The shoulder joint (gleno-humeral joint)
The articulation of the head of the humerus with the glenoid cavity of the scapula forms the shoulder joint. This is a ball and socket joint and movements in any direction are easily obtained. Attached to the edge of the glenoid cavity and serving to deepen it is a rim of fibrocartilage known as the glenoid labrum. Stability of the joint depends on the muscles which surround it; the ligaments contribute little to the joint’s stability .
MUSCLES AROUND THE SHOULDER JOINT (a) The subscapulars muscle covers the front of the shoulder joint and is attached to the lesser tuberosity of the humerus and to the bone about half an inch below it. It is a medial rotator of the shoulder. (b) The supraspinatus tendon lies above the shoulder, and the muscle initiates the action of ab duction. (c) The infraspinatus muscle lies above and behind the shoulder joint. It is a lateral rotator of the shoulder. (d) The teres minor lies behind the shoulder joint. It is a lateral rotator of the shoulder.
The tendons of the supraspinatus, infraspinatus and teres minor muscles are inserted into the greater tuberosity of the humerus from above downwards. The four muscles (a, b, c, d) give stability to movements of the shoulder by syncrgistically steadying the head of the humerus in the glenoid cavity thus preventing it from slipping and skidding. These muscles are frequently referred to as the ‘rotator cuff. There is no support by muscle below the joint and the capsule is lax to allow abduction of the arm. It is through this weak part that the head of the humerus escapes when a dislocation occurs.
The latissimus dorsi, teres major and pectoralis major give some support to the front and inferior part of the shoulder joint as they converge on the bicipital groove and its ridges. If there is a fracture in the upper humeral shaft, the tendency, therefore, will be to pull the humerus towards the trunk with displacements of the lower fragments inwards at right angles to the axis of the humerus. These muscles are powerful adductors of the shoulder.
The deltoid muscle, as it runs from the clavicle and acromion to the deltoid tuberosity of the humerus, surrounds the lateral aspect of the joint, and contributes to the natural shape of the shoulder. It is a powerful abductor of the shoulder.
LIGAMENTS (FIG. 26/2) (a) Capsule ligament: this is thickened anteriorly to form the gleno-humeral ligaments. These consist of three bands of longitudinal fibres on the internal sur face of the front of the capsule. (b) Glenoid ligament: this deepens the glenoid cavity. (c) Coraco-humeral ligament: this lies anteriorly, and on the upper aspect of the joint. It fuses with the supraspinatus tendon as it blends with the capsule.
There is a large bursa beneath the acromion process and deltoid, the floor being formed by the supra- and infraspinatus tendons.
The sterno-clavicular joint
This is a synovial joint of the plane type with the medial end of the clavicle articulating with the manubrium of the sternum and the first rib.
Movements occur only in association with movements of the shoulder and the arm; the sternal end of the clavicle always moving in the opposite direction to the acromial end. The stability of the joint depends almost entirely on the ligaments which surround it; the shape of the joint contributing little in the way of stability.
LIGAMENTS (a) The superior ligament or the inter-clavicular ligament, runs from one clavicle to the other and is attached to the top of the sternum between the two joints. (b) The posterior ligament is only a weak ligament running from the clavicle to the sternum. (c) The anterior ligament is a comparatively weak ligament running between the sternum and the clavicle. (d) The inferior ligament or the strong rhomboid or costoclavicular ligament attaches the clavicle to the sternal end of the first rib.
There is a complete meniscus dividing the joint into two cavities.
The acromio-clavicular joint
This is a small synovial joint between the lateral end of the clavicle and the acromion. The plane lies antero-posteriorly, but the joint slopes downwards and medially so that the clavicle tends to override the acromion laterally. The front and back of the joint are covered by the attachments of the deltoid and trapezius muscles respectively. Together with the sternoclavicular joint these two joints form the shoulder girdle.
Movement of this joint only occurs with movement of the arm or shoulder. Stability depends on the ligaments which support this joint, the articular surface providing no stability.
LIGAMENTS (a) The superior ligament is fairly strong and lies superiorly. (b) The inferior ligament is a strong ligament lying inferiorly. (c) The coraco-clavicular ligaments, I.e. the trapezoid and conoid ligaments, bind the lateral end of the clavicle to the coracoid process. Through this liga ment the weight of the arm is transmitted to the cla vicle, and thence to the axial skeleton. The tone of the trapezius, levator scapulae and the rhomboids support the weight of the upper limb.
