Effectiveness of Ankle-Foot Orthoses for Patients with Weakness of the Plantarflexors and Dorsiflexors: Biomechanical Comparison of Different Orthotic Concepts

ABSTRACT Introduction Weakness of plantarflexor and dorsiflexor muscles is a complex individual condition and can result in pathological gait, such as crouch gait or knee hyperextension. Affected patients can be supported with ankle-foot orthoses (AFOs) to improve gait and safety. Objective This study aims to compare three orthotic ankle joint designs in AFOs for patients with muscle weakness in the plantarflexors and/or dorsiflexors: a conventional hinged ankle joint with rigid stops (CAJ), a jointless orthosis (JLO), and a reactive-dynamic ankle joint with adjustable spring modules (RDA). Study Design Seven patients with plantarflexor and/or dorsiflexor muscle weakness tested three orthosis configurations in randomized order during a single session. Methods Biomechanical gait analysis was performed during standing and walking on level ground and up and down 10° slopes. The main outcomes were ground reaction forces, joint angles, moments, and power at the ankle, knee, and hip joints. Mean values of outcome measures for patients and values of an able-bodied control group were compared with nonparametric analyses of variance and pairwise post hoc tests. Results Throughout all motion tasks, statistically significant differences ( P < 0.05) were predominantly found in ankle and knee joint kinematics between RDA and CAJ, as well as between JLO and CAJ, whereas only few differences were found between RDA and JLO. Conclusions For this patient group, RDA enabled the most physiological gait, with outcomes measure values closest to those of the able-bodied control group, and the best perception of support for an active lifestyle and physically demanding activities. In less physically demanding situations, such as short walking distances and even surfaces, JLO also showed sufficient support for physiological gait and may be an adequate orthosis for patients living with supportive infrastructure or a more sedentary lifestyle. CAJ restricted physiological movements, showed the highest deviations from the values of the able-bodied controls in most activities, and provides the least comfort for patients in the tested situations. Clinical Relevance Statement Determining the best possible orthotic care and support for different patient groups is essential to enable independence, safety, and comfort during activities of daily living based on individual requirements.