Effects of carbon fiber custom dynamic orthosis stiffness on lower limb motion and loading during gait: A pilot study

Background

Traumatic lower limb injuries can have long-lasting detrimental effects. Carbon fiber custom dynamic orthoses (CDOs) are used to improve function, reduce pain, and alter foot loading following such injuries. Most prior investigations in this area have focused on very stiff CDOs designed to return patients back to physically demanding activities, with few studies evaluating more compliant CDOs.

Research question

Does CDO stiffness influence gait kinematics and kinetics, ground reaction forces, and forces acting on the foot in individuals following traumatic injury.

Methods

Seven individuals who had sustained a unilateral distal tibia intra-articular fracture completed testing without an orthosis and in three CDOs of differing stiffnesses (Compliant, Moderate, Stiff). Biomechanical gait data were collected while participants walked at a controlled speed. Instrumented insoles were used to measure peak forces and force impulse for the hindfoot, midfoot, forefoot, and total foot.

Results

Significant effects on joint kinematics and kinetics were primarily observed at the ankle. All CDOs significantly reduced ankle motion and power compared to walking without a CDO. Moderate and Stiff CDOs both significantly reduced knee flexion at initial contact. All CDOs significantly reduced peak medial and braking ground reaction forces compared to walking without a CDO. Peak hindfoot force was significantly reduced with Compliant and Stiff CDOs. Peak forefoot force and forefoot force impulse were significantly reduced with all CDOs. Large effect sizes were observed for most significant pairwise comparisons.

Significance

Study CDOs similarly reduced ankle motion while allowing greater power generation compared to very stiff CDOs in previous publications. Peak hindfoot force, peak forefoot force, and forefoot force impulse were significantly reduced with CDO use. The limited effect of CDO stiffness on outcomes suggests that more compliant CDOs may be sufficient in individuals where pain with motion and loading is a primary consideration following traumatic injury.