The rotator cuff is a group of four muscles and their tendons that surround the shoulder joint, working together to hold the head of the upper arm bone (humerus) securely in the shallow socket of the shoulder blade and to power arm rotation and overhead movement.
A rotator cuff tear occurs when one or more of these tendons is partially or completely torn from the bone, and it is one of the most common causes of shoulder pain and disability in adults — it becomes significantly more common with age, and by the 60s and 70s, a meaningful proportion of people have at least some degree of rotator cuff tear, even if they have no symptoms at all.
A torn rotator cuff can make everyday movements — reaching overhead, getting dressed, washing your hair, reaching behind your back, or lifting even light objects — surprisingly painful or difficult. Not every tear needs surgery, and not every tear causes symptoms, which is precisely why understanding your specific tear (its size, location and cause) matters so much in deciding the right treatment path.
Understanding the Rotator Cuff: The Anatomy Behind the Condition
The rotator cuff is made up of four specific muscles, each originating from the shoulder blade and attaching via a tendon to the head of the humerus, working together like a sling to stabilise the shoulder during movement:
- Supraspinatus: Sits on top of the shoulder and initiates the first part of raising the arm out to the side — the most commonly torn of the four tendons.
- Infraspinatus: Located at the back of the shoulder and powers external (outward) rotation of the arm.
- Teres minor: A smaller muscle beneath the infraspinatus that also assists with external rotation.
- Subscapularis: The largest of the four, located at the front of the shoulder, powering internal (inward) rotation.
Above the rotator cuff sits a bony arch called the acromion, with a fluid-filled cushion (the subacromial bursa) in between to reduce friction during arm movement. Many rotator cuff tears are linked to a process called subacromial impingement, in which the space between the rotator cuff tendons and the acromion narrows — due to bone spurs, a naturally curved acromion shape, or swelling of the bursa — causing the tendons to be repeatedly pinched and irritated with overhead movement. Over time, this repetitive irritation can progress from tendon inflammation (tendinitis) to fraying and, eventually, a tear.
Types and Grading of Rotator Cuff Tears
Not all rotator cuff tears are the same, and the specific type, size and pattern of a tear meaningfully influences both symptoms and treatment choice.
- Partial-Thickness Tear: The tendon is frayed or damaged but not completely severed from the bone — it remains attached, though thinned or weakened. Further classified by which surface of the tendon is affected (the joint side, the bursal side, or within the tendon itself), which can influence treatment planning.
- Full-Thickness Tear: The tendon is completely detached from the bone, creating a hole through its full depth. Full-thickness tears are further described by size — small (under 1cm), medium (1–3cm), large (3–5cm), or massive (over 5cm, or involving two or more tendons).
- Massive & Irreparable Tears: Massive tears involve two or more of the four rotator cuff tendons and are often complex to treat. A tear is considered irreparable — regardless of size — when severe tendon retraction, poor tissue quality, or significant fatty degeneration of the muscle prevents the tendon from being reliably reattached to the bone; these represent some of the most challenging cases in shoulder surgery and often require specialised reconstructive techniques, discussed below.
- Acute Tear: Occurs suddenly, typically from a specific injury such as a fall onto an outstretched arm, a heavy or jerking lift, or a shoulder dislocation. Usually causes immediate, significant pain and weakness.
- Chronic (Degenerative) Tear: Develops gradually over months to years as tendon tissue wears down with age, repetitive stress, or reduced blood supply to the tendon. Often relatively painless in its early stages, which is why degenerative tears are sometimes only discovered incidentally or once they have progressed.
Symptoms of Rotator Cuff Tear
- Persistent pain when lifting or raising the arm overhead, or reaching behind the back
- A dull, deep ache in the shoulder, sometimes radiating down the side of the upper arm (but typically not below the elbow)
- Difficulty sleeping on the affected side, or waking due to shoulder pain at night
- Weakness when lifting or rotating the arm, or a sense that the arm is giving way
- Cracking, popping or grating sensations (crepitus) with shoulder movement
- Reduced range of motion, or difficulty performing everyday tasks such as reaching for a seatbelt, combing hair, or fastening a bra
- In acute, injury-related tears — sudden, severe pain and immediate weakness at the time of injury, sometimes with an audible pop
It is worth noting that not all rotator cuff tears cause pain — some people with a confirmed tear on imaging have no symptoms at all, while others with only a small tear experience significant pain. This mismatch between tear size and symptom severity is one of the reasons treatment decisions are based on the whole clinical picture, not imaging findings alone.
What Causes Rotator Cuff Tear
- Acute injury: Occurs from a specific event, such as a fall onto an outstretched arm, attempting to catch a heavy falling object, or a forceful, jerking lift. Can occur alongside a shoulder dislocation or fracture.
