Dynamic assist by carbon fiber spring AFOs for patients with myelomeningocele

Patients with calf muscle insufficiency and a calcaneus gait are often dependent on ankle-foot orthoses (AFO). The orthosis is intended to improve walking and posture and should prevent structural deformities. AFOs are often manufactured with a dorsiflexion stop. The design of this type of orthosis has been investigated in several previous studies. In the current study, orthoses with a dorsal carbon fiber spring were compared with the classic design. Five patients with Spina Bifida took part in the current study. All participants underwent a 3D gait analysis including kinematic (VICON infrared cameras) and kinetic (Kistler force plates) data collection. The measurements showed that the carbon spring was able to support the patient during the complete stance phase. It was found that the use of a carbon fiber spring significantly increases the energy return during the 3rd rocker, simulating the natural push-off action (p<0.05). Via a simple mechanical test, the contribution of the carbon spring to the overall kinetics could be estimated proving that the spring does assist the patient for push-off. The more physiological ankle and knee kinematics implies a functional improvement from the carbon springs compared to classic orthosis. This investigation showed, further, that in the fitting process a neutral alignment with the shoe wear has to be carefully checked since the spring kinematics and kinetics during stance phase were influenced significantly by the alignment. Further studies are needed to assess the clinical outcome and to prove the functional benefit of this kind of orthosis.