Primary Total Hip Arthroplasty in Patients Less Than 50 Years of Age at a Mean of 16 Years: Highly Crosslinked Polyethylene Significantly Reduces the Risk of Revision

The purpose of this study is to evaluate clinical and radiographic outcomes of patients less than 50 years of age undergoing primary total hip arthroplasty (THA) at a minimum of 10 years.

Three hundred nine consecutive THAs performed on 273 patients were reviewed. At a minimum of 10 years, 13 were deceased and 23 were lost to follow-up leaving 273 THAs in 237 patients who were followed for a mean of 16 years (range 10-19.9). The cohort consisted of 116 females (49%) and 121 males (51%), with a mean age of 42.3 years at the time of surgery (range 19-49). The majority of preoperative diagnoses included osteoarthritis in 149 (63%) and avascular necrosis in 55 (23%). Two hundred sixteen had highly crosslinked polyethylene (HXLPE) and 57 had non-HXLPE acetabular liners. The femoral stems were cementless in 98% (266/273) and the acetabular components were cementless in all cases. Femoral head composition was cobalt-chromium in all cases and the majority of sizes in the non-HXLPE cohort were 28 mm (52/57; 91%), while the HXLPE group primarily consisted of 28 mm (141/216; 65%) and 32 mm (74/216; 34%) heads. Analysis involved Kaplan-Meier survivorship with a log-rank test for equivalence, Fisher’s exact test for pairwise comparisons, and a paired t-test for Harris Hip Score, with alpha = 0.05 being statistically significant.

There were 6 revisions for wear in the non-HXLPE group (10.5%) compared to none in the HXLPE group ( P < .001). Similarly, survivorship with revision for any reason as the endpoint at 16 years was significantly higher at 93.0% in the XLPE group (95% confidence interval 88.7-95.7) compared to 85.7% (95% confidence interval 73.5-92.6) in the non-HXLPE group ( P = .023). Additional revisions in the HXLPE group included 6 for instability (2.8%), 5 secondary to infection (2.4%), and 3 stem failures (1.4%). Non-wear-related revisions in the non-HXLPE group included 5 due to instability (8.8%) and 3 due to stem failures (5.3%). The mean Harris Hip Scores for the entire cohort improved from a mean of 46.2 points preoperatively to 89.8 points at most recent follow-up ( P < .001).

The use of HXLPE has led to a significant reduction in the risk of failure in patients <50 years old, with over 93% survivorship at 16 years. Instability and infection, however, remain substantial causes of failure.

Therapeutic Level III.