Acute Shoulder Pain — Common Causes and their Management

Definition of acute shoulder pain

Shoulder pain is a common symptom that might originate from an intrinsic shoulder problem or an extrinsic problem. The most common causes of extrinsic referred shoulder pain include myocardial ischemia and neck pathology.

Intrinsic shoulder pain originates from the structures that make up the shoulder joint which include: the humerus, glenoid, scapula, acromion clavicle, and surrounding soft tissues. 

Causes of shoulder pain

According to the duration of pain, the causes of shoulder pain can be classified into acute and chronic:

Fracture and dislocation

Clavicle fracture

A fractured clavicle accounts for 5% of all fractures and it also accounts for more than 50% of injuries around the shoulder joint. It is 1 of the most common childhood fractures. Most fractures occur in the middle 3rd of the clavicle. The most common cause of clavicular fractures is trauma.

Examination

Patients with a clavicular fracture present with pain and tenderness over the clavicle. Swelling is another common finding. The patient is unable to abduct his or her shoulder. There is deformity over the shoulder with the unopposed action of pectoralis major muscle; the lateral fragment is displaced downwards and medially while the proximal segment is displaced upwards by the unopposed action of the sternocleidomastoid muscle.

Diagnosis

Diagnosis is simple in most cases and based on:

• A recent history of trauma followed by pain, swelling, deformity, and loss of function at the site of the fracture and involved joint.
• One must look for any evidence of a neurovascular deficit in the distal limb.
• The diagnosis can be confirmed on an X-ray.

Treatment

Clavicular fractures rarely require rigid fixation as the strong muscles surrounding the bone act to reduce and hold the fractured segments together. In adults, immobilization using a triangular sling suffices in cases with minimum displacement. A figure-of-8 bandage may be applied to a young adult with a displaced fracture. Immobilization and reduction serve the purpose of pain relief in the acute setting and later allow for the formation of callus and healing without deformities.

Open reduction and internal fixation with a plate or a nail are indicated in:

• Fractures that are associated with the neurovascular deficit.
• In some severely displaced fractures, where it may be more of a cosmetic concern.

Complications

• Early complications: Injury to the neurovascular bundle more so the subclavian vessels or brachial plexus.
• Late complications: Shoulder stiffness, malunion, and nonunion (the latter being very rare).

Scapular fracture

Fractures of the scapula are less common, and, in most cases, unimportant because patients recover well without much treatment.

The scapula can break at 4 sites:

• Body
• Neck
• Acromion process
• Coracoid process

Most often, the fracture is undisplaced because the fragments are held in position by the surrounding muscles.

Treatment

The mainstay of treatment is to restore shoulder mobility by active exercises as soon as the pain subsides. A triangular sling for the period of pain and swelling (usually 1 week–10 days) is usually sufficient. 

Subluxation or dislocation of the AC joint

This is an uncommon injury, caused by a fall on the outer prominence of the shoulder.

Pathology

The injury may result in a partial or complete rupture of the AC or coracoclavicular ligaments. AC joint injuries are classified according to the 6-grade system described by Rockwood depending upon their severity.

The following table summarizes the most recent classification of AC joint injuries:

Diagnosis

Diagnosis is depicted by pain and swelling localized to the AC joint. In a grade 3 injury, the lateral end of the clavicle may be unusually prominent.

Investigations

Bilateral shoulder X-ray with the AC joints of both sides exposed for comparison. Subluxation or dislocation of the joint may be seen.

Treatment

Grade 1 and 2 injuries are treated by rest in a triangular sling and analgesics. Grade 3 injury in young athletic individuals is treated by surgical repair.

Dislocation of the shoulder

This is the most common joint in the human body to dislocate. It occurs more commonly in adults and is rare in children. Anterior dislocations account for more than 95% of dislocations, with posterior dislocations making up 4% and inferior dislocations (luxatio erecta).

Superior and intrathoracic dislocations are extremely rare.

