Total Hip Arthroplasty Improves Pain and Function but Not Physical Activity.

Background: People with hip osteoarthritis are likely to limit physical activity (PA) engagement due to pain and lack of function. Total hip arthroplasty (THA) reduces pain and improves function, potentially allowing increased PA. PA of THA patients was quantified to 12 months postoperation. The hypothesis was that postoperatively levels of PA would increase.

Methods: PA of 30 THA patients (67 ± 7 years) was objectively measured preoperatively and 3 and 12 months postoperation. Harris Hip Score (HHS), Oxford Hip Score (OHS), and 6-minute walk test (6MWT) were recorded. Mixed linear modelling was used to examine relationships of outcomes with time, baseline body mass index (BMI), age, gender, and baseline HHS.

Results: Time was not a significant factor in predicting volume measures of PA, including sit-to-stand transitions, upright time, and steps. Notably, baseline BMI was a significant predictor of upright time, steps, largest number of steps in an upright bout, HHS, and 6MWT. Baseline HHS helped predict longest upright bout, cadence of walking bouts longer than 60 seconds, and OHS. The significant effect of participant as a random intercept in the model for PA outcomes suggested habituation from presurgery to postsurgery.

Conclusion: Volume measures of PA did not change from presurgery to 12 months postsurgery despite improvement in HHS, OHS, and 6MWT. Baseline BMI was a more important predictor of upright activity and stepping than time. Preoperative and postoperative PA promotion could be used to modify apparently habitual low levels of PA to enable full health benefits of THA to be gained.