DE2401482A1 - THIGH PART FOR HIP JOINT ENDOPROSTHESES - Google Patents

Description

Augsburg, January 10, 1374

Rational Research Development Corporation, Xingsgate House, 66-74 Victoria Street, London 3 ₉ Ml , England

Thigh section for hip joint endoprostheses

The invention relates to a thigh part for hip joint ßndoprothesen, with one in cooperation with one appropriately designed ball socket of a pelvic part of such a prosthesis ball head that can be brought,

Hip joint endoprostheses are basically shaped

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ziieier different types of surgery applied, namely one as a partial replacement and the other as a total replacement. In this context, partial replacement is understood to mean the replacement of only the natural femoral head, which is normally done by a femoral head prosthesis that has a conical shaped canal spur, which at its thicker end over a Neck part merges into a spherical, artificial femoral head part laterally offset with respect to the longitudinal axis of the medullary canal spur, the latter interacting with the relevant natural hip socket of the prosthesis wearer Thigh part together with a correspondingly designed joint socket, which is arranged in an additional pelvic part of the prosthesis, the latter corresponding accordingly Position of the pelvis of the prosthesis wearer is attached. In both cases, the thigh parts of the prosthesis are almost identical in their basic structure. The only difference is that the femoral head part of a thigh part intended for a partial replacement has a larger diameter than that of a thigh part for a total replacement, since in the former case the femoral head part, as already mentioned ₃ , interacts with the natural hip socket of the prosthesis wearer

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must be able to, while in the latter case from obvious Reasons the ball-and-socket socket of the pelvic part of the prosthesis must have a smaller diameter and consequently also the femoral head part of the thigh part of the prosthesis must have a correspondingly smaller diameter.

In the surgical treatment of femoral neck fractures and similar fractures, which impair the function of the femoral head but not the joint socket, nails, plate reinforcements or similar fasteners for the femoral neck were used in the past The partial substitute just explained is used because it allows the patient to regain full mobility in a shorter time. This technique is also to be preferred especially in older patients, in whom the risk of a recurrence of similar fractures is greater than in the rest of the average patient population, so that new interventions are necessary »

Unfortunately, it has been shown that the more frequent the use of the partial substitute, the more cases in which, in the course of time, a total replacement must be made, because with advancing time the natural acetabulum gradually wears out »

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The difficulty now arises that in the later transition from already existing partial replacement to then after all necessary total replacement the thigh part already inserted in the patient can be removed and through a Thigh part must be replaced with an artificial femoral head part of smaller diameter, which then with a correspondingly dimensioned joint socket of an artificial pelvic part that is then still to be inserted comes.

The invention aims to solve the problem necessary for the transition from the partial replacement already available for the prosthesis wearer concerned to later the replacement of the existing thigh part of the prosthesis with a new thigh part to avoid.

This object is achieved according to the invention, starting from a thigh part for thigh joint endoprostheses of General design set out at the outset, achieved in that in addition to the thigh part, an on this attachable, the spherical head of this thigh part encompassing artificial thigh head part of larger outer diameter chmessers is provided that with the associated natural acetabulum of the prosthesis wearer in

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Can be brought together.

The thigh part according to the invention brings about Thigh parts of the known type set out above the technical progress that in patients with which initially only a partial replacement needs to be made, the thigh part according to the invention together used with the attached artificial femoral head part of larger outer diameter and the latter with the relevant natural hip joint socket of the prosthesis wearer is brought into cooperation, and that later, if after years with the prosthesis wearer still a total replacement should only be required of the thigh part according to the invention that is already present in the patient the artificial femoral head part encompassing its spherical head to be removed and the spherical head of the thigh part with the joint socket of a prosthetic pelvic part to be attached to the patient's pelvis in Needs to be brought together.

The prosthetic thigh part according to the invention is preferably a one-piece Iletallteil, while the artificial femoral head part preferably a two-layer body is, its radially inner, with the ball head in

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Contact coming layer is made of plastic while the radially outer layer that comes into contact with the natural acetabulum is made of metal »

The hip joint prosthesis thigh part according to the invention is described below with reference to the accompanying drawing, which shows a partially sectioned and partially exploded schematic front view of a preferred embodiment of such a thigh part, in its details for example described.