INJURIES OF THE SHOULDER JOINT Supraspinatus injuries SUPRASPINATUS TENDINITIS The patient may or may not have a history of injury to the shoulder for the mechanism is an abduction strain. The patient complains of pain near the insertion of the deltoid muscle in to the humerus when abducting the arm between 70° and 120°. Above and below that arc the movements are pain free.
On examination a painful arc of movement is found. There is no pain on movement in other directions as would occur in an arthritis of the joint. There is no loss of movement as would occur following a periarthritis, when adhesions had formed in the joint and capsule. There is no loss of power such as would follow a rupture of the supraspinatus tendon. X-rays of the shoulder show no abnormality.
In the immediate painful phase the shoulder should be rested in a collar and cuff sling. Physiotherapy with short wave diathermy or ultrasound may help relieve the pain; movements are encouraged as the pain becomes less. An injection of 2% Xylocaine and Depo-Medrone (60mg) and analgesics plus antirheumatic drugs such as phenylbutazone (Butazolidin) and indomethacin (Indocid) are helpful.
SUPRASPINATUS CALCIFICATION The patient presents with a painful shoulder. The pain is referred to the deltoid insertion and often beyond that point. The pain can be very severe and limit all movements of the shoulder joint.
On examination the shoulder is stiff and painful; abduction is to about 60° only. X-rays show deposits of calcium salts of carbonate and phosphate in the supraspinatus tendon.
Treatment is as for tendinitis. An injection of Xylocaine and Depo-Medrone will help to relieve the pain. Physiotherapy in the form of short wave diathermy or ice packs is helpful. Sometimes operative treatment to remove the calcium, either by needling the mass or opening the mass with a scalpel, may be required to relieve the pain.
RUPTURE OF THE SUPRASPINATUS TENDON This often occurs in the older patient and can follow an abductiCn strain which is often trivial.
On examination the patient cannot abduct the shoulder – all he can do is to raise it. If he lies on his back he can lift the arm forwards because the biceps tendon is still intact. X-rays usually show degenerative changes in the joint.
In mild cases which are seen early, the arm is immobilised in an abduction frame for 8 to 12 weeks. In the more severe cases which are seen early, repair of the ruptured tendon and capsule, perhaps with excision of the acromion, is required. In the later cases operative treatment is of little value and conservative management is all that can be offered.
The biceps tendon
The patient presents with painful stiffness of the shoulder. The pain is felt more to the front of this joint, and the tendon of the biceps muscle is painful.
On examination there is tenderness over the biceps tendon in its groove and pain when the muscle is stressed. The pain is felt at the front of the joint and into the biceps muscle.
Short wave diathermy and ultrasound help the painful tendon and an injection of Xylocaine and Depo-Medrone into the bicipital groove near the biceps tendon relieves the pain. Graduated exercises are begun as the pain becomes easier.
RUPTURE OF THE BICEPS TENDON The tendon of the long head of the biceps muscle may rupture suddenly on lifting a weight or it may occur spontaneously. The patient often has had pain at the site of rupture for some time before the actual rupture occurs. The rupture occurs either in the bicipital groove (extracapsular) or at the upper margin of the glenoid (intracapsular). At the time of the rupture the patient feels a sharp pain at the top of the shoulder spreading down to the upper arm. The arm feels weak and the biceps muscle will bulge in the lower half of the upper arm. Rarely, the rupture occurs spontaneously and unknown to the patient.
Treatment is usually by conservative measures. If there is marked weakness of the arm, an operation to suture the stump of the distal end of the tendon to the periosteum of the humerus will help to give the biceps muscle some stability.
Periarthritis of the shoulder
The symptoms of pain and stiffness may occur after a trivial injury or strain. At other times they may arise spontaneously. The condition tends to affect the older person. The pain is diffuse and not localised to the deltoid insertion.
On examination, shoulder movements are limited by muscle spasm unlike the stiffness of a true arthritis. Abduction and external rotation are affected principally; tenderness is not confined to the tuberosity of the humerus. In the later development of the condition, movements are limited by the formation of adhesions between the gliding surfaces of the ligaments and muscles of the joint finally producing a frozen shoulder.
