Author: David Limb, John P Sloan / Editor: John P Sloan / Reviewer: David Leverton / Codes: C3AP2b, CAP20, CAP33, HAP19 / Published: 01/11/2017
In UK ED practice a large group of patients present with musculo-skeletal disorders. The limbs are key to human function, and they are subject to significant forces, particularly at the shoulder, and injuries here are common.
There is also a high incidence of spontaneous shoulder pathology in patients over 60 years of age. Many trainees demonstrate a poor understanding of the shoulder joint. Gaining a good understanding of its anatomy and biomechanics is absolutely essential in order to learn how to manage shoulder pathology.
The shoulder girdle consists of a series of four joints. A total of 26 muscles connect the axial skeleton to the humerus.
Neuromuscular control allows these muscles to function in concert to give accurate positioning.
The glenoid fossa of the scapula is pear shaped and encloses about 1/3 of the articular cartilage circumference of the humeral head. It is deepened by the glenoid labrum, a fibrocartilage structure similar to the menisci of the knee but firmly attached to the glenoid margin.
To allow external rotation of the shoulder, the anterior ligaments and capsule are lax in all positions except full external rotation. Similarly the inferior capsule is lax in all positions except overhead abduction and flexion. The volume of the shoulder joint capsule is about three times the volume of the humeral head, and consequently the capsule and ligaments do not contribute to stability except at the extremes of movement.
The rotator cuff
Stability is mostly conferred by robust neuromuscular control of the rotator cuff group of muscles
These arise from the scapula and insert on the tuberosities of the humerus, giving them the mechanical capacity to stabilise the ball in the socket against the pull of the powerful muscles that move the arm.
Subscapularis internal rotation
Infraspinatus and Teres minor external rotation
The clavicle acts as a strut, keeping the upper limb away from the chest. The sternoclavicular joint relies on powerful ligaments to prevent displacement, which is therefore relatively unusual.
The clavicle has a complex relationship with the scapula. This allows scapular rotation in full abduction, while assisting in maintaining the position of the upper limb. It achieves this by the strong conoid and trapezoid ligaments which anchor the clavicle to the coracoid process of the scapula.
The upper limb is effectively suspended from the clavicle
In full abduction the gleno-humeral joint can only achieve around 90 of abduction at which point the scapula rotates on the chest wall to achieve the remainder of the arc.
The articulation of the scapula on the chest wall is the means by which full abduction is achieved.
The upper limb is supplied from the C4 to T1 nerve roots.
Occasionally T2 is also involved. The dermatomes of the upper body are as shown, and each of the roots can readily be assessed.
The myotomes are as follows:
Generally, be reluctant to diagnose a sprain. A minor sprain may be the diagnosis, but often there is something more significant to find. Always examine the rotator cuff. If it is intact and there is no bony tenderness or neurological impairment, most will resolve.
Examination should take the form of the traditional sequence of: look, feel, move and image:
- Look for deformity, swelling, congestion etc.
- Feel for site and nature of tenderness (eg, bony, diffuse, subacromial space etc). Check for sensory loss.
- Move passively, then look for the active range of movement. Bear in mind the myotomes if there appears to be any motor loss. Next assess the rotator cuff. Active resisted movements are tested as follows;
- Supraspinatus abduction 20-40 in extreme internal rotation with palms outwards
- Subscapularis extending hand away from back
- Infraspinatus and Teres minor external rotation
- Image: choose the best form of imaging see later
Many radiological investigations have radiation considerations and therefore by law they have to be justified1.
Most EDs have well developed guidelines for common problems. Where there are no guidelines available in the department then the next step would be to look up the small handbook produced by the Royal College of Radiologists2. This lists all the available radiological investigations, appropriate indications and the level of evidence to support their use.
It is important to focus the examination in upon the correct area. If in doubt ask the radiographers for their opinion. Always ask for 2 views, ie AP, and a modified axial. The modified axial is preferable to the often used Y view as it is less likely to be misinterpreted.
Radiographic findings should always be correlated with the clinical findings, and if there is strong concern that a joint or bone injury exists but the radiographs appear normal, the patient should still be treated on clinical grounds.
Normal tendon appears as a predominantly reflective fibrous structure bordered by a reflective sheath3. Damaged tendon loses this normal reflectivity and appears dark, a phenomenon known as anisotropy.
