Glenohumeral Dislocation, Anterior

By admin Last updated Sep 14, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Jason Glowney

Sourav K. Poddar

Basics

Description

Humeral head is displaced anteriorly beyond the glenoid fossa due to external rotation while arm is in abduction.
Sometimes (less commonly) caused by direct contact to the posterior aspect of the shoulder.

Epidemiology

Most commonly dislocated diarthrodial joint; 45% of all dislocations are of the shoulder.
Bimodal incidence with peaks in the 2nd and 6th decades of life
2% lifetime incidence between 18 and 70 yrs of age
96% of glenohumeral dislocations are anterior.

Risk Factors

History of previous dislocation
Generalized ligamentous laxity
Sports such as wrestling, football, rugby, skiing, and skateboarding

Commonly Associated Conditions

Bankart lesions: Detachment of inferior glenohumeral ligament-labral complex from anterior glenoid rim. Very common in younger patients. Strongly associated with dislocation recurrence.
Rotator cