Anterior Shoulder Dislocation: PathoAnatomy, Reduction techniques, Clinical Features & Complications

Anatomy of the shoulder joint

• Glenohumeral (shoulder joint) is a ball and socket synovial joint (humeral head articulates with glenoid) that allows a wide range of movement (and that make it relatively unstable)
• Congruity of the shoulder joint is maintained by static and dynamic stabilizers
• Shoulder joint; Young Lae Moon, CC BY 3.0 <link>, via Wikimedia Commons
• Young Lae Moon, CC BY 3.0 <link>, via Wikimedia Commons

Static stabilizers

• Bone shape: the glenoid socket is a shallow concave surface, in comparison to the acetabulum (hip joint) it is much deeper, that is why the glenoid provides much less stability compared to the acetabulum
• Glenoid labrum: fibrocartilaginous rim which markedly increases the glenoid depth
• Joint capsule: fibrous layer that surround and supports the joint and act as a limiter to the external rotation
• Capsular ligaments: there is superior, middle and inferior glenohumeral ligaments on the joint capsule, also there is coracohumeral, transverse humeral and coracoacromial ligaments
• Negative intraarticular pressure: it is produced by the intact closed joint
• Shoulder joint capsule; Henry Vandyke Carter, Public domain, via Wikimedia Commons
• Shoulder joint capsule; Henry Vandyke Carter, Public domain, via Wikimedia Commons

Dynamic stabilizers

• Rotator cuff muscles: those include supraspinatus, infraspinatus, teres minor and subscapularis; they form a cuff of muscles around the glenohumeral joint and they held keep it stable throughout movement
• Long head of biceps brachii: arise from the superior glenoid rim within the shoulder joint and travel over the anterosuperior aspect of the humeral head downward and in its position it work to resist anterior dislocation of the humeral head
• InjuryMap, CC BY-SA 4.0 <link>, via Wikimedia Commons
• InjuryMap, CC BY-SA 4.0 <link>, via Wikimedia Commons
• Anatomography, CC BY-SA 2.1 JP <link>, via Wikimedia Commons
• Anatomography, CC BY-SA 2.1 JP, via Wikimedia Commons

Why Shoulder Dislocates?

• Shoulder the most common joint to dislocates (50% of all major joint dislocations), that is due to a number of factors:
• Shallowness of the glenoid which articulate with small part of the humeral head
• Wide range of movement
• Underlying conditions such as ligamentous laxity or glenoid dysplasia
• Sheer vulnerability of the joint during stressful activities of the upper limb
• Normal Shoulder Grashey view, Mikael Häggström, CC0, via Wikimedia Commons
• Normal Shoulder Grashey view, Mikael Häggström, CC0, via Wikimedia Commons

Shoulder dislocations types

• Anterior shoulder dislocation
• Posterior shoulder dislocation
• Inferior shoulder dislocation

Anterior shoulder dislocation

• Complete anterior displacement of the humeral head out of the glenoid
• The most common type, 95% of all shoulder dislocations
• In anterior shoulder dislocation, the humeral head lie either subcoracoid (most of the cases), subglenoid, subclavicular or intrathoracic (very rare)
• Occur mainly in young men more who play contact sports, skiing and cycling
• In these types of activities, the shoulder is placed in at risk position of abduction, external rotation and extension and then pushed further beyond its range
• 50% of anterior shoulder dislocations occur in elderly and it is associated with rotator cuff tears
• Main mechanism is fall on the outstretched hand and fall on the shoulder while the shoulder being at risk position
• In patients with lax shoulder, minimal trauma maybe involved

Pathological Anatomy

• Anterior Shoulder dislocation result in a combination of one or more injures to structures inside the joint and outside, these injuries may include:
• Bankart lesion: avulsion of the anterior part of the labrum (seen on MRI)
• Bony Bankart lesion: anterior glenoid rim avulsion fracture (seen on X rays)
• Hill Sachs lesion: is an impaction fracture of the posterior humeral head as it is compressed against the anterior glenoid after dislocation
• Hill Sachs lesion occur in 25% of first time should dislocation and in 75% of recurrent shoulder dislocations
• Fractures in the humeral head or neck
• Stretching or avulsion of the joint capsule
• Rotator cuff tendon tear occur in 40% of patients over 40 years of age and 60% of patient over 60 years of age
• Brachial plexus injury manifests as an axillary nerve palsy
• Bony bankart lesion and Hill sachs lesion in Shoulder X rays; Mikael Häggström, CC0, via Wikimedia Commons
• Bony bankart lesion and Hill sachs lesion in Shoulder X rays; Mikael Häggström, CC0, via Wikimedia Commons