This makes it an ideal means of imaging in SAI. However, the normal appearance of tendon depends upon the incident ultrasound beam being perpendicular to the tendon and a change of the incident beam angle produces a reduction in tendon echogenicity relative to that of muscle and may mimic tendinitis/tendinosis, hence a certain amount of expertise is required4.
Computed Tomography (CT)
Multislice CT, with multiplanar reconstruction is an effective way to assess fractures. It is also useful in the detection of fine calcification, which is particularly important in the diagnosis of cartilage or bone forming tumours and myositis ossificans.
CT is now the cornerstone of trauma imaging with the scanners being capable of imaging the vertex to the symphysis in one pass, and in seconds. High quality images of the whole torso are possible with reformats providing diagnostic information in a 3 dimensional context.
Bone scintigraphy is a highly sensitive method for demonstrating bone pathology, particularly covert fractures and bone metastases. A gamma camera images the patient a few hours following injection of technetium-99m labelled substituted diphosphonates. Following intravenous injection, over 50% of the injected dose is taken up by the skeleton by three hours. It can be performed as a whole body scan or a limited spot view.
MR has the advantage of high contract resolution5, making it particularly useful for the assessment of soft tissue injuries. It is also sensitive to marrow oedema, aiding the diagnosis of subtle bony injuries, and is superior to scintigraphy in the detection of such injuries6. The image is an MR arthogram which demonstrates a tear of the antero-inferior aspect of the glenoid labrum which is displaced from its normal position (arrow). This is the soft tissue Bankart lesion.
Following plain radiographs, ultrasound is an excellent means of imaging the shoulder
A Traumatic conditions
- Acromio-clavicular joint disruption
- Sterno-clavicular joint disruption
- Anterior/inferior gleno-humeral dislocation
- Posterior gleno-humeral dislocation
- Clavicle fracture
- Scapula fracture
- Humeral fracture
- Biceps rupture
- Brachial plexus injury
- Rotator cuff tear
B Spontaneous conditions
- Rotator cuff degeneration
- Subacromial impingement (painful arc)
- Calcific tendonitis
- Other rotator cuff pathogy
- Adhesive capsulitis (frozen shoulder)
- Pathological fracture
- Degenerative and other arthropathy
1 Acromio-clavicular disruption
Dislocations of the acromioclavicular joint are common, usually being caused by a fall onto the point of the shoulder. There is an apparent upward displacement of the end of the clavicle, though it is the whole of the shoulder girdle on the affected side, which has sagged to leave the clavicle prominent. This is due to rupture of the coracoclavicular ligaments which have a suspensory function for the upper limb. The majority recover to a reasonable degree of function in 3 weeks with a simple sling and analgesia, and only the most severe need surgery. In the ED, do not confuse this injury with a distal clavicular fracture: an xray may be helpful. The literature suggests that the long-term results of operative and nonoperative treatment are balanced1. This first case was managed conservatively, but the second was grossly unstable and required surgery
Stress x-rays are not required in the majority of cases, and may even look normal, due to the upward pull of the trapezius on the scapula.
2 Sterno-clavicular disruption
Direct force to the front of this joint can cause a posterior dislocation, one of the few upper limb injuries that can cause an immediate threat to life. It can give rise to cough, hoarseness and even pneumothorax or tracheal compression. These dislocations are usually associated with severe pain. There may be venous congestion due to compression of the internal jugular vein, along with ipsilateral arm venous congestion. The medial end of the clavicle is usually easily palpated but with a posterior dislocation it has disappeared on the affected side.The sternoclavicular joint is notoriously difficult to interpret on plain X rays and in cases of airway compromise clinical assessment alone may be all that is required before treatment is attempted.
An attempt can be made at closed reduction. Traction is applied to the arm and it is sometimes possible to grasp the clavicle through the skin and pull it forwards, hopefully resulting in a pop as reduction occurs.
In extremis the traditional method of bringing the clavicle away from the trachea is to grasp it with a towel clip through the skin and pull forwards.
3 Anterior/inferior gleno-humeral dislocation
Dislocations of the shoulder joint (ie glenohumeral joint), particularly anterior or anteroinferior dislocations, are common, often resulting from forced external rotation of the upper limb.
From the rear the shoulder assumes a Cows bottom appearance clinically as the acromion becomes the most lateral aspect of the shoulder.
The xray is typical.