In the early stages, physiotherapy in the form of heat and short wave diathermy is helpful. Active movements are encouraged but not passive movements which will only irritate the joint. Anti-rheumatic and pain relieving tablets will help the pain and a hydrocortisone injection will also be of value. When the pain has gone, a manipulation of the shoulder under a general anaesthetic will relieve the stiffness due to adhesions, but this would only be carried out when the pain has gone and the adhesions are avascular.
Dislocation of the shoulder
This type of dislocation is caused by a fall which forces the arm into abduction leaving the head of the humerus out of the glenoid cavity anteriorly through the inferior part of the capsule. In this way the head of the humerus lies anteriorly below the coracoid process of the scapula. It is the most common form of dislocation and can occur in a wide variety of sports.
On examination the normal rounded contour of the shoulder is absent and the head of the humerus can be felt just below the coracoid process. An x-ray examination confirms the position and excludes a fracture. Physical examination must exclude any danger to the brachial plexus or to the circumflex nerve.
The Hippocratic method of reduction is the safest way to reduce the dislocation under a general anaesthetic. Kocher’s method can be used but great care is needed to avoid stretching the nerves around the shoulder joint. The arm is held by the side with a collar and cuff sling for three weeks.
The Hippocratic method of dislocation reduction was first described in about 600 BC. The technique consists of putting a pad in the axilla and pushing on this pad with the unbooted foot, at the same time pulling in a longitudinal direction the arm of the affected side. The final stage of reduction is obtained by lifting the humeral head into the glenoid by pressure from the foot. This manipulation is carried out under a general anaesthetic. This method is probably the safest way to reduce a dislocated shoulder and is less likely to damage any nerves or blood vessels surrounding the shoulder joint.
Kocher’s method was first described over a century ago and was designed for reduction without a general anaesthetic. It requires great care as stretching the nerves around the shoulder joint, especially when reduction is carried out under a general anaesthetic, is a real hazard. The method consists of first externally rotating the humerus using the flexed elbow as a lever; this brings the head of the humerus under the glenoid and near the tear in the capsule and rotator cuff. The elbow is now adducted towards the mid-line, further lifting the head of the humerus nearer the glenoid. The final stage of reduction is obtained by internally rotating the humerus using the flexed elbow as a lever.
This dislocation is caused by a fall or blow over the front of the shoulder as might occur in a heavy frontal shoulder charge in field games or a fall in motorcycling. It may be caused by a fall causing internal rotation of the humerus as well as forcing the head of the humerus backwards. It is rarer than the anterior dislocation.
Examination can be difficult, as the shape of the shoulder may appear normal, but if examined carefully the head of the humerus can be seen and felt more posteriorly than the normal, with the coracoid process being more prominent. X-rays in two planes will give confirmation. It is important to note that the x-ray may appear to be normal on first inspection.
Reduction is obtained by traction with external rotation of the arm. To avoid re-dislocation the shoulder is not fixed in internal rotation but in a light plaster spica with the shoulder in some 40° of abduction and external rotation. The elbow is placed at a right angle. The plaster is removed after about three weeks and gentle exercises begun.
FRACTURE DISLOCATION OF THE SHOULDER Dislocation with fracture of the greater tuberosity of the humerus is treated as for an anterior dislocation of the shoulder joint. The fracture of the greater tuberosity usually reduces itself at will at the time of reduction of the shoulder by the Hippocratic method. The treatment is the same as for an anterior dislocation with immobilisation in a collar and cuff sling under the clothes for three weeks.
Dislocation with a displaced fracture of the humeral neck is more difficult to treat. Traction of the limb in the Hippocratic manner with the arm in 50° of abduction is carried out using an image-intensifying screen. The head of the humerus is palpated in the axilla and reduced into the glenoid cavity if possible. Care must be taken of the axillary vessels and nerves. Failure may need an open operation, but this is difficult and may be dangerous in the hands of the inexperienced surgeon.
RECURRENT DISLOCATION OF THE SHOULDER This may occur after a severe type of anterior dislocation with a lot of soft tissue damage. The anterior pan of the capsule is torn from the glenoid cavity and the labrum is detached anteriorly.
The condition can be limited by adequate immobilisation for three weeks in the early stages with the arm in full internal rotation. There may also be a small crush fracture in the posterior lateral aspect of the humeral head which can be seen in special x-rays. This condition allows the shoulder to dislocate easily in abduction with external rotation.
Treatment is by surgical repair either by the Putti-Platt type which tightens the anterior capsule and muscles of the shoulder, or Bankart’s operation which attaches the capsule to the bare anterior wall of the glenoid (Bankart, 1938).
