Paraplegia
Image showing a tear of the glenoid labrum

Definition

SLAP is the abbreviated term for Superior Labral Anterior to Posterior tear and refers to a damage to the glenoid labrum occurring from the anterior to the posterior side.

A rupture to the biceps tendon can be located to the proximal (L) or distal (R) side

Pathology

The biceps muscle is the largest muscle of the upper arm, which is used when bending the arm or lifting weights. The biceps tendons connect the biceps muscle to the shoulder and the elbow. The upper biceps tendon has two endings, one that connects to the glenoid (long head, right) and the other to the coracoid process (short head, left). The lower part of the biceps has one tendon inserting to the elbow. 

The rupture of any section of the biceps tendon can be complete or partial. The long head of the biceps tendon is more frequently subjected to rupture than the short head. A complete tear of the is visible through the formation of a bump of the biceps at the elbow. The rupture of the is located near the elbow. In this case the biceps muscle retracts towards the shoulder joint. The patient is unable to flex the elbow and has difficulties to supinate (turn hand upwards). A rupture to the biceps tendon can be determined by other pathologies including chronic biceps tendonitis, shoulder impingement and rotator cuff injury.

Arm abduction is restricted by the inflamed bursa and tendons, reducing the joint space
Cross section of the shoulder depicting the compression of the bursa (red) above the rotator cuff (white) and below the deltoid muscle

Classification

There are various classification systems for a shoulder impingement syndrome.

Stages of subacromial impingement in athletes - Jobe’s Classification
(1989):

Pure impingement with no instability

Primary instability, with capsular and labral injury with secondary impingement, which can be internal or subacromial impingement

Primary instability due to intrinsic ligament laxity with secondary impingement

Pure instability with no impingement.

Grading of impingement changes - Milgrom’s Ultrasound Classification:

Stage 1 Bursal thickness from 1.5 to 2.0 mm

Stage 2 Bursal thickness over 2.0 mm

Stage 3 Partial or full thickness tear of the rotator cuff.

Impingement lesions - Copeland Levy Classification:

This is based on the location of the impingement, either on the acromial or the bursal side.

Acromial side

A0 normal - smooth surface

A1 minor deterioration, haemorrhage or local inflammation

A2 marked scuffing/damage of the undersurface of the acromion and coraco-acromial ligament

A3 exposed bone areas.

Bursal side

B0 normal - smooth surface

B1 minor deterioration, haemorrhage, inflammation

B2 major deterioration of the cuff, partial thickness tear

B3 full thickness tear of the rotator cuff

B4 massive cuff tear.

Two-part proximal humerus fracture

According to the Habermeyer Classification the fractures to the proximal humerus are divided into:

Type 0 one fractured part without dislocation

Type A two-part fracture of the great tuberosity and lesser tuberosity avulsion

Type B involves the humerus “surgical” neck below the femoral head as two-part, three-part and four-part with one or both tuberosities

Type C involves the humerus anatomical neck (between the head and greater tuberosity) as two-part, three-part and four-part with one or both the greater and lesser tuberosities.

These are defined further as:

One-part fractures are non-displaced fractures or fractures with minimal displacement

Two-part fractures only involve a single segment

Three-part fractures involve two segments

Four-part fractures occur when all humeral segments are involved (see image in pathology section)

The injury severity is proportional to the increasing number of fractures.

Three-part proximal humerus fractures

Proximal humerus fracture can also cause an injury to the axillary nerve

Causes

Axillary nerve injury may be caused by:

Shoulder dislocation (anterior and inferior)

Blunt trauma to the shoulder/upper arm

Humerus fracture

Persisting nerve pressure (entrapment) with cast/splint

Wrong positioning of crutches in the arm pit

Ongoing pressure on the axillary nerve from surrounding tissues

Sports such as cricket may lead to shoulder instability due to repetitive overhead movements

