Rotator cuff injury is a condition characterized by partial or complete tearing of one or more of the rotator cuff muscles. The rotator cuff is formed by supraspinatus, infraspinatus, subscapularis and teres minor. The supraspinatus is most commonly affected. The frequency of full-thickness rotator cuff tears ranges from 5-40%, with an increasing incidence of cuff pathology in advanced age. Prevalence of rotator cuff injury increases with age, rare in persons younger than 40 years and usually found in persons aged 55-85 years.
Causes and Pathophysiology
Rotator cuff injury can be sudden or it could be repetitive in nature. A tear occurs when there is a high force which tissue is not able to withstand as in heavy or awkward lifting, a fall onto an outstretched hand, heavy pushing or pulling, or a forceful throw.
A repetitive strain due to repetitive activities, may over the time cause gradual degeneration and weakening of the rotator cuff predisposing it to further injury. These could repetitive lifting, pushing, pulling, throwing sports, swimming, racquet sports, weight lifting or paddling sports such as kayaking.
In young adults, rotator cuff injury can occur as a result of repetitive overhead activities or trauma. Most of the tears in old age are result of chronic degeneration that present with gradual onset pain and have tear often without predisposing trauma.
Patient related factors that increase risk of rotator cuff injury are kinematics abnormalities, altered tendon blood supply, microstructural collagen fiber abnormalities, age related degeneration, compromised microvascular suppl, outlet impingement, glenohumeral instability and morphology of the coracoacromial arch. Most people with ligamentous may have relative rotator cuff muscle weakness may predispose the impingement.
Poor throwing techniques, stiffness of neck and upper back, muscle weakness and imbalances, muscle tightness, poor posture and inadequate warm-up are associated with known to increase risk of rotator cuff injury.
Presentation [ Signs and Symptoms of Rotator Cuff Injury]
Pain is the most common symptom with rotator cuff injury. Acute tearing sensation occur on provocative activity, which if continued may increase the severity of the pain is the usual complaint. Pain may be disabling enough to performing further activity. Pain is usually localized to the shoulder but may radiate into the upper arm, shoulder blade, upper back or neck.
Pain may occur with arm elevation, lifting heavy objects overhead, heavy pushing or pulling or when lying on the affected side. In severe or chronic cases, muscle wasting may occur and night painmay occur in all sleeping positions.
Limitation of motion my be associated with the pain. There may be complaints of clicking, catching, stiffness, and crepitus.
Examination may reveal muscle atrophy and tenderness which is often localized to the greater tuberosity and subacromial bursa. Active and passive range of motion should be noted. Individual muscles should be tested for strength including the scapula rotators (trapezius and serratus anterior). The biceps tendon is also palpated to rule its involvement.
Tests For Impingement
The examiner performs maximal passive abduction in the scapula plane, with internal rotation, while scapula is stabilized.
This causes impingement of supraspinatus tendon against anterior inferior acromion.
With patient sitting, the the arm and elbow is flexed at to 90°, supported by the examiner. The examiner then stabilizes proximal to the elbow with their outside hand and with the other holds just proximal to the patient’s wrist. It is then quickly move the arm into internal rotation Pain and a grimacing facial expression indicate impingement of the supraspinatus tendon, and this is a positive Hawkins-Kennedy impingement sign.
10 mL of 1% lidocaine solution into the subacromial space and then repeats the tests for the impingement sign. Reduction of pain constitutes a positive impingement test result.
Drop Arm test
This evaluates for a supraspinatous muscle tear. In this test, shoulder is abducted 90 degrees, flexed to 30 degrees and point thumbs down. The test is positive if the patient is unable to keep arms elevated after the examiner releases.
Supraspinatus Isolation Test
It is also known as empty can and full can test. The original test described by Jobe and Moynes to test integrity of the supraspinatus tendon is called empty can test. Full Can Test was later suggested by Kelly as it was less provocative and tested in same manner.
Empty can and full can represents the position . The patient is tested at 90° elevation in the scapula plane and full internal rotation (empty can) or 45°external rotation (full can).
