Sub-acromial Impingement/Bursitis and Decompression

What is it?

The roof of the shoulder is called the acromion; it is an extension of the scapula. Under the acromion lie the rotator cuff tendons. There are 4 muscles that make up the rotator cuff (supraspinatus, infraspinatus, subscapularis and teres major) and thus 4 tendons. The rotator cuff serves to keep the shoulder “in joint” and push the humeral head down when you elevate your arm.

Shoulder anatomy

There is a space between the rotator cuff tendons and the acromion called the sub-acromial bursa. This is a fluid filled sac that ensures the rotator cuff tendons glide smoothly under the acromion, particularly when the arm is elevated (overhead activities). If the rotator cuff tendons and acromion rub against each other repeatedly (i.e. each time the arm is lifted), this causes the painful condition known as sub-acromial impingement. This happens in two main ways:

  • A bony spur develops on the undersurface of the acromion; this may occur with ageing or can be part of the normal shape of the acromion (curved or hooked acromion). The spur impinges on the bursa causing injury and inflammation (bursitis) and on the rotator cuff tendons causing injury and perhaps tears.
  • If the rotator cuff tendons are strained or injured, this can cause local inflammation, which can involve the subacromial bursa (bursitis).

The condition is more common over 40 yrs of age.

Who should have sub-acromial decompression?

Treatment for sub-acromial impingement begins with the following:

  • Analgesia – anti-inflammatories
  • Physiotherapy
  • Injections – cortisone/hyaluronate

It is well documented that non-operative treatment is very successful. However, if this fails, then arthroscopic surgery to increase the space between the acromion and the rotator cuff tendons can be performed: sub-acromial decompression.

Will I need any tests/scans?

It is likely that X-rays and an Ultrasound scan will be requested for sub-acromial impingement. MRI maybe requested if any concomitant intra-articular pathology is suspected. Please see the section Surgery FAQs to see if you will need any other tests e.g. blood tests before your surgery.

How is it done?

Sub-acromial decompression is performed under general and/or regional anaesthesia. It is an arthroscopic procedure (see shoulder arthroscopy).

shoulder anatomy viewed from the front

Using a shaver and a burr, bone is carefully shaved from the undersurface of the acromion, including the spur if it exists, to create more space between the acromion and the rotator cuff. Ocassionally the coraco-acromial ligament is released to facilitate this.

At the end of the operation, steri-strips or one stitch is used to close each portal. Waterproof dressings and then a bulky dressing pad are applied to absorb the natural ooze from the joint. The arm is almost always placed into a polysling for comfort and to immobilise the shoulder to allow tissues to heal.

Can I go home the same day?

More often than not, as with most arthroscopic surgery, this is a day case procedure. Occasionally an overnight stay is advised depending on post-operative comfort levels, medical co-morbidity and time of day of the surgery.

What about after the operation?

You will see a physiotherapist before discharge to be instructed on simple exercises to carry out in the short term. This usually involves simple pendulum exercises out of the polysling and light stretches, often with assistance (e.g. your other arm or your physiotherapist) and you will be instructed on axillary hygeine. You should aim to exercise the shoulder 3-4 times a day; although the shoulder will be sore to start, there should be no lasting pain or pain that is not alleviated by the analgesia prescribed to take home. Sleeping with a pillow under the shoulder is recommended. It will be painful to sleep on the side of the operated arm for several weeks.

You will be prescribed analgesia to take home and Mr Patel strongly advocates its use to keep pain to a minimum; it should be noted that pain is more difficult to control if allowed to establish itself. Mr Patel recommends the regular application of ice as an adjunct to relieve pain and swelling in the acute post-operative period.

You will see Mr Patel two weeks after surgery for a wound check (and stitch removal) and a physiotherapy program will ensue thereafter which is paramount to the success of the operation. You are likely to have been seeing a physiotherapist before the operation and Mr Patel will liaise with him/her in detail to advise on the post-operative exercise program.

What are the potential complications?

All surgery carries a risk. Specific risks to arthroscopic sub-acromial decompression are:

Infection – this can be either superficial (portals) or within the joint. You will be given antibiotics to reduce this risk

Stiffness – It is very important that some mobility of the shoulder is maintained after surgery. The physiotherapist will advise on simple exercises that can be carried out at home. Mr Patel also recommends that you take regular analgesia and use ice (see Surgery FAQs) to help minimise post-operative discomfort and facilitate early movements.

Bleeding – this may require a return to the operating room for removal of blood clots and to stop the bleeding.

Neurological – patients often describe a patch of numbness or a heavy feeling around the shoulder in the early post-operative phase. This is commonly swelling related and resolves as swelling reduces and full shoulder mobility is recovered.

Residual symptoms – unfortunately, no guarantees can be offered regarding curing your symptoms, despite the surgeon’s best efforts. In this case, further management and treatment options will be discussed with you.