Effect of the Center Bridge-Type Knee Orthosis on the External Knee Adduction Moment During Gait in Patients with Knee Osteoarthritis.

PURPOSE: This study aimed to investigate the biomechanical effects of a center bridge-type knee orthosis prescribed for patients with knee osteoarthritis (OA) based on real-time, direct quantification of external knee adduction moment (EKAM), a key mechanical indicator associated with progression of knee OA.

PATIENTS AND

METHODS

To evaluate the effect of the center bridge-type knee orthosis, 17 patients with knee OA performed level-ground walking under two conditions: with and without the orthosis. Each participant completed gait trials in both conditions in a randomized order. Additionally, 18 healthy older individuals were assessed during free walking for comparisons. The analysis focused on the gait stance phase, during which substantial mechanical loading was exerted on the knee joint. Gait data were obtained using a six-axis force-torque sensor.

RESULTS

In patients with knee OA, wearing the orthosis significantly reduced EKAM during the loading response compared with that in the no-orthosis condition. Furthermore, EKAM values in patients wearing the orthosis became comparable to those in healthy participants during the loading response and pre-swing phases. No significant differences in gait parameters, such as walking speed or stride length, were observed between groups or conditions.

CONCLUSION

These findings suggest that in patients with OA, achieving EKAM values comparable to those in healthy individuals would require a valgus corrective moment at least 5.34 times greater than that produced by the center bridge-type knee orthosis. Clinically, this indicates that current orthotic designs may provide insufficient mechanical offloading, and that further structural refinements are required to enhance valgus correction and achieve more effective reduction of medial knee loading during gait.