FR2758714A1 - Cotyloid prosthesis for hip joint - Google Patents

Abstract

A cotyloid prosthesis consists of a supporting ring (110), designed to be fixed to healthy bone in the cotyloid cavity, and a cup (120) which can be joined to the ring. The ring's inner diameter is sufficient to allow the cup to be pivoted inside it and located in a selected position. The ring also has fixings (130) which are independent of the cup and designed to hold the cup inside it in the desired position. The independent fixings consist of a locking ring (130) which is fixed in place against the supporting ring by a series of nut and bolt fastenings (133, 134) engaging with holes in both rings. The supporting ring, the locking ring and fastenings are made from titanium or a titanium alloy, while the cup (120) is made from polyethylene.

Description

 The present invention relates to an acetabular prosthesis for recovery of the hip.

More particularly, it relates to a prosthesis which comprises a support ring intended to be positioned in a determined orientation in the acetabular cavity of the hip and fixed on healthy bone parts, and a cup capable of being secured to the support ring. being oriented relative to it.
lJne such acetabular prosthesis is used in the case of hip replacement arthroplasty occurring after a loosening of the first artificial acetabulum or in particular after a rupture of the bone cavity in which this first artificial acetabulum was sealed.

 To restore mobility to a diseased hip-femur joint of a patient, in a conventional manner, an arthroplasty is carried out during which the acetabular cavity concerned is hollowed out and a position is positioned inside it. artificial acetabulum This artificial acetabulum comprises on its external surface means for anchoring in the bone of the acetabular cavity and is sealed with cement inside the latter.

 In addition, the head of the femur concerned is sectioned in order to fix an artificial patellar sphere intended to cooperate with the artificial acetabulum.

 The defective hip-femur joint is thus reconstructed.

 In some cases, it may be that the patient contracts osteoporosis which leads to bone rupture in the acetabular cavity containing the first artificial acetabulum. Osscuscular rupture can also be caused by bone defections linked to infections or wear debris.

 In addition, it may turn out that the sealing cement of the first artificial acetabulum breaks.

 It is then necessary to perform an arthroplasty to take over the diseased hip-femur joint.

 During such an intervention, remove the artificial acetabular cup and all or part of the associated seal, and compact it inside the cotyloid cavity of the patient of the bone graft in order to fill the gaping hole left by the removal of said first artificial cup. Then an acetabular prosthesis is placed which is fixed on healthy bone parts.

 Currently, an acetabular prosthesis of known type comprises a support ring capable of being positioned in a determined orientation in the acetabular cavity concerned and fixed on healthy bone parts, and a cup capable of being secured to the support ring in being oriented relative to it.

 The abovementioned acetabular prosthesis is arranged so that the cup is previously oriented in an orientation chosen as a function of the future position of the support ring in the acetabular cavity of the patient and is secured in this orientation to a fixing flange.

 The cup positioned in the chosen orientation and integral with the fixing flange, is then placed inside the support ring, the fixing flange being fixed to the support ring.

 The main drawback of such a cotyldid prosthesis is that the orientation of the cup relative to the support ring is fixed in advance and is final when the cup is placed in the support ring.

 Therefore, if the support ring is not oriented as expected in the acetabulum of the patient's hip, the associated cup will not be oriented satisfactorily and the subsequent risk of hip dislocation will be significant.

 In general, it should be known that a cup of acetabular prosthesis must be oriented in a plane located at enviroll 4r degree relative to the vertical axis of the hip, turned slightly towards the front to cooperate satisfactorily with the patellar sphere of the femur.

 With the aid of this already known acetabular prosthesis, it is not possible during the operation to modify the orientation of the cup as a function of the position of the support ring since the orientation of the cup is definitive and fixed before its positioning inside said support ring.

 In addition, such a prosthesis has the following additional disadvantages.

 The support ring is not rigid enough and can deform when the anchor screws are tightened in the healthy bone parts. To avoid such deformation, an absolutely flat osteotomy should be carried out before the fitting of said support ring in the same plane, whether above, below, in front, behind the acetabulum, which is practically impossible to achieve.

 This acetabular prosthesis has a fixing tab, called the antero-superior tab, which essentially constitutes the upper anchoring of the support ring in the healthy bone parts.

 The anchoring of this ring is then insufficient.

