JOINT PROSTHESIS

Abstract: A joint prosthesis and a joint prosthesis organ comprising a cup-shaped element having two parts. One part (1) is a ring which may be connected to the cup-shaped second part (2) with use of click-joint elements (2', 2'') which are such that ring and cup-shaped part are allowed to rotate freely relative to each other. Described is that said ring may be formed such as to hamper luxation; the ring therefore may partially have an enlarged height. The surgeon using a joint prosthesis according to the invention on a patient has the possibility to rotate the ring with respect to the cup-shaped part until an optimal position is reached. If necessary the two parts may then be fixed to each other using separate means for fixation.

Description: JOINT PROSTHESIS The invention in the first place concerns a joint prosthe in particular a hip-joint prosthesis, at least consisting of an organ comprising a ball and an organ comprising a cup-shaped element for reception of said ball wherein the organ comprising a cup-shaped element at least consists of a first and a second part which are connected with eac other and which are mutually secured with use of a click- and wherein the sphere-sector surface-shaped part of the contact surface between the cup-shaped element and the ba with the complete prosthesis corresponds to a solid angle of at most 180 degrees, of which the top coincides the he of the ball. In the above given description of a joint-prosthesis is indicated that the applied ball may in no case be complet enclosed in the cup-shaped element. For that reason the sphere-sector surface-shaped part of the contact surface has been limited to at the most the surface of a half ball Xn the European patent application 0 065 482 a joint prosthesis organ is described that can be applied to the joint prosthesis in the above mentioned manner. Such a known joint-prosthesis organ is a hip-joint prosthesis org consisting of two parts, of which the first part is formed -. by a reception-part to be secured in the pelvis and the -"second part s formed by a cup-shaped part " hich is meant for reception of the ball-shaped part of the hip-joint. The second part which is cup-shaped can be fitted in the first part by means of a click-joint. The construction of the second part and of the first is such that after fit . of the second part in the first part both parts are mutual secured in a "fixed position. In the described well-known hip-joint organ there can be several forms to the second part, in order to adapt the form and the position of the cup-shaped element according to the for each case existing requirements in the best possible way. By placing th'e second part ±n a certain posit-ion when it is fitted there is aimed at prevention of dislocation (luxation) of the ball as much as possible; because of the fact that the position of the first and second part cannot be altered after having been connected, an optimal positio of the said second part is however not in all cases guaran .teed. The disadvantage of a not entirely correct fitting of the cup-shaped element is that luxation may still occur with all its consequences for the patient and which in most cas will lead "to yet another operation. The aim of the invention at issue is to provide a solution for the disadvantage mentioned in the form of a joint prosthesis in which the part containing a cup-shaped eleme is constructed is such way that luxation is prevented to a large extent. According to the invention the described joint prosthesi in particular a hip joint prosthesis is for this purpose characterized by the fact that the said first part and t said second part of the organ that contains a cup-shaped element, comprise click-joint elements which cooperate by forming a click-joint which allows free mutual rotation of both elements mentioned. By applying click-joint elements to the second and first parts, which are shaped in such way that after connection of the first to the second part a mutual rotation of both parts is allowed, an optimal positioning of the second pa within the first part can be achieved. The application of the click-joint elements implies that it will have to be possible to elastically deform prefera at least one of the click-joint elements. For that reason at least one of the click-joint elements or that part of the organ of which the element is a part, will in general be made of synthetic material. Should the second part in the joint prosthesis of the org containing a cup-shaped element be a part with a special form for prevention of luxation, then the second part of the hip joint prosthesis can, after fitting of the comple hip joint prosthesis organ, be rotated in such way that in accordance with the on the spot established farthest positions an optimal position of the second part is reach After this mentioned optimal position has been reached th second part can be further maintained in this position. In particular seperately working means are provided for the mutual fixation of the said second part and first par after reaching an optimal position of the second part in regard to the first part. It is however noted that such -ά- seperately