Lucan · Conditions

Rotator cuff disease

Australian guidance: HealthPathways WA — Shoulder Pain + eTG Rheumatology — Rotator cuff disease/subacromial pain syndrome + RACGP AJGP clinical review

1. Definition and epidemiology

Rotator cuff disease is an umbrella term for the spectrum of tendinopathy, partial-thickness tearing, and full-thickness tearing that affects the four tendons of the rotator cuff, most often the supraspinatus. It is the single most common cause of shoulder pain presenting to Australian general practice, and shoulder pain overall is one of the most frequent musculoskeletal complaints seen after back and knee pain. The older term "impingement syndrome" is being progressively replaced in contemporary guidance, including HealthPathways WA, by "subacromial pain syndrome" or "rotator cuff related shoulder pain", reflecting evidence that intrinsic tendon degeneration rather than purely mechanical impingement under the acromion drives most cases. Prevalence rises steeply with age: rotator cuff tears are found incidentally on imaging in a substantial minority of asymptomatic people in their sixties and in a majority of those over 80, which is central to how these findings are interpreted clinically, since a tear seen on a scan does not necessarily explain a patient's pain and does not by itself mandate surgery.

Risk factors for symptomatic disease include age, repetitive or sustained overhead activity (occupational or sporting), smoking, diabetes mellitus (which impairs tendon microvascularity and healing), and a family history of cuff tearing. A distinct, smaller group presents with an acute traumatic tear, typically an older patient (over 40) who tears the supraspinatus after a fall onto an outstretched arm or a shoulder dislocation, in contrast to a younger patient whose shoulder dislocation more often causes recurrent instability than a cuff tear.

2. Pathophysiology

The rotator cuff comprises four muscles arising from the scapula whose tendons blend into a confluent cuff around the humeral head before inserting onto the proximal humerus: supraspinatus (supraspinous fossa to the superior facet of the greater tuberosity), infraspinatus and teres minor (infraspinous fossa and lateral scapular border to the middle and inferior facets of the greater tuberosity), and subscapularis (subscapular fossa on the anterior scapula to the lesser tuberosity). Functionally, the cuff acts as a dynamic stabiliser rather than a prime mover: together with the long head of biceps it compresses and centres the humeral head within the shallow glenoid fossa throughout the arc of movement, forming a force couple with the much larger deltoid so that the deltoid can elevate the arm without the humeral head riding upward and jamming against the acromion. Supraspinatus initiates and assists abduction, infraspinatus and teres minor produce external rotation, and subscapularis produces internal rotation and provides the principal anterior restraint to the glenohumeral joint.

The supraspinatus tendon passes through the subacromial space, a narrow corridor bounded above by the acromion, the coracoacromial ligament, and the acromioclavicular joint, and below by the humeral head, and containing the subacromial-subdeltoid bursa and the long head of biceps tendon alongside the cuff itself. Two overlapping mechanisms narrow this space and load the tendon: a primary or structural process, in which a hooked acromial morphology, subacromial spurring, a thickened coracoacromial ligament, or acromioclavicular joint osteophytes mechanically crowd the space, and a secondary or functional process, in which glenohumeral instability or scapular dyskinesis (poor scapulothoracic control) allows the humeral head to translate superiorly during arm elevation and dynamically narrows the same space. Superimposed on this is an intrinsic degenerative process within the tendon itself: the supraspinatus insertion has a relatively hypovascular "critical zone" a centimetre or two proximal to its footprint, and age-related tendinosis (collagen disorganisation, mucoid degeneration, and neovascularisation without significant inflammatory infiltrate) develops here independently of any mechanical crowding, which is why current teaching regards tendon degeneration as often preceding, rather than simply resulting from, impingement. These processes together produce a continuum rather than discrete diseases: tendinopathy and subacromial bursitis progress to partial-thickness tearing (articular-sided, bursal-sided, or intratendinous) and then to full-thickness tearing of one or more tendons, and a long-standing, large, unrepaired tear can allow progressive superior migration of the humeral head against the acromion, ultimately producing rotator cuff arthropathy with secondary glenohumeral osteoarthritis (Robbins Ch 26).

