Duchenne Muscular Dystrophy (DMD) refers to a genetic disorder that results in gradual deterioration of muscle strength, from proximal to distal, leading to a number of kinematic anomalies and gait alterations.
This condition is attributed to the absence of or defect in the protein dystrophin that causes progressive muscle weakening between the ages of 3 and 6 years and a complete loss of ambulation around 10-12 years of age.
Among the pathological gait patterns reported in case-control studies, excessive anterior pelvic tilt, loss of knee flexion in stance, increased plantar flexion in swing and lumbar hyperlordosis have all been observed in patients with this disorder.
Ropars et al. studied muscle activation and co-activation in the lower limbs of children with DMD during the gait cycle and compared these results to those of developing children of the same age.
The authors found a prolonged activity of principal muscles namely, the rectus femoris, the hamstrings and the tibialis anterior; the latter was established to be the most abnormal of all the muscles studied in children with DMD.
Hyper-activity and co-activation were determined as compensatory measures for the instability caused by muscle weakness which ultimately result in negative consequences on the muscles and increased energy cost of gait.
The beneficial effects of ankle-foot orthosis on kinematic, kinetic and spatial/temporal gait parameters of DMD patients were investigated by de Souza et al. by assigning twenty ambulatory patients between the ages of 4-12 years to one of three groups – no orthosis, nighttime orthosis and daytime orthosis.
The findings of the study revealed that daytime use of ankle-foot orthosis had a positive effect on ankle kinematic and kinetic parameters in DMD patients, which were not maintained when patients removed the device for walking.
Early and continuous nighttime ankle-foot orthosis use was seen to minimise spatiotemporal and kinematic compensations caused by DMD.
This led the authors to suggest that daytime and nighttime ankle-foot orthosis use should be prescribed early on and maintained during the course of the disease for better results.
MASS4D® custom foot orthotics may contribute to the rehabilitation efforts of a population of DMD patients; these orthotics would work in conjunction with other orthoses to control compensatory abnormal movements of the feet while helping the patient remain ambulatory for as long as possible.
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Repetitive plantarflexion can lead to pain and mechanical limitation in the posterior ankle joint which is known as posterior ankle impingement syndrome. This pathology commonly occurs in ballet dancers and football players.