working means of fixation are not absolutely necessary; the friction against contortion of the second part in regard, to the first nay for instance be adjusted in such way that under normal conditions no contortion wil occur and that contortion is only possible if the attendin surgeon exercises a directed force. Tn order to provide a higher friction between the first and the second part of the cup-shaped organ the contacting surfaces may be roughened. Alternatively there may be a protrusion on one surface and a series of depressions in the opposite surface whereby _ upon rotation of the first and second parts relative to each other the said protrusion may be received by a select one of said depressions. A protrusion may have the form of a small ball received in an enclosing cavity in one of the contacting surfaces, for example in the first part of the cup-shaped organ, i.e the cup-shaped element. The invention also concerns * a joint prosthesis organ which contains a cup-shaped element for application in a joint prosthesis which according to the invention consists at least of a first and a second part which can be connected with each other and mutually secured by means of a click-j and with which the sphere-sector surface-shaped part of the contact -surface between - e cup-shaped element and the ball equals the earlier mentioned solid angle of at the most 180 degrees which is characterized by the fact that the first part mentioned and the second part mentioned con click-joint elements which can cooperate by forming a click-joint .which allows free mutual rotation of both mentioned parts. With advantage the first part in the joint prosthesis org according to the invention is formed by a cup-shaped elem and the second by a ring of appropriate form which can, by means of a click-joint be interchangebly connected wit a recess in the upper-inner edge of the mentioned cup-sha element, with which the inner edge of the ring and the in side of the cup-shaped element connect without difference of level and the height of the ring is at least equal to the depth of the recess. The ring is made of synthetic material, for instance high density polyethylene. The cup-shaped element can be made of synthetic material; cer metals or ceramic material can be used as well. The ring mentioned can be selected in such form and size that depe on the patient's physical condition an optimal p evention of luxation can be achieved. As a result of the application of the above described construction form of the invention there is large accesib upon fitting of the ball in the cup-shaped element; by applying the second part in the form of a ring the disengagement of the ball from the socket is impeded. In connection with the application of a ring there is pointe to the European patent application 0 053 794. In this application too the application is described of a ring whi is placed in a recess in the upper-inner edge of a cup-sha element of a joint prosthesis organ. The ring in question in the publication mentioned is applied for reduction of abrasion-occurences between a cup-shaped element and a her included ball and not for reduction of the risk of luxatio by a ring of appropriate form; furthermore the height of the ring in question is limited to a value equal to the depth of the recess. The above described ring-shaped second part may have differ forms; for instance, at least a part of its circumference may have been heightened or a part of such a heightening may be inclined towards the center of the cup-shaped elemen The earlier mentioned ring may also have been fit with a bevel in order to make a larger rotation angle of the ball ■ fitting in the cup-shaped part possible. In a most attractive construction form of the joint prosthe organ according to the invention the second part of that organ is formed by a split ring. A construction form such as this is most attractive in thos cases in which the originally placed ring in a completely fitted joint prosthesis appears not to have a optimal form during the operation. The earlier fitted ring can then easi be removed and replaced by a new ring of a better adjusted form. Such a split ring may also be most advantageous in case of a subsequent operation of a patient; an earlier fitted ring which does not (any longer) have an optimal f-orm can then easily be replaced by a new ring without the original fitted prosthesis having to be removed. In a special construction form of the joint prosthesis orga according to the invention the first part is formed by a mass of synthetic material provided with a hollow for the reception by forming a click—^joint of the mentioned second part in the form of a cup-shaped element with which in that case the click-joint elements are present respectively at the upper edge of the earlier mentioned hollow in the synthetic mass and at the outer-upper edge of the cup-shape -element. For the application of the above described joint prosthesis organ the synthetic mass with a possible appropriate form is connected to or fitted in the pelvis; after this the cup-shaped element is fitted and the ball connected to the bone is placed after which finally by rotating the