The rotator cuff is a group of 4 muscles that support and rotate the glenohumeral joint (see below).
Rotator cuff tears are common; acute full thickness tears have an incidence around 2.5 per 10,000 patients for those aged 40-70, whilst the prevalence of a rotator cuff tear in the general population is around 20%.
Rotator cuff tears are classified as either acute (lasting <3 months) or chronic (lasting >3 months) tears. They can be either partial thickness or full thickness tears.
Full thickness tears can be further classified into small (<1cm), medium (1-3cm), large (3-5cm), or massive (>5cm or involves multiple tendons) tears.
The Rotator Cuff Anatomy
The rotator cuff is composed of four muscles:
- Supraspinatus– abduction
- Infraspinatus – external rotation
- Teres minor – external rotation
- Subscapularis – internal rotation
Alongside their role in movement of the shoulder, these muscles act to stabilise the humeral head in the glenoid fossa, playing a key role in maintaining overall shoulder stability.
Acute tears commonly occur within tendons with pre-existing degeneration, typically occurring alone following minimal force. However, acute tears can occur in young individuals when the force required to cause a tear can be large, therefore often occur alongside other injuries.
Chronic tears occur in individuals with degenerative microtears to the tendon, most commonly from overuse and seen in greater incidence with increasing age.
The main risk factors for rotator cuff tears are age, trauma, overuse, and repetitive overhead shoulder motions (e.g. athletes, certain occupations). Other risk factors include BMI>25, smoking and diabetes mellitus.
Patients will present with pain over the lateral aspect of shoulder and an inability to abduct the arm above 90 degrees. Tears are more common in the dominant arm.
On examination, there is often tenderness over the greater tuberosity and subacromial bursa regions. Supraspinatus and infraspinatus atrophy can be seen in massive rotator cuff tears.
There are specific tests that can be performed to help assess for the presence of a rotator cuff tear and elucidate which tendon(s) are affected:
- Jobe’s test (the ‘empty can test’; tests supraspinatus) – place the shoulder in 90° abduction and 30° of forward flexion and internally rotate fully (as if you’re ‘emptying a can’). Gently push downwards on the arm. A positive test is present if there is weakness on resistance.
- Gerber’s lift-off test (tests subscapularis) – internally rotate the arm so the dorsal surface of hand rests on lower back. Ask the patient to lift hand away from back against examiner resistance. A positive test is weakness in actively lifting the hand away from back (compare to the contralateral side).
- Posterior cuff test (tests infraspinatus and teres minor) – the arm positioned at patient’s side, with the elbow flexed to 90°. The patient is instructed to externally rotate their arm against resistance.A positive test is present if there is weakness on resistance.
The main differentials to be considered include fracture, persistent glenohumeral subluxation, brachial plexus injury, or radiculopathy.
Patients presenting with clinical features of a rotator cuff tear should have an urgent plain film radiograph to exclude a fracture.
Most plain film radiographs will be unremarkable. In chronic tears, there may be evidence of reduced acromiohumeral distance, or sclerosis and cyst formation the rotator cuff insertion on the greater tuberosity of the humerus.
Once fracture has been excluded, rotator cuff tears can be assessed through further imaging. Ultrasonograhy can establish the presence and size of tear (Fig. 2), whilst MRI imaging can also be used to detect the size, characteristics, and location of any tear.
Management is dependent on the type of tear and functional status of the patient.
Conservative management is preferred in patients who are not limited by pain or loss of function, or those who have significant co-morbidities and unsuitable for surgery.
Those who are presenting within 2 weeks since injury can be advised for a conservative management approach, including analgesia and physiotherapy with activity modification. Corticosteroid injections into the subacromial space can also be trialled.
For those presenting 2 weeks since the injury or remaining symptomatic despite conservative management should be referred for surgical intervention. Large and massive tears should also be considered for surgical repair.
Repairs can be done arthroscopically (allowing for earlier recovery) or via open approach (preferred in large or complex tears)
Prognosis following surgical repair tends to be very good, however those with large or massive tears, age >65yrs, poor compliance with rehabilitation programs, or current smokers have worse outcomes.
The main complication from the condition is adhesive capsulitis, leading to stiffness of the glenohumeral joint.
40% of those with age-related tears will have enlargement of their tears within 5 years. Of those whose tears enlarge, 80% will become symptomatic.
- Rotator cuff tears are classified as either acute (lasting <3 months) or chronic (lasting >3 months) tears
- Patients will present with pain over the lateral aspect of shoulder and an inability to abduct the arm above 90 degrees
- Once fracture has been excluded, US or MRI can be used to further assess the condition
- The condition can be managed both conservatively or surgically