In the musculoskeletal system, disorders of the soft tissues (muscles, tendons, ligaments, fascia, capsules, etc.) are often considered separately from those of the hard tissues (bone and cartilage). Indeed ‘soft tissue rheumatism’ is a term frequently applied to miscellaneous disorders causing musculoskeletal pain arising from structures outside the joint, such as bursae, tendons, ligaments and muscles. ‘Fibromyalgia’ is also sometimes included under this heading, but will be considered separately in Chapter 8. Upper limb pain in general, and shoulder pain in particular, is commonly due to disease of these soft tissues. Careful history-taking often provides a provisional diagnosis. Different age groups suffer different pathologies. Physical examination should be both general and directed towards the most likely diagnoses. Specific investigations, some of them expensive, should be used thoughtfully, and not in a shotgun fashion. Multiple modalities of treatment should be considered and may be employed simultaneously. These include rest, physical modalities, such as ice and heat, physiotherapy, specific exercise programmes (including stretching and strengthening), and both non-steroidal anti-inflammatory medication and corticosteroids by injection. Surgery is sometimes the definitive treatment, and in appropriate cases should not be delayed unduly.

This chapter uses rotator cuff pathology (tendonitis, impingement and tear) as a model for discussing soft tissue disorders, and reviews normal shoulder anatomy and function. Common soft tissue conditions of the elbow are also briefly considered.

The human shoulder joint’s virtually global range of motion exceeds that of any other joint in the body. In quadrupedal animals, the shoulder moves almost purely in the sagittal plane. As arboreal and bipedal apes evolved, so too did the ability to place the arm (and with it the hand) overhead and to the side. This extraordinary multiplanar range of movement distinguishes the shoulder from other joints in the body. The only bony connection between the shoulder girdle and the trunk is via the clavicle and the acromioclavicular joint. The relative unimportance of that joint is illustrated by the ability of those with dislocated acromioclavicular joints to function normally. The attachment of the arm to the trunk is almost totally dependent on musculature.

The scapula is held on and moves on the chest wall. This connection is called the ‘scapulothoracic articulation’. The humerus is, in turn, attached to the scapula by the glenohumeral joint, where the head of the humerus sits on the glenoid surface of the scapula (Fig. 2.1A). While this may be seen as a ‘ball and socket’ joint, the socket is very shallow, almost a plate. Shoulder movement occurs simultaneously at both the glenohumeral and the scapulothoracic joints, in a ratio of approximately two to one.

The articular surfaces of the glenoid and the humeral head are lined by articular cartilage. The glenoid socket is deepened by a fibrocartilaginous labrum or rim which surrounds its edge. The joint is lined by synovium and enclosed by a fibrous capsule.

The commonest site of pathology is in the supraspinatus tendon. The supraspinatus runs under an arch formed by the coracoid, the coracoacromial ligament and the anterior acromion (Fig. 2.2). Rubbing of the tendon on the undersurface of this arch produces the ‘subacromial impingement syndrome’, which is common in patients over the age of 40. Typically, impingement is related to repetitive overhead activity causing repeated pinching of the cuff beneath the arch. This may be exacerbated by an associated bone spur on the undersurface of the anterior acromion. The repetitive activity may be sports-related (golf swing, tennis serve or throwing) or work-related, but many impingement cases appear entirely idiopathic. It is not clear whether acromial spurs are the primary cause of impingement or whether they form in response to impingement.

In considering a patient’s history, the patient’s age, the mechanism of pain onset, the progression of the symptoms, the site of pain and the nature of any resultant disability all provide an insight into the responsible pathology. Different conditions occur at different ages. Musculoskeletal shoulder problems before the age of 30 often relate to shoulder instability, with associated secondary impingement and inflammation of the rotator cuff tendons (discussed below). Over the age of 40, chronic tendonitis of the rotator cuff, especially the supraspinatus tendon, is common. This too is often associated with subacromial impingement (discussed below), and may progress to tearing of the rotator cuff. Over the age of 60, partial and full thickness tears of the supraspinatus tendon are common. Osteoarthritis of the glenohumeral joint is also more common in this age group.

The mechanism of onset provides some clues. Sudden onset, associated with a single traumatic event (such as trying to catch a falling cupboard), suggests a mechanical event, such as a tendon tearing. A more insidious onset suggests degenerative disease, or possibly repeated micro-trauma.

In cases of sudden onset, the position of the arm and the nature of the initial injury may provide some clue. If the arm was forced into abduction and external rotation, anterior subluxation is a real possibility. If the arm was at or near the side at the time of onset, or if the mechanism involved contraction of the shoulder muscles against resistance, an injury to the rotator cuff mechanism is more likely.

The progression of symptoms helps diagnosis. Increasing pain implies progressive pathology. Increasing weakness may be due to painful inhibition of shoulder activity. If the loss of strength is profound, this suggests progressive disruption of a muscle–tendon unit, possibly the rotator cuff. Increasing stiffness (loss of range) suggests an inflammatory process, possibly adhesive capsulitis (frozen shoulder).

The site of pain is important. Subacromial pain is usually felt at the front of the shoulder. Radiation of pain to the deltoid insertion is common but non-specific, as it also occurs with glenohumeral pathology and cervical pathology, especially a C5 radiculopathy (nerve root lesion). Involvement of the trapezius, the parascapular muscles and the side of the neck are also common but relatively non-specific. Pain over the posterior joint line is frequently glenohumeral in origin. Involvement of the hand may suggest neurological or neurovascular pathology, including neck pathology, thoracic outlet syndrome or even carpal tunnel syndrome (see Ch. 3). Regional pain syndromes may also involve both shoulder and hand.

It is important to assess the patient’s degree of disability. An inability to attend to activities of daily living, and particularly an inability to sleep at night, warrants serious attention, as does any condition which affects the patient’s occupation. For a keen sportsperson, an inability to throw or to serve at tennis may be equally distressing. The use of patient questionnaires and visual analogue scales aids assessment. A typical patient-questionnaire directed at the assessment of shoulder pain is shown below (Fig. 2.3). Questionnaires do not replace history taking. They can be repeated at later dates to help assess progress.

Inspection and palpation are best carried out with the examiner standing behind the seated patient. When present, significant wasting of the spinati muscles will be obvious in all but the most obese patients. The best-known tests for subacromial impingement are the Neer and Hawkins tests (Fig. 2.4). In both, the greater tuberosity, the attached supraspinatus tendon, the overlying bursa and the adjacent biceps tendon are compressed beneath the coracoacromial arch. If either manoeuvre recreates typical symptoms, this suggests cuff impingement, but may also reflect biceps pathology. Yergason’s test for biceps tendinitis is less sensitive but moderately specific (Fig. 2.5).