In these positions downward pressure exerted by examiner at patients elbow or wrist. Muscle weakness or pain or both represent a positive test.
Tests for Instability
In this test, the examiner grasps the patient’s elbow and applies downward traction. Dimpling of the skin subjacent to the acromion (the sulcus sign) indicates inferior humeral translation. This indicates instability of the shoulder joint.
Anterior Drawer Test
With patient in sitting position, one hand stabilizes the shoulder by holding coracoid and spine of scapula, and the other hand moves the humeral head anteriorly and posteriorly.Abnormal movement is noted.
The Apprehension and Relocation Test
With patient in supine position, the examiner brings the affected arm into an abducted and externally rotated position. If patient apprehensively guards and does not allow further motion, it indicates a positive anterior shoulder instability.
The test is repeated with shoulder supported anteriorly. The absence of guarding and pain confirms the instability.
Differential Diagnoses of Rotator Cuff Injury
Imaging Studies for Rotator Cuff Injury
Shoulder radiography should include anteroposterior, axillary, and lateral views. The outlet view or transscapular view (a lateral radiograph in the scapular plane with the beam tilted 10° caudad) helps identify acromion shape and slope.
Radiographic changes may reveal subacromial sclerosis, osteophyte, sclerosis and cystic changes in the greater tuberosity, reduction of the acromiohumeral distance (< 7 mm is significant).
Magnetic resonance imagingis standard for diagnosing injuries to the rotator cuff and can be used to detect the size, location, and characteristics of rotator cuff injury. It also helps to differentiate a frank tear from tendinosis.
Ultrasonography is highly accurate in detecting the extent of the rotator cuff tear and to visualize biceps tendon.
For treatment, it needs to determined first if the rotator cuff injury is acute or chronic.
Chronic Rotator Cuff Injury
Chronic rotator cuff injury injury that have progressed to a rotator cuff tear is treated conservatively.Initial treatment aims at reduction of inflammation and correct any biomechanical probelm. NSAIDs and rest are initiated. Activity modification is advised. Corticosteroid injections in subacromial space may relieve the pain.
In follow up, range of motion and a basic strengthening exercises should begun.
If the patient does not improve by six weeks, surgical treatment should be considered.
Acute Rotator Cuff Injury
Acute traumatic tears in young athletes and complete tears of rotator cuff should be considered for surgery. In rest management is same as above.
Indications for surgery are
- < 60 years
- Complete tear
- Failure of conservative management following a period of 6 – 8 weeks
- Young and active people, athletes and sports persons
- Profession that requires repetitive or overhead shoulder activities
Early repair is useful to avoid fatty degeneration and retraction of the remnant rotator cuff musculature.
Acromioplasty is usually performed in the presence of a type II (curved) or type III (hooked) acromion with an associated rotator cuff tear. Glenohumeral instability should also be addressed.
Muscle transfers and debridement are generally reserved for massive, irreparable rotator cuff tears.
Platelet-rich fibrin matrix applied to the tendon-bone interface at the time of rotator cuff repair has not been shown to be effective.
Exercises for Rotator Cuff Tear
The following exercises are commonly prescribed. The exercises should be done under supervision, at least initially. Stop if symptoms worsen during exercise.
Shoulder Blade Squeezes
Stand or sit with your back straight. Tuck your chin slightly. Take your shoulders slightly back and squeeze the shoulder blades together as hard and far as possible. Hold for 5 seconds and repeat 10 times.
Support on table with your uninjured forearm and lean forwards keeping your back straight and your shoulder relaxed.
Gently swing your injured arm forwards and backwards as far as possible without pain. Repeat 10 times.
Another variation of this exercise is pendular circles in which the injured arm is swung in circles clockwise.
Foam Roller Stretch
Place a foam roller under your upper back. Breathe normally keeping your back and neck relaxed. Hold this position for 15 – 90 seconds.
Return to task or sports should be individualized for every player. Patient should not have pain at rest or with activity, should have full muscle strength and normal range of motion including scapulothoracic motion and provocative tests should be negative before return to play/work is considered.
About 4% of patients develop rotator cuff arthropathy.
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