Weight-bearing asymmetries during Sit-To-Stand in patients with mild-to-moderate hip osteoarthritis

The Sit-To-Stand (STS) transition is a mechanically demanding task that may pose particular challenges for individuals with lower limb osteoarthritis (OA). Biomechanical features of STS have been investigated in patients with OA, but not in patients with early stage hip OA. The purpose of this study was to explore inter-limb weight-bearing asymmetries (WBA) and selected kinematic and kinetic variables during STS in patients with mild-to-moderate hip OA compared with healthy controls. Twenty-one hip OA patients and 23 controls were included in the study. Sagittal and frontal plane kinematic and kinetic data were collected using an eight-camera motion analysis system synchronized with two force plates embedded in the floor. There were no distinctive biomechanical alterations in sagittal or frontal plane kinematics or kinetics, movement time, or time to reach peak ground reaction force (GRF) in hip OA patients compared with controls. However, the hip OA patients revealed a distinct pattern of WBA compared with the controls, in unloading their involved limb by 18.4% at peak GRF. These findings indicate that patients with early stage hip OA are not yet forced into a stereotypical movement strategy for STS; however, the observed pattern of WBA requires clinical attention.