Incomplete seating of a metal-backed alumina liner in ceramic-on-ceramic total hip arthroplasty.

Metal-backed modular ceramic bearing systems using a recessed alumina liner in a titanium sleeve were developed to decrease ceramic chipping or fracture due to femoral neck impingement after total hip arthroplasty (THA). However, malseating of the metal-backed ceramic liner has recently been described. The goal of this study was to assess the prevalence, etiology, and clinical relevance of this event. Between 2005 and 2008, 51 consecutive patients (61 hips) underwent THA with a metal-backed alumina liner housed in a titanium shell. The metal-backed ceramic liner was aligned, seated, and impacted into the shell, and satisfaction in terms of liner stability and seating was confirmed intraoperatively. Postoperative assessment of seating was assessed with standard radiographs. Liner seating was classified as well seated, suspicious, or malseated. Seven liners (11.5%) were found to be malseated and 4 (6.5%) were considered suspicious. Radiographically, there was a gap between the liner and the shell located inferomedially in 4 patients and superolaterally in 3 patients. Two liners subsequently seated at 1 and 3 months postoperatively, respectively. No dislodgement, failures, or adverse events were identified. There were no revision surgeries. The significant percentage of malseated liners were potentially attributed to poor exposure, bony/soft tissue interposition, and surgeon learning curve.