- Degenerative wear (age-related): The most common cause overall — tendon tissue naturally weakens with age, and blood supply to the rotator cuff tendons (particularly the supraspinatus) diminishes over time, making the tendon more prone to fraying and tearing, often without any specific triggering event.
- Subacromial impingement: Ongoing narrowing of the space beneath the acromion, whether from bone spurs, the natural shape of the acromion, or bursal swelling, leads to repetitive tendon irritation that can progress to a tear over time.
- Repetitive overhead activity: Occupations or sports involving frequent overhead arm motion (such as painting, carpentry, tennis, swimming, baseball and weightlifting) place repeated stress on the rotator cuff tendons, accelerating wear.
Degenerative tears are more common in the dominant arm, and it is not unusual for a tear to be present in one shoulder without symptoms while causing pain in the other — underscoring how much individual factors, not tear presence alone, determine symptoms.
Risk Factors for Rotator Cuff Tear
- Age: The single strongest risk factor — tendon degeneration accumulates over decades, and rotator cuff tears become substantially more common from the 40s onward.
- Occupational demands: Jobs requiring repetitive overhead reaching or heavy lifting — such as carpentry, painting, and warehouse or construction work — carry a higher risk of cuff injury over time.
- Certain sports: Sports involving repetitive overhead motion, including tennis, baseball, swimming and weightlifting, place the rotator cuff under repeated strain.
- Family history: Having a close relative with a rotator cuff tear is associated with a higher personal risk, suggesting a genetic contribution to tendon quality and structure.
- Posture: Poor posture, particularly a rounded-shoulder position, can alter shoulder mechanics and increase subacromial impingement risk over time.
- Smoking: Reduced blood flow to the rotator cuff tendons, a risk factor for degenerative tears, is more common in people who smoke.
- Diabetes: Type 2 diabetes is associated with reduced tendon quality and healing capacity, and with a somewhat higher risk of rotator cuff problems.
What Happens If a Rotator Cuff Tear is Left Untreated
- Progressive enlargement of the tear over time, as an untreated tear does not heal on its own and tends to gradually increase in size
- Ongoing muscle weakness and, with prolonged disuse, muscle wasting (atrophy) and fatty infiltration of the rotator cuff muscles — changes which, once significant, can make the tear far more difficult to repair successfully
- Progressive loss of shoulder range of motion and function, sometimes described as a "pseudoparalysis" in severe, longstanding, massive tears where the arm cannot be actively raised
- Chronic pain that increasingly limits daily activities, sleep and quality of life
- Development of cuff tear arthropathy — a specific pattern of shoulder joint wear and arthritis that can develop over years in longstanding, large, untreated tears, as the humeral head shifts upward without the rotator cuff to hold it in place
- A tear that was initially reparable becoming irreparable over time, narrowing future treatment options
How a Rotator Cuff Tear is Diagnosed
- Clinical History & Physical Examination: A discussion of how symptoms began (sudden injury vs gradual onset), their pattern, and impact on daily activities, along with a physical examination assessing shoulder strength, range of motion, and specific movements or positions that reproduce pain — including targeted clinical tests for each rotator cuff tendon.
- X-Ray: Does not show the rotator cuff tendons directly (they are soft tissue), but is useful for identifying bone spurs, joint arthritis, or changes in bone position that suggest a longstanding, large tear, and for ruling out fracture.
- Ultrasound: A dynamic, real-time imaging test that can effectively detect full-thickness tears and assess tendon movement, often used as an accessible first-line imaging option, though its accuracy is more operator-dependent than MRI.
- MRI: The most detailed imaging test for assessing the rotator cuff, showing tear size, location, degree of tendon retraction, and the quality (including fatty infiltration) of the associated muscle — all of which are important in planning treatment, particularly if surgery is being considered.
Reducing Your Risk of Rotator Cuff Tear
- Warm up and strengthen regularly: Warming up with gentle shoulder stretches before exercise, and maintaining regular rotator cuff and shoulder girdle strengthening exercises, helps keep the tendons resilient to everyday stress.
- Practise good posture: A forward-rounded shoulder posture increases subacromial impingement risk over time; paying attention to posture, particularly during long periods of desk work, can help.
- Modify repetitive overhead activity where possible: If your work or hobby involves frequent overhead reaching, ask a specialist or physiotherapist about techniques, equipment adjustments, or exercises to reduce cumulative strain on the shoulder.
- Don't ignore early shoulder symptoms: Degenerative tears often start painlessly; persistent shoulder discomfort, even if mild, is worth having assessed rather than waiting until pain becomes severe or the tear enlarges.
- Use safe lifting and sport technique: Techniques for lifting heavy objects, and appropriate warm-up before sports involving overhead motion, can reduce the risk of an acute tear.
