Complete immobility as a potential biomechanical complication of Achilles tendon lengthening.

Proximal muscle weakness is a common association of muscular dystrophies. Knees and hip extensor weakness limit the patients' ability to counteract flexor knee joints' moments. Therefore, patients try to toe walk to move the ground reaction force (GRF) anteriorly to help to stabilise the knee. We report a case of a patient with Becker's muscular dystrophy who lost his ability to walk completely following a bilateral Achilles tendons operation. The patient's ability to heel-strike moved his GRF posteriorly resulting in creation of excessive knees flexion moments. Three years following the operation and following a lengthy rehabilitation programme, the patient managed to mobilise using an orthosis.