Published 9/21/2020
Terry Stanton

Outcome Differences Among THA Approaches Not Clinically Meaningful

Editor’s note: The following content was originally scheduled for the AAOS Now Daily Edition, which publishes each year onsite at the AAOS Annual Meeting, but this year’s meeting in March was canceled due to COVID-19. Despite the cancellation, members can access virtual content from the Annual Meeting by visiting the Academy’s Annual Meeting Virtual Experience webpage at aaos.org/VirtualAAOS2020.

A study that was presented as part of the Annual Meeting Virtual Experience evaluated outcomes with three major approaches for primary total hip arthroplasty (THA) and found that a surgical approach was a statistically significant factor for pain at one year but did not have a significant effect on physical function or activity scores or on reoperation rates. Overall, no clinically meaningful differences were found among the approaches.

The study, presented by James Bircher, DO, a resident at Cleveland Clinic–South Pointe Hospital, compared one-year patient-reported outcome measures (PROMs) of those who underwent THA by direct anterior (DA), transgluteal anterolateral (AL)/direct lateral (DL), or posterolateral (PL) approach. The PROMs were Hip Disability and Osteoarthritis Outcome Score (HOOS) pain subscore; HOOS-Physical Function Shortform (HOOS-PS); and University of California, Los Angeles (UCLA) activity score.

The study involved 2,455 patients who underwent primary unilateral THA for primary osteoarthritis. Procedures were performed by 20 surgeons across five facilities adhering to a standardized care pathway. Of the patients, 913 (38 percent) underwent DA, 505 (21 percent) underwent AL/DL, and 972 (41 percent) underwent PL approach.

Fig. 1 Boxplots displaying the marginal distribution of each Patient-reported Outcome Measure (PROM) of interest at one year by surgical approach. HOOS, Hip Disability and Osteoarthritis Outcome Score; PS, physical function; UCLA, University of California, Los Angeles
Courtesy of James Bircher, DO
James Bircher, DO, a resident at Cleveland Clinic–South Pointe Hospital

At one year postoperatively, PROMs were available for 1,842 patients (77.1 percent) (Fig. 1). Surgical approach was a statistically significant factor for one-year HOOS pain score (P = 0.002), but the approach was not a significant factor for HOOS-PS (P = 0.16) or UCLA activity score (P = 0.382). There was no significant difference in one-year pain scores between patients receiving the DA approach and patients receiving the PL approach. However, patients receiving the AL/DL approach had statistically significantly lower (worse) HOOS pain scores than patients receiving the DA or PL approach (differences in median score, 3.47 and 2.43 lower on a 100-point scale, respectively, for patients with AL/DL approach).

Regarding their finding that patients receiving the AL/DL approach had statistically worse pain scores at one year than those with the DA or PL approach, the authors noted that the minimum clinically important differences in HOOS pain scores have been evaluated in multiple recent studies and are reported to be between nine and 36 points for individual patients. “The difference in HOOS pain scores in our study fall well below that threshold, which indicates that despite the statistically significant difference in pain scores among the surgical groups, no clinically meaningful difference exists,” they wrote. “Additionally, surgical approach was not a statistically significant factor in one-year function or activity, and there was no difference in one-year reoperation rates or 90-day readmission rates among approaches.”

Dr. Bircher said the results are consistent with several prospective studies with longer-term data showing no differences in pain, function, or activity one year postoperatively. A meta-analysis of five randomized, controlled trials with 475 patients comparing DA to DL approach in primary THA found no difference in Harris Hip Score (HHS), with follow-up ranging from three months to 48 months. A more recent systematic review and meta-analysis of prospective studies comparing DA versus PL approach found that patients treated with DA reported less pain, consumed fewer narcotics, and had better HHS, but that was limited to 90-day follow-up.

Dr. Bircher told AAOS Now that collection of longer-term PROM data remains necessary for evaluating the effects of approach on THA outcomes.

Among the limitations of the study, he said, are that it did not include short-term follow-up data regarding the various PROMs. “The approach was chosen by the surgeon based on their individual experience and preferences and was not randomized or controlled,” he said. “The inclusion of surgical procedures from multiple surgeons and uncertain adherence to care pathways does introduce additional variability. We did not assess the surgeon- or hospital-specific differences in PROMs.”

Dr. Bircher’s coauthors of “No Clinically Meaningful Difference in 1-Year Patient-Reported Outcomes among Major Approaches for Primary Total Hip Arthroplasty” are Atul F. Kamath, MD; Nicolas S. Piuzzi, MD; Alison Klika, MS; Carlos Higuera Rueda, MD; Kurt Spindler, MD; Gregory J. Strnad, MS; Alexander Zajichek; and Michael R. Bloomfield, MD.

Terry Stanton is the senior medical writer for AAOS Now. He can be reached at tstanton@aaos.org.