A new modification of extensor indicis proprius transfer to extensor pollicis longus using a retinacular pulley

A new modification of the extensor indicis proprius transfer to the extensor pollicis longus tendon through a fourth dorsal compartment retinacular pulley is described. This new modification has been assessed in cadavers biomechanically via computer simulation and in a limited number of patients with success. It affords the benefit over the standard subcutaneous extensor indicis proprius to the extensor pollicis longus tendon transfer of maintaining the adduction moment arm of the thumb. The moment arm mechanics of the pulley transfer resemble those of the intact extensor pollicis longus. Therefore this new modification offers better thumb function in both adduction and circumduction motions.