Rotator Cuff Tears

A rotator cuff tear is a partial or full-thickness disruption of one or more rotator cuff tendons, from an acute traumatic tear to a chronic degenerative one, and supraspinatus is the tendon most often torn.

Cuff abnormalities become more common with age, in people with and without symptoms: in a pooled analysis they rose from about 10% at 20 or younger to 62% at 80 and over. The clinical task is to decide whether a tear explains the symptoms and whether repair would improve function.

The rotator cuff (supraspinatus, infraspinatus, teres minor and subscapularis) provides dynamic stability and controls humeral head position. Supraspinatus initiates abduction and is the most vulnerable, beneath the coracoacromial arch and with a zone of relative hypovascularity near its footprint.

Mechanisms:

• •Acute tear: a fall onto an outstretched hand, forced abduction, a sudden eccentric load or an anterior dislocation; acute-on-chronic tears are common
• •Chronic tear: progressive degeneration, usually starting at the articular surface of supraspinatus and extending posteriorly to infraspinatus
• •Overhead athletes: internal impingement causes undersurface partial tears

In the suspension bridge model (Burkhart), intact subscapularis and infraspinatus balance the humeral head, so some large supraspinatus tears stay functional.

Classification:

• •Thickness: partial (articular, bursal or intratendinous) or full-thickness
• •Size of a full-thickness tear: small (under 1 cm), medium (1 to 3 cm), large (3 to 5 cm), massive (over 5 cm, or 2 or more tendons)
• •Chronicity: acute, chronic or acute-on-chronic. Chronic tears develop retraction and fatty infiltration, which reduce repairability

Risk factors include age over 40, smoking, diabetes, hypercholesterolaemia and repetitive overhead work.