Mr Roger Hackney FRCS(Orth) FFSEM (UK) Dip Sports Med (Dist) Consultant Orthopaedic Surgeon
Mr Roger Hackney FRCS(Orth) FFSEM (UK) Dip Sports Med (Dist)Consultant Orthopaedic Surgeon

 

IIMPINGEMENT

 

 

The rotator cuff is a group of 4 muscles which arise from the shoulder blade whose function is to wrap around the ball part of the shoulder joint and hold it into the socket. In addition it helps in movement of the shoulder, but the prime, or stronger movers of the shoulder are muscles such as deltoid, pectoralis major and latissimus dorsi.

 

The rotator cuff muscles form a sheet of tendon that passes under the roof of the shoulder. The roof is formed by a part of the shoulder blade called the acromion process and a ligament that runs between the acromion and another projection of the shoulder blade called the coracoid process.

 

There is a piece of tissue called a bursa which lies under the acromion (sub acromial bursa) and over the top of the rotator cuff. The bursa is a thin walled sac with some lubricating fluid inside which allows smooth movement between the undersurface of the roof of the shoulder and the rotator cuff.

 

Sub-acromial impingement/Bursitis

 

When the function of the rotator cuff is compromised, the deltoid muscle pulls the ball part of the joint upwards, reducing the space occupied by the rotator cuff tendon and sub-acromial bursa. This squeezing of the bursa causes thickening of the wall of the bursa, hence occupying more of the reduced space and more fluid within the bursa, this is called a bursitis. This is sore, which in turn switches off the rotator cuff muscles still further leading to more upriding of the ball part of the joint and leads to a vicious cycle producing more pain and loss of function. This is termed sub-acromial impingement.

 

History

 

Impingement typically leads to pain at rest, particularly at night. Pain is felt down the upper arm. It may cause waking is when that side is laid upon at night. Overhead activity is compromised, with pain on reaching out to the side. It may cause difficulty dressing and undressing (especially the bra and T-shirts) and managing hair. Driving, in particular gear changes and applying a handbrake can be sore.

 

Examination

 

You will be asked to remove any clothing covering the shoulder and shoulder blades.

Examination will include looking at shoulder posture and then observing active range of motion, for the presence of any abnormal rhythm or trick movements and pain. Patients with impingement typically complain of pain when moving the arm sideways at 90 degrees of elevation. The power of the various muscles which comprise the rotator cuff will be assessed, and the presence of positive tests for impingement.

 

The joint between the collar bone and shoulder blade (acromioclavicular or AC joint) is frequently symptomatic in patients with impingement, and this will also be assessed.

 

Investigation

Ultrasound scan (USS) is a dynamic investigation which allows the radiologist to visualise the state of the rotoator cuff and assess the quality of the tendon, the presence of any tearing of the tendon and any muscle wasting. It allows the radiologist to see the tendon as it moves and observe directly the effect of impingement and swelling of the bursa, bursitis.

 

Ultrasound is much cheaper and quicker than MRI scanning for assessment of impingement, and in some cases can be used to guide the needle for an injection directly into the bursa

Tearing of the rotator cuff can be diagnosed by USS.

 

Treatment.

 

There are a number of options for treating impingement.

 

 

Self help

 

The first is to avoid aggravating activity. This may be difficult if, for example, your occupation involves using the shoulder in an elevated position. At risk are hairdresser’s, painter and decorators, mechanics and engineers. Slouching over a desk with the shoulder forwards is another occupational cause of impingement.

 

Try sitting with your shoulder slumped forwards and lifting you arm about 30 degrees forwards from the side. Try again whilst pulling your shoulder blades together at the back. You will see that with the shoulder blades pulled together the range of motion is much greater, and the risk of developing impingement dramatically reduced. Your mother was correct in telling you not to slouch!

 

Physiotherapy

 

Physiotherapy aims to regain control of the rotator cuff and reduce the upriding causing the impingement process. The physiotherapist will assess range of motion and rotator cuff function. Exercises designed to start the rotator cuff working effectively will be taught. This will involve ensuring the shoulder blade is moving correctly and is held steadily during the exercise. One the correct pattern of movement is established then you may be given some elasticated bandage and some exercises to strengthen the muscles of the rotator cuff.

 

You should do all exercises to the point of discomfort only. ‘Pushing on through the pain’ will lead to failure of physiotherapy, more pain and nothing else.

 

Remember the exercises are for you to work on at home. It is no good expecting a session a week of physiotherapy to cure you if you do nothing between appointments.

 

You should gain significant benefit within 6 weeks of starting treatment. If no improvement has been made by then, it is time to more to another treatment option.

 

Injection

 

Injection of local anaesthetic and steroid is a well researched treatment for subacromial impingement. There is mixed evidence as to whether the steroid actually adds much to the benefit of injection, but the majority of upper limb surgeons continue to use steroid and local anaesthetic.

 

There are two purposes for injection. The first is to confirm the diagnosis. If local anaesthetic in the subacromial bursa relieves pain during the period of effectiveness of the local anaesthetic then you can be pretty sure you have impingement as the cause of your pain. Depending upon which local anaesthetic is used, it may last from 2 – 6 hours.

 

If examination has demonstrated that the acromioclaviular (AC) joint is a source of pain then this can also be injected. 