 In addition, the support ring of the coty'ldide prosthesis conventionally comprises a lower hook intended to pass under the lower rim of the cotyloid cavity of the patient and to engage in the ischio-pubic hole of the hip to ensure the lower anchoring of said ring.

 This hook generally has too long a length and protrudes considerably inside the small pelvis, which risks causing new pathologies by contact.

In order to overcome the aforementioned drawbacks of the state of the art,
The invention proposes a new acetabular prosthesis for hip recovery which allows, when it is placed, an adjustment of the orientation of the cup relative to that of the support ring in the acetabular cavity, so as to allow the satisfactory positioning of said cup so that it cooperates with the patellar sphere of the femur without risk of subsequent dislocation.

 More particularly, according to the invention, the acetabular prosthesis for hip recovery comprises a support ring intended to be positioned in a determined orientation in the acetabular cavity of the hip and fixed on healthy bone walls, and a cup capable of being secured to the support ring while being oriented relative thereto.

 It is characterized in that the support ring has an internal diameter such that it allows a pivoting movement of the cup positioned inside said ring to orient it according to a chosen orientation with respect to it, and in that there are provided independent fixing means for the cup, capable of fixing the cup positioned inside the latter to the support ring according to the chosen orientation.

 The description which follows with reference to the appended drawings, given by way of nonlimiting examples, will make it clear what the invention consists of and how it can be implemented.

FIG. I represents a schematic exploded perspective view of the cotyldid prosthesis of recovery according to the invention,
- Figure 2 shows a schematic perspective view of the acetabular prosthesis according to the invention, once assembled.

 In Figures 1 and 2, there is shown an acetabular prosthesis dc recovery 100 of the hip, which comprises a support ring 1 10 intended to be positioned in a determined orientation in the acetabular cavity concerned of the hip.

 This support ring 11 () comprises a first fixing leg 111, called antero-superior leg, intended to be fixed on healthy bone parts by means of the fixing means (here not shown) cooperating with two circular openings 111a provided in said leg.

 In addition, it comprises a hook 115 placed diametrically opposite the antero-superior leg 111, this hook 115 being intended to hang in the ischio-pubic hole while passing under the lower edge of the acetabulum cavity. The hook 115 has a length such that it does not protrude too much inside the small pelvis.

 On either side of the hook 115, there are provided second and third internal fixing lugs 113, 114 intended to reinforce the anchoring of the support ring 110 in healthy bone parts. These second and third internal fixing lugs 113, 114 are positioned in an angular sector of said support ring 11 () opposite to that to which the antero-upper lug 111 is connected, and extend in a direction substantially perpendicular to the plane of said ring. support 110 towards the bottom of the acetabulum of the hip. They have a thickness such that they have a certain malleability allowing an adjustment of their orientation relative to the support ring 11 () for their fixing to the healthy bone parts of the hip.

 In addition, the acetabular revision prosthesis 1 () () comprises a cup 120 of spherical shape with an internal housing 121 intended to receive the patellar sphere fixed to the corresponding femur to reconstruct the diseased hip-femur joint.

 The cup 120 is able to be secured to the support ring 110 while being oriented relative thereto.

 More specifically, the acetabular prosthesis 1 () () is arranged so that the support ring 1 10 has an internal diameter D such that it allows a pivoting movement of the cup 120 positioned inside said ring 110 support to orient it relative to it.

 Thus, during the surgical intervention for the installation of such an acetabular prosthesis, the surgeon then positions the support ring 110 in the acetabular cavity according to an orientation determined in advance according to the case, then places inside the support ring 110 the cup 120 in a determined orientation and optionally adjusts the orientation of said cup 12 () by pivoting the latter once positioned inside the ring 11 () to perfect its orientation.

 You should know that such a cup is generally oriented about 45 degrees from the vertical axis of the hip and slightly turned forward.

 Depending on the positioning of the support ring 1 10 in the acetabular cavity, it may be necessary to slightly modify the orientation of the cup 120 to subsequently avoid problems with dislocation of the hip due to poor cooperation cup sphere patellar.

 This adjustment is made possible by the particular arrangement of the acetabular recovery prosthesis 100 in accordance with the present invention.

 In addition, the acetabular recovery prosthesis 1 () () comprises independent fixing means 130 of the cup 120, capable of fixing the cup 120 to the support ring 110 after it is positioned inside this last according to the chosen orientation possibly adjusted.

