FR2904530A1 - Total elbow prosthesis for restoring flexion extension and prono supination, has cylindrical body immobilized by two tongues on end of humeral splint, and receiving complete patella by replacement of humero-radial and humero-ulnar joints - Google Patents

Abstract

The prosthesis has a cylindrical body (1) joined on a supporting base and immobilized by two tongues on an end of previously machined humeral splint. The cylindrical body receives a complete patella (16) by replacement of humero-radial and humero-ulnar joints. Two lumens (12, 13) facilitate the passage of exterior pivots (14, 15), which extend the patella and which are respectively immobilized on a head of a radial bone and ulna, where the prosthesis is divided into two for the replacement of one of the joints according to a case.

Description

 The present invention relates to a total prosthesis of the elbow which restores flexion extension and prono-supmat ion.

The elbow is made up of two joints: The humeroulnar ^and humeroradial. Both are supported by a particular articulation, the superior radio-ulna. Plate 1/9. See how the prono-supination actually occurs in the ELBOW chapter on the site: http://genoux.free.fr

The analysis of the pronation movement showed me that it was the result of a simple twist of the radius with the ulna. The movement of supination, which is the opposite movement, is the result of the devilage of the two elements, which are then parallel to each other.

Analysis that also allowed me to discover that the joint that connects Fhumérus ulna is not a trochléenne but a patella because only one side of the trochlea is concerned. More specifically, it is an asymmetric ball joint portion. A trochlean allows a deflection on a single plane, which means that it has only one axis; The twisting of one or more elements necessarily requires three axes. On the other hand, the numeroradial and humero-cubital association, the elbow therefore, forms a trochléenne.

The articulation between humerus and radius is also a kneecap which is also asymmetrical. Inverse reciprocal asymmetries that require the help of the superior radio-cubital ... The radius, which transmits the movement necessary for the prono-supination, drives the ulna through the cupula to compensate for the differences that occur. produce between them during twisting and turning.

In my conclusion on the superior radio-ulna I note that this joint can be removed on one condition ...? Condition that facilitates the development and realization of a total elbow prosthesis.

Simple condition that is obtained by removing the asymmetry of the two joints of the elbow. For this it is sufficient that the humerocubital and rheumo-radial are completely independent, so that each is a complete patella (male element prisoner of the female element) such as the steering knuckles of an automobile.

- the axis of flexion extension proper to the humerus, passes through the center of rheuméroradiale and the center of Thuméro-cubitale, thus the condyle on the outside and the internal slope of the trochlée (Portion of sphere) inside . It is possible and even desirable to maintain one's natural position.

The axis of rotation of radius originates from the center of the condyle which is obligatorily on the axis of flexion extension and ends in the middle of the interscapho-lunar ridge, more simply in the middle of the base of the radius. Its position with respect to the diaphysis is particular because the latter is naturally twisted for a better amplitude of pronation, moreover the neck of the radius is not in The extension of the diaphysis. It is possible to retain here again its natural position.

- The axis of rotation of the ulna originates from the center of the sphere portion represented by the internal slope of the trochlea and which is also obligatorily on the axis of flexion extension, it ends at the center of the cubital head at the lower level. It is not possible to maintain its natural position for lack of space but it can be moved to the upper level in the middle of the diaphysis, so it merges with the diaphyseal axis.

Several situations can occur. Consider the destruction of the articular surfaces of the two main joints. The machining of the elements can be closer to the axis of flexion extension as in the example presented.

Plate 1 / 9. The figures are at scale 1.

The bold lines embody the machining plans on humerus radius and ulna.

The machining of the end of the numeral pallet will be perpendicular thereto and parallel to the axis of flexion extension just to the rear of the condyle and will stop at the boundary between the internal slope of the trochlea and the epitrochlée that must be preserved. The surface produced will be on a plane at about 50 ° to the origin of the pallet and therefore at about 45 ° to the diaphyseal axis of the humerus. The radius will surface pe endiculally to the axis of the neck under the cup, reminding that the upper radiocubital is removed. A second solution will be presented at the end of the chapter.

