Triceps denervation as a predictor of elbow flexion contractures in C5 and C6 tetraplegia

Objective: To determine whether the existence of elbow flexion contractures in persons with C5 or C6 tetraplegia is related to a lack of residual voluntary triceps function and triceps denervation (ie, lower motoneuron damage). Design: A retrospective study of impairment data from 74 arms to identify the incidence of elbow flexion contractures and the contributing factors toward this deformity. Setting: Five spinal cord injury (SCI) rehabilitation centers in the United States, 1 in England, and 1 in Australia. Participants: Forty-three subjects with motor complete C5 or C6 traumatic SCI. Interventions: Not applicable. Main Outcome Measures: Active and passive elbow extension, triceps voluntary muscle strength, and triceps response to electric stimulation. Results: Subjects with weak voluntary triceps had significantly fewer and less severe elbow flexion contractures than those with paralyzed triceps (P=.024). Subjects with completely denervated triceps (ie, no response to electric stimulation) had significantly more elbow flexion contractures than subjects with even a weak response to electric stimulation (P=.003). Overall, 51% of the arms could not be passively extended to zero. Forty-six percent of the arms classified as C5 lacked full passive elbow extension, compared with 63% of the arms classified as C6 (P=.302). Conclusions: A relationship has been found between elbow flexion contractures and lack of residual voluntary triceps and triceps denervation in subjects with C5 or C6 tetraplegia. There should be a greater awareness of the elbow flexion contractures that may develop as a result of this relationship. A better understanding of this deformity and its characteristics can lead to more effective clinical treatment and prevention strategies.