Timing of Frontal Plane Trunk Lean, Not Magnitude,Mediates Frontal Plane Knee Joint Loading in Patients withModerate Medial Knee Osteoarthritis

The purpose of this study was to examine the influence of trunk lean and contralateral hip abductor strength on the peak kneeadduction moment (KAM) and rate of loading in persons with moderate medial knee osteoarthritis. Thirty-one males (17 withosteoarthritis, 14 controls) underwent 3-dimensional motion analysis, strength testing of hip abductors, and knee range of motion(ROM) measures, as well as completing the knee osteoarthritis outcome score (KOOS). No differences were found between groupsor limbs for gait cycle duration, but the osteoarthritis group had longer double-limb support during weight acceptance (𝑝<0.001)and delayed frontal plane trunk motion towards the stance limb (𝑝<0.01). This was reflected by a lower rate of loading for theosteoarthritis group compared to controls (𝑝<0.001), whereas no differences were found for peak KAM. Trunk angle, contralateralhip abductor strength, and BMI explained the rate of loading at the involved knee (𝑝<0.001), an association not found for thecontralateral knee or control knees. Prolonged trunk lean over the stance limb may help lower peak KAM values. Rate of frontalplane knee joint loading may partly be mediated by the contralateral limb’s abductor strength, accentuating the importance ofbilateral lower limb strength for persons with knee osteoarthritis