the tail (4) of the  basic prosthesis (1), under the base of said shoulder  (3), to allow said basic prosthesis  (1) to take support at different levels of the barrel  diaphyseal, after cutting according to the  fracture or lesion.  2) femoral prosthesis system according to claim 1, characterized in that the tail (4) of the base prosthesis (1) has a rectangular section, at least in its upper part (4a), as well as the internal hollow of the spacers (9) which are open towards the rear to be inserted from front to back on the prosthesis stem (4).  3) femoral prosthesis system according to claim 1 or 2, characterized in that the spacers (9) are fixed to the prosthesis tail (4) by screws which can be screwed on the anterior side or the posterior side of the 'spacer, depending on the installation side or the ease of operation first.  4) femoral prosthesis system according to one of claims 1 to 3, characterized in that the faces (5, 6, 7) of the base of said shoulder (3) of the base prosthesis (1) are inclined, in rising slope towards the outside, as well as the upper (13, 14, 15) and lower faces of the spacers (9), the angles of inclination of the faces of said base and the angles of inclination of the corresponding upper and lower faces spacers (9) being equal.  5) femoral prosthesis system according to one of claims 1 to 4, characterized in that the prosthesis tail (4) has a straight profile in an anteroposterior plane.  6) femoral prosthesis system according to one of claims 1 to 5, characterized in that at least the lower part (4b) of the prosthesis tail (4) has longitudinal grooves.  7) femoral prosthesis system according to one of claims there 6, characterized in that it further comprises a claw (19) in the form of a plate (20) with two upper hooks (23a, 23b), said plate (20) comprising a receiving hole (25) for a fixing screw intended to enter a tapped hole (8) in the shoulder (3) of the base prosthesis (1), said claw (19) serving to fix the medallion trochanteric in anatomical position in case of trochanterotomy.  8) femoral prosthesis system according to claim 7, characterized in that said claw (19) also comprises a lower hook (24).  9) Femoral prosthesis system according to one of claims 1 to 8, characterized in that its elements are made of titanium.