The ulna can be machined in different ways, two other ways will be presented. In all cases it is necessary to remove the bill of the olecranon and the beak of the coronoid process as the corresponding dimples are used to let through the two tabs that immobilize the element humerai, which removes the essential of the large sigmoid cavity.

Figure 2 and Figure 3, the circles in bold materialize the cylindrical body of the prosthesis which is found, Figure 1, positioned laterally thus showing the occupied volume.

The drawings of the elbow joint represent the elements of a medium size skeleton, all dimensions of the prosthesis are adapted to this specific case. Dimensions that must evolve and adapt to each receiver. C F A O (Computer Aided Design and Manufacturing) at this level is essential. The standard must be rejected.

Plate 2/9. The drawings are in scale 2. Figure 4 the prosthesis seen from the front. e is happy to have a good time when they are fully and supine. Figure 5, external profile, same configuration.

Prosthesis composed of a cylindrical body (1) of a diameter equal to that of the condyle of the humerus, it is fixed on a U-shaped base (2) whose branches (3) and (4) complete the connection.

Two tabs (5) and (6) which both end with a peak (7) and (8) are welded to the edges at the corresponding dimples (Figure 8 Plate 4/9). Tabs ^for immobilizing the prosthesis using the peaks (7) and (8) after positioning its base on the machined surface of the numerical pallet provided by two peaks (9) and (10). The immobilization will be completed after precise positioning by a flat head bolt (11) hollow cavity.

Two lights (12) and (13) each ensure the passage of a round rod, the outer tenons (14) and (15) from the ball joints (plate 3/9) which extend by a cross section which will be sealed in a bore made in the diaphysis of the radius and ulna. Cross section to avoid loosening of the tenon under the action of alternating and repetitive rotations. The cross section of each tenon begins under a bearing surface (S) matching the profile of the corresponding machined section and which will come into contact with it. Once again the ideal would be a collar (C in section) Figure 5 of five millimeters in height marrying the machined section to comb it to counteract all the mechanical effects generated by the tenon. It is always possible to add small peaks under the support surface in order to counter, at least, the rotational stresses, especially on the radius. I have already presented the advantages of the support surface and the collar. Patents for knee prostheses and a patent for hip prosthesis.

The light (12) on the radius side has dimensions allowing the clearance of the tenon (14) from the artificial kneecap and which in this case replaces the axis of the neck of the radius to extend by the immobilization tenon. The lateral deflections of the Radius are important at the lower level. See the chapter on ulna valgus ... Site: http: // knees. free. en These movements are reflected in the higher level but with a very low amplitude because close to the origin.

In contrast to the axis of rotation of the radius that moves inwardly, the neck tax, so the round tenon (14), moves outward from the rear by rotating around the axis of rotation of the radius. See radio-cubitale superior ... Site: http://genoux.free.fr

Values of the angles in this case in supination Figure 4: The axis of the neck forms an angle of 10 ° inwards with the axis of rotation of the radius. The axis of rotation of the radius which is directed towards the outside has a physiological valgus of 10 ° so an angle of 80 ° outside with the axis of flexion extension, which means that the axis of the neck is perpendicular to the bending axis extension from the supination, which is reflected in the light (12) by a margin of clearance of two millimeters on the outer side. The value of the margins to be given to the lights is calculated from the vertical of the concerned edge with respect to the bending extension.

The deflection of the lower extremity of the radius of the radius at the end of pronation is about 15 °, which means that the post has not exceeded the perpendicular with the axis of bending, so a margin of one millimeter inner side is sufficient to allow the movements of the tenon.

The light (13) passes the post (15) for the ulna. Having moved the axis of rotation of the ulna in the middle of the diaphysis at the upper level (Figure 1) it makes with the axis of flexion extension an angle of about 80 °, so it is also the value of the The angle that the tenon will make with the axis of flexion extension when the ulna is supine since the tenon is in the diaphyseal axis of the ulna. Note that the displacement at the upper level of the axis of rotation of the ulna positions it parallel to that of the radius so its total length, that of the axis, will decrease very slightly and their spacing on the axis of bending extension but more importantly. The first consequence will be an increase in the amplitude of the lateral displacement inward of the inferior radiocubital during pronation, without any significant consequence. (See the ulna valgus on: http://genoux.free.fr) The amplitude of the deflection of the ulna towards the inside at the end of pronation will be about 10 °, which means that the tenon will be perpendicular to the flexion axis extension. This translates into a margin of deflection of the outer side light of three millimeters and one millimeter inwards.

