Preoperative gait mechanics predict clinical response to total hip arthroplasty.

Some patients do not have an adequate clinical response to total hip arthroplasty (THA) for reasons that are not fully understood. Identifying modifiable factors that are associated with nonresponse could lead to new ways to identify and treat potential nonresponders. This study investigated whether any preoperative gait characteristics were associated with THA clinical response, and whether or not there were corresponding postoperative gait differences in THA nonresponders compared to responders. A secondary analysis was conducted of 124 subjects (age 61 ± 10 years; 64 female/60 male), evaluated before and 1 year after primary unilateral THA, using quantitative gait analysis and Harris Hip Scores (HHS). Responders and nonresponders were identified using the OMERACT-OARSI responder criteria, modified for use with the HHS. Pre- and postoperative dynamic sagittal plane range of motion (ROM) and 3D peak external moments were compared, for responders and nonresponders, using t-tests and logistic regression. 11.3% of subjects were nonresponders. Before surgery, the ROM was 26% higher for nonresponders than responders, but the peak external rotation moment was 30% lower (p = 0.003-0.043). Preoperative gait and HHS predicted response with a sensitivity of 71.4% and a specificity of 99.1%. There were persistent postoperative deficits in the peak external rotation moment in nonresponders compared to responders (p = 0.028). This study showed that gait analysis, where available, can augment clinical scores in predicting THA response. Moreover, it suggests that further analysis of the subtle role of transverse plane hip mechanics could lead to interventions to promote better THA response.