 

My common practice is to have the first injection given by ultrasound scan guidance. This is because the needle can be observed entering the bursa, so I can be certain that the local anaesthetic is in the correct position. If pain is lost on moving the arm into a position where it would normally be present after an hour or so, then the diagnosis is confirmed. Ultrasound scan  will also exclude a rotator cuff tear. The radiologists have been requested not to administer steroid in the presence of a tear.

 

The steroid is there as a powerful anti-inflammatory agent. It should start to work during the week after the injection. Steroid has an effect on the whole body, not just the area of injection, and for that reason is not specific in identifying the source of pain. Indeed, one study from Finland showed the general effectiveness of steroid by comparing injection of steroid into the shoulder or buttock and found no difference between the two!

 

The duration of effectiveness of the injection is highly variable. I frequently use injections with physiotherapy as it is difficult for physiotherapy to be effective when the shoulder is very sore. Injections can be repeated if effective for several months at a time. The general rule is no more than 3 steroid injections into an area. The reason for this is that steroid is a very powerful agent and can cause tissue damage.

 

Surgery

 

If non surgical treatments fail and symptoms remain sufficiently severe to justify surgery, then a simple operation can be curative. Occasionally patients with severe pain will be offered surgery early as conservative treatments may be prolonged and ineffective. When the AC joint is sore then physiotherapy tends not to work as well. Surgery is the quickest way to recovery for some patients.

 

Surgery for subacromial impingement is a very successful procedure with success rates of 90-95% in the academic literature.

 

The surgery is performed during a day case admission, under general anaesthetic. Whilst asleep the anaesthetist will inject some local anaesthetic around the nerves in the neck. This gives excellent post-operative pain relief and may last 12 -24 hours.

 

Arthroscopy

 

The surgery is keyhole surgery preformed with you sitting up. A small incision at the back of the shoulder allows the arthroscope to be inserted into the shoulder. A full inspection of the inside of the joint is performed, and a minor tidying up of any frayed or torn tissue undertaken. The rotator cuff is inspected for any tearing or damage.

 

Long head of biceps

One of the tendons of the bicep muscle runs through the shoulder joint, inserting at the top of the shoulder socket. This is frequently involved in shoulder pain with impingement and becomes degenerate, swollen and begins to tear. If this is the case then the tendon will be divided inside the shoulder. In about 25% of patients this results in a bunching of the biceps muscle in the upper arm, the so-called pop-eye sign. The older you get the more likely this is to occur spontaneously, and most patients are blissfully unaware that this has happened. Some patients experience aching or cramping for up to 3 months.

 

Subacromial decompression

The arthroscope is then inserted into the subacromial bursa. I will be looking for any swelling and inflammation of the bursa and wearing of the tendon. Using another stab incision at the side of the shoulder an instrument is introduced which will be used to remove the bursa. Older patients may have some overgrowth of the bone of the roof of the shoulder, and this would be smoothed down to the level at which the deltoid muscle attaches using an arthroscopic burr.

 

Excision of the lateral end of the clavicle.

If the AC joint is tender and a source of pain then this will require treating at the same time. Another stab incision is made at the front of the shoulder and the soft tissue around the AC joitn removed. The burr is then used to smooth away about 5mm from the end of the collar bone or clavicle.

 

2 stitches will be used to close the incisions at the front and side of the shoulder only.

 

All of the above will take 10-20 minutes only, so the anaesthetic is very light and short. Generally patients do not suffer from nausea hang over or other ill effects from the  anaesthetic. Your arm will be rested in a sling, one of the effects of the nerve block is to paralyse the arm, temporarily only.

 

After the operation

You will be returned to the ward. Usually by the time I have finished my operating list patients are sat up in bed eating lunch and raring to go home. The physiotherapist will come and advise you what to do in terms of exercises and removing the sling when you have regained control of the arm. You will be supplied with some painkilling tablets to take home.

 

Recovery

I generally advise patients to take 2 weeks off work. You should not try to drive until you have proper control of the arm, generally about 2 weeks. I will review you around that time. Youwill receive physiotherapy to guide your rehabilitation.

 

Recovery time is very variable between patients. Some patients make a very early recovery and are moving fully, pain free by 2 weeks. Most will take 6-8 weeks to achieve that. Some suffer discomfort for longer. If pain persists beyond 3 months then an injection into the painful area will usually settle things down.

 

The commonest reason for persisting pain is patients ignoring advice and doing too much too soon. Your rehabilitation should be to the point of discomfort and no further. If anything you do hurts, then stop. If the physiotherapist gives you the next set of exercises and they hurt, then stop.

 

Risks and complications

The surgical risks are of bleeding into the dressings. The surgery is performed with fluid under pressure which can leak into the shoulder and leak out afterwards.

Infection. The infection risk is 1 in 10,000 arthroscopies.

Recurrence, see above, DON’T DO TOO MUCH TOO SOON

Frozen or stiff shoulder. Some patients are susceptible to developing a frozen shoulder after any trauma to the shoulder, including surgery.  The risk is quoted as 1-2%, although a degree of stiffness after surgery is ore common than this. If the shoulder becomes stiff and painful, particularly at rest then a post-operative frozen shoulder may be the cause. Treatment of this is to wait for it to settle on it’s own and stop any stretching exercises. If severe then the options under treatment of frozen shoulder can be started.