Long-term Wear Data From a Prospective Multicenter Study of Second-Generation Highly Cross-linked Polyethylene Inserts in Total Hip Arthroplasty.

ABSTRACT

In a prospective multicenter trial on highly cross-linked polyethylene inserts in patients undergoing total hip arthroplasty, 118 patients consented to 10-year follow-up. Medium-term follow-up results showed low wear at 5 and 7 years after surgery. The current study focuses on long-term data at 10 years. Patients were followed up by either phone or office visit to collect long-term clinical data including Harris hip score and adverse events. There were 2 deaths and 2 revisions, 1 at 6.5 years for pelvic cyst and severe pain and another at 8.0 years for recurrent dislocation. For wear analysis, suitable radiographic images for 48 patients (52 hips) at minimum 10-year follow-up were available. Mean age of the cohort was 62.5 years (62% female). Femoral head penetration was measured using Martell's method from the radiographic images between the 6-week and the subsequent follow-ups. Polyethylene wear rate was calculated from the penetration data. Descriptive statistics were performed. There was no evidence of significant oxidation or locking mechanism failure. Mean Harris hip score of the group was 94.3. No osteolysis was noted by an independent radiographic reviewer. The slope of the bestfit regression line to the femoral head penetration data, which represents the overall linear wear rate of the polyethylene, was 0.014 mm/y. The wear rate was significantly below the 0.100 mm/y critical threshold for development of osteolysis. Volumetric wear rate was calculated to be 11.6 mm3/y. The second-generation highly cross-linked polyethylene acetabular inserts had low wear in the long term (10.3 years) with no incidence of osteolysis. [Orthopedics. 2018; 41(4)e529-e533.].