More Detail on That Landmark Implant Selection Study

To what extent does hip implant selection affect patient outcomes? At one year, according to a new study, not much. At 10-years or 20-years? Stay tuned.

This provocative question was the impetus behind a new, likely landmark study, coming out of the research team at the Cleveland Clinic. To recap: the research team found that implant characteristics don’t move the needle as far as patient pain and function outcomes are concerned. The study, “Does Implant Selection Affect Patient-Reported Outcome Measures After Primary Total Hip Arthroplasty?” appears in the December 15, 2021 edition of The Journal of Bone and Joint Surgery.

Here is additional detail from the authors of this important study.

“As the focus in orthopaedics shifts toward value-based care, it is important that surgeons critically consider what patient- and surgery-related factors contribute to quality care,” co-author Nicholas Piuzzi, M.D., adult reconstructive surgery research program director at Cleveland Clinic told OTW. “Therefore, the identification of modifiable factors that may influence patient outcomes after primary THA [total hip arthroplasty] is crucial. To date, there is inadequate literature discerning the impact of implant selection on patient-reported outcomes after primary THA.”

The study authors collected data 4,716 patients who had been treated with primary total hip arthroplasty between July 2015 to August 2018. The researchers categorized the study patients according to type of femoral and acetabular components and bearing surface.

They then measured one-year postoperative patient-reported outcomes and improvement using the Hip Disability and Osteoarthritis Outcome Score and the University of California at Los Angeles (UCLA) activity score. The team defined inadequate improvement as postoperative patient-reported outcome measures that changed by less than the minimal clinically important difference for the Hip disability and Osteoarthritis Outcome Score (pain) and (physical function short form) and as failure to improve beyond a primarily homebound activity status according to the UCLA activity score.

Perhaps Surprisingly, Implant Selection Was Not a Factor in Outcomes – at ONE YEAR

In the final analysis, one-year patient-reported outcome measures were available for 3,519 patients (74.6%). The authors found that multivariate regression showed that implant selection was “not a significant driver of inadequate improvement, according to the Hip Disability and Osteoarthritis Outcome Score (pain) and the Hip Disability and Osteoarthritis Outcome Score (physical function short form). Larger (36mm) femoral heads demonstrated lower odds of inadequate improvement versus 28mm femoral heads according to the UCLA activity scores. Implant-related criteria were not significant drivers of attaining a patient-acceptable symptomatic state or achieving a substantial clinical benefit with respect to Hip Disability and Osteoarthritis Outcome Score (pain).”

“At one year after THA,” said Dr. Piuzzi to OTW, “there were no significant and clinically important differences in the characteristics of modern THA implants used with respect to the proportion of patients who achieved or failed to achieve the minimal clinically important difference in Hip Disability and Osteoarthritis Outcome Score (pain), Hip Disability and Osteoarthritis Outcome Score (physical function short form), or the UCLA activity scores. Furthermore, multivariate logistic regression analysis demonstrated that implant selection was not a significant driver of inadequate improvement according to The Hip Disability and Osteoarthritis Outcome Score (pain) and Hip Disability and Osteoarthritis Outcome Score (physical function short form). In contrast, a larger femoral head size (36mm) was associated with lower odds of inadequate improvement in activity at 1 year than a small femoral head (28mm).”

“For the most part, THA implant characteristics are not drivers of inadequate improvement with respect to pain and function. Surgeons should utilize implants with an acceptable track record that allow stable fixation and restoration of hip biomechanics.”