In the axial view a lesion is often seen in dislocation, known as a Hill-Sachs deformity. This always occurs in recurrent dislocations, and tells the treating physician that at least one previous dislocation has occurred. Another lesion tends to occur as the shoulder dislocates because it tears the anterior labrum, especially in younger patients. The tear is usually to lower part of the labrum, and this is called a Bankart lesion (Sometimes a tear develops in the upper labrum, often referred to as a superior labral antero-posterior tear (or SLAP lesion), though this is often due to sports injuries and not dislocation). In the image, the progression from the normal anatomy (left) to anterior dislocation (right) results in both these typical lesions.
The sooner these injuries are diagnosed the easier they are to reduce. This can often be achieved under entonox alone. The practice of giving synchronous opiates and benzodiazepines is not regarded as safe practice8. Procedural sedation should be in accordance with a locally determined and approved policy with appropriate monitoring. Intra articular local anaesthetic has been reported to be useful9 though when operating on a patient with an acute dislocation it is clear that the injection is often placed erroneously.There are a variety of reduction methods in popular use, though evidence from clinical trials supporting one method over another is lacking. The Hippocratic method is safe, provided that any counter traction does not apply local force in the axilla. The Spaso manoevre has gained popularity in recent years, and is a safe, easy method10. The upper limb is held externally rotated by the body, in traction, then gradually flexed through, if necessary, 180 degrees. The classic Kochers manoeuvre is successful as a method, but does carry the risk of intra-articular or spiral humeral shaft fracture.
Traditionally the arm is immobilised in a sling for three weeks. Recently MR studies have demonstrated that the glenoid labrum is held in the best theoretical position for healing if the arm is placed in an external rotation splint11. The management of first dislocation may influence the rate of recurrent dislocation12. This is based on the fact that a Bankart lesion will probably be present and if this does not heal recurrent dislocations will be inevitable.
Although figures vary it is generally accepted that below the age of 20 the risk of recurrent dislocation is as high as 90%, and the risk remains as high as 30% in those over 3013. This has prompted many shoulder surgeons to adopt a policy of arthroscopy for all first dislocations, repairing the glenoid labrum in all those found to have a labral tear.
4 Posterior gleno-humeral dislocation
Acute posterior dislocations are relatively rare but are often missed as they can look surprisingly normal.
here is an association with epileptic seizures, and the obtunded state of these patients in the Emergency Department may contribute to the miss. They occur with forced internal rotation and adduction of the shoulder and characteristically the patient loses the ability to externally rotate. The light bulb sign seen on an AP view of the shoulder is characteristic.
These injuries are seen best in the axillary view (or modified axial), and failure to take this view will inevitably result in missed injuries, and consequent litigation.
Occasionally a reverse Hill Sachs deformity, known as the Trough sign, is present
Posterior shoulder dislocations are associated with seizures and electrocution, and the incidence of bilateral posterior dislocations is higher than bilateral anterior dislocations, which are very rare, though they do occur following seizures. For this reason, a low threshold for xray investigation of both shoulders should be maintained in these clinical settings.
5 Clavicle fracture
The clavicle is one of the most common bones to be fractured, most often in the middle third. Children are particularly prone to the fracture, and newborns may present with a clavicle fracture following a difficult delivery. The sterno-mastoid raises the proximal part of the fracture, and the weight of the upper limb causes the shoulder to drop.In this image that clavicle fracture is obvious. However, the associate fractured ribs and pneumothorax were missed, as the eye is readily drawn to one injury, resulting in the assumption that no other injury is present.
Pathological fractures are not uncommon in the clavicle. In this image the moth-eaten nature of the bone is obvious.
Treatment of the uncomplicated # is generally to provide a sling, analgesia, and allow the bone to heal itself, monitoring progress with X-rays every week or few weeks. Surgery is employed in a minority of cases. It is indicated when one or more of the following conditions presents:
- Comminution with separation
- Significant shortening of the clavicle
- Skin penetration
- Associated neurological or vascular injury
- Non Union after 3-6 months
6 Scapular fracture
The scapula is sturdy and located in a protected place, so it rarely breaks. When it does, it is an indication that the individual was subjected to a considerable amount of force and that a chest injury be present14.Direct falls on to the back, especially involving force are the most common cause, such as being thrown from a horse. The injury may not be noticed because it may be accompanied by other, more severe injuries. Diagnosis may require a skyline view
Treatment involves pain control and immobilizing the affected area, and, subsequently physiotherapy.