The shown in the drawing helps joint-endoprosthesis-thigh part has a medullary canal spur 2, a neck part 3 and a spherical head 4. The medullary canal spur 2 tapers in a wedge shape towards its free end within a plane perpendicular to the plane of the drawing. The thick end of the. Ilarkkanalsjjorns is within a perpendicular to the picture plane iibene bent or cranked so that the ball head 4 is relatively to the longitudinal axis of the straight section of the medullary canal spur is offset laterally. The entire thigh part essentially corresponds to the "Charnley" type, as it is, for example in total aid joint replacement is used. The thigh part consists of a one-piece Metal body.

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The prosthesis part shown also includes a generally releasable attachable to the thigh part 1 with the reference number 5 designated leg head part, which in turn consists of a spherical Cap 6 and two essentially identical sleeve parts assigned to the jaw part 3 of the thigh part 1 7 consists ♦ The spherical cap 6 has essentially hemispherical shape and has a radially inner, for Ball head 4 of the thigh part 1, complementary hollow spherical surface on «The cap 6 is designed as a two-layer body and has a radially inner body 6a made of plastic and a radially outer, thinner, made of metal body 6d. The radially inner one Plastic body 6a protrudes axially at the cap mouth over the radially outer metal body 6b and has at its protruding part an outer circumferential groove 6c on «

The radially inner surfaces of the two half-sleeve parts are each complementary to the ileal part 3 of the thigh part 1 and each have a protruding part of the radially at their ends facing the cap 6 inner plastic body 6b and in particular to its circumferential groove 6c complementary profile. The outside surfaces of the two half-sleeve parts 7 are designed so that their ends facing the cap 6 gently touch the spherical

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Outer surface of the metal outer body 6b of the cap 6 connect and then conical and slightly curved, tapering in the direction of that facing the medullary canal spur 2 ii-nde of the üalteiles 3 of the thigh part 1 extending

One of the two Halbrauffenteile 7 has two mutually parallel, perpendicular to the parting plane of both Halbiiiuff fleeth extending 3 ore aubendurchgangsbohr Ungen on the SiCN with two mutually parallel, perpendicular to the parting plane threaded bores of the respective other half of the socket member 7 by cover _e The Sehraubendurehgangsbohrungen S to the outer surface of the respective iialbmuffteils 7 expanded towards 9 in order to be able to accommodate the heads of fastening screws 10, which latter can be screwed into the threaded holes of the respective other Iialbmuffteils. The screw through-bores 8 are countersunk on the parting line of the respective calf socket part 7 in order to be able to accommodate circlips 11, by means of which the fastening screws 10 are held on the half-socket part 7 provided with the screw through-holes 8.

The spherical cap 6 can be snapped over the spherical head U of the thigh part 1 and is then

8th -

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by applying the two inner sleeve parts radially on both sides 7 to the neck part 3 of the thigh part 1 and at the same time sealingly inserting the counter profile of the Cap 6 facing sides of the radially inner surfaces of the two half-muff ent parts in the Urafangsnut 6c of the protruding Part of the radially inner plastic body 6a and at the same time screwing the fastening screws into the threaded bores of the other Ilalbmuff part 7 on the Thigh part 1 can be securely and sealingly fastened.

In this assembled form, the prosthesis serves as a partial replacement, the spherical outer surface of the radially outer metal body of the cap 6 of the artificial femoral head part 5 with the natural associated acetabulum of the Prosthesis wearer cooperates.

