Torsional mal-alignment increases external knee adduction moment during walking in patients with medial knee osteoarthritis

Abstract

Introduction: Malalignment is one of the key factors of disease progression in patients with knee osteoarthritis (KOA). The mal-alignment along the frontal plane (varus/valgus angle) is associated with increased joint loading during walking. This study aimed to investigate the relationship between the torsional mal-alignment and the impact loading at the knee during normal gait. Methodology: Symptomatic medial compartment KOA patients confirmed with radiography of KL grades of 2 and 3 were recruited from a regional hospital. Lower limb alignment was measured by a bi-planar x-ray system (EOS imaging, Paris, France) and external knee adduction moment (KAM) was estimated from gait analysis (Vicon, Oxford, UK). Partial correlations between knee varus angle, tibial torsional angle and KAM were assessed and controlled for gender, walking speed and co-existed musculoskeletal problems at the more affected knee. Results and Analysis: Forty-three medial KOA patients were included (32 female, age 62.8±6.0years, BMI 26.9±3.6kg/m2). Significant relationship was detected between the varus angle and KAM (r=0.57, p<0.001) but not tibial torsional angle (r=0.16, p>.05). When sub-grade analyses were conducted, KAM was significantly related to varus angle (r=0.47, p<0.05) in patients with KL-2; KAM was significantly related to varus angle (r=0.69, p<0.05) and TTA (r=0.56, p<0.05) in patients with KL3. Discussion and Conclusion: The findings of this study indicate that torsional malalignment is also a factor contributing to the abnormal knee joint loading in patients with moderate radiographic severity knee. Therefore, to control external torsion in addition to varus-vaglus deformity of the lower limb might benefit medial KOA patients with moderate radiographic severity when clinical management targets on modifying abnormal mechanical loading.