Physical activity and the risk of aseptic loosening after total hip arthroplasty: a case–control study from the Norwegian Arthroplasty Register

Abstract

Introduction

Previous studies have shown increased wear rate and aseptic loosening of total hip arthroplasty (THA) in patients with high physical activity levels. However, highly cross-linked polyethylene (HXLPE) has a reduced wear rate compared to conventional polyethylene. Thus, studies on the amount of physical activity in THA with HXLPE are needed. We aimed to determine if the level of physical activity in patients with THA containing HXLPE was associated with the risk of aseptic loosening of this implant.

Methods

In this retrospective case–control study, we identified patients aged 40–75 years with a primary THA containing HXLPE registered in the Norwegian Arthroplasty Register (NAR) from 2005–2012 (n = 10,904). With a mean follow-up of 9.1 years, 176 patients were revised for aseptic loosening of their THA and invited into the study together with a sample of 856 patients with unrevised THA. Participants reported their physical activity level by answering the University of California, Los Angeles (UCLA) activity score at their best-remembered condition after the primary surgery. The peak physical activity levels were compared to the risk of being revised due to aseptic loosening in a multivariate logistic regression analysis.

Results

Patients treated with revision surgery for aseptic loosening (n = 77 (44%)) had a lower retrospective peak level of physical activity before revision surgery compared to unrevised control patients (n = 429 (50%)); UCLA score median (IQR) 7 (5–8) vs. 8 (6–8). Adjusted logistic regression analyses of these UCLA scores on the risk of revision surgery due to aseptic loosening of the THA, showed that a higher level of physical activity was associated with a decreasing risk of revision surgery (OR 0.8, 95% CI 0.7–0.9, P = 0.001).

Conclusion

A retrospectively self-reported level of physical activity at the patient`s best-remembered condition after primary THA was not associated with a higher risk of revision surgery due to aseptic loosening of the THA. Patients with THA should be encouraged to gain the health benefits of regular physical activity rather than restricting their activity level because of fear of implant wear and loosening.