The amplitude of the active extension flexion is of the order of 145 °. The length of the arc of the lights will be increased by a few degrees on the bending side to avoid a harmful action of the tenons (lever arm) at the end of flexion on the end of the machined surfaces.

The tenon of the radius (14) will, in complete extension, in the extension of the diaphysis of the humerus so the origin of the light (12) will be arranged accordingly. Figure 5

The tenon of the ulna (15) by its anchoring position, Figures 4 and 5, is on the horizontal plane in the axis of the diaphysis, so it does with the axis of flexion extension an angle of 80 ° outside . On the vertical plane it moves backward and is peφendicular with the machined surface of the base of the olecranon, which represents a delay in relation to the tenon of the radius of 25 °, so the departure of the light (13) is As a result, the amplitude of the total flexion is the same as that of the radius. Figure 5

Also remember that the blockage of the full extension is caused by the olecranon, the beak in the dimple. As the radius is not concerned, it is necessary to extend the amplitude of the light (12) on the full extension side so that the tenon does not come into contact with the bottom of the light before that of the ulna, without forgetting that it is in neutral and in complete extension that the cervix of the radius is at its maximum rear.

Plate 3/9 The drawings are at scale 2.

Figure 6 (section A A) shows the inside of the body of the prosthesis.

The cylindrical body (1) receives the two replacement joints, two ball joints each composed of a male element (16) and (17) identical to ten millimeters in diameter. The female elements (polyethylene, metal-metal ...?) Of the two ball joints are gathered in a single element which will be divided into three parts (18) (19) and (20) their immobilization in rotation will be by a groove common to three elements that will fit on a tenon (21) integral with the cylindrical body. Division which allows the assembly but especially to modulate the lateral position of the male elements as well as their spacing at the request. For example, the displacement of the axis of rotation of the ulna, as well as the decrease in the distance between them, causes a decrease in its own valgus and therefore the increase in internal lateral displacement during pronation. In the present case it is possible to recover two millimeters of center-to-center distance ulna to reduce the phenomenon, it is possible to double this value by acting also radius side.

Measures may vary from one person to another but also according to the damage on the articular surfaces.

The prosthesis body is closed on the outside by a crimped cap (22), other solutions are possible.

Figure 7 The profile prosthesis (section B B) shows the detail of the mounting of the outer post (radius) on the male element and the position of its light. The squared surface corresponds to the outer face of the central portion (19) of the female element. The pin (14) is aimed in a threaded bore in the sphere and then immobilized by a screw (23).

Plate 4/9 The drawings are in scale 1.

The figures show the body of the prosthesis in position on the machined surface of the pallet of the humerus.

Figure 8 (section C C) shows the truncated profile of the base on the outer side so that it does not exceed the limits of the machined surface (grid Fig. 8) which Ta receives. It also shows the position of the immobilization tabs. The tongue (5) in the pit of the coronaid apophysis, and the (6) in the fossa of the olecranon. Passage possible after machining the pallet.

Figure 9 (section DD) and Figure 10 (section EE). The pallet of rhumérus had cut, shows the tabs forming a bridge above each cavity. Plate 5/9 The prosthesis in position. Scale 1.

Figure 11 the supination and full extension joint. Figure 12 the internal flexural profile. Figure 13 the external flexural profile. About 60 ° of flexion for both profiles.

Plate 6/9 Figures 14, 15 and 16 show another form of machining of the surface of the ulna responsible for receiving and immobilizing the corresponding tenon of the prosthesis. Of course the tenon is modified accordingly. The machining will be parallel to the diaphysis as a whole and on a plane parallel to the axis of flexion extension supine ulna. The machining removes the essential of the large sigmoid cavity with the bill of the olecranon and coronoid process. Figure 14 dotted bold, substantially the periphery of the machined surface that will receive the bearing surface of the tenon.