Clinical features

• Patient supporting their injured arm with the opposite one and they are in severe pain and muscular spasm
• They decline any kind of examination
• Lateral shoulder outline looks flat (normal is rounded) with prominent acromion
• And if patient is not too muscular, a bulge maybe felt just below the clavicle (humeral head)
• Ask about the mechanism of injury, for a first time dislocation there is usually a high energy trauma caused the dislocation but recurrent dislocations will need trivial trauma or normal activities to be achieved (this gives an idea of the severity of the injury)
• The arm must always be examined for nerve and vessel injury before reduction is attempted

Imaging

• AP shoulder x ray will show overlapping shadows of the humeral head and glenoid fossa with the head lying below and medial to the socket
• On AP shoulder x ray, Also look for fractures in the humeral head or neck
• A lateral view show the humeral head out of the line with the socket
• AP shoulder X ray showing anterior shoulder dislocation, Hellerhoff, via Wikimedia Commons
• AP shoulder X ray showing anterior shoulder dislocation, Hellerhoff, via Wikimedia Commons
• Lateral shoulder X ray showing anterior shoulder dislocation, Hellerhoff, via Wikimedia Commons
• Lateral shoulder X ray showing anterior shoulder dislocation, Hellerhoff, via Wikimedia Commons

Treatment

• Closed reduction
• Open reduction

Closed reduction

• Close reduction is most effective and comfortable the earlier it is performed after dislocation
• Imaging is important to exclude significant fractures before reduction
• The key in achieving successful closed reduction is muscle relaxation (because muscle spasm is what holding the humeral head from returning back into the glenoid in most of the cases) so ask your patient to take deep breaths and relax
• Various methods can be used to reduce the dislocated shoulder, but non showed convincing superiority over another, so they all can be attempted
• The physician should be skilled at multiple methods and move fluidly between them
• These methods can be used with or without sedation, GA maybe used sometimes
• Simple traction is always helpful in relieving pain because it draws the humeral head away from the glenoid rim
• In patient with previous dislocations, simple traction on the arm might be enough to reduce the shoulder
• Start with gentle traction + external rotation
• Don’t pull hard because this may lead to axillary nerve injury and fractures and don’t let go of your traction (because this will cause pain and spasm)
• While maintaining your gentle traction add Cunningham massage With your other hand start massaging their trapezius, deltoid and biceps
• Cunningham massage to reduce anterior shoulder dislocation, Neiljcunningham, via Wikimedia Commons
• Cunningham massage to reduce anterior shoulder dislocation, Neiljcunningham, via Wikimedia Commons
• At the same time, assistant will apply a counter traction (very gentle) to the body by a towel slung around the patient’s chest under axilla (Hippocratic method)
• The humeral head might reduce at any point during the previous maneuver and next maneuvers

Spaso technique

• Patient is supine
• Maintain your gentle traction and then lift vertically while keeping the traction and externally rotating the arm

Fares technique

• Patient is supine
• Maintain gentle traction
• Then the patient arm is abducted and adducted by small movements (10 cm each) while maintaining the traction and externally rotating the arm

Milch’s technique

• The patient is placed supine, this technique takes 5- 10 minutes so it is done very slow
• Flex patient elbow and maintain traction, and put your other hand on the humeral head
• Then the arm slowly and gradually abducted fully, once it is above the patient head, gentle external rotation is applied to the wrist and at the same time lateral pressure is put on the head of the humerus

Scapular manipulation

• Patient sitting upright
• Ask an assistant to maintain the traction by pushing down on the patient flexed elbow
• Stand behind the patient and rotate the scapula by using one thumb to push scapula medially and the other thumb to push the acromion inferiorly

