Functional evaluation of a novel fibreglass-reinforced polyamide custom dynamic AFO for foot drop patients: A pilot study

Background: Ankle-foot orthoses (AFOs) are orthopaedic devices often prescribed to treat foot drop. For patients who are not satisfied with off-the-shelf solutions, custom AFOs personalized to the patient's lower limb anatomy are required. Dynamic AFOs provide stability while allowing for physiological ankle mobility in the stance phase of walking. Research question: Can a morphology-based dynamic custom AFO made of fiberglass-reinforced polyamide restore a quasi-normal gait pattern and improve comfort in patients with foot drop? Methods: In this pilot study, the legs and feet of ten foot drop patients (age=64.9 +/- 11.4 years; BMI=26.2 +/- 2.1 kg/m2) were scanned using a Kinect-based 3D scanner. A custom AFO was designed and produced for each patient using a fiberglass-reinforced polyamide through selective laser sintering. To assess kinematics, skin markers were placed on relevant bony landmarks according to a validated protocol. Each patient was instructed to walk at a self-selected comfortable speed under three conditions: wearing the custom AFO, wearing an off-theshelf orthosis (Codivilla spring), and without any AFO (shod condition). Muscle activation in the tibialis anterior, gastrocnemius, rectus femoris and biceps femoris muscles in both legs was recorded using wireless sEMG sensors. The comfort and of each AFO was evaluated using a Visual Analogue Scale. Results: The custom AFO resulted in significant increase of stride length and walking speed compared to the shod condition. Except for the hip joint, which exhibited greater maximum flexion and reduced range of motion, the kinematic parameters of all other joints were similar to those observed in a healthy control population. Furthermore, the custom AFO received significantly higher comfort scores compared to the Codivilla spring. Significance: This study has provided evidence supporting the effectiveness of custom orthotic solutions in restoring lower limb kinematics and improving the perceived comfort in foot drop patients compared to off-theshelf solutions.