Are Functional Outcomes of a Total Hip Arthroplasty Predictive of a Contralateral Total Hip Arthroplasty: A Retrospective Cohort Study

Background: Current literature suggests that 8%-35% of patients undergoing total hip arthroplasty (THA) undergo a subsequent contralateral THA. This study aims to determine if functional outcomes after primary THA predict outcomes in the subsequent primary THA of the contralateral side. Methods: A retrospective cohort of patients undergoing staged bilateral primary THA was reviewed. The Oxford Hip Score (OHS) was utilized as the functional outcome measurement tool and was assessed preoperatively and at one year postoperatively. The minimal clinically important difference (MCID) was assessed. Based on the first-side THA one-year outcomes, the odds of maintaining an MCID, or not, for the second-side THA were determined. Results: The study cohort consisted of 551 patients and 1102 primary THAs. The average postoperative OHSs were similar after the first and second THA. Patients achieving the MCID with the first-side surgery were 2.6 times (95% confidence interval 1.0 to 6.64, P=.04) more likely to achieve the MCID for the secondside surgery than patients failing to reach theMCID for their first-side surgery. After the first THA, 29 (5.3%) patients failed to reach the predefined MCID for the OHS compared with 54 (9.8%) patients undergoing their second THA (odds ratio: 1.96 [95% confidence interval: 1.23 to 3.1], chi(2) = 8.14, P=.005). Conclusions: Functional outcomes after the first THA are predictive of functional outcomes of the second THA. Patients are more likely to achieve a clinically significant improvement after their first THA related to higher preoperative OHSs before the second THA. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

This study reviewed a cohort of patients undergoing staged bilateral primary THA and found that functional outcomes after the first THA are predictive of outcomes after the second THA. Patients who achieved the MCID after the first surgery were more likely to achieve it again for the second surgery.