Arthroscopic Subacromial Decompression
The operation of sub-acromial decompression, which was conceived in the early 1970’s, is designed to provide more room in the sub-acromial space so that the rotator cuff tendons, which pass through that space no longer rub on the under surface of the acromion, a condition known as impingement. It is thought that this rubbing over a period of time is the cause of both shoulder pain and tears or holes in the rotator cuff tendons. Therefore a sub-acromial decompression, removing the bony spur is an essential part of this operation.
The first step in this procedure is to introduce the arthroscope into the shoulder joint itself. This allows the stability of the joint to be assessed, to check for the presence of arthritis, to assess the long head of biceps tendon and to evaluate the under surface of the rotator cuff tendons.
The next part of the procedure is to perform a subacromial decompression. This is usually performed arthroscopically to minimise the damage to the deltoid muscle and to make the procedure less painful.
The arthroscope is then introduced into the subacromial space between the rotator cuff tendons below and the acromion above though the same small incision at the back of the shoulder. This is the area in which most of the rotator cuff problems occur.
Almost everyone who experiences subacromial impingement or has a rotator cuff tear is found to have an acromion that is slightly prominent or hooked on the under surface. This leaves less room for the tendons to glide and move as the shoulder is placed through a range of motion. The tendons rub (impinge) on the hook causing inflammation, degeneration of the tendon and eventually a tear. Following the removal of inflamed and thickened soft tissue in the sub-acromial space the under surface of the acromion was flattened and partially removed.
The aim of a sub-acromial decompression is to increase the space below the acromion so that the tendons do not rub on the under surface of the acromion. This involves a slight shortening of the acromion and removing the abnormal spur at the front of this bone (acromioplasty), which is achieved by using small power burrs that are visualised during the procedure through the arthroscope.
Sometimes after having performed a standard acromioplasty it is noted that the outer end of the collar bone (clavicle) is seen to protrude into the space as well. The outer end of this bone is next to the acromion and actually forms a small joint with it. In some cases it may also be necessary to burr off part of the underside of this bone.
The joint between the acromion and the clavicle may produce pain it its own right, particularly if arthritis develops in it. The treatment for this is to excise the outer one centimetre of this bone, again using the power burrs under arthroscopic control.
Impingment lesion on the coracoclavicular ligament
Fraying of the coracoclavicular ligament and bursal surface of the rotator cuff
Removal of the coracoclavicular ligament
Removal of the subacromial spur
Subacromial spur removed
Probing the surface of the rotator cuff
Increased subacromial space
After Your Operation
Post-operative pain relief is obtained by injecting large amounts of local anaesthetic around the nerves that supply sensation to the shoulder joint and also into the sub-acromial space at the end of the operation. Cold fluid is also used during the arthroscopy to inflate the joint and this also produces pain relief. The anaesthetist will prescribe painkilling tablets for you. You should, if possible take anti-inflammatory tablets in the first few weeks after the operation as this will diminish inflammation in the shoulder and speed your recovery.
- Initially post-operatively a bulky dressing is used on the shoulder and covered with a disposable absorbent dressing. This will be changed to a smaller dressing before you leave the ward. After your 10 day review all dressings are removed and the wound can get wet at that stage.
- You will spend one night in hospital and after your review the next morning if all is well I will discharge you home to be reviewed at day 10. A sling is necessary for comfort for the first few days after surgery.
- It is important not to stress the shoulder by moving the arm overhead. This does not mean that the arm should not be moved postoperatively.
- Maintaining motion prevents scarring in the sub-acromial space from forming and hence helps to prevent shoulder stiffness. If the shoulder does get stiff in the early post operative weeks it will take approximately 6-9 months to regain a good range of movement.
- The best way of maintaining shoulder movement is to lean forwards and hold the wrist of the operated on arm with the opposite hand and to gently move the shoulder through a small range of motion on a regular basis. At 6 weeks post operation the arm can be lifted overhead by means of a pulley system using the opposite arm to pull it up. The input of a physiotherapist into your rehabilitation will be very useful at this point.
- Despite regaining motion early on, the ache in the shoulder or upper arm may not settle for several months. Whilst some of the pre-operative pain may not be evident shortly after surgery it is common for a burning pain and clicking in the shoulder to persist for several months until the swelling of the inflamed tendon has settled sufficiently. Maximum improvement in your symptoms may take six to twelve months to occur.
- During the first four to six weeks following your acromioplasty your shoulder may get progressively more stiff and painful, this is a frozen shoulder which can occur after any intervention on the shoulder. If this happens I can inject the shoulder with steroid which will halt the problem almost immediately.
- Until the shoulder really starts to settle it is difficult to lie on that side in bed. It is usually best to sleep propped up in bed for the first few post-operative weeks. Driving a car is practically impossible for the first 6 weeks after surgery but thereafter this would be possible if the car has power steering.
- Each of the small wounds usually has a stitch under the skin which does not need to be removed.
If you are having problems with your shoulder please do not hesitate to contact me through my office on 028 9752 1143 or the Ulster Clinic on 028 9066 1212.