A smaller number have an atraumatic origin and may be related to congenital, acquired, or degenerative conditions.

Shoulder instability refers to the condition where the head of the humerus is not stable in the glenoid. It has a wide spectrum – from minor instability or a ‘loose shoulder’ to frank dislocation. In the former, the patient may present with just pain in the shoulder, more on using the shoulder. Pain occurs due to stretching of the capsule, as the head ‘moves out’ in some direction without dislocating. A patient with frank instability may present with an ‘abnormal’ movement of the head of the humerus. This could be partial movement (subluxation) which gets spontaneously reduced or a dislocation.

The instability may be in 1 direction (unidirectional) or more (bidirectional). It may be in multiple directions – anterior, inferior, or posterior, where it is called multidirectional instability (MDI).

Classification

Dislocations of the shoulder may be of the following types:

Anterior dislocation: In this injury, while the arm is held in slight abduction and external rotation, the shoulder is ‘squared-off’ (i.e., box-like) with the loss of deltoid contour compared to the contralateral side. The humeral head is palpable anteriorly (in the subcoracoid region, beneath the clavicle). The patient resists abduction and internal rotation and is thus unable to touch the opposite shoulder. It may be further classified into 3 subtypes depending on the position of the dislocated head.

1. Preglenoid: The head lies anterior to the glenoid.
2. Subcoracoid: The head lies inferior to the coracoid process which is the most common type of dislocation.
3. Sub clavicular: The head lies below the clavicle.

Posterior dislocation: In this injury, the arm is held in adduction and internal rotation. The anterior shoulder is ‘squared off’ and flat with the prominent coracoid process. The head of the humerus comes to lie posteriorly behind the glenoid. The posterior shoulder is full of the humeral head, palpable beneath the acromion process. The patient resists external rotation and abduction. Shoulders may look identical in bilateral dislocation, making it a commonly missed injury.

Luxatio erecta (inferior dislocation): This is a rare type, where the head comes to lie in the sub glenoid position.

Clinical feature and diagnosis:

The patient’s shoulder is held in abduction and the elbow supported with the opposite hand. There is a history of a fall on an outstretched hand, followed by pain and loss of function at the shoulder. There may be a history of similar episodes in the past.

On examination:

The patient keeps his arm abducted. There is an obvious deformity with the normal round contour of the shoulder joint being lost.

On careful inspection, one may notice fullness below the clavicle due to the displaced head. This can be felt by rotating the arm. Tests that indicate anterior dislocation include:

• Dugas’ test: The inability to touch the opposite shoulder.
• Hamilton ruler test: Because of the flattening of the shoulder, it is possible to place a ruler on the lateral side of the arm. This touches the acromion and lateral condyle of the humerus simultaneously.

The diagnosis is easily confirmed on an anteroposterior X-ray of the shoulder. An axillary view is sometimes required.

Treatment

Treatment of acute dislocation is reduction under sedation or general anesthesia, followed by immobilization of the shoulder in a chest-arm bandage for 3 weeks. Shoulder reduction is done by:

• Kocher’s maneuver
• Hippocrates maneuver

The surgical methods adopted for treatment are

• Putti-Platt operation
• Bankert’s operation
• Bristow’s operation
• Arthroscopic Bankert repair 

Adhesive Capsulitis (frozen shoulder)

Definition

It is defined as a clinical syndrome characterized by painful restriction of movement of both active and passive shoulder movement due to causes within the shoulder joint or remote causes.

Epidemiology

• Prevalence is 2% of the population.
• In diabetic patients, the prevalence is higher i.e., 20–30%.
• The female gender is more susceptible.
• It mostly occurs in middle-aged people.
• 10% of cases have bilateral distribution.

Causes

• Idiopathic
• Tendinitis of the rotator cuff, bicipital tendinitis
• Fracture and dislocation of shoulder joints
• Other diseases that increase the risk of frozen shoulder are diabetes, cardiovascular disease, reflex sympathetic dystrophy, Colle’s fracture, etc.

