Comparison of Conventional and Large Diameter Femoral Heads for the Prevention of Hip Dislocation

A Randomized Multi-Centre Controlled Trial of Large Diameter (36/40 mm) Versus Conventional Diameter (32 mm) Femoral Heads for the Prevention of Post Revision Arthroplasty Dislocation

About ten percent of revision hip replacements will dislocate. Although dislocation is not a life-threatening problem, it is stressful and costly and requires hospitalization to treat. Subjects who have repeated dislocations live with the constant fear of another dislocation. The purpose of this study is to test the effectiveness of a large ball prosthesis in preventing post-surgical dislocation. A large diameter ball has greater freedom of movement before it impinges; therefore, theoretically, it should not dislocate as easily.

Inclusion Criteria:

1. Eligible patients will be those undergoing revision hip arthroplasty, either first revision or subsequent re-revision.
2. Revision must require replacement of both the acetabular component and femoral component, except when revising femur only with well-fixed Trilogy socket.
3. The acetabular component must have a minimum outer diameter of 50 mm.
4. The femoral component inserted should be a Zimmer Versys™ beaded full-coated stem or Zimmer ZMR™ stem or collarless polished taper (CPT™)
5. Patients must be able to reply to questionnaires in either French or English.

Exclusion Criteria:

1. Patients who are undergoing revision for recurrent dislocation.
2. Revision of the acetabulum requiring structural allograft or reconstruction ring.
3. Revision of the acetabulum requiring the use of cemented all-polyethylene cups.
4. Revision of the acetabulum using a liner cemented into an existing metal shell.
5. Intra-operative decision to use a constrained liner.