Introduction
- The intrinsic muscles of the shoulder arise from the scapula (shoulder blade) and insert into the humeral head.
- The supraspinatus, the infraspinatus and the teres minor insert on the top and back of the humeral head, one behind the other.
- The supraspinatus elevates the arm (abductor); the infraspinatus and the teres minor rotate the arm outwards (external rotators).
- The subscapularis is attached to the front of the humeral head and rotates the arm internally (internal rotator).
- The tendons of these muscles fuse with each other near their insertion and form the rotator cuff.
- Although these muscles move the humeral head, their more important function is to stabilize the humeral head against the socket (glenoid). This allows the more powerful extrinsic muscles to move the arm.
- The acromial process, the clavicle and the coraco-acromial ligament form the upper boundary of the rotator cuff outlet. Narrowing of the outlet results in pressure on the tendons leading to attrition and tearing of the cuff.
Rotator cuff impingement and tear
- The rotator cuff is subjected to stress in day-to-day activities. As the age advances, the elastic fibres are replaced by non-elastic fibres, making it more prone to tears. Hence rotator cuff attrition and tear is common after the age of fifty.
- Some people have a hook-shaped acromion which causes pinching of the tendons. Arthritis of the acromio-clavicular joint results in bony thickening and impingement.
- Micro-instability of the humeral head can result in the inner side of the cuff rubbing against the glenoid (internal impingement).
- Muscle imbalance (scapular dyskinesis) can cause abnormal motion of the humeral head and result in impingement. Poor position of scapula (drooping and forward rotation) also causes impingement.
- Pathologic conditions of the cervical spine can also affect the muscle balance and position of the scapula – and contribute to impingement. In addition, the nerve supply to the shoulder comes from the cervical region and this may also get affected.
- In young patients, the rotator cuff is affected by injuries like those sustained in collision sports or road traffic accidents.
Natural history of rotator cuff tears
- Partial thickness tears are very likely to progress to full thickness tears. The rate at which this happens depends upon many factors: the anatomy of the shoulder, patient’s activities, the degree of muscle imbalance (if any), and possible contribution from cervical spondylosis. As the tear worsens, there is associated worsening of the shoulder function (increase in pain and reduction of activity level). Hence the initial treatment of these tears is non-operative – with physiotherapy, exercises and activity modification. If the pain and disability persist surgery is indicated.
- Full thickness tears will definitely progress with enlargement of the tear and worsening of shoulder function.
- In long-standing tears, there is infiltration of the rotator cuff with fat. This reduces the mechanical strength of the tissue and makes any surgical repair very difficult.
- Rotator cuff tears have been observed in 30 percent or more of normal (asymptomatic) people over the age of 70 years. This finding makes it difficult to assess whether a given patient is normal or abnormal. Therefore the degree of pain and disability are very important in choosing the right treatment.
Treatment of rotator cuff tears
- Partial tears are initially treated by non-operative measures – like physiotherapy, exercises and activity modification. If the pain and disability persist surgery is indicated.
- Various types of exercises are advised:
- Exercises to improve range of movement
- Exercises to strenghten the rotator cuff
- Exercises to correct scapular diskinesia
- Exercises to improve core strength (mainly cervical spine)
- The exercise programme can be quite complex and may require many sessions of supervised physiotherapy to get it right.
- Steroid injections can be given for symptomatic relief but are best avoided. This is because they do not give permanent relief and adversely affect the quality of the tissue – further weakening the rotator cuff and possibly converting a partial tear into full tear. Steroids interfere with the basic repair mechanisms of the body.
- Full thickness tears that are painful and associated with functional disability need surgical repair.
Surgery
- Sub-acromial Decompression: This procedure involves removal of the bony and soft tissues that cause mechanical impingement of the rotator cuff. Typically, this involves removal of the thickened subacromial bursa and the under-surface of the acromial bone. Bony and soft tissue impingement from acromio-clavicular arthritis are similarly addressed. There is controversy regarding release of coraco-acromial ligament.
- Rotator Cuff Repair: In this procedure, the torn cuff is freed of any adhesions and repaired to its native site (footprint). The key aspects of this operation are mobilization of the cuff and a secure, tension-free repair. Repair is facilitated by the use of Suture Anchors.
- Suture Anchors are screw type or barb-like devices that help in getting a secure fixation of sutures to the bone. They can be made of metal or polymers.
- Both these procedures can be done using arthroscopic or mini-open techniques.
- Post-operative protocol varies depending on the quality of the tissues and the strength of repair. A period of immobilization may be advised. Mobilization progresses through passive exercises, assisted exercises and active exercises.
Results
- Pain relief: This is the biggest benefit after rotator cuff surgery. However, this does not occur immediately and can take a few weeks.
- Recovery of function: After proper rehabilitation good functional improvement can be expected.
Neglected cuff tear and end-stage disease
- If rotator cuff tear is not treated the shoulder function slowly deteriorates over time. The rotator cuff becomes retracted (shortened) to such an extent that it cannot be repaired. In such situations decompression can give some pain relief, but functional impairment will remain. Repair of the rotator cuff using natural and artificial grafts (augments) can be done but the results are not as good as early stage repairs. Also, transfer of lattissimus dorsi or other muscles can be done to provide some functional improvement.
- Sometimes, the repaired rotator cuff gets torn again due to poor quality of tissue or weakening with age. This is again a difficult problem – and is treated along the same lines as above.
- If the cuff tear is not addressed at all or there is a failure of the original surgery, it leads to abnormal motion at the shoulder joint. This results in advanced wear and tear of the shoulder joint called Rotator Cuff Arthropathy. This cannot be treated by repairing the cuff. This condition needs a special form of shoulder replacement called Reverse Shoulder Replacement. This gives very good results in terms of pain relief and functional improvement.
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