cup-shaped element in regard to the first pa in the form of a synthetic mass an optimal positioning of the cup-shaped element is reached. Finally the cup-shaped element may in turn be secured by means of seperate means in regard to the synthetic mass in which there is a hollow. In the above described construction form the cup-shaped element may of course also be constructed in the manner as was described earlier; i.e. a cup-shaped element with in its inner-upper edge a recess in which a special ring can be included which is connected by means of a click-jo allowing free rotation of the ring in regard to the cup-s element. If a joint prosthesis organ as described above is used th the first part will most advantageous have the form of a synthetic mass which is of such size that it may be adapt during the operation, to the bone area to which the menti synthetic mass is to be connected; by in orthopaedics use means such a shaping can easily be performed during the operation. In order to make it possible to check the fitting of the joint prosthesis inside a patient there will in general be seen to that at least the second part of the joint prosthesis organ that can be rotated in regard to the firs part preceding the mutual fixation of both parts, will be visible in X-ray. A mark such as this may for instance be preεent on the second part in the form of a metal mark. It is noted that click-joint elements which allow mutual rotationof the first and second part of the prosthesis orga can be completely circular while it may also be that the click-joint element on one of the parts is interrupted. The last construction has in particular the advantage that the force applied to the formation of the click-joint can be lesser in -which way the possibility of damage to the prosthesis or to its place as well as damage to the concern bone parts is reduced. The invention also concerns a ring for application in a joint prosthesis organ which is characterized by the fact that the ring * is shaped according to the above given description of the ring-shaped second part of the joint prosthesis organ according to the invention. The invention furthermore concerns a cup-shaped element for application in a joint prosthesis organ which is characterized by the fact that the mentioned element is shaped according to the above given description of the cup-shaped second part of the joint prosthesis organ accor to the invention. The invention will now be described with the aid of the accompanying drawing in which: Pigure 1 presents a section diagram of a joint prosthesis organ with a fitted ball according to the invention with which, as an exemplification, the part in which the click-joint elements are found is presented on a larger scale. Figure 2 presents a sectional drawing and an elevation of another construction form of a joint prosthesis organ according to the invention. Figure 3 presents yet another construction form of a join prosthesis organ according to the invention. Figure 4 presents yet another construction form of a join prosthesis organ according to the invention. Figure 5 presents an illustration of the application of a joint prosthesis organ according to the invention. Figure 6 presents a special construction form of a joint prosthesis organ according to the invention. Figure 7 presents a joint prosthesis organ according to the invention with which the second part is formed by a cup-shaped element. Figure 8 presents a fitted joint prosthesis organ accordi to the invention. In figure 1 the first part is formed by a cup-shaped elem 1 with a recess in the upper-inner edge in which a split ring 2 of synthetic material is incorporated of which the height is more than the depth of the recess. The height mentioned may, dependent on the eventual aim, be varied. Ring 2 is incorporated in the recess and is fitted by mea of click-joint elements 2 and 2' which may have the form as presented here but which may also have any other suita click-joint element form, as the expert knows, and which may both extend around the element 1 and ring 2 respectiv but of which one may also be interrupted as mentioned bef The cup-shaped part contains a flange 3 while it is furthermore indicated that fixation of the ring-shaped pa 2 in regard to the cup-shaped part 1 can be achieved by fixation means 4 and 5 of which the screw 5 can be incorporated in hollow 6. The construction form of the prosthesis organ presented here is a basic construction form. The split of the ring at 8 makes it possible to fit the ring even if the prosthesis is completely finished; i.e. when the biall has been incorporated in the cup-shaped element. Above indicated fixation can of course, as indicated afore, be accomplished without the use of special fixation means, ,_i..e. by roughening of surfaces which contact .each other. Also the earlier described protrusion and recesses in the contacting surfaces offer a good possibility. hen it is preferred to use seperate fixation means they can also have the following form. The ring may have one or- more not-ches in its outer circumference which extend over its height; by means of fasteners which fit in a notch and fall in recesses in the cups