Should then the partial replacement at a later point in time of the prosthesis wearer are replaced by a total replacement, then by loosening the fastening screws 10, radial removal of the two Ilalbrauffenteile 1 and axial Pulling off the cap 6 from the thigh part 1 first exposes the ball head 4, whereupon the natural pelvis of the If an artificial pelvic part is attached to the patient, the joint socket is dimensionally exactly the same as the ball head 4 of the already existing thigh part 1 corresponds. The disassembly required on the patient's upper scissors part 1

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is limited to taking off the artificial Scnenkelkopffteils 5, which by the presence of the Gprengringe is made easier, as they allow the with screw through-holes 8 provided ilalbmuhle part 7 after loosening the fastening screws 10 radially pull off together with them, whereupon turning the each other calf socket part 7 and the corresponding radial removal of the same no longer makes any major difficulties. The focus of the operation to be carried out is therefore limited to the attachment of the associated prosthetic pelvic part on the patient's natural pelvis,

With reference to the preferred embodiment of a hip joint prosthesis thigh part shown in the drawing Various modifications are possible. For example, the one facing the two half-sleeve parts 7 Edge of the cap 6, instead of running in a plane perpendicular to the axis, as shown in the drawing, in a plane lying to the axis of the straight part of the medullary canal spur 2 is inclined so that it is essentially perpendicular to the axis of the relevant curved or cranked portion of the thigh part runs to which it is assigned. This takes better account of the fact that the maximum load of the artificial head part does not run in the axis of symmetry of the thigh part, but in the just mentioned

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given way is offset from the same, so that, starting from the most heavily loaded point of the metal outer body 6b of the cap 6, an approximately evenly loaded point in each direction Peripheral area of the spherical outer surface of this radially outer metal body is available. It can also be desirable be, the artificial femoral head part 5 with reference on the ball head 4 of the thigh part 1 so that no mutual rotation of the two prosthesis parts is possible. This can be achieved, for example, in that in the area of the circumferential groove 6c and the complementary Counter-profiles of the two half-sleeve parts 7 correspondingly cooperating flat surface areas are provided · Instead of the fastening screws 10, other fasteners can be used as fastening means for the two inner sleeve parts Fasteners are used that prevent the smoothness of the outer surfaces of the two half-sleeve parts is interrupted.

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Claims (2)

7Λ0ΗΒ2 Claims 1 J thigh part for hip joint endoprostheses ₃ with a ball head which can be brought into cooperation with a correspondingly designed ball socket of a pelvic part of such a prosthesis, characterized by an additional ₃ ball head (4 ) encompassing artificial femoral head part (5) of larger outer diameter, which can be brought into cooperation with an associated natural hip and joint socket of the prosthesis wearer, 2. Prosthetic device according to claim 1, characterized in that the artificial femoral head part I (5)? Iit respect to the thigh part (1) designed in such a sealing (6c) _s that body fluids from entering the located between the two parts of columns or Gaps £ ^{e are} reduced. 3 »Prosthesis part according to claim 1 or 2 _3, characterized by means for preventing mutual rotation between the thigh part (1) and the artificial head part (5). 4 «, prosthesis part according to one of claims 1 to 3, - 12 - characterized in that the thigh part (1) is a one-piece metal part; and that the artificial head of the femur (5) has a two-layer body (6) whose radially inner, with the ball head (4) of the thigh part (1) The layer (6a) coming into contact is made of plastic, while the radially outer layer (6a) is made of the natural acetabulum the layer (6b) coming into contact with the prosthesis wearer consists of metal, 5β prosthesis part according to one of claims 1 to 4, characterized in that the thigh part (1) has an elongated, approximately conical medullary canal spur (2) which at its thicker end over a neck part (3) into the Ball head (4) passes over, and that the artificial leg head part (5) consists of a spherical, encompassing the ball head Cap (6) and two roughly identical loaf muffs that embrace the neck part of the thigh part and hold the cap divide (7) consists, 6, prosthesis part according to claim 4 or 5 _3, characterized in that the cap (6) has an outer body (6b) made of metal and a radially inner, axially protruding over the cap mouth, with its protruding part slimmer in diameter and profiled (6c) plastic body (6a) shows that, furthermore, the two halves - 13 409830/0364 socket parts (7) are made of plastic and each the cap mouth facing areas of their radially inner surfaces have mating profiles that with the profile (6c) of the protruding part of the cap inner body can be brought into cooperation, and that means (10) are provided, by means of which the two half sleeves can be releasably connected to one another. 0/0364