Impingement syndrome is the commonest problem of the shoulder. It causes shoulder pain and difficulty in lifting the arm. It is frequently misdiagnosed as frozen shoulder.
The rotator cuff is composed of four tendons that blend together to help stabilise and move the shoulder. It lies below the ‘acromion’ which is the outer bony prominence of the shoulder. The rotator cuff tendons pass below the acromion whenever the arm is raised. If the acromion protrudes down into the ‘sub acromial space’ (the space between the acromion above and the rotator cuff tendon below), the rotator cuff tendons rub and ‘impinge’ against the acromion. Impingement causes difficulties with activities such as driving, hanging clothes, brushing one’s hair and lying on the affected shoulder at night.
How does impingement start ?
The rotator cuff tendons can be injured by a single episode of trauma. Often, however, the tendons are injured by repetitive overuse, such as from long distance swimming, tennis, jobs that involve having the arms raised for prolonged periods of time (painting ceilings, plastering), or repetitive lifting of heavy objects.
Once the rotator cuff tendons have been damaged they become inflamed and swollen, and thus lessen the area in the sub acromial space. This causes the painful cuff tendons to impinge against the acromion more and more. This continued rubbing (i.e. impinging) may eventually cause a tear in the rotator cuff tendon, which can cause further pain and weakness of the shoulder. In young people, the cuff tendons are strong and require a major force to tear. Cuff weakened due to old age can be torn easily, even while carrying out activities of daily living.
Treatment initially involves a temporary rest from the pain provoking activities, be it sport or work. A modification of technique may be necessary for athletes. Anti-inflammatory tablets may also be prescribed.
After a period of rest, an exercise program is required to strengthen and re-balance the muscles around shoulder. This involves exercising the 4 rotator cuff muscles – supraspinatus, infraspinatus, teres minor and subscapularis. Therabands are very effective in rotator cuff rehabilitation. In addition, deltoid and pectorals need to be strengthened. A stretching program is also important to regain any lost shoulder movement. Patients who do not get better with the above regime, or who have long standing impingement or rotator cuff tears, will require operative treatment.
The surgery for impingement is called subacromial decompression (or acromioplasty). The protruding undersurface of the acromion is removed so as to increase the area of the subacromial space. This is done by arthroscopy through two or three small incisions. Usually only 24 hours is needed in hospital and the motion of the shoulder is regained early. Most shoulders improve significantly in the first two to three months, and continue to improve for up to 12 months. It is thought that the delay in recovery is because the tendons have to recover even after the impingement has been relieved.
The surgery is highly successful in relieving pain and in improving the shoulder’s ability to perform activities of daily living, work and recreation. An exercise program that lasts for 3-4 months is begun immediately after the surgery and is directed by the physiotherapist. Clerical work can be recommenced 1 week after the operation. Heavy work must be avoided for at least 6 weeks.
If a tear of the rotator cuff tendons is diagnosed, it is repaired along with subacromial decompression using arthroscopic (keyhole) techniques. The goal of the surgical repair is to re-establish the connection between the torn tendon and the arm bone (humerus). The tendon is implanted into a groove in the humerus using suture anchors and thus held in position. Modern suture anchors can be inserted with arthroscopic techniques without the need for open surgery. They are usually bioabsorbable and do not need to be removed.
Healing of the repaired tendon is slow and the loads applied to the tendon are large. Thus protection of the repair is required for 6-8 weeks following repair. The shoulder is moved during this time but only passively ie the good arm is used to move the shoulder to prevent stiffness and to help the repair process.
Patients usually need a week off work following surgery. After this, they can use the hand for activities such as typing and writing as long as the elbow is kept at the side. Strengthening exercises are begun after 2-3 months and continue for 6 months. Exercises are done under a physiotherapist’s supervision.
Sometimes the tendon is too frayed and retracted to be repaired. Under these circumstances the tendon is ‘cleaned up’ and the decompression is performed. This gives good pain relief.
Almost all patients after arthroscopic surgery for impingement and rotator cuff tears are happy with the outcomes
Right Shoulder Arthroscopy