Clinical features

• Pain
• Decreased range of movement (external rotation > abduction > internal rotation)
• Accessory joint movement restriction
• Unable to do a routine daily activity

Staging

Adhesive capsulitis has 3 stages:

• Stage 1: stage of pain
• Stage 2: stage of stiffness
• Stage 3: stage of recovery

Investigation

An X-ray usually reveals a normal appearance of the joint, but a few cases show sclerosis around greater tuberosity.

Treatment

• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Intra-articular steroids
• Exercise – both active and passive

Rotator cuff lesions

Painful arc syndrome

Definition

It is also known as shoulder impingement syndrome or subacromial impingement. It arises from the irritation or inflammation of the rotator cuff muscles and tendons as they pass through the subacromial space. This causes pain in the shoulder and upper arm during the mid-range of glenohumeral abduction.

Causes

The subacromial space is a narrow space that is narrowed further during abduction; thus, any lesion that takes up space is likely to cause a painful arc syndrome because, once the space between the upper end of the humerus and the acromion gets compromised, during mid-abduction the tendon of the rotator cuff gets nipped between the greater tuberosity and acromion. Examples of such conditions include:

• Minor tears of the supraspinatus tendon
• Supraspinatus tendinitis
• Calcification of supraspinatus tendon
• Subacromial bursitis
• Fracture of the greater tuberosity

Investigations

An X-ray of the shoulder may show a calcific deposit or a fracture of the greater tuberosity or acromion.

Treatment

• Ultrasonic to the tender point
• Anti-inflammatory drugs
• Injection of hydrocortisone in the subacromial space 

Rotator cuff lesions

Rotator cuff lesions include:

• Rotator cuff impingement syndrome
• Rotator cuff tear

1) Impingement syndrome is commonly associated with supraspinatus tendons. The following are the causes of impingement syndrome:

• Supraspinatus tendonitis
• Calcific deposits
• Subacromial bursitis
• Subdeltoid bursitis
• Periarthritis
• Bicipital tendonitis
• Fracture of a greater trochanter

The most common cause is supraspinatus tendonitis. The most vulnerable structures for impingement between the subacromial space and head of the humerus.

2) Rotator cuff tear

It occurs mostly in people over 40 years old. People who have an occupation demanding repetitive overhead movement are most prone. Athletes like throwers, swimmers, and tennis players are also vulnerable. It is mostly observed in men.

Classification of rotator cuff tear

• Small (< 1 cm)
• Medium (1–3 cm)
• Large (3–5 cm)

Clinical features

• Pain
• Swelling
• Limitation of movement
• Muscle atrophy
• Tenderness of greater tuberosity

Differential diagnosis

• Frozen shoulder
• Cervical spondylosis
• AC and shoulder joint arthritis
• Bursitis
• Snapping scapula
• Suprascapular neuropathy

Investigations

• X-ray changes in rotator cuff lesions are decreased subacromial space, anterior spurring of AC joint, humeral head degeneration, and sclerosis.
• A single contrast arthrogram is considered the gold standard.
• Ultrasonography
• MRI is very accurate but expensive.

Treatment

Conservative treatment: heat massage, NSAIDs, local infiltration of steroids, subacromial steroid injections, exercise, and temporary immobilization.

Surgical treatment

• Arthroscopic repair of small and partial tears
• Open methods in major tears 

Subacromial bursitis

Bursitis commonly occurs in the shoulder of the subacromial area. Inflammatory bursitis usually results from injuries resulting from repetitive injury to the bursa. The subacromial bursa assists the supraspinatus tendon with any overhead movements of the shoulder.

• Subacromial bursitis symptoms include tenderness at the tip of the shoulder, pain with passive abduction, and symptoms of shoulder impingement syndrome.
• Treatment includes rest, nonsteroidal anti-inflammatory medications, and orthopedic referral.