Risk factors

Athletes performing repetitive overhead movements in baseball, cricket, volleyball and swimming may easily overstretch or tear the shoulder ligaments eventually causing instability and dislocation. If a patient suffers from a Bankart lesion of the anterior glenoid labrum, there is an increased risk of shoulder instability and anterior dislocations. An additional predisposition to shoulder instability include congenital pathologies such as the Ehler Danlos Syndrome consisting of weakness of the connective tissue that forms ligaments and tendons

Symptoms

Axillary nerve injury may occur after a shoulder dislocation

A patient with an unstable shoulder may feel a sensation of laxity instability when moving the shoulder. However, the main manifestations of shoulder instability present with frequent joint subluxation or complete dislocation. A luxation likely occurs with movements such as lifting the arm over the head and during throwing sport activities triggering a painful sensation. Following a dislocation the contour of the shoulder is visibly altered. If the dislocation involves the stretching of the axillary nerve the patient may feel numbness on the external side of the arm. If the shoulder cannot be immediately reduced, the patient requires treatment at the emergency department with a reduction under anaesthesia. For additional details on this pathology please see Shoulder dislocation.

Clinical examination is required to form the diagnosis of a shoulder impingement syndrome

Diagnosis

The diagnosis of a shoulder impingement syndrome is formed with the initial medical history to evaluate the occurrence of incidents or physical activities that may have caused the disease. Clinical examination is based on a variety of tests to determine changes in the range of movement of the shoulder and special tests such as the provocative Neer’s test, Hawkin’s test and impingement sign.

X-rays are taken to detect associated pathologies like arthritis, formation of bone spurs or abnormal acromion anatomy. Two additional diagnostic tools are used to ascertain the quality of the rotator cuff, tendons and bursa: Ultrasound is taken with abduction of the shoulder between 70º and 120º and MRI to rule out the presence of a rotator cuff tear. The diagnosis of an impingement syndrome is confirmed with the relief of pain upon injection of an anaesthetic into the space under the acromion.

Surgical treatment

Top left: Shoulder arthroscopy for debridement of an acromion spur; Top right: Shoulder hemi-arthroplasty; Low left: Total shoulder replacement; Low right: Reverse total shoulder replacement

If conservative treatment for shoulder osteoarthritis is unsuccessful and the
degeneration of the joint is advanced, surgery is the only option. This can be
achieved via minimally invasive arthroscopic or open access surgery. Different
techniques are available to repair the arthritic shoulder and vary relative to
the disease conditions, use of the shoulder and age.

Arthroscopic resection arthroplasty is used to debride (remove) fragments on the inner joint to create more space and restore mobility. This procedure however will not eliminate arthritis but alleviate the symptoms temporarily. In most cases it is done arthroscopically. When the degenerative process has destroyed either the humeral head or the glenoid a prosthetic shoulder replacement is necessary.

This type of surgery requires open approach and comprises a partial or total shoulder prosthesis whereby:

Humeral head resurfacing is a simplified approach of joint reconstruction. The goal of this surgery is to resect part of the humeral head, which is covered using a metal cap. This treatment is a good compromise prior to proceed with hemi or total shoulder replacement and is specifically advised in younger patients practicing sport.

Hemiarthoplasy consists in the replacement of the entire humeral head with a metal sphere and a stem inserted in the humeral shaft.

Total shoulder arthroplasty involves a complete prosthetic replacement of both the humeral head as described in hemiarthroplasty and the glenoid (socket) of the shoulder, which is substituted with a concave plastic prosthesis.

Reverse total shoulderarthroplast is similar to the replacement of the socket and glenoid but employs a reversed ball-socket prostheses. The bio-mechanical concept is reversed and the glenoid becomes the ‘humerus head’ whereas the previous humerus head becomes the ‘glenoid’.

Resection arthroplasty is a procedure used for the treatment of arthritis of the acromio-clavicular joint. A section of the clavicle adjacent to the humeral head is resected and eventually replaced with scar tissue.

In the surgeries described a number of post-operative complications include: infections, bleeding, blood clot formation, damage of vessels and nerves, ongoing pain issues, reduced mobility and in very severe cases, ankylosis (stiffening) of
the shoulder joint. Loosening and dislocation of the prosthesis may occur especially early after surgery. This may require surgery if recurrent.