Biomechanics performance in 30-s chair stand test in patients with medial knee osteoarthritis

Knee osteoarthritis (OA) is characterised by weakness and knee joint pain which may affect the performance in some activities of daily life like sit-to-stand. The aim of this study is to evaluate the strategies used by patients with knee OA when performing the 30-second chair stand test (30s-CST), and its association with their well-being. Twenty-one patients with knee OA were recruited. A 3D motion analysis system and two force plates were used to capture the kinematics and kinetics during the 30s-CST. The sit-to-stand and the stand-to-sit phases of the test were analysed independently. Significant differences were found (p < 0.05) between the first three and the last three repetitions in the 30s-CST for knee joint moment and power. No significant differences have been found between the most painful knee and the contralateral knee. The correlations found between the subscales of the knee injury and osteoarthritis outcome score (KOOS) and biomechanical parameters were significant (p < 0.05). Patients with the best score in KOOS subscales also showed better performance in the 30s-CST. Assistive technologies that maximise biomechanical strategies could be a valuable contribution to improve the well-being of these patients.