The posterior deltoid to triceps transfer: a clinical and biomechanical assessment.

Transfer of the posterior deltoid muscle to the triceps insertion for elbow extension provides improved function in patients with C5 and C6 level tetraplegia. We have modified the surgical technique using the tibialis anterior tendon as a graft. The length-tension characteristics and available amplitude of the posterior deltoid muscle were determined with intraoperative electrical stimulation. The excursion of the posterior deltoid muscle was 7.31 cm with a standard deviation of 1.23 cm. Postoperative mean torque measurements of elbow extension power were 36.4 kg cm with a standard deviation of 15 kg cm. All patients had maximal strength between 90 degrees and 120 degrees of elbow flexion. Length-tension curves for the posterior deltoid muscle showed a large range of effective strength and helped confirm optimum tension of the posterior deltoid muscle and proper shoulder and elbow positions at surgery. Clinical results in 10 patients were excellent.