Plate 7/9 The figures are on the scale l.

Figures 17 and 18 show the male member (17) and its modified post (15) fixed on the bearing surface (24), Figure 19 shows the post modified in position. The bearing surface (24) will be as wide as possible in order to cover as much as possible the machined surface, small grid of the periphery figure 17, and will follow the axes which it covers, the diaphyseal axis of the ulna for the lower part and an axis parallel to the diaphysis of the humerus for the upper part. See: http://genoux.free.fr

The angle of the round post on the horizontal plane does not change, it remains in the axis of the diaphysis. On the vertical plane, or anteroposterior, it will be modified so that the tenon moves more in the center of the bearing surface (24) and will make with it, so with the machined surface of the olecranon, an angle of 42 °. This is a delay in relation to the radius of the tongue of 37 °. The light (13) will be shifted accordingly.

The round post slightly longer will receive on its front face a reinforcement (25) and on its back side a second reinforcement (26) to give it more rigidity and especially a more effective connection with the support surface.

The immobilization will be done using two flat head bolts, the (27) on the axis of the ulnar diaphysis and the (28) on the axis parallel to the diaphysis numeral.

The lower (27) partial section. The nuts are integral with the bearing surface and serve as locating pins, the flat head screws have a hollow footprint for locking on the ulna.

This solution offers an effective protection to the olecranon and can be used in case of fracture of it By cons it appears that four essential insertions are destroyed (Brachial anterior - Weitbrecht's coronoid - coronoid beam of pronator teres - superficial flexor superficial)

By combining this second solution with the first presented a happy compromise can be made. Plate 8/9 The figures are at scale 1. FIGS. 20 and 21 show a bearing surface (29) composed of two perpendicular planes.

Figure 15 plate 6 / 9. The surface parallel to the diaphysis will descend lower than the oblique plane (dashed lines) of the first presentation to join the plane perpendicular to the diaphysis (thick dashes).

The tenon (15) is welded in the angle of the bearing surface (29) still in the diaphyseal axis of the ulna, but it will see its angle on the anteroposterior plane increase to 45 °, change the light (13). ) Consequently. A reinforcement (30) allows a better connection with the bearing surface. The immobilization will be done as before with two bolts with flat head, the nuts will, there too, secured to the support plate.

The nut (31) in partial section will be in the extension of the small surface perpendicular to the diaphysis to facilitate the positioning of the bore which will receive it, it is positioned on the diaphyseal axis of the ulna, the upper is on the axis of the olecranon therefore parallel to the diaphyseal axis of the humerus. Provide a soft pad (32) on the bearing surface (29) in the axis of the upper bolt to dampen contact with the tongue (6) during blockage of the full extension.

Regarding the radius if the neck is completely destroyed another solution is possible, but the post (14) will have to lengthen.

Plate 9/9 Figures 22, 23, and 24 are on the scale 2. Figure 25 has the scale 1.

Figure 22 the profile post in the supination position ... Figure 25 the post in position.

The tenon (14) extends a few millimeters to reach the level of the bicipital tuberosity. It will be immobilized laterally on the outer surface of the supination radius. This position corresponds substantially to the position of the axis of rotation of the radius, which will restore the crank arm destroyed by the disappearance of the elbow. See the radio-cubitale superior on the site: http://genoux.free.fr

The section of the radius will be perpendicular to the diaphysis and will receive a circular bearing surface (32) corresponding to the diameter of the radius at this level, it will be provided with a peak (33). This surface is integral with a gutter (34) itself integral with the pin (14). From this gutter the tenon is extended by a rectangular section which will end with a second gutter (35). The identical gutters have indentations (36) which will position the immobilizing collars (37) and (38). A light (39) will be made between tenon and gutter high, and a light (40) at low level, to let each collar.

Figures 23 and 24 (Section FF) show the position of the gutters with respect to the tenon and the rectangular section but also the position with respect to the bicipital tuberosity of the upper gutter (Dashed Fig. 24).