upper surface the ring can be fixed against rotation relative to the cup. The ring may also extend to over the cup edge. One or more notches may then be used to obtain fixation of the ring, by use of suitable fasteners, to a part normally used in uncemente prosthesis types, such as a metal ring which is screwed in the bone. Figure 2 presents a cup-shaped element 1 that is fitted with a ring-shaped part 2 with a heightened part 12 of whic the height continuously increases from right to left. Furthermore the ring is provided with a bevel part 9 thus positively influencing the farthest positions of the ball-part- of the joint. Such a ring of a special construct form, as well as the ring from figure 1 may be incorporated in the cup-shaped part 1, which is presented in figure 1. A patient may therefore at first be helped with a prosthesi according to figure 1; during the operation or maybe later, at a subsequent operation the part 2 can easily be replaced by a part as indicated in figure 2 and equally well by part 2 as indicated in the figures that are still to be discusse Figure 3 presents a ring-shaped second part of a special form while in figure 4 a similar prosthesis organ is pres with which the heightened part of the ring iε inclined to the center of the cup-shaped first part; in figure 4 is also indicated, at 14, that during the operation the ring-shaped part can be cut to the right size. It is note that in figure 3 and 4 the heart of a ball that is to be fitted is fitted lower than in figure 1 and 2. A situatio in which the heart of the ball lies in the plane of the upper side of the cup-shaped element 1 is of course also possible in the figures meant; which holds good for the following figures as well. In figure 5 a construction form as in figure 3 is present with which it is schematically indicated that during the operation the heightened part 12 of the ring 2 can be giv the right size by means of cutting as presented in 13. In figure 6 a situation is presented in which the ring 2 is constructed with a segment-shaped heightening 12 of li size which extends only to a small part of the circumfere Such a ring is applied in case partial enclosure is neces due to the most weak condition of the soft tissue. In respect of afore given figures there is indicated that normally the inner edge of the ring and the inner side of the cup-shaped element connect without difference of leve However, in certain circumstances the ring may be adapted such that its inner surface displaced outward in respect of the inner surface of the cup at places of the ring whi do not function to hamper luxation, i.e. generally at the right side of the firgures. Such displacement may be desirable to minimize the number of locations in which an overpressure of body fluids may occur. In figure 7 a situation is presented in which the first part of the joint prosthesis organ consists of a synthetic • mass 21, which-, as is indicated, has been given a form whi can be fitted in a hollow which is present in the pelvis-p while the second part 22 is constructed as a cup-shaped element. The cup-shaped element has in this case a form equal to that of figure 1; it is however fitted in a speci manner. In order to fit such a joint prosthesis organ the synthetic mass 21 is first given the required size by mean of cutting, sawing etc. After this part 21 is fitted, for instance by means of a cement, in a hollow which is presen or made in the pelvis-part. After the fitting the cup-shap element 22 is clicked into the hollow in the synthetic par •" by * rotating part 22 the correct position of the high side is adjusted after which the part 22 can be secured in rega to part 21 for instance by means of self-tapping screws. In that case the click-ring elements 22' and 22* ' are fitt in the inner side of the hollow in 21 and in the outer circumference side of the cup-shaped element 22 respective In the figures described above a number of constructions of a ring-shaped second part respectively a cup-shaped sec part of a prosthesis organ have been presented. The invention is however not restricted to the latter; the user will have a large number of construction forms at his disposal which can be applied according to choice. .Finally in figure 8 a diagrammatic representation is given -of a fitted hip-joint prosτ_he _ sis according to the inventio In the pelvis 34 a cup-shaped element 31 has been fitted in the known manner; the ball 31 r has been incorporated. Connected with the ball is the pin 35 which is incorporate in the thigh-bone. Indicated here is a ring-shaped part 32 , which is incorporated in "a recess in the cup-shaped part 31; the ring-shaped part is here indicated with a stro bevel at 37 and light bevel at 38. The light bevel is pres in the area where the danger of luxation is greatest. It iε furthermore indicated at 36 that perforations have been made in the ring in order to stimulate ingrowth of soft tissue in which way an extra strong connection of th entire prosthesis is achieved. Perforations can be made in all of the above drawn constructions; the application of an aεymetric bevel pattern as drawn can be made with all construction forms as well.