7 Humeral neck fracture
The surgical neck of the humerus is so called because it is the area of the neck where fractures occur, rather than the anatomical neck. A fracture in this area may cause damage to the axillary nerve. In this image the surgical neck fracture has resulted in complete separation of the fragments, with a greater tuberosity fracture. Not surprisingly the associated axillary nerve injury did not recover despite early surgery.
Pathological fractures are fairly common at this site. Here is a likely giant cell tumour in an 8yr old,
and here is a likely bony metastasis in a 65 yr old who sustained this fracture pulling on his socks.
8 Slipped upper humeral epiphysis
This is a child/adolescent injury, seen most often between ages of 11 and 15 years. The majority are, in fact, Salter I or II fractures. Occasionally an associated brachial plexus injury occurs. They may give the clinical appearance of anterior dislocation,
but have a typical xray appearance.
Treatment in children less than 5 years of age is generally conservative. However in children from 5 to 12 years closed reduction may be required for significantly displaced or angulated fractures in children near the end of growth. Operative treatment is rarely indicated. An injury associated with a neurovascular complication is an indication for surgical treatment.
9 Biceps tendon ruptures
Rupture of the long head of the biceps tendon leads to bunching of the muscle lower in the arm the so-called popeye sign.
It occurs through a degenerate tendon in the upper part of the bicipital groove. In the majority of cases surgical repair is not indicated. Distal biceps ruptures occur in a younger age group and usually have no premonitory symptoms. The rupture typically occurs during a strong contraction and the tendon avulses from its usual point of insertion on the radial tuberosity. The injury is commoner in those who have taken anabolic steroids, with muscle strength developing faster than tendon strength. Repair is important, and is much easier if it is carried out within 2 weeks or so of injury. If repair is not carried out patients tend to notice poor supination, which is perceived as weak.
Do not confuse the management of proximal and distal biceps tendon injury, as the latter usually requires surgery
10 Brachial plexus injuries
The brachial plexus may be injured in severe distracting injuries to the shoulder, particularly when the shoulder is forced caudally.
This is typically seen in rugby injuries, falls from horses and falls from motorcycles. In these cases the upper roots are more vulnerable to injury (ie C4/C5), as shown. Success in the repair of proximal brachial plexus injuries is well documented15. More distal, the axillary nerve is particularly vulnerable as it winds around the neck of the humerus. Injury of axillary nerve is a condition that can be associated with humeral neck fracture. It can also be associated with a dislocated shoulder. It can result in paralysis of the teres minor muscle and deltoid muscle (so that abduction of the shoulder is impaired) and loss of sensation over a small part of the lateral upper arm.
11 Rotator cuff tear
Tendons passing out to the greater tuberosity have, for several centimetres, a synovial cavity both below and above. This leads to a watershed zone in the tendons about 1-2cm from the insertion that has a poor vascular supply and cannot react with a prompt healing response to either local acute injury or chronic wear and tear. The process of degenerative tearing of the supraspinatus tendon in particular begins early, with up to half of the population in their 50s having a partial thickness rotator cuff tear. The population in their 70s have approximately a 1 in 3 incidence of full thickness cuff tears and many are asymptomatic16, 17. This creates problems in the interpretation of acute injury as ultrasound scans performed in patients in their 70s reveal that at least 1 in 3 have cuff tears.
Following a shoulder injury, the finding of a tear may mean that the fall caused an acute strain of the cuff (perhaps already weakened by a degenerative tear), or alternatively that it pre-dated the fall.
12 Rotator cuff degeneration
A Subacromial impingement (SAI)
Supraspinatous pathology accounts for >30% of all shoulder pathology, and 20% of over 60s have features of impingement of the supraspinatous beneath the acromion. Weak or absent Jobes test is the clinical sign. Ultrasound determines if a tear is present.
Perhaps the commonest presentation in shoulder clinics, impingement syndrome describes the clinical picture of pain on elevation of the arm, often with acute pain in mid-range. This is the classic painful arc and is caused by impingement of the supraspinatus,
that has been attributed to entrapment of tissues between the humerus and acromion. Examination will reveal a painful arc in abduction and positive impingement tests.
Arthroscopic surgery makes more space available by acromioplasty and has a dramatic effect.
