Clinical features

A partial rotator cuff tear which complicates chronic tendinitis may be quite indistinguishable from tendinitis in the early stages, the main feature being active abduction with a painful arc. However, with a tear, the shoulder pain persists and is accompanied by increasing stiffness and weakness. Occasionally, a palpable click is detected when performing "pot stirring" rotation of the shoulder.

Complete tears and traumatic partial tears typically present with sudden shoulder pain and inability to abduct the arm. The pain is often severe and initially, even may limit or prevent passive abduction.

In the early stages of injury, the type of tear may be identified from the response to an injection of local anaesthetic around the tendon - a partial tear will permit active abduction once pain is controlled but a complete tear will not, instead producing a characteristic shrug.

In the later stages of injury, differentiation of the two types of tear is much easier. In a complete tear:

• pain subsides within a few weeks as there is little or no reaction and no repair
• active abduction is always abolished - it gradually recovers in a partial tear, although weakened
• passive abduction is full and once the arm has been raised above 90 degrees, abduction can be completed by the power of the deltoid - "abduction paradox"
• an arm which is gradually lowered from full abduction will suddenly drop once it moves out of the range under the influence of the deltoid - "drop arm sign"

Other features of a tear may include bicipital tendinitis, tenderness of the acromioclavicular joint and in time, wasting of supraspinatus and infraspinatus.

Attrition tears usually give a history of intermittent shoulder pain in the absence of acute symptoms.