In patients with unilateral hip osteoarthritis (OA)—where the risk of progressive symptomatic OA developing in contralateral knees is higher than in ipsilateral knees—loading and structural asymmetries appear early in the disease course, while the knees are still asymptomatic. These early asymmetries may have corresponding long-term consequences, providing further evidence for the potential role of loading in OA onset and progression.
Shakoor and coworkers evaluated data on 62 patients with unilateral hip OA. All patients underwent pelvis and knee radiography; were assessed for pain in both knees and both hips; and underwent gait analysis, which included collection of 3-dimensional kinematic and ground reaction force data. Dual x-ray absorptiometry was used for bone mineral density (BMD) analysis. Differences between the knees were noted.
Peak dynamic knee loads were significantly higher at the contralateral knee than at the ipsilateral knee, and medial compartment tibial BMD was significantly higher in the contralateral knee. The ratio of contralateral:ipsilateral medial compartment knee BMD was directly correlated with contralateral:ipsilateral peak external knee adduction moment and contralateral:ipsilateral knee medial compartment load.
The authors noted that their findings provide support for the notion that alterations in dynamic joint loading may precede the onset of symptomatic knee OA.