Outcomes of Arthroscopic and Open Surgical Repair of Isolated Subscapularis Tendon Tears
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Tears of the subscapularis tendon (isolated and combined) were initially documented in a post- mortem analysis by Smith in 1834, and the first repair technique was described by Hauser in 1954. Despite the relatively early description of this injury, the subscapularis muscle-tendon unit has received relatively less attention compared with the remainder of the rotator cuff. Lo and Burkhart have suggested that the subscapularis often remains the “forgotten tendon” of the shoulder joint. However, over the last 2 decades, the importance of the subscapularis muscle-tendon unit has been recognized through the work of Gerber and Krushell. The importance of surgically repairing the subscapularis tendon relates to its intrinsic biomechanical and functional properties, which include active internal rotation of the shoulder, force coupling in the transverse plane, and a contribution to the dynamic anterior stability of the glenohumeral joint.
Autopsy and cadaveric series have determined the incidence of subscapularis tears to be between 3% and 13%, the latter being partial-thickness degenerative tears. Whereas 1 large arthroscopic study of patients with symptomatic rotator cuff tears (mean age, 56 years) also reported the incidence of isolated subscapularis tendon tears to be 3%, another arthroscopic diagnosis study showed an incidence of 27%. The heterogeneity in observed rates can be partially explained by the variety in the way these tears present clinically—as isolated complete tears, isolated partial-thickness tears, anterosuperior tears involving the supraspinatus tendon, complete rotator cuff tears or avulsions, and rotator interval lesions with instability of the long head of the biceps. However, the true incidence of subscapularis tears is likely unknown because many patients lack the classic rotator cuff symptoms10 and magnetic resonance imaging (MRI) diagnosis of subscapularis tears is poor, with 1 study showing a sensitivity of only 36%.
Although initial outcomes studies were performed after open repair, more recent research has documented the results of arthroscopic repair, after the initial technique and results were published by Burkhart and Tehrany in 2002. To our knowledge, there are no systematic reviews that have looked at outcomes after the surgical repair of subscapularis tendon repairs. Given the large number of injury permutations and clinical heterogeneity that is associated with this injury pattern, the purpose of this systematic review was to describe patient and injury characteristics of isolated subscapularis tears, as well as to analyze functional outcomes in patients undergoing repair of isolated subscapularis tendon tears. We hypothesized that isolated subscapularis repair would yield excellent results, with reduction in preoperative pain, improved strength, and improved outcome scores.