The effect of carbon fiber custom dynamic orthosis type on kinematics and kinetics of lower extremity joints in individuals with lower limb traumatic injuries

Background: Carbon fiber custom dynamic orthoses have been used to improve gait mechanics after lower limb trauma in military service members, with the goal of restoring function and improving outcomes. However, the effects of commercially available carbon fiber orthoses available to civilians on lower extremity joint kinetics and kinematics are poorly understood.

Research question: The aim of this study was to examine the effect of two commercially available orthoses on lower extremity kinematics and kinetics in individuals with lower limb trauma.

Methods: A total of 23 participants with a lower extremity traumatic injury underwent gait analysis while walking without an orthosis, and while wearing a monolithic carbon fiber orthosis or while wearing a modular carbon fiber orthosis, in a randomized order. Study participants accommodated to each orthosis for three months prior to testing. Joint kinematics and kinetics at the ankle, knee, and hip joints, and ground reaction forces were assessed.

Results: The two study orthoses significantly reduced ankle motion compared to no orthosis, with large effect sizes observed. Peak plantarflexor moment was greater with the modular orthosis compared to the monolithic orthosis. Ankle push-off power did not differ between orthoses but was significantly reduced relative to no orthosis. Push-off power with the study orthoses was over 25% greater as compared to previous studies with military orthoses. Peak loading response power generation at the knee was greater with the monolithic orthosis as compared to the modular orthosis. The kinematics and kinetics at the hip did not differ between orthoses.

Significance: Orthoses commonly used in civilian settings to treat limb trauma primarily alter joint kinematics and kinetics at the ankle, in a manner consistent with orthoses used in the military. Additionally, despite the apparent large differences in the designs of the two study orthoses, between-orthosis differences on gait mechanics were limited.