Disruption of the upper motor neuron inhibitory pathways by stroke, brain trauma, or spinal cord injury leads to muscle spasticity. Spasticity is characterized by increased muscle tone, hyperactive reflexes, and possible clonus or rigidity. The increased muscle tone may result in loss of joint motion, leading to contractures. Treatment of established contractures is difficult. Prevention of contractures by joint mobilization is emphasized as a goal in the management of patients with spasticity.