Home / Conditions Treated / Shoulder Anatomy / Shoulder Dislocation

Anatomy

The shoulder joint is the second largest and most mobile joint in the human body and can be easily understood if divided into three layers. view 

Shoulder Contusion

Trauma is the term used to describe injury. Trauma is classified by its severity depending on the amount of force used to cause the injury. view 

Shoulder Fractures

Shoulder Fractures or breaks in the shoulder can occur in the humeral bone, collar bone or the in shoulder blade.  view

Shoulder Dislocations

A shoulder dislocation is classified according to the direction of the dislocation (Anterior, posterior or multi-directional), the amount of force it took to dislocate the shoulder (Traumatic or Atraumatic), and whether it is accompanied by a fracture (fracture dislocation).  view 

Shoulder Arthiritis

Shoulder Arthritis is the loss of the cartilage cushion in the joint surfaces (blue section) that allows the smooth pain free gliding required during shoulder motion. view

Shoulder Nerve Compression Syndromes

Nerve compression syndromes are normally found in adults of all ages and it is rare to find nerve compression syndromes in patients younger than 20 years of age.  view 

Shoulder Tendon Disorders

Shoulder pain is the most common presenting shoulder complaint in an orthopedic practice.  view 

Shoulder Infection

The shoulder is one of the most well perfused areas of the human body and because of this ample blood supply to the shoulder which carries circulating white blood cells, offers excellent protection against infection, consequently making a shoulder infection a rare occurrence.  view 

Frozen Shoulder

A Frozen shoulder also called adhesive capsulitis is a condition presenting with shoulder stiffness and severe shoulder pain when shoulder motion is initiated. view 

Shoulder Tumor

Tumors are divided into benign and malignant types.  view 

SHOULDER DISLOCATION

Pathology

Parameters to Classify Shoulder Dislocation

Direction of the dislocation

  • Anterior
  • Posterior
  • Multi-directional

Amount of force

  • Traumatic
  • Atraumatic

Is it accompanied by a fracture?

  • Fracture dislocation

The parameters of the shoulder dislocation are used to select the appropriate treatment category. The age of the patient and activity level are also important details in selecting an operative vs. non-operative approach.

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Anterior Shoulder Dislocation

Shoulder ligaments and the labrum are most commonly torn in the front of the joint. A frontal united rip of the labrum and joint capsule is called a Bankart lesion. When this occurs in the back, it is called a reverse Bankart lesion. Bankart lesions occur in the following positions:

  • Right shoulder- between the 3 o’clock and 6 o’clock position
  • Left shoulder- between the 6 o’clock and 9 o’clock position

Another lesion produced by this dislocation is a Hillsachs lesion. A Hillsachs lesion is a small compression fracture in the humeral head. It is called a reverse Hillsachs lesion when occurring with a posterior dislocation.

An anterior dislocation can also create a fracture in the anterior glenoid rim.

Another lesion produced by this dislocation is a Hillsachs lesion. A Hillsachs lesion is a small compression fracture in the humeral head. It is called a reverse Hillsachs lesion when occurring with a posterior dislocation.

An anterior dislocation can also create a fracture in the anterior glenoid rim.

Multidirectional Instability (MDI)

  • Result of minor injury in patients between 20-25 years old
  • Occurs in patients whose joint anatomy predisposes the shoulder joint to dislocation due to congenital deficiencies in the ligaments and labrum.

Ligaments are too elastic Labrum is very thin in front. It fails to act as a bumper and fails to seal to the humerus (upper arm bone) with normal suction cup mechanism.

It is common for both ligament and labrum anatomic differences to exist together. Once a dislocation occurs, recurrent dislocations often result. Patients with multidirectional loose shoulders are often also found to have loose joints or hyperlaxity in other areas of the body.

Examples of loose joints/hyperlaxity

  • Hyperextension in elbows and/or knees
  • Ability for the thumb to bend towards the forearms without difficulty

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Shoulder ACJ Dislocation

  • Commonly the result of a direct blow to the shoulder.
  • When the ligaments of the acromioclavicluar joint (the connection between the top of the shoulder and the clavicle) are disrupted.

– ACJ ligaments
– Coracoclavicular ligaments

These ligaments allow the collar bone to have stability and limited motion when the shoulder blade moves to follow the arm bone. When both sets of ligaments are torn, the collarbone displaces from the shoulder blades anterior extension. The normal and torn ligaments of the ACJ are depicted above.

There are six patterns of ACJ tears. Patterns III, IV, V and VI are the types requiring reconstruction if they develop chronic pain.

SLAP Lesion

  • Superior Labrum Anterior Posterior Lesion (SLAP)
  • A condition related to dislocation causing an unstable feeling in the shoulder
  • This injury can occur from either a pulling arm injury or following a compression-sliding injury

This labral injury can occur in front and behind the long head of the biceps tendon.

Treatment

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Treatment of a Shoulder Dislocation w/ Lesions or Tears

  • Open approach
  • Arthroscopic procedure

Arthroscopic approach uses tiny incisions in the shoulder. A camera system and surgical instruments are inserted through the incisions. Suture anchors, tiny screws with special strong thread attached, are placed in the bone. The suture is then tied over the torn tissue in exactly the correct position. Illustrated above.

Initial healing of the repair takes 6-8 weeks. During this period, a sling is used in conjunction with a passive motion home exercise program. After 8 weeks, an active exercise regimen is begun and in the beginning of the fourth month, strengthening begins.

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Treatment of Multidirectional Unstable Shoulder

  • First, changes in normal activities are initiated to reduce the incidence of recurrent dislocation is initiated
  • Second, patient begins rehabilitation. Rehabilitating a Multidirectional Unstable Shoulder focuses on building up the dynamic stabilizers of the shoulder which are the rotator cuff muscles.
  • If six months of therapy is unsuccessful; surgery is considered

Surgery for recurrent dislocations has several reconstructive surgical options to consider, depending on prior treatment and the anatomic problem. The goal is to treat the recurrent dislocations and to allow normal function. Recurrent dislocations can lead to humeral head arthritis developing secondary to humeral head cartilage injury.

Above is a picture of a loose joint capsule and ligaments which are arthroscopically tightened (Capsulorrhaphy).

 

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Laterjet/Bristow Procedure

The Laterjet/Bristow Procedure is the widening of the surface of the anteroinferior glenoid rim. It is not our first surgical choice since it is a reconstructive procedure that does not restore normal anatomy. However, in Europe surgeons often use this option as a first choice because of its high success rate.

Eligibility for Laterjet/Bristow Procedure

  • Recurrent dislocations have worn the anteroinferior glenoid rim
  • A repaired capsule has failed
  • A shifted and imbricated capsule has failed

This procedure is done through a cosmetic anterior shoulder incision, on an outpatient basis.

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Treatment of ACJ Chronic Dislocation (Grade III-IV)

Weaver Dunn Procedure:

  • The coracoacromial ligament is transferred into the lateral end of the collarbone to replace the coracoclavicular ligaments preventing the collarbone from migrating superiorly.
  • This procedure is done in conjunction with resection of a small part of the lateral end of the collarbone.