Cementing polyethylene liners into non-modular acetabular components in revision total hip arthroplasty.

PURPOSE To review mid-term results after replacing the polyethylene liner in a well-fixed acetabular shell. METHODS 22 patients underwent replacement of the polyethylene liner in a well-fixed acetabular shell using cementation. The inner surface of the metal shell was scored with grooves (1 to 2 mm deep) for cement interdigitation. Trial liners were used to assess the appropriate size, with an aim to provide at least 2 mm of an even cement mantle behind the polyethylene liner. None of the liners were constrained or lipped. Clinical and radiographic outcomes were evaluated, and Harris Hip Scores obtained. Radiographic loosening of the acetabular shell was recorded. Implant survival was evaluated using the Kaplan- Meier estimator. RESULTS After a mean follow-up of 70 (range, 21-189) months, 17 patients had stable hips and their mean Harris Hip Score was 89 (range, 72-93). Four patients underwent re-revision after 28 to 108 months for aseptic loosening of the acetabular shell (n=2) and recurrent dislocation (n=2). One patient showed radiographic evidence of acetabular migration but was stable. The femoral components of all patients were stable. 92% of patients had good-to-excellent results. Implant survival at 60 months was 81% (95% confidence interval [CI], 51-94%); it became 91% (95% CI, 61-99%) if reductions for dislocations were excluded. CONCLUSION Cementation of an undersized polyethylene liner into a non-modular shell is one option for revision of a well-fixed acetabular shells. Nonetheless, further follow-up is required to determine if it remains a viable option in the long term. If there is any doubt about the stability of the acetabular shell, a complete revision should be performed.