Abstract
Purpose: We report our results of revision procedures for severe acetabular loosening with saddle prostheses. The series concerned six patients, mean age 67 years age range 58–82 years, who initially presented rheumatoid disease (n=3), degenerative hip disease (n=3, one secondary to trauma), and radiation-induced hip disease (n=1). These patients had undergone one to three procedures for reconstruction with a bone graft and metal implants.
Material and methods: Failure was the indication for salvage with a saddle prosthesis due to massive loss of acetabular bone stock, complicated in five cases by an unstable hemipelvis due to transverse nonunion. An allograft was screw fixed in the iliac wing in two cases to stabilise the saddle prosthesis. Weight bearing was allowed early after surgery in all cases except two. The hip was immobilised in four cases for three to six weeks in a bermuda cast or with traction (n=4). Follow-up was 2 to 5 years.
Results: There was only one complication: stress fracture of the iliac bone at two years which did not heal. Bone graft with ostheosynthesis was proposed. Pain relief was nearly total in all cases. Four patients could walk without crutches and two walked with two crutches or an ambulator due to associated disease or alar fracture. The fixation was at 60 – 95° with abduction at 10–30°. All patients were satisfied and two felt the result was very superior to simple ablation of the prosthesis which they had experienced. Radiograpically, there was no evidence of ascension of the saddle but the risk remains at this short follow-up due to the rates described in the literature. One major migration was observed as was one stress fracture of a weak iliac bone which required removal of the implant.
Discussion: This difficult technique provides a better result and thus would be indicated for young patients able to sustain the intervention. It would be logical to associate a supporting bone graft on the iliac bone to prevent stress fracture and migration of the saddle. The saddle prosthesis appears to be the last resort after failure or insufficient results after prior reconstruction. The leading cause of failure is nonunion with hemipelvis mobility. This suggests the intervention should be considered before reaching this stage of well tolerated ace-tabular loosening.
The abstracts were prepared by Docteur Jean Barthas. Correspondence should be addressed to him at Secrétariat de la Société S.O.F.C.O.T., 56 rue Boissonade, 75014 Paris.
