AbstractsBiology & Animal Science

Introduction: Persons with medial knee osteoarthritis (OA) are thought to adopt increased frontal plane trunk sway to reduce medial compartment loading. This type of compensatory motion may affect bilateral muscle function and loading of the lower extremity joints, and thereby impact risk of developing multi-articular OA. Unloading valgus knee braces are frequently prescribed for symptomatic relief for individuals with uni-compartmental knee OA. However, little is known about their potential effect on the biomechanics of other lower extremity joints, or about their influence on hip abductor muscles that may contribute to trunk sway. Furthermore, most studies have focused on an older population while perhaps it is the <60 years who stand to gain the most from conservative therapy. The purpose of this study was therefore to assess frontal plane hip and trunk biomechanics and hip muscle function in a relatively young, active OA patient population and examine the effects of an unloading brace (UnloaderOne®) thereon. Methods: Seventeen male patients (age 40-60 years) with symptomatic medial knee OA and confirmed Kellgren-Lawrence grade II or III radiographic scores were recruited for the study. All had received a prescription for an unloading brace. Fourteen asymptomatic males were recruited as controls and conventional gait analysis was performed to assess kinematic and kinetic patterns. OA participants were assessed both with and without the brace during an initial assessment within 48 hours of brace fitting and again 4 weeks later. Isometric hip abductor strength was measured and activation levels of Gluteus medius (Gmed) and tensor fasciae latae (TFL) muscles were monitored with surface electromyography (EMG). OA participants were stratified into responders (R) and non-responders (NR) according to OARSI – OMERACT criteria. Alpha was set at 0.05 for statistical analyses, which included correlations, t-tests and repeated measures analysis of variance. Results: No group differences were found for age, BMI, or normalized hip abductor muscle strength. Overall, self-report scores of OA participants improved (p<0.05), but great variability was seen in the response. OA participants demonstrated less trunk lean to stance side at initial contact (IC) (p=0.015), and a delay in transition of trunk lean from stance to contralateral side, compared to CTRLs. Rs also had greater frontal plane trunk excursion (p=0.034) than CTRLs and NRs. No intergroup or interlimb differences were found for hip adduction moments or angles and no changes were detected over time for those parameters. No significant group or interlimb differences were found for peak muscle activation levels of Gmed at baseline but peak activation levels of TFL were significantly higher for R than CTRLs (p<0.001) and NRs (p<0.001). Rs demonstrated an increase in Gmed peak muscle activation level when wearing the brace (p<0.01). Conclusions: Overall, self-report scores improved significantly with brace use, while frontal plane angles or moments at the hip were not…