Stimson’s technique

• Patient is put in prone position with the arm hanging over the side of the bed
• Wait for 15-20 min the shoulder may reduce
• Stimson’s technique to reduce anterior shoulder dislocation, James Heilman, MD, via Wikimedia Commons
• Stimson’s technique to reduce anterior shoulder dislocation, James Heilman, MD, via Wikimedia Commons

• X ray is taken to confirm reduction and exclude fractures
• Active abduction is tested to exclude axillary nerve injury or rotator cuff tear
• Other neuro and vascular exam looking for arterial and other nerves injuries is done too
• Arm is rested in a sling or a collar and cuff for 3 weeks in patients under 30 years of age to avoid recurrence and for 1 weeks in patients over 30 years of age to avoid stiffness in these patients, during this time elbow and fingers movements are practiced and then shoulder movements after
• The rate of recurrent instability will depend on:
• the size of Hill Sachs lesion
• presence of other bony injuries (e.g. glenoid rim fractures)
• state of soft tissue

Open reduction

• Indications of surgery:
• Irreducible acute dislocation
• Fracture dislocation (humeral neck fractures, displaced tuberosity fractures that doesn’t reduce)
• Neurovascular compromise
• Acute rotator cuff tears
• Prophylactic stabilization in high chance of recurrence patients (age < 35 and intention to return to contact sports)
• Stabilization in recurrent instability patients

Complications

Early complications

• Rotator cuff tear:
• Patient will have difficulty abducting their dislocated arm after reduction
• More in old age patients
• Palpable contraction of the deltoid exclude axillary nerve injury so the diagnosis is rotator cuff tear
• If there is large tear then repaired surgically if otherwise then conservative treatment is better
• Nerve injury:
• Axillary is the most common nerve to be injured in shoulder dislocation
• Patient unable to abduct and rotator cuff tear should be excluded
• Axillary neuropraxia recover after few weeks
• Radial nerve, musculocutaneous, median, ulnar nerves, brachial plexus also can be injured but all are rare
• Vascular injury:
• Axillary artery at risk of getting injured, especially in elderly people with fragile vessels
• It could be injured at time of injury or during reduction maneuver
• Examination is crucial before and after reduction to exclude this injury
• Associated fracture: if the fracture just involve the greater tuberosity then it might fall into place during reduction and no operation is needed, but if larger fracture or didn’t fall into place then operative management is necessary

Late Complications

• Shoulder stiffness:
• Prolonged immobilization after reduction may lead to shoulder stiffness
• The risk for stiffness is higher in patients older than 40
• Active exercises will loosen up the joint
• Unreduced shoulder dislocation (undiagnosed)
• Due to patient being unconscious or very elderly
• Closed reduction is worth the attempt up to 6 weeks after injury, beyond that, manipulation may fracture the bone or tear vessels or nerves, so open reduction is done
• Recurrent dislocation:
• Shoulder joint capsule is torn during dislocation but it heals once the joint is reduced, but if the glenoid labrum is detached or the joint capsule is stripped off the front of the glenoid neck then healing is less likely and this would increase the risk of recurrent dislocation
• Also injury to the posterolateral aspect of the humeral head (Hill Sacks lesion), or presence of rotator cuff tear or greater tuberosity fracture increase the risk of recurrence much more
• Recurrent dislocation diagnosis
• The history is diagnostic for recurrent dislocation, patient complains of shoulder dislocations with normal everyday actions and often reduced by themselves
• Any doubt in dx is solved by apprehension test: patient arm is abducted first and laterally rotated , if patient resist and apprehension are diagnostic
• AP shoulder with arm medially rotated show Hill- Sachs lesion for most of the times

Course Menu

This article is a part of the Shoulder and Arm Trauma Free Course, this course also contains:

• Course Introduction
• Clavicle Bone Fractures
• Scapula Bone Fractures
• Acromioclavicular Joint Injuries
• Sternoclavicular Joint Injuries
• Anterior Shoulder Dislocation
• Posterior Shoulder Dislocation
• Inferior Shoulder Dislocation
• Proximal Humerus Fractures
• Humeral Shaft fractures
• Shoulder X-ray Interpretation