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

Wearing the center bridge-type knee orthosis significantly reduced external knee adduction moment (EKAM) during the loading response phase in patients with knee OA compared to the no-orthosis condition.

• 17 patients with knee OA performed level-ground walking under two conditions: with and without the orthosis in a randomized order.
• 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 enabling real-time, direct quantification of EKAM.
• The reduction in EKAM during the loading response was statistically significant when comparing orthosis versus no-orthosis conditions.

EKAM values in patients wearing the orthosis became comparable to those in healthy participants during both the loading response and pre-swing phases.

• 18 healthy older individuals were assessed during free walking for comparison.
• During the loading response, EKAM values with the orthosis approached those of the healthy control group.
• During the pre-swing phase, when the foot prepares to leave the ground, medial knee loading was also close to healthy levels.
• No significant differences in EKAM were observed between the orthosis condition and healthy participants during these two phases.

No significant differences in gait parameters were observed between groups or conditions.

• Gait parameters assessed included walking speed and stride length.
• There were no significant differences in these parameters between patients with knee OA and healthy participants.
• There were also no significant differences in gait parameters between the orthosis and no-orthosis conditions in knee OA patients.
• This suggests the orthosis did not alter walking mechanics beyond the reduction in medial knee loading.

Fully normalizing EKAM throughout the entire stance phase would require a valgus corrective moment at least 5.34 times greater than that produced by the center bridge-type knee orthosis.

• The required valgus corrective force was estimated to be approximately five-fold stronger than what the current orthosis generates.
• This finding indicates that current orthotic designs may provide insufficient mechanical offloading to fully normalize EKAM.
• The authors suggest that further structural refinements are required to enhance valgus correction and achieve more effective reduction of medial knee loading during gait.
• These insights are intended to guide the development of future knee orthoses capable of adjusting support dynamically throughout walking.

The center bridge-type knee orthosis provides substantial mechanical support during the early stance phase and continues to reduce medial knee loading during the transition to swing.

• The orthosis demonstrated biomechanical effects specifically during the loading response (early stance) and pre-swing (late stance/transition) phases.
• EKAM was not fully normalized across all phases of the stance phase with the current orthosis design.
• The six-axis force-torque sensor built into the device allowed real-time, direct quantification of the support provided by the orthosis.
• The partial normalization observed suggests phase-specific effectiveness of the current orthotic design.