When Does Hip Dysfunction and Osteoarthritis Outcome Score for Joint Replacement Peak After Primary Total Hip Arthroplasty?

Background: The Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement (HOOS, JR) metric has been increasingly utilized to evaluate pain and function following total hip arthroplasty (THA); however, less is known about when these scores reach a maximum. The purpose of this study was to determine when HOOS, JR scores peak and surpass established clinical thresholds. Methods: A cloud-based patient engagement platform was queried for all HOOS, JR responses before and after elective primary THA at our institution. This resulted in a total of 8615 responses from 1866 THAs collected between December 2019 and March 2024. Procedures were performed between January 2011 and March 2024. Surveys were collected preoperatively and at 4 weeks, 4 months, and 1, 2, 5, and 10 years postoperatively. Primary outcomes included time points when HOOS, JR peaked, and when clinically important improvements were achieved. Survey responses were analyzed to compare recovery times for specific pain and function parameters. Substantial clinical benefits (+22) from baseline (53.4 ± 14.1) and the patient acceptable symptom state (76.7) were both achieved between 4 weeks (73.6) and 4 months (84.5) postoperatively. After 4 months, no additional clinically meaningful improvements occurred. Conclusions: The statistical peak in HOOS, JR scores after primary THA occurred around 1-year follow-up, and most clinically meaningful improvements occurred by 4 months. Patients can expect early meaningful improvements walking on an uneven surface and can expect prolonged difficulty with bending to the floor. Clinicians may incorporate this information to better set patient expectations and encourage their postoperative rehabilitation.