Pelvis/lower extremity alignment and range of motion in knee osteoarthritis: A case-control study in elderly Japanese women.

Background: The prevalence of radiographic knee osteoarthritis (OA) in Japan is high, with an estimated 25,300,000 affected individuals.

Objective: The purpose of this study was to clarify the characteristics of knee osteoarthritis by comparing differences between patients with knee osteoarthritis and healthy elderly individuals with respect to alignment of the pelvis and lower extremities and range of motion.

Methods: Twenty-six women (13 with medial knee osteoarthritis and 13 healthy elderly) participated in this study. Pelvic tilt, knee extension angle, femoro-tibial angle, quadriceps angle, navicular drop, and leg-heel alignment were measured. In addition, the range of motion was measured at the hip, knee, and ankle joints.

Results: Patients with knee osteoarthritis showed a posterior pelvic tilt, knee flexion, varus, and foot pronation alignment compared to healthy subjects. The range of motion for hip extension, adduction, knee flexion, extension, and ankle dorsiflexion was significantly smaller while the range of motion for eversion was significantly larger in the knee osteoarthritis group.

Conclusion: People with medial knee OA have different static alignment and ROM compared to those without knee OA. The results clarify the comprehensive characteristics of the pelvis and lower extremities in knee osteoarthritis.