Shoulder Impingement

Impingement defines the process that occurs when soft tissues are compressed between two solid moving surfaces.

In the shoulder this involves the pinching of the rotator cuff tendons that surround the top of the humerus, beneath the acromium and/or the ligament between the coracoid and the acromium ( coraco acromial ligament)

The acromium is a bony process at the front edge of the shoulder blade. It sits over and in front of the humeral head.

Overlying the rotator cuff sits a bursa, which is a fluid filled sac protecting the tendons from pressure. This too may become inflamed in association with impingement and this is referred to as bursitis. Anything that causes the space between the top of the rotator cuff muscles and the acromium to narrow will cause impingement.

The rotator cuff tendons can become inflamed as a result of injury, but more commonly without injury as a result of impingement.There may be a deposit of bone beneath the acromium called a bony spur, further aggravating the impingement.

A narrowing of the subacromial space will mean the adjacent surfaces of the rotator cuff and acromuim rub together when the arm is moved causing pain and further inflammation, especially when raising the arm high.

In younger patients it is important to exclude an instability in the shoulder which can create an impingement as the humeral head migrates upwards on movement of the arm. When the rotator cuff muscles cease to work efficiently and in a co-ordinated way, the humeral head is likely to migrate upwards and cause increasing impingement: thus setting up a ‘vicious circle’ and continuing deterioration.


Pain usually comes on slowly, often without a clear cause and gets progressively worse. Pain increases with overhead activities. The shoulder may feel stiff but when the pain resolves this will go.

Impingement is more likely to affect either people who work with their arms overhead eg plumbers, carpenters, etc, or those who play racket sports. It can also occur as a result of other conditions within the shoulder that can be diagnosed accurately with a skilled physical examination and may require an MRI or ultrasound .

It is more common between the ages of 40 to 70 years.

Treatment Options

  1. Cortico-Steroid injection ( e.g hydrocortisone)into the space beneath the acromium with an anaesthetic to reduce the pain.
  2. Physiotherapy to strengthen the rotator cuff muscles, pulling the humerus away from the acromium.
  3. Surgery – Sub acromial decompression – Open or Arthroscopic.



To decompresss the impingement of the rotator cuff against the coraco-acromial arch ( acromium process, spur, coraco-acromial ligment) and thickened/inflamed bursa.


Patients with shoulder pan from impingement. Patients may also have an associated acromioclavicular joint degeneration requiring excision. Patients may also have an associated rotator cuff tear, which may or may not, require separate repair.

Skin Incisions

Sagittal: this gives the best cosmetic result


The deltoid is detached from the antero-lateral aspect of the acromium and split distally to a maximum of 3 cm. The under surface of this region of the acromium is then removed( a Neer type acromioplasty). A limited or full excision of the bursal sac is caried out, depending on the severity of the condition. The deltoid is carefully repaired (including sutures through the bone)

Possible Associated ProceduresArthroscopy of the gleno-humeral joint
Excision of the acromioclavicular joint
Repair of rotator cuff tear
Possible Associated Complications

Detachment of the repaired deltoid
Nerve injury, e.g suprascapular nerve
Shoulder stiffness



To decompress the impingement of the rotator cuff against the coraco acromial arch ( acromium process, spur, coraco- acromial ligament) and thickened /inflamed bursa.


Patients with shoulder pain from impingement in which the rotator cuff is intact or where there is a tear not suitable forrepair. Rarely, it may be necessary to convert to an open procedure.

Skin Incisions

Posterior- arthroscope
Lateral- arthroscopic instruments and arthroscope
Anterior- used for gleno-humeral joint assessment and as an outflow portal; or should acromioclavicular joint require excision/or chlectomy.


Removal of the antero-lateral ,inferior aspect of the acromiu and the acromial attachment of the coracoacromial ligament with arthroscopic power tools and radiofrequency instruments.

Possible Associated Procedures

Arthroscopic assessment of the gleno-humeral joint
Acromioclavicular joint excision
Rotator cuff repair
Biceps stabilisation, or tenodesisMain Possible Complications

Nerve Injury

Failure to completely decompress

After your operation

A sling is applied in theatre and worn for 48 hours. The post operative swelling usually resolves in 24 hours.
The sutures cn be removed after 2 weeks and the physiotherapist will check the range of movement.

4 Weeks post op

Your surgeon will asses the range of passive and active range of movement. If there is no progression in the range of motion from the two week assessment then a referral will be made for increased physiotherapy; an MUA may be considered (or a capsular release) at a later stage.
Neurological function will be assessed.

12 Weeks post op

Assess active and passive range of movement
Assess rotator cuff function
Assess scapulothoracic function
Examine for concurrent pathology

6 Months Post op

Assess active and passive range of motion
Discharge with continuation of physiotherapy or review in 3 months