Total Hip Arthroplasty Outcomes Remain Exceptionally Strong in 8-Year PROMs Analysis

Patient-reported outcome measures (PROMs) following primary total hip arthroplasty (THA) have remained remarkably consistent over nearly a decade, according to a recent Cleveland Clinic study. These findings reflect what many orthopaedic surgeons already know, that THA continues to deliver excellent outcomes.

At the same time, the findings raise important questions about PROMs’ ability to capture further gains in an already highly successful procedure.

“In U.S. orthopaedics, we’re seeing a major shift toward value-based care, thanks to the Centers for Medicare & Medicaid Services PROMs mandate,” says Nicolas S. Piuzzi, MD, Vice Chair of Research for Orthopaedics and Rehabilitation at Cleveland Clinic. “We wanted to determine whether advances in THA over time have translated into meaningful improvements in PROMs.”

Cleveland Clinic investigators analyzed 9,822 patients who had primary unilateral THA at Cleveland Clinic between 2016 and 2023. Dr. Piuzzi presented the findings at the American Academy of Orthopaedic Surgeons (AAOS) 2026 meeting.

One-year outcomes remained excellent

Across the study period, one-year HOOS-Pain (Hip disability and Osteoarthritis Outcome Score), HOOS-PS (Physical Function Shortform) and HOOS-JR (Joint Replacement) scores were stable or modestly improved. Rates of clinically meaningful improvement — defined by minimal clinically important difference (MCID), patient acceptable symptom state (PASS) and substantial clinical benefit (SCB) thresholds — remained high throughout.

MCID achievement rates were consistently high across all three HOOS domains:

• 96.6% for HOOS-Pain
• 90.9% for HOOS-PS
• 95.2% for HOOS-JR

PASS achievement was:

• Stable overall at 89.5%
• Stable for HOOS-Pain at 74.9%
• Improved for HOOS-PS, from 74% to 82%
• Modestly increased for HOOS-JR, from 67.8% to 70.9%

SCB rates were stable for HOOS-Pain and HOOS-JR, at 74% and 68%, respectively, while HOOS-PS showed a modest decline from 71% to 65%.

“The one-year postsurgical outcomes remained excellent,” says Dr. Piuzzi. “We’re seeing great outcomes overall, with little change over all these years.”

Why haven’t PROMs improved further?

Study co-author Matthew Deren, MD, an orthopaedic surgeon and Director of the Adult Reconstruction Fellowship at Cleveland Clinic, notes that THA is distinct among surgical procedures.

“Total hip replacement is one of the best surgeries for patients’ quality of life of any surgery done on any part of the body,” he says. “Our findings underscore the effectiveness of THA in providing sustained, high-quality results.”

Dr. Piuzzi points to two likely explanations for the lack of further improvement in PROMs despite ongoing advances in surgical technique, implants and perioperative care:

1. Ceiling effects in existing PROMs tools. Current instruments may be approaching the upper limit of what they can detect in a procedure that already performs exceptionally well.
2. Increasing patient complexity. Expanding indications and evolving candidacy mean surgeons are treating younger, more active patients as well as patients with greater comorbidity burdens, potentially offsetting incremental gains in surgical care.

“In either case, it is a good metric to have, showing that we continue to provide an extremely high quality of care,” Dr. Piuzzi says.

Looking beyond PROMs alone

For surgeons, one of the study’s most important implications may be that PROMs, while valuable, should not be the sole lens through which outcomes are assessed.

“We need to start looking at functional and objective assessments of activity, including gait, step count, walking speed and other metrics, so that we can better understand patient performance,” Dr. Piuzzi says.

That perspective aligns with other research presented at the 2026 AAOS meeting. In a wearable-device study of patients having total knee arthroplasty, step-count data varied substantially by age, sex and BMI, differences that would not have been captured by PROMs alone.

Relevance in the era of CMS PROMs reporting

The findings of this study are particularly timely as hospitals prepare for the Centers for Medicare & Medicaid Services (CMS) mandate requiring PROMs collection from patients having elective joint replacement. Noncompliance could bring financial penalties for hospitals, scheduled to take effect in 2028.

“This is an extremely important topic because it provides a real-world benchmark across eight years, and it helps us interpret PROMs performance in light of the new CMS mandate,” Dr. Piuzzi says.

For orthopaedic surgeons and health systems, the message is both reassuring and practical, he says.

“Primary THA continues to produce excellent one-year patient-reported outcomes. Stable PROMs over time may reflect the high baseline performance of the procedure rather than a lack of progress. As a result, we should be assessing patients holistically, not purely based on PROMs. Integrating objective functional measures will truly enable personalized risk stratification and the value-based care that CMS is targeting.”