Long-term follow-up of total hip arthroplasty using polyethylene-ceramic composite (sandwich) liner.

INTRODUCTION: Ceramic-on-ceramic bearings have been widely used since their introduction in the 1970s. First-generation ceramics have very high fracture (breakage) rates. To overcome this, in the 1990s, modular cotyloid insert designs were developed, consisting of a ceramic and polyethylene composite (sandwich-type) liner; however, high implant fracture rates were observed in the medium term. We aimed to estimate the cumulative incidences of revision surgery (implant failure) and implant failure due to fractures, survival rates (time-to-revision surgery and time-to-fracture), and the long-term clinical and radiological outcomes in our series.

METHODS: This was an observational, longitudinal, ambispective, single-centre study based on patients who underwent primary total hip arthroplasty (THA) using a sandwich-type liner (Cerasul), only available in our tertiary hospital between January 1999 and December 2002. Cumulative incidences were estimated and the 95% confidence interval (95% CI) was calculated. The Kaplan-Meier method was used to assess the time-to-revision surgery and time-to-fracture.

RESULTS: 54 patients (49 men) were included, accounting for 59 sandwich-type linear implants. The mean (range) age was 47.4 (22-57) years. The primary THA indications were osteoarthritis (28 patients), osteonecrosis (14), childhood pathology sequelae (11), and inflammatory arthritis (6). The cumulative incidence of revision surgery by implants was 8.5% (5/59, 95% CI, 3.5-19.2%), 9.3% by patients (5/54, 95% CI, 4.0-19.9%), and 5.1% by implant fractures (3/59, 95%CI, 1.7-13.9%). The median (Interquartile Range, IQR) time-to-revision surgery was 158 (72.5-161) months, and the time to fracture was 182 (138-215) months. All primary THAs had good clinical and long-term survival outcomes. All implants had signs of solid fixation.

CONCLUSIONS: After a 20-year follow-up period, the polyethylene-ceramic sandwich-type liner showed a long survival rate and low cumulative incidence of implant fracture; however, implant fractures remain the main complication. Orthopaedic surgeons should be aware that some patients still have this type of prosthesis and must be capable of responding quickly if a fracture occurs.