A well-fixed femoral stem facing a failed acetabular component: to exchange or not? A 5- to 15-year follow-up study.

INTRODUCTION: There is no consensus about the necessity of exchanging a stable femoral component during revision total hip arthroplasty (RTHA) when only the acetabular component requires replacement. Sparing the femoral component reduces morbidity, but can make acetabular replacement technically more difficult. Moreover, the outcome of the retained femoral component is also a question, especially with older implants.

HYPOTHESIS: Isolated acetabular component RTHA results in lower surgical morbidity, and does not increase the risk of later femoral complications.

PATIENTS AND METHODS: Eighty-nine patients, mean age 68, underwent surgery (anterior approach on traction table) for isolated acetabular component revision between 1994 and 2005. The femoral component had been implanted a mean 10.5 years before revision.

RESULTS: Fifteen patients died, mean age 84.5. Eleven patients, mean age 81.3, were lost to follow-up and four underwent revision due to a subsequent infection (range 14 months - 11 years). Fifty-nine patients were evaluated after a mean 8.6 years (range 4 - 15 years). At follow-up the mean Harris score was 89.2 [IC=6.89; 44 - 100] and the mean Merle d'Aubigné score was 15.3 [IC=1.57; 11 - 18]. Five patients (5.6%) underwent surgery again due to postoperative dislocation. Six patients underwent surgery for recurrent acetabular loosening due to allograft resorption. The size of the bone defects did not increase the risk of these failures (P>0.6). Fractures occurred in two femoral components 6 and 9 years after revision. Polyethylene wear occurred in three patients requiring two repeat revisions at 6 and 7 years. In both cases the femoral component included a titanium head, which caused the wear. Implant survival at 8.6 years was 85.16 ± 0.117% all causes of revision combined, 88.47 ± 0.113% if infectious causes were excluded and 93.6 ± 0.07% if only cases of acetabular component failure were taken into account.

CONCLUSION: Intermediate term outcomes are satisfactory if stable femoral components are retained. Nevertheless, this procedure should be performed in situations of correctly oriented modular components. In single piece (monoblock) femoral implants, or in implants with a history of failure, this technique should be restricted to elderly and/or fragile patients.

LEVEL OF EVIDENCE: Level IV, Retrospective study.