 According to the preft "rentiel embodiment shown in FIGS. 1 and 2, these fixing means comprise a clamping ring l 3 () capable of being placed (as shown more particularly in FIG. 2) on the support ring 1 10, around the cup 12 () positioned inside the support ring 110 in the chosen orientation, in contact with the latter, and to be fixed on said support ring so as to tighten the cup 110 to fix it in the oriented position chosen in said support ring 11O.

 To do this, the clamping ring 1 3 () comprises through holes 132 distributed around its circumference, intended to receive a fixing system of the screw-nut type 133, 134 for fixing the clamping ring 130 on the support ring 110.

 More particularly, the through holes 132 of the clamping ring 130 are intended to be fitted (see FIG. 2) on the threaded rods of fixing screws 133 mounted on the support ring 110 of the nuts 134 being able to be screwed onto the ends of said protruding screws of the through holes 132 for securing the clamping ring 130 to the support ring 110 and by the same fixing by tightening the cup 120 in the latter.

 Of course, other fixing systems can be provided, such as a system with staples which hooks into respective through holes of the support ring and the clamping ring.

 By tightening the nuts 134 on the screws 133, the clamping ring is scanned on the cup and then fixed in the support ring 110 in the chosen determined orientation.

 It should be noted that the support ring 110, the clamping ring 130 and the system for fixing said support and clamping rings are made of titanium or of a titanium-based alloy.

 The support ring advantageously has a thickness such that it gives it good mechanical rigidity in order to avoid any deformation of said support ring positioned in position in the acetabular cavity.

 In addition, the cup is conventionally made of polyethylene.

 The present invention is in no way limited to the embodiments described and shown, but a person skilled in the art will know how to make any variant which conforms to his spirit.

Claims (8)

 1. Cotyloid prosthesis for resumption (100) of the hip, comprising a support ring (11 ()) intended to be positioned according to a determined orientation in the acetabular cavity of the hip and fixed on healthy bone parts, and a cup ( 120) able to be secured to the support ring (11 ()) while being oriented relative thereto, characterized in that the support ring (11 ()) has an internal diameter (D) such that '' it allows a pivoting movement of the cup (120) positioned inside said support ring (1 10) to orient it in a chosen orientation with respect to it, and in that there are provided fixing means (130) independent of the cup (12 ()), capable of fixing the cup (12 ()) positioned inside the latter according to the orientation chosen, to the support ring (110).  2. acetabular prosthesis according to claim 1, characterized in that said fixing means comprise a clamping ring (130) able to be placed on the support ring (110) around the cup (1 2 ()) positioned in said support ring (110) in the chosen orientation, in contact with it, and to be fixed on said support ring (1 1 ()) dc so as to tighten the cup (11 ()) to fix it in oriented position in said support ring (11 ()).  3. acetabular prosthesis according to claim 2, characterized in that the clamping ring (130) comprises through orifices (132) distributed over its circumference, intended to receive a fixing system of the screw-nut type (133, 134) or clip for fixing the clamping ring (13 ()) on the support ring (11 ()).  4. the cotyldid prosthesis according to any one of claims 1 to 3, characterized in that the support ring (110) has a thickness such that it gives it good mechanical rigidity.  5. acetabular prosthesis according to any one of claims 1 to 4, in which the support ring (11 ()) comprises a first fixing leg (111), called antero-superior leg, on healthy bone parts, characterized in that said support ring (11 ()) further comprises second and third internal fixing lugs (11 3, 114) positioned in an angular sector of said support ring (110) opposite to that to which the antero-superior tab (111) is connected, and extending in a direction substantially perpendicular to the plane of the support ring (110) towards the bottom of the acetabulum of the hip.  6. acetabular prosthesis according to claim 5, characterized in that the second and third internal fixing lugs (113, 114) of the support ring (110) have a thickness such that they have a certain malleability allowing an adjustment of their orientation relative to the support ring (110) for their attachment to the healthy bony parts of the hip.  7. acetabular prosthesis according to one of claims 5 or 6, characterized in that the support ring (110) comprises between the deusièmc and third internal fixing lugs (113, 114) a hook (115) intended to s' hook into the hamstring hole passing under the lower rim of the acetabulum, said hook (11 5) having a length such that it does not protrude too much inside the small pelvis.  8. acetabular prosthesis according to any one of claims l to 7, characterized in cc that the support ring (110), the clamping ring (130) and the fixing system (133, 134) are made of titanium OR in a titanium-based alloy, and the cup (120) is made of polyethylene.