Muscle Tendon Transfers Around the Shoulder

Muscle tendon transfers (MTTs) are effective surgical procedures for reducing pain and for improving active shoulder range of motion and patient-reported outcomes for a wide range of pathologies, including serratus anterior and trapezius muscle palsy, irreparable subscapularis tears, irreparable posterosuperior rotator cuff tears, irreparable posterior rotator cuff tears in the setting of reverse shoulder arthroplasty, and symptomatic complete deltoid deficiency.The principles of MTT include ensuring that the transferred muscle is expendable, the muscle tendon unit has similar excursion, the line of pull of the transferred tendon and of the recipient muscle are similar in terms of biomechanical force, and the transferred muscle should replace at least 1 grade of strength of the deficient recipient muscle.When MTT procedures are considered, patients must have exhausted all nonoperative management, have preserved passive range of motion, and have an understanding of the postoperative expectations and potential complications.For patients with scapulothoracic abnormal motion (STAM) due to long thoracic nerve palsy, the indirect or direct pectoralis major tendon transfer is an effective procedure for reducing pain and improving active forward elevation. For patients with STAM due to spinal accessory nerve palsy, the Eden-Lange or the triple tendon transfer procedures reduce pain and improve active forward elevation and abduction as well as patient-reported clinical outcomes.Both pectoralis major and latissimus dorsi transfer procedures for isolated irreparable subscapularis deficiency without anterosuperior humeral head escape result in improvement with respect to pain, patient-reported outcomes, and forward elevation, with the pectoralis major tendon transfer demonstrating durable long-term outcomes.The latissimus dorsi or lower trapezius tendon transfer procedures for irreparable posterosuperior rotator cuff tears reliably improve patient-reported outcomes, forward elevation, abduction, and external rotation range of motion. Additionally, latissimus dorsi transfer with or without teres major transfer can be used to restore active external rotation, both in the native shoulder and in the setting of reverse shoulder arthroplasty.The complications of MTTs include infection, hematoma, and failure of tendon transfer healing; therefore, it is recommended that these complex procedures be performed by shoulder surgeons with appropriate training.