Are Harris Hip Scores and Gait Mechanics Related Before and After THA?

Discordance between subjective and objective functional measures hinders the development of new ways to improve THA outcomes. We asked if (1) any kinematic or kinetic gait variables are correlated with preoperative Harris hip scores (HHS), (2) any kinematic or kinetic gait variables are correlated with postoperative HHS, and (3) pre- to postoperative changes in any kinematic or kinetic gait variables are associated with the change in HHS? For this retrospective study, an institutional review board-approved data repository that included all individuals who participated in motion analysis research studies was used to identify subjects evaluated before (n = 161) and at least 6 months after primary unilateral THA (n = 156). Selected kinematic (sagittal plane dynamic hip ROM and kinetic (peak external moments about the hip in the sagittal, frontal, and transverse planes) gait variables were collected at subjects' self-selected normal walking speeds. We used first-order partial correlations to identify relationships between HHS and gait variables, controlling for the influence of speed. Preoperative HHS correlated with hip ROM (R-|speed = 0.260; p < 0.001) and the peak extension moment (R-|speed = 0.164; p = 0.038), postoperative HHS correlated with the peak internal rotation moment (R-|speed = 0.178; p = 0.034), and change in HHS correlated with change in hip ROM (R-|speed = 0.288; p = 0.001) and peak external rotation moment (R-|speed = 0.291; p = 0.002). Similar associations were seen when the HHS pain and function were analyzed separately. This study identified relationships between a common clinical outcome measure and specific, modifiable gait adaptations that can persist after THA-ROM and transverse plane gait moments. Addressing these aspects of gait dysfunction through focused rehabilitation could be a new strategy for improving clinical outcomes. Prospective studies are needed to evaluate this concept. Level III, diagnostic study. See the Instructions for Authors for a complete description of levels of evidence.