Releases of subscapularis contracture: an anatomic and clinical study.

Correction of anterior subscapularis contracture is an important step in soft-tissue balancing at the time of total shoulder replacement (TSR). An anatomic and clinical investigation was undertaken to investigate the effect of steps involved in subscapularis release. In 14 cadaveric shoulders studied, the subscapularis insertion consisted of three regions: a thick superior tubular tendon (STT), a flat middle tendon, and an inferior portion where the muscle fibers insert directly into the humerus. In 16 consecutive patients undergoing primary TSR for osteoarthritis, measurements of subscapularis length were taken after different releases. An average of 0.9 cm (confidence interval, 0.7-1.1 cm) of excursion was added after anterior capsular release, and an additional 0.7 cm (confidence interval, 0.5-0.9 cm) of excursion was obtained after STT release. Incision of the STT is an alternative means of gaining subscapularis length when balancing the soft tissues in patients with osteoarthritis undergoing TSR.