INJURIES OF THE SHOULDER GIRDLE
The acromio-clavicular joint
This joint is injured by a fall on the point of the shoulder, a common occurrence in rugby football.
On examination there may be a mild sprain of the joint with tenderness over the joint line. If the coracoid ligaments have been torn then the lateral end of the clavicle will be elevated. This is more marked if the patient stands up and the joint is palpated while the patient holds a weight in the hand. X-ray examination confirms the displacement, the films being taken in the erect position and the joint stressed by holding a weight in the hand on the injured side.
The easiest way to manage the injury is to hold the joint in the reduced position using a pad over the lateral end of the clavicle and under the point of the elbow with strapping to compress the two points. The arm is put in a full sling with a pad in the axilla. Pain may later be treated with ultrasound and hydrocortisone injections if it persists. Rarely operative treatment with fixation of the joint with Kirschner wires is required. (Kirschner or ‘K’ wires are used in orthopaedic surgery to apply skeletal traction to a fractured bone or to hold fragments together.) The mild cases with only a strain of the joint require a sling for a week or so when the joint has not been subluxated.
Most injuries of this joint settle with no pain. There may be some displacement but this does not seem to matter with regard to function. Persistent pain may require an excision of the outer end of the clavicle.
Fracture of the clavicle
This injury is caused by a fall on the point of the shoulder as might occur in rugby football or a horse-riding accident. It may also result from falling on the outstretched hand.
On examination the fracture site can be felt easily under the skin. The inner fragment is pulled up by the sternocleidomastoid muscle and the outer fragment is depressed by the weight of the arm. There is overlap of the fragments. The fracture occurs usually in the middle third of the bone. X-rays confirm the fracture.
The injury is best treated by a figure-of-eight bandage re-applied every^second day. The arm is supported in a full arm’ sling and the fracture is united in three to four weeks.
In rare cases involving the outer third of the clavicle, the coraco-clavicular ligaments are torn. This allows the medial end of the fractured clavicle to be elevated and a pad and strapping over the medial end of the fracture and under the elbow is required to correct the displacement.
The sterno-clavicular joint
This joint may also be injured in falling on the point of the shoulder and the inner end of the clavicle is usually displaced anteriorly. In the few cases when the displacement is posterior, the clavicle may press under the trachea. This requires urgent reduction because of respiratory embarrassment.
On examination this dislocation is easily seen and palpated. The dislocation is confirmed by x-rays.
The dislocation is easily reduced but it is difficult to maintain the reduction. It is best treated with a figure-of-eight bandage and a collar and cuff sling for about three to four weeks. In the anterior type injury operative repair is not indicated. The rare form of posterior dislocation with pressure on the trachea or the great vessels calls for urgent reduction, and in this type of case a repair of the anterior capsule is required.
Fractures of the scapula
This type of injury usually occurs after a direct injury to the scapula. The displacement is slight due to the muscles which surround the bone, but fractures of the underlying ribs may occur. An avulsion fracture of the coracoid process may occur in throwing injuries; a fall on the point of the shoulder may fracture the acromion or glenoid neck.
On examination there is pain and tenderness at the site of the fracture and this is confirmed by x-rays. If the neck of the scapula is fractured, pain, but no tenderness, may be found due to the overlying thick band of muscle.
Muscles prevent much displacement of the fracture and treatment is to immobilise the shoulder in a full arm sling for a few days after which exercises should be begun as soon as possible to prevent stiffening of the shoulder joint.
In sport, injuries to the shoulder are common. They may be major with a dislocation or a fracture of the bones about the joint or they may be minor when only soft tissue is damaged. The minor injuries often pro- duce persistent pain and stiffness due to damage to the rotator cuff, or a painful arc syndrome. These are the muscles which produce the stability of the shoulder joint which, without their help, is unstable. External rotation is an essential component of abduction and this movement of external rotation must be encouraged by active movement and not by passive movement. As the pain in the shoulder decreases, so the amount of active movements can be increased. If the shoulder is persistently stiff and painful, exercise has probably been too vigorous and should be decreased. The shoulder should never be manipulated to relieve stiffness of the joint in the presence of pain.
Bankart, A. S. B. (1938). The pathology and treatment of recurrent dislocation of the shoulder joint. British Journal of Surgery, 26, 23-29.