Experience with sandwich liner and its high rate of failure.

Abstract

Composite ceramic with polyethylene backing was introduced to enhance the quality of ceramic articulation, but the liner's high rate of ceramic fracture has brought serious concern. In this study, the authors investigated the failure rate of sandwich liner in long-term follow-up patients at single institution. In this series, we retrospectively reviewed 134 patients (143 hips), and six patients (6.2%) were found to have liner fracture. They were compared to nonfracture patients to identify the associating factors. General patient characteristics were obtained through review of charts. All patients were implanted with SPH Contact acetabular cup and sandwich liner. Function (Harris hip score) and activity (Devane score) were recorded preoperatively and at final follow-up. Radiologically, inclination and abduction angles were measured for comparison. The study did not show any statistical differences between fracture and nonfracture groups in age, weight or body mass index. Side, type of stem used and radiologic parameters were not also significantly different. The operation had significantly improved function and activity postoperatively in both groups, but no statistical significance was noted between the two groups exception to preoperative Harris hip score. On inspection, retrieved ceramic heads and liners showed substantial metal transfer on their surfaces, and linear wears were evident on the ceramic heads. Compared to other studies, our series also experienced high rate of sandwich liner fracture. Though its use was generally discontinued, it is worrisome to note that failure rate of the liner will substantially increase over time.