Figure 25 shows the pin in position, dotted the natural position of the neck with the cup, the center of the ball (16) corresponds to the center of the condyle.

In bending, a large void volume appears between the machined olecranon and the body of the prosthesis whatever the immobilization mode, FIG. 12, 13 and 19. It is possible to reduce this volume by reducing the gap (E) FIG. 12 plate 5/9.

The solution, FIG. 19, plate 7/9, consists in moving the extension flexion axis (O) towards the posterior face of the numerical pallet (O '). For this it is sufficient to move the cylindrical body of the prosthesis on its base, Figure 19 the position in fine line.

The angle of the tongues (5) and (6) with the base (2) will be modified accordingly as well as the angle of the tenons (14) and (15) with the bearing surface.

Total prosthesis that can evolve to intervene only on a single joint, it will then be cut in two to keep a single patella that will correspond to either rheumatoid or rhuméro-cubitale. Of course the machining of the palette will be targeted to receive only the concerned part.

Interesting principle on the radius side. The upper radio-ulna, if it is affected, can be suppressed because the humerubital can be self-sufficient, the bottom of the trochlea limits its deflections. Immobilization is more difficult to obtain.

Side ulnar same thing, the machining of the pallet will be between condyle and epitrochlée and will require a great precision, the immobilization will be facilitated. The upper radio-ulna if touched can be removed but will make rheumo-radial more fragile.

Regarding the ulna valgus, would there be an advantage in removing it?

My conclusion on the ulna valgus: http://genoux.free.fr shows that the internal lateral displacement that occurs during pronation is the consequence of the difference in length between radius and ulna. By intervening on the length of a tenon, or both, it is possible to establish the equality, which would remove the physiological valgus thus the ulna valgus because the prono-supination would be done on the spot. The forearm would then be in the prolongation of the humerus in supination as well as in pronation ...

Claims (9)

 claims 1) Total prosthesis of the elbow characterized in that it is composed of a cylindrical body (1) welded to a base of support (2) the connection is reinforced by two borders (3) and (4) the end outside is adapted to the profile of the machining of the numerical pallet. 2) total prosthesis of the elbow according to claim 1 characterized in that the cylindrical body contains two complete independent ball joints each with a post that can move in all directions, including rotation. 3) total prosthesis of the elbow according to the preceding claim characterized in that the female elements are integral but divided into three parts (18, 19 and 20) allowing the mounting of the ball joints but also a lateral positioning and a precise spacing of the ball joints according to the request. A longitudinal groove common to the three elements engages on a tenon (21) integral with the body to ensure their immobilization in rotation. 4) total prosthesis of the elbow according to claim 2 characterized in that the cylindrical pins (14) and (15) extend from their respective bearing surface by a cross section ensuring a better seal strength to the movements of alternating and repetitive rotation. 5) total prosthesis of the elbow according to claim 1 characterized in that the support base (1) has two peaks (9) and (10) and two tabs (5) and (6) at the coronoid and olecranon dimples allowing positioning and immobilization of the body of the prosthesis on the machined surface of the numerical pallet. 6) total prosthesis of the elbow according to the preceding claim characterized by the fact that the two tongues (5) and (6) have at their respective end a peak (7) and (8) to allow a first immobilization which will be completed immediately by a bolt (11) has a flat head. 7) total prosthesis of the elbow according to the preceding claim characterized in that if the neck is completely destroyed the cylindrical pin (14) will lengthen accordingly and its immobilization will be on the outer side of the radius supine position by two gutter (34) and (35) with collars, the pin then taking the position of the axis of rotation of the radius restores the crank arm. 8) total prosthesis of the elbow according to claims 2 and 4 characterized in that the ulnar pin (15) is fixed on a support plate (29) consisting of two perpendicular planes, the immobilization will be through the intermediary of two bolts on the largest machined surface parallel to the ulnar diaphysis. 9) total prosthesis of the elbow according to claim 1 characterized in that the cylindrical body (1) of the prosthesis is divided in two and contains a single complete patella in order to intervene on a single joint, or the humerubital or the humeroradial.