Mechanisms of increased passive compliance of hamstring muscle-tendon units after spinal cord injury.

Background: People with spinal cord injury sometimes develop abnormally compliant hamstring muscle-tendon units. This study investigated whether the increased muscle-tendon compliance is due to a change in the passive properties of the muscle fascicles or tendons, or to muscle tears.

Methods: Semimembranosus muscle fascicle lengths were measured from ultrasound images obtained from 15 spinal cord injured subjects and 20 control subjects while the hip was passively flexed with the knee extended.