3. Clinical presentation and diagnostic criteria

The typical presentation is a gradual onset of lateral and anterior shoulder pain, worse with overhead activity and reaching behind the back, and characteristically worse at night, particularly when lying on the affected side. Weakness is a variable feature: it is often mild and pain-limited in tendinopathy but becomes a genuine, reproducible deficit once a full-thickness tear is present, especially of infraspinatus or subscapularis. A sudden, dramatic loss of active elevation or external rotation after an acute injury, particularly in a patient over 40, points to an acute traumatic tear rather than degenerative disease and should prompt earlier imaging and referral rather than a prolonged watch-and-wait approach.

Several bedside tests characterise which tendon is affected. The painful arc is elicited during active abduction in the coronal plane: pain that appears between roughly 60 and 120 degrees of abduction but eases both below 60 degrees and above 120 degrees is classic for subacromial pathology, corresponding to the portion of the arc where the diseased tendon and bursa are compressed under the acromion. The empty can test (Jobe test) isolates supraspinatus: the arm is held at 90 degrees of abduction, 30 degrees forward of the coronal (scapular) plane, with the thumb pointing down as though emptying a can, and the examiner applies downward resistance; reproduced pain or weakness in this position implicates supraspinatus tendinopathy or tear. The external rotation lag sign tests infraspinatus and teres minor: with the elbow tucked at the side and flexed to 90 degrees, the examiner passively externally rotates the arm to near its end range and then releases it; an inability to actively hold that position, with the forearm drifting back towards the body ("lag"), indicates a tear of the posterosuperior cuff. Subscapularis is assessed with the lift-off test (Gerber's test), in which the patient places the hand behind the lower back and attempts to lift it away from the back against resistance, an inability to do so signalling subscapularis dysfunction; where shoulder stiffness or pain prevents reaching behind the back, the belly-press test substitutes, in which the patient presses the palm flat against the abdomen while keeping the wrist straight and the elbow forward, and a positive test is seen as the elbow drops backward or the wrist flexes to compensate for weak internal rotation. Neer's sign (pain on passive forward flexion with the scapula stabilised) and the Hawkins-Kennedy test (pain on passive internal rotation with the shoulder flexed to 90 degrees and the elbow flexed to 90 degrees) are traditional impingement provocation tests that remain widely used, though individually each has only moderate sensitivity and specificity, and cuff pathology is best characterised by a cluster of positive findings rather than any single test in isolation.

4. Investigations and AU-specific cutoffs

Plain radiographs (anteroposterior, scapular Y, and axillary views) are the appropriate first-line imaging for most patients with shoulder pain, not to visualise the cuff itself but to exclude fracture and calcific tendinopathy, to assess glenohumeral and acromioclavicular joint osteoarthritis, and to look for acromial morphology and superior migration of the humeral head; an acromiohumeral distance narrowed below about 7 mm is generally regarded as abnormal and raises suspicion of a large cuff tear, while a distance narrowed further, below about 5 to 6 mm, is more specifically associated with a massive or irreparable tear and with cuff tear arthropathy; these figures should be treated as approximate rather than precise cutoffs.

Beyond plain films, ultrasound and MRI both have defined roles and are complementary rather than interchangeable. Ultrasound is dynamic, comparatively inexpensive, widely accessible, and does not require the patient to lie still in a scanner, and in experienced hands has sensitivity and specificity approaching that of MRI for full-thickness tears; it is the pragmatic first-line dynamic imaging test recommended in RACGP and HealthPathways WA guidance for suspected rotator cuff pathology, but its accuracy is strongly operator-dependent and it is less reliable for partial-thickness tears and for assessing muscle bulk and quality. MRI offers superior soft-tissue detail and reproducibility, characterising partial-thickness tears more reliably, quantifying tear size and tendon retraction, and grading fatty infiltration of the cuff musculature (the Goutallier classification), which is an important determinant of whether a tear remains surgically repairable; MRI is reserved for surgical planning, for cases where ultrasound findings are equivocal or discordant with the clinical picture, or where clinical suspicion of a tear remains high despite a normal ultrasound.

