PURPOSE: The aim of this study was to examine biomechanics alterations during sit-to-stand and stand-to-sit in elderly female with mild-to-moderate knee osteoarthritis (OA) compared with health control (CG).
METHODS: Participants of knee OA (n=37) and CG (n=19) recruited from three communities in Shanghai. Participants performed sit-to-stand and stand-to-sit. Kinematic and kinetic data were collected. The main variables of interest were maximum ankle, knee and hip joint angle and joint moments in sagittal and frontal planes. The criteria measures were analyzed using two factors analysis of variance (ANOVA).
RESULTS: Main effects of group (p = .001) and group X limb interactions (p = .009) were observed for the sit-to-stand. Only group main effects (p = .002) was observed during stand-to-sit. Knee OA participants exhibited significantly less maximum ankle dorsiflexion angle (sit-to-stand, OA: 15.1±5.3, CG: 17.7±4.8; stand-to-sit, OA: 13.2±6.3, CG: 15.8±5.2 degrees) and greater ankle abduction/adduction moment (sit-to-stand, OA: 0.085±0.045, CG: 0.056±0.030; stand-to-sit, OA: 0.085±0.045, CG: 0.060±0.029 Nm/kg) during both tasks compared with CG. In addition, knee OA participants showed a significant greater maximum hip extension angle (OA: 68.45±7.69, CG: 65.35±9.37 degrees) during sit-to-stand and maximum ankle dorsiflexion moment (OA: 0.34±0.085, CG: 0.28 ±0.083 Nm/kg) during stand-to-sit compared with CG. Otherwise, the maximum knee extension angle (OA: 73.87±6.80, CG: 76.75±6.43 degrees) of knee OA participants showed a significant lower than CG during stand-to-sit. And also, significant group X limb interaction was observed in the maximum knee extension moment (OA: Involved: 0.60±0.17, Uninvolved: 0.58±0.15; CG: Left: 0.60±0.17, Right: 0.71±0.16 Nm/kg) during sit-to-stand.
CONCLUSIONS: Knee OA participants show less ankle dorsiflexion angle and greater ankle abduction / adduction moment than the CG during both tasks. Therefore, knee pain or knee joint degeneration may induce freezing ankle range of motion and greater joint loading.