B Calcific tendonitis
There is a sudden onset of excruciating pain, typically preventing sleep. This is due to leakage of calcium deposits from the supraspinatus tendon into the joint space. In most cases, clinical symptoms will resolve spontaneously in 7-10 days. In some cases the oedema is so severe that downward displacement of the humeral head occurs
C Other Rotator cuff pathology
Tears to subscapularis may be part of a Bankart lesion. Tears to infraspinatus are unusual but a direct fall onto straight arm by the body can produce this.
13 Adhesive capsulitis (frozen shoulder)
This usually results from trauma which in turn leads to capsular contraction. Clinically there is globally reduced ROM, with enhanced scapulo-thoracic movements as the patient can only abduct in this way.
The hands on hip test (Sloans test) is helpful. It should be possible to move the elbows more anterior to the fixed wrists.
The pain gets worse with activity, and night pain is always present. Angiogenesis is the early hallmark, which is clearly seen on arthroscopy. As the condition is not inflammatory, NSAIDs are of limited value, but steroids can limit the angiogenesis. Capsular contraction follows the angiogenesis. Biopsy shows type 3 collagen, similar to Dupuytrens. Judicious physiotherapy can limit capsular tightness, but manipulation under anaesthetic (MUA) produces good results with many patients gaining an almost full ROM in 2-3 months18.
MUA is an effective management of adhesive capsulitis
14 Pathological fracture
The commonest causes are secondary to simple bone cysts, fragility fractures, metastatic lesions,
fibrous dysplasia, giant cell tumor of bone
or multiple myeloma. This pathology has already been referred to,
Bone scintigraphy may reveal other bone lesions which are not evident from radiographs, (but multiple myeloma is not usually hot ).Sometimes it is clear that a fracture is pathological, but the cause is not immediately clear.
Degenerative and other arthropathy
Osteoarthrosis is less usual, and more forgiving in the shoulder as it is not load-bearing. Most problems are the late effects of trauma. Consider aspirating an acute arthropathy to secure the diagnosis. In this case the shoulder effusion, readily seen on ultrasound, was due to poor warfarin/INR control.
Gout may affect the shoulder.
Dont forget pleural, bilary and diaphragmatic causes of shoulder pain. Osteonecrosis of the humeral head is in situ death of bone within the humeral head due to disruption of its blood supply. It is also known as avascular necrosis. The aetiology is secondary to fracture / dislocation, steroid therapy, sickle cell disease, decompression sickness, or sepsis.
Physiotherapy assessment consists of a combination of history and physical testing19. Gentle passive ROM exercises are a useful tool in maintaining shoulder function and alleviating inflammatory pain. The capsule can tighten after many traumatic injuries, especially if there has been a period of immobilisation in a sling, and therapy is designed to overcome this.
Young patients with traumatic dislocations often present relatively pain free after a period of immobilisation. Treatment is usually directed to regaining the range of motion, and particular attention is paid to the subscapularis which helps to control anterior glide of the humeral head.
- Older patients with dislocations have more pain and it is the rotator cuff which is often implicated as a source of the pain. It is also much more common to see stiffness as a secondary complication in the older patient, and post traumatic capsulitis can develop.
- The volume of the shoulder joint capsule is about three times the volume of the humeral head, and consequently the capsule and ligaments do not contribute to stability except at the extremes of movement.The upper limb is effectively suspended from the clavicle
- The articulation of the scapula on the chest wall is the means by which full abduction is achieved
- Following plain radiographs, ultrasound is an excellent means of imaging the shoulder
- In acromio-clavicular disruption, stress x-rays are not required in the majority of cases, and may even look normal, due to the upward pull of the trapezius on the scapula.
- In extremis following posterior sterno-clavicular dislocation, the traditional method of bringing the clavicle away from the trachea is to grasp it with a towel clip through the skin and pull forwards.
- Posterior shoulder dislocations are associated with seizures and electrocution, and the incidence of bilateral posterior dislocations is higher than bilateral anterior dislocations, which are very rare, though they do occur following seizures. For this reason, a low threshold for xray investigation of both shoulders should be maintained in these clinical settings.
- Do not confuse the management of proximal and distal biceps tendon injury, as the latter usually requires surgery.
- Following a shoulder injury, the finding of a rotator cuff tear may mean that the fall caused an acute strain of the cuff (perhaps already weakened by a degenerative tear), or alternatively that it pre-dated the fall.
- MUA is an effective management of adhesive capsulitis.
- Dont forget pleural, bilary and diaphragmatic causes of shoulder pain.
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