ACETABULAR RECONSTRUCTION FOR METASTATIC LESIONS IN THE PELVIS WITH A NEW CAGE IMPLANT

Abstract

The treatment of acetabular metastases with total hip arthroplasty is technically challenging often with significant loss of structural continuity in the medial wall and roof of the acetabulum, as described by Harrington in 1981 as class III defects. Traditionally the acetabular component is stabilised with Harrington rods but the risk of post-operative complications, especially bleeding is significant.

We performed 10 consecutive total hip arthroplasties in patients with metastases involving the acetabulum with Harrington class III defects. The first three patients had acetabular reconstruction with a Kerboull cage, (Stryker Howmedica.) The cage was secured using a combination of screw fixation to the ileum and PMMA cement filling voids behind the cage. A polyethylene acetabular cup is then cemented into the cage. There was concern about the superior fixation using this implant and so the remaining 7 patients were treated using the Graft Augmentation Prosthesis (GAP II), (Stryker How-medica.) This is a titanium reconstruction cage with two superior flanges allowing extensive screw fixation onto the ileum. Two patients had very large defects where there was not sufficient support to use this cage alone, so the technique was augmented with Harrington rods.

No implants have failed to date. One patient, an 83 year old female, died 23 days post-operatively after suffering a stroke. Two patients died of their disease 95 and 115 days after surgery. The remaining patients continue to have good pain and mobility following surgery as demonstrated by the Oxford hip score.

We conclude that in suitable patients with extensive metastatic involvement of the acetabulum, a flanged acetabular reconstruction cage prosthesis is much improved way of providing support for a total hip replacement. This procedure can greatly improve quality of life, and to date we have had no mechanical failures of fixation using this technique.