Rotator cuff tears are partial or full-thickness disruptions of one or more rotator cuff tendons, ranging from acute traumatic tears to chronic degenerative tears. Supraspinatus is the most commonly torn tendon. Asymptomatic tears increase with age and are present in up to 50% of those over 60 on imaging. The clinical challenge is distinguishing symptomatic tears requiring intervention from incidental degenerative findings.
The rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis - SITS) provides dynamic stability to the glenohumeral joint and controls humeral head position during movement. Supraspinatus initiates abduction and is most vulnerable due to its position beneath the coracoacromial arch and its critical zone of relative hypovascularity near the insertion footprint.
Acute tears: result from a single traumatic event - typically a fall onto an outstretched hand, forced abduction, or sudden eccentric load. Around 40% of patients over 40 with traumatic anterior dislocation have a concomitant cuff tear (BESS / BOA). Acute-on-chronic tears are common.
Chronic tears: progressive tendon degeneration. Tears typically begin at the articular surface of supraspinatus and may propagate posteriorly to involve infraspinatus and teres minor. In overhead athletes, internal impingement causes undersurface partial tears.
Suspension bridge concept (Burkhart): the anterior (subscapularis) and posterior (infraspinatus) cuff act as cables balancing the humeral head; intact cables can compensate for a torn central canopy (supraspinatus), explaining why some large tears remain functional.
Classification:
Risk factors: age >40, diabetes, smoking, repetitive overhead activity, hypercholesterolaemia, previous corticosteroid injections.
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