Rotator Cuff: What It Does and How It Is Injured

The Four Rotator Cuff Muscles

Supraspinatus

Runs along the top of the shoulder blade to the greater tuberosity of the humerus. It helps start lifting the arm out to the side (abduction) together with the deltoid, and its tendon is the one most often involved in tendinopathy and tears.

Infraspinatus

Lies below the spine of the shoulder blade and inserts on the greater tuberosity. It rotates the arm outward (external rotation).

Teres minor

Runs from the outer border of the shoulder blade to the greater tuberosity and also assists external rotation.

Subscapularis

The largest of the four, on the front surface of the shoulder blade, inserting on the lesser tuberosity. It rotates the arm inward (internal rotation).

How the Rotator Cuff Is Injured

Rotator cuff problems follow two broad patterns. In younger and active people, an injury such as a fall on the outstretched arm or a sudden heavy load can tear a healthy tendon. Racket sports, throwing and overhead gym work load the cuff repeatedly and can lead to tendinopathy. In middle-aged and older adults, tendons change gradually with age, and tears are often degenerative; many such tears are found on scans in people with no symptoms (Lewis, 2010).

Rotator Cuff Problems and Frozen Shoulder

Frozen shoulder (adhesive capsulitis) is a different condition. It involves thickening and tightening of the joint capsule, with pain followed by marked loss of movement in all directions, and it is more common in women and in people with diabetes. It is not caused by a rotator cuff tear, although the two can be confused early on. See the frozen shoulder guide for more.

What Conservative Rotator Cuff Care Involves

A rotator cuff program is progressive loading, not rest. It starts with settling the irritated tendon and restoring the movement the shoulder blade and thoracic spine have lost, then moves to isometric work, then to graded strengthening through range, then to the loads your work or sport actually asks for. It takes around twelve weeks to run properly, and the most common reason it fails is that it was stopped at week four when the pain eased (Kuhn, 2009).

How it compares matters too. A meta-analysis of randomized trials in shoulder impingement found that exercise eased pain more than non-exercise care, that specific exercises beat general ones, and that manual therapy, laser and shockwave each did better than sham treatment (Steuri et al., 2017). In a randomized trial of people with subacromial pain, a specific exercise program reduced the number who went on to choose surgery (Holmgren et al., 2012). In older adults with small, non-traumatic supraspinatus tears, a trial comparing surgery with conservative care found no clinically important difference in outcomes (Kukkonen et al., 2021).

At CSC, a program may also include manual therapy for the shoulder, shoulder blade and upper back, and, for calcific tendinopathy, shockwave therapy, which has supporting evidence for that specific condition (Simpson et al., 2020). Chiropractic and physiotherapy are planned together; see chiropractic treatment and the rotator cuff injury guide.

Steroid Injections

A corticosteroid injection can reduce shoulder pain in the short term, and on the evidence above its effect may be similar to exercise over that period. It does not repair the tendon, and repeated injections into a tendon are generally avoided because they may weaken it. It is best seen as an option to discuss with a doctor, alongside rather than instead of a loading program.

When Surgery Is the Right Call

Surgery is still the right answer for some shoulders. An acute full-thickness tear from a genuine injury in a younger shoulder, a tear causing real weakness rather than pain alone, an inability to lift the arm against gravity, or a shoulder that has not responded to a properly run three-month program all warrant an orthopedic opinion. Sudden weakness after a fall or dislocation should be assessed promptly.

Repair does not always hold. A systematic review found a weighted mean retear rate of 26.6% at a mean of about two years after repair, while patient-reported outcomes generally improved whether or not the repair stayed intact (McElvany et al., 2015). What we would rather you avoided is the middle path: a scan showing a degenerative tear, an operation booked before loading has been tried, and a rehabilitation program started afterward that could have been started first.