Subscapularis Tears

The topic insists you "always address the biceps" and repeatedly names the biceps pulley and the comma (SGHL) — here is the anatomy that ties an upper-subscapularis tear to biceps instability.

• What the pulley is. The biceps reflection pulley is a sling at the entrance of the bicipital groove formed by the superior glenohumeral ligament (SGHL) and coracohumeral ligament (CHL), reinforced medially by the superior border of the subscapularis and laterally by fibres of the supraspinatus; it holds the long head of biceps in the groove.
• Why an upper-subscap tear destabilises the biceps. The upper subscapularis is the medial wall of this sling, so a tear of the upper fibres opens the medial pulley and the biceps subluxes or dislocates medially — seen on axial MRI as the biceps lying medial to the groove, often draped over or into the torn subscapularis. This is the classic "hidden lesion", easily missed if only the main cuff is inspected.
• The comma-sign link. The comma sign the topic relies on is precisely the SGHL/CHL (pulley) tissue avulsed with the superolateral subscapularis corner — following the comma leads you both to the retracted subscapularis stump and to the disrupted pulley.
• The practical consequence. Because the tear and the biceps instability share the pulley, an unstable biceps must not be left in situ — hence the routine tenotomy or tenodesis at subscapularis repair (the biceps-side decision-making is developed in the biceps topic).

The topic repeatedly names pectoralis major transfer as the salvage for an irreparable subscapularis (Goutallier 3-4, retracted, poor tissue) but never develops it — here is the operation and its logic.

• Indication. A symptomatic irreparable anterior cuff (advanced fatty infiltration, retraction, attritional tissue) in a patient with functional demand, preserved passive motion and no significant glenohumeral arthritis — arthritis or a massive combined tear points instead to reverse arthroplasty.
• The subcoracoid (Resch) technique. The superior half-to-two-thirds of the pectoralis major is detached and routed deep to (behind) the conjoint tendon to the lesser tuberosity; passing behind the conjoint tendon redirects the muscle's line of pull to better approximate the subscapularis vector, with the conjoint tendon acting as a pulley.
• The supracoracoid alternative. Transfer superficial to (in front of) the conjoint tendon is technically simpler but more non-anatomic (a straighter, transverse pull) and risks tethering the musculocutaneous nerve — ease versus a less physiological vector.
• Its ceiling, and the alternatives. Because pectoralis major pulls in a different plane from the subscapularis, the transfer reliably relieves pain and restores anterior stability but only partially restores internal-rotation strength; a lower-trapezius or latissimus dorsi transfer is a more line-of-pull-matched option some now prefer, with no head-to-head trials to separate them.

Global epidemiology. Subscapularis involvement is found in roughly 10-25% of surgically treated rotator cuff tears, but arthroscopic series report a far higher rate of upper-fibre lesions (up to 27-30% of all shoulder arthroscopies in some cohorts) once surgeons actively look for them. The classic isolated traumatic tear (forced hyperextension/external rotation) affects predominantly middle-aged men; degenerative anterosuperior tears affect both sexes in the 6th-7th decades.