Novel Arthroscopic Tendon Transfers for Posterosuperior Rotator Cuff Tears: Latissimus Dorsi and Lower Trapezius Transfers.

Background: Massive irreparable rotator cuff tears in both the primary and the revision setting are challenging problems. There remains controversy over the ideal treatment methods for these patients. In the case of an irreparable posterosuperior rotator cuff tear, tendon transfers have emerged as a reliable option, with a durable outcome. The most commonly used tendon transfer options are the latissimus dorsi (LD)and the lower trapezius (LT).

Description: The LD transfer is performed by first harvesting the LT tendon from the humeral shaft. It is critical to release the many adhesions to the muscle belly as well as to separate it from the teres major muscle. The tendon is then transferred intra-articularly, in an interval between the deltoid and the teres minor. The tendon is anchored arthroscopically after preparation of the anterolateral aspect of the tuberosity. The LT transfer is performed by harvesting the LT muscle and tendon off its insertion on the medial aspect of the scapular spine. It should be mobilized to maximize excursion by releasing adhesions. An Achilles tendon allograft is anchored into the anterior aspect of the greater tuberosity arthroscopically. The Achilles tendon is then secured to the LT tendon.

Alternatives: In addition to tendon transfer, options include:Partial or complete attempted repair.Augmentation or bridging with allografts.Superior capsular reconstruction.Subacromial balloon.

Rationale: There remains a paucity of literature comparing tendon transfers with alternatives. However, when considering a tendon transfer, certain principles are critical in order to achieve an optimal outcome:The recipient and transferred tendons must have similar musculotendinous excursion.The recipient and transferred tendons should have similar lines of pull.One tendon (the transferred) should be designed to replace 1 function (of the recipient).The function of the transferred tendon and muscle should be expendable without substantial donor site morbidity.The strength of the transferred muscle must be at least grade 4.When deciding between the LT and LD transfer, certain considerations should be taken into account. The LD transfer has a proven history of successfully treating massive irreparable posterosuperior rotator cuff tears in studies with long-term follow-up. Alternatively, although the LT transfer has only recently gained popularity, it has the advantage of "in-phase" muscle function, since the trapezius naturally contracts during shoulder external rotation. Furthermore, its line of pull almost completely mimics the infraspinatus.