Impingement syndrome

Introduction
There is a good centimetre of space between the bony shoulder roof and head of the upper arm. This region contains the rotator cuff, which is indispensable to centralise the head of the upper arm in the joint, and to carry out rotational movements. There is a fluid sack (bursa) between the rotator tendons and the bony shoulder roof (acromion). Several arm movements, and in particular those above the head, cause this space to narrow, which can cause catching symptoms. Acute pain usually arises from an inflamed bursa, while chronic pain is due to changes in the tendon. Repeated damage to the tissue of the tendon results in fragility, partial tears and later complete tears of the tendon. Eventually the rotator cuff fails to function properly and the head of the upper arm rides up and makes direct bone-to-bone contact with the shoulder roof. This disease is referred to as «impingement».

Several theories for the development of impingement are debated, however the role of tissue ageing, the triggering of impingement by instability or thickening of the tendon (e.g. by calcification) and the influence of excessive strain on the shoulder when positioned above the head are beyond doubt. Degenerative changes in the acromioclavicular joint also play a role in impingement (AC-arthritis).

Surgical procedure
These days, operations in the so-called «subacromial space» are carried out arthroscopically. For this, we use a rod-shaped lens of pencil thickness and a small camera to acquire a greatly magnified view of the interior of the joint on a screen.
You will usually receive a combination of a nerve block and a light general anaesthesia (please discuss the details with the anaesthesiologist!). Subsequently you will be placed in a semi-sitting («beach-chair») position. The shoulder must be free to move. Once the arthroscope has been placed in the joint from behind, all parts of the joint are inspected. This permits the completion, and not infrequently correction of the diagnosis established prior to the operation, and now a definitive plan for the operation can be decided.

Then the arthroscope is placed in the subacromial bursa. Under direct view, bone spurs can be cleared away, the coracoacromial ligament relaxed and, if necessary, the acromioclavicular joint smoothed or cut out. Finally the rotator cuff is thoroughly inspected and palpated from above. In the case of partial tear of the rotator cuff, a suture can be avoided, when we estimate that less than 50 % of the fibres are torn.

Complete tears should however be fixed up by sutures using an appropriate technique. The aim of the operation is the removal of the impingeing symptoms and the free, smooth gliding of the tendon in the subacromial space.

Follow-up
Although only small stab-like wounds are visible from the outside, the internal wounds may still cause considerable pain for the first two weeks. You will receive the required painkillers for this. The arm can and should be moved actively and passively without restriction straight away. As soon as the pain subsides, strengthening and stretching exercises are desirable. Following instructions from the physiotherapist you can carry out many of the exercises yourself. Depending on the results you can count on being largely pain-free after 3 to 6 weeks. You will not be considered fit for work for 2 to 4 weeks in the case of a sedentary job and otherwise for 4 to 8 weeks, depending on the degree of shoulder use.

Prognosis
After arthroscopic expansion of the subacromial space approximately 85 % of patients can count on being free of complaints. In a few cases, when this minimally damaging intervention fails, a second shoulder operation (tendon suturing) becomes necessary.