5. Management

Consistent with the RACGP approach to atraumatic rotator cuff disease, structured conservative management is first-line regardless of whether imaging shows a partial or even a full-thickness tear, because degenerative tears are common in asymptomatic people and because a well-designed exercise programme achieves outcomes comparable to surgery for many patients with degenerative (non-traumatic) tears. Initial management combines simple analgesia, relative activity modification (avoiding provocative overhead loading rather than complete rest), and referral to physiotherapy for a graduated rotator cuff strengthening and scapular stabilisation programme, with an adequate trial generally meaning a structured programme of at least 6 to 12 weeks before response is judged. Subacromial corticosteroid injection is considered as an adjunct to, not a substitute for, this exercise-based rehabilitation, principally for patients whose pain is severe enough to limit meaningful participation in physiotherapy; injection is ideally performed under ultrasound guidance to confirm accurate placement, and patients should be counselled that benefit is typically modest and short-lived (weeks to a few months) with no long-term functional advantage over exercise therapy alone. Because repeated corticosteroid injection is associated with tendon weakening and a theoretical increase in rupture risk, injections are generally limited to no more than two to three per year into the same shoulder, and glycaemic monitoring should be discussed with diabetic patients given the transient rise in blood glucose that follows injection.

Surgical referral is appropriate in several defined circumstances: an acute traumatic full-thickness tear, particularly in a younger or functionally active patient, warrants prompt referral (ideally within a few weeks) because delayed repair is associated with tendon retraction and fatty infiltration that reduce the chance of a successful repair; failure to improve after an adequate structured conservative trial (typically 3 to 6 months) in a patient with a confirmed tear and ongoing functional limitation is an indication for orthopaedic assessment; and a significant, reproducible weakness on examination, such as a clear external rotation lag or a positive lift-off test, suggests a larger tear that is less likely to respond to rehabilitation alone and merits earlier referral. Surgical options range from arthroscopic rotator cuff repair (the mainstay for a repairable tear) to reverse total shoulder arthroplasty, which is reserved for older patients with an irreparable massive tear and established cuff tear arthropathy where repair is no longer feasible.

6. Pharmacology and AU PBS notes

Paracetamol is first-line analgesia, with a short course of an oral or topical NSAID (for example topical diclofenac gel) added where paracetamol alone is insufficient and there is no contraindication; neither agent alters the underlying disease process. Subacromial injections typically combine a corticosteroid (commonly triamcinolone acetonide or methylprednisolone acetate) with a local anaesthetic; the corticosteroid itself is typically a PBS-listed agent, but in practice it is usually drawn from practice-held stock rather than dispensed against an individual patient's PBS script, and it is the injection procedure and consultation, not the drug, that attracts the relevant MBS item number.

There is no disease-modifying pharmacotherapy for rotator cuff tendinopathy or tearing; oral corticosteroids have no role, and evidence for adjuncts such as platelet-rich plasma injection remains inconsistent and these are not part of standard AU practice.

7. Complications and monitoring

Left untreated, a full-thickness tear can enlarge over time and the affected muscle can undergo progressive fatty infiltration, both of which reduce the likelihood that a later repair will succeed, which is part of the rationale for timely referral once a tear has failed an adequate conservative trial rather than deferring indefinitely. A long-standing, large or massive tear that goes on to allow chronic superior migration of the humeral head produces rotator cuff arthropathy, a pattern of secondary glenohumeral osteoarthritis with a characteristically high-riding humeral head that is more difficult to treat than either problem in isolation. Adhesive capsulitis (frozen shoulder) can coexist with or follow rotator cuff disease, particularly where pain has led to prolonged guarding and reduced range of movement, and should be considered when stiffness rather than weakness dominates the clinical picture.

Recognised complications of subacromial corticosteroid injection include a transient post-injection pain flare, a small infection risk, and, with repeated injections, tendon weakening that can predispose to rupture. Postoperative outcomes after cuff repair depend heavily on tear size, tissue quality, and patient age, with re-tear rates rising for larger, chronic, or fatty-infiltrated tears; postoperative stiffness and infection are recognised but comparatively uncommon complications, and structured postoperative physiotherapy is required in all cases to restore range of movement and strength.

Written for Australian practice and grounded in the guidance named above. Study material only — not medical advice. Always check against current guidelines.