Claims: Claims : 1. Joint prosthesis, in particular hip-joint prosthesis, at least consisting of an organ comprising a ball and an organ comprising a cup-shaped element for 5 reception of said ball in which the organ that comprises . a cup-shaped element at least, consists of a first and a second part which are connected with each other and which are mutually secured by means of a click-joint and wherein the spheresector surface-shaped part of the contact surfac 10 between the cup-shaped element and the ball with the compl prosthesis equals a solid angle of at the most 180 degrees, of -which the top coincides with the heart of the ball characterized in that of the organ comprising a cup-shaped element said first part (1) and said second part (2) conta 15 click-joint elements (2', 2") which cooperate by forming a click-joint which allows free mutual rotation of both mentioned parts (1, 2). 2. Joint prosthesis according to claim 1, character in that there are separately working means (4, 5, 6) for -20 mutual fixation of said first- and said second part. 3. Joint prosthesis organ containing a cup-shaped element for application in a joint prosthesis according to claims 1 - 2 at least consisting of a first and a secon part which can be connected with each other and mutually 25 secured using s click-joint and with which the sphere-sect surface-shaped part of the contact surface between the cup-shaped element and the ball equals a solid angle of at the most 180 degrees, of which the top coincides with the heart of the ball, characterized in that said first 30 part (1) and said second part (2) comprise click-joint elements 20 (2 1 , 2") which can cooperate by forming a click-joint which allows free mutual rotation of both mentioned parts (1 , 2) . 4. Joint prosthesis organ according to claim 3, characterized in that this comprises a first part consisti of a cup-shaped element (1) and comprises a second part consisting of a ring (2) of appropriate form which can be interchangebly connected with a recess in the inner-upper edge of said cup-shaped element (1) with which the inner side of the ring (2) and the inner side of the cup-shaped element (1) connect without difference of level and the height of the ring (2) is at least equal to the depth of the recess. 5. Joint prosthesis organ according to claim 4, characterized in that said second part is formed by a ring (2) with at least on part (12) of its circumference a grea height over its click-joint element than on the remaining part. 6. Joint prosthesis organ according to claim 5, characterized in that a part of the part with a greater height (12) of the mentioned second part in the form of a ring is inclined towards the center of the cup-shaped element (1). 7. Joint prosthesis organ to claims 4-6, characteri in that said second part is formed by a ring (2) of which at least a part of its inner-upper circumference has been given an appropriate bevel (9). 8. Joint prosthesis organ according to one or more of the claims 4-7, characterized in that the mentioned seco part in the form of a ring is a split ring. 9. Joint prosthesis organ according to claim 3, characterized in that said first part is formed by a plast mass (21) in which a cavity has been made for reception by forming a click-joint, of said second part in the form of cup-shaped element (22) with which said click-joint elements (22', 22") are preεent respectively at the upper edge of said cavity and at the outer-upper edge of said cup-shaped element (22). 10. Joint prosthesis organ to claim 9, characterized in that said cup-shaped element may have one or more of the following construction elements; at least a part of the circumference of the cup-shaped elem (22) has a greater height over its click-joint element than the remaining part of its circumference; a part of its circumference with a greater height is inclin t_owards the center of the cup-shaped element; said cup-shaped element (22) has a bevel on at least a part of its inner circumference; said cup-shaped element has on its upper-inner side a reces for the reception of a ring-shaped part fitting herein with which the connection between said cup-shaped element and sa±d -ring-shaped part is made 'by means of a click-joint which is such that rotation of said ring-shaped part in regard to said cup-shaped element is allowed when both are mutually connected by means of a formed click-joint. 11. Joint prosthesis organ according to claims 9-10, characterized in -that the mentioned first part in the form of a plastics mass (21) is of such size that it can be adjusted as required to the bone-area with which it is to be connected. 12 ™ -. Joint, prosthesis organ according to one or more of the fore-going claims 3-11, characterized in that at least the second part of the joint prosthesis organ has been given a mark which is visible in X-ray. 13. Joint prosthesis organ according to one or more of the claims 3-12, characterized in that there are separ working means (4, 5, 6) for mutual fixation of the first, the second and possibly other parts. 14. Joint prosthesis organ according to one or more of the claims 3-12, characterized in that perforations ha been made in the seperate parts in order to make the ingr of soft tissue possible. 15. Ring for application in a joint prosthesis orga characterized in that the ring is shaped in accordance wi the description of the second part of the joint prosthesi organ according to one or more of the claims 4-8. 16. Cup-shaped element for application in a joint prosthesis organ, characterized in that the cup-shaped el is shaped in accordance with the description of the second part of the joint prosthesis organ according to one or mor of the claims 9-10.

Inventors: MULLERS JAN BERNARD, MULLERS, JAN, BERNARD
Applicants: MULLERS JAN BERNARD, MULLERS, JAN, BERNARD
Application year: 1988
Main classification: A61F2
IPC codes: A61F2