Family doctor

What is the most likely cause of shoulder pain?

Pain in the shoulder is a common condition, caused to some extent by the anatomy of this joint. The shoulder is the most mobile joint in the body, but is dependent on surrounding soft tissues for its stability. These soft tissues are known as the 'rotator cuff' and are made up of four muscles and their tendons that interconnect from the upper arm to the collarbone in front and to the shoulder blade behind, passing under a bony arch as they do so. In addition, one of the tendons of the biceps muscle inserts nearby, and there is a bursa (a fluid-filled bag) that acts as a gliding mechanism between the rotator cuff and adjacent bone. Disorders of this rotator cuff and bursa are the cause of most cases of shoulder pain.

 How common are these conditions?

Around 11 patients out every 1000 visit their GPs with shoulder complaints each year.

 What are the common disorders of the rotator cuff and bursa, and what are their symptoms?

Rotator cuff tendinitis is inflammation in the common tendon of the rotator cuff; it is the most common shoulder disorder, accounting for 29% of cases. Subacromial bursitis is inflammation of the bursa. Both conditions occur when there is impingement of these soft tissues by the adjacent bony arch with everyday wear-and-tear, and both produce similar symptoms.

 They are characterised by pain in the shoulder when lifting the arm out from the side of the body (abduction), causing restriction of movement. Thus, there is a 'painful arc of abduction' when lifting the arm between ~60º and 120º; once raised beyond this point, there is little pain in conditions related to the rotator cuff or subacromial bursa. As the condition worsens, the pain becomes more persistent, and particularly severe at night. Eventually, if the tendinitis/bursitis continues without treatment, a rotator cuff tear may occur.

 Rotator cuff tears occur after long-term wear causes degeneration in the soft tissues of the shoulder, and in association with untreated tendinitis. Tears usually occur in the dominant arm, and are more common in men aged over 40 years, especially those who have strenuous jobs with much overhead activity. In ~10% of cases, the rotator cuff ruptures after a specific traumatic event (without a preceding history of shoulder problems) &endash; usually breaking a fall by stretching out the hand, lifting a heavy object, or falling directly onto the shoulder. This is known as an acute tear and causes severe pain in the shoulder, radiating into the arm, and associated with limitation of movement and muscle spasm. Although the patient cannot move the arm out himself, the arm can be lifted passively, although will drop back to the side with the slightest pressure on the wrist.

 Most rotator cuff tears (90%) occur gradually, after a history of shoulder problems including a painful arc of abduction, night pain, and gradual weakness in the arm. These chronic tears can eventually cause limitation of all directions of movement of the shoulder, and may result in wasting of some of its muscles.

 Calcific tendinitis is another condition of the rotator cuff that can cause pain and weakness in the shoulder. Calcium deposits laid down in the tendons of the rotator cuff are seen in up to 20% of x-rays of adults with no symptoms. However, in some people (usually women, aged between 30-60 years, who have sedentary jobs) these deposits cause symptoms that can be severe. Initially there may some pain at rest or with abduction, 'catching' on movement of the shoulder, and pain at night. Severe pain and marked restriction of the shoulder then develops as calcium crystals from the tendon moves into the subacromial bursa. The shoulder is red, warm and tender to touch, and the arm is usually held close to the chest. These severe symptoms generally last about two weeks, and may be associated with generalised illness and fever. Eventually, the calcium is resorbed and the rotator cuff repairs and heals, although during this process there may be some residual pain and restriction of movement.

 What other conditions cause a painful shoulder?

Adhesive capsulitis or 'frozen shoulder' is a disorder in which there is inflammation in the ball-and-socket joint of the upper arm bone and shoulder, resulting in adhesions (i.e. unnatural connections) within the joint and contraction of its 'capsule'. Adhesive capsulitis may occur without any precipitating factors, or occur secondary to any condition that results in prolonged immobilization of the arm, including rotator cuff disorders, calcific tendinitis, mastectomy, or even fractures of the fore-arm.

 Adhesive capsulitis results in limitation of both active and passive movement of the shoulder, causes pain at the extremes of motion, and interferes with normal daily activities. Night pain may be severe. There may be a sense of restriction of the joint when it is passively moved. It typically occurs in women aged between 40-60 years, and often in the non-dominant arm.

 Pain localized to above the shoulder or the shoulder blade usually occurs because of problems in the acromioclavicular joint (i.e. between the shoulder blade and collar bone) or the neck. These do not usually cause a painful arc of abduction. Pain at the tip of the shoulder may be referred from an abdominal problem such gall bladder disease, or from a lung condition such as pulmonary embolism.

 What investigations are performed to diagnose shoulder problems?

Patients with painful shoulders should be asked to give a full history of their pain, and of any possible overuse or trauma that may have occurred. A full examination of the shoulder will be performed, to determine if there is any tenderness, and the extent of any painful arc of abduction. Imaging studies of the arm are often performed, including x-rays, ultrasonography or occasionally, MRI scans. Those with generalised symptoms (e.g. in calcific tendinitis) may have blood tests taken, although these are usually normal.

 How are shoulder problems treated?

The treatment of shoulder problems depends on their cause. Rotator cuff tendinitis and subacromial bursitis are initially treated with rest, non-steroidal anti-inflammatory drugs (e.g. ibuprofen, naproxen, or diclofenac), and modification of activities that cause pain. An injection of a corticosteroid-local anaesthetic mixture into the joint may be beneficial in those in whom the pain persists. Those with night pain may be given physiotherapy to maintain flexibility and a full range of movement. There is still much debate as to which treatment is best, although many trials have compared different non-steroidal anti-inflammatory drugs, physiotherapy, and corticosteroid injections. One recent study noted that patients treated with corticosteroid injections appeared to get faster relief of symptoms than those who received physiotherapy, although other investigators have found no difference between these treatments in their long-term effects.

Acute rotator cuff tears require immobilization in a sling, and early referral to an orthopaedic specialist for surgical repair. Chronic rotator cuff tears are treated conservatively with pain control (with non-steroidal anti-inflammatory drugs) and shoulder rehabilitation. A corticosteroid injection into the joint may help relieve a painful arc of abduction. An orthopaedic specialist should be consulted if pain and weakness persists, because surgical repair may also be necessary in these cases.

 Non-steroidal anti-inflammatory drugs (including aspirin or paracetamol) and restriction of pain-inducing activities are used to treat patients with early symptoms of calcific tendinitis. In those with severe pain, the arm should be put in a sling, and medications prescribed: non-steroidal anti-inflammatory drugs and perhaps an injection of local anaesthetic into the joint. Some doctors do not recommend injection of a corticosteroid, as they believe it may slow down the process calcium resorption and healing. Application of an ice pack may help ease the pain. A recent study found that the frequent use of ultrasound (the use of high-frequency, inaudible sound waves) relieved symptoms and promoted healing in patients with calcific tendinitis. Once pain is controlled, exercises should be performed to maintain the function and mobility of the shoulder, and strengthen the rotator cuff.

 Adhesive capsulitis is treated initially with non-steroidal anti-inflammatory drugs, and a gentle exercise programme of stretching once the pain is controlled. A corticosteroid injection or a short course of oral corticosteroids may be prescribed to control pain, although joint movement will not be restored by these drugs. Occasionally, the affected joint is manipulated with the patient anaesthetised, in order to improve the range of movement. Adhesive capsulitis is a condition that is best prevented: in any shoulder disorder, prolonged immobilization should be avoided and early return to movement should be encouraged.

 What are the side-effects of the drugs used to treat shoulder problems?

Non-steroidal anti-inflammatory drugs such as aspirin, ibuprofen, naproxen and diclofenac may result in irritation or even ulceration of the lining of the stomach. The risk of this is higher in older people with other medical problems and medical advice should be sought prior to taking them .

Paracetamol is not associated with these effects, but exceeding the recommended dosage may cause liver problems.

 Injection of corticosteroids carries a risk of tendon rupture or damage to the joint cartilage, Repeated injection carries a higher risk.

The benefit vs risk needs to be discussed with your doctor.

 Do these shoulder problems recover fully?

In a study of patients with shoulder pain who visited their GPs, almost one-quarter were completely recovered after one month, and almost 60% were completely recovered after one year. Patients whose pain was preceded by overuse or slight trauma were more likely to have a speedy recovery. Conversely, patients who presented with severe pain during the day or associated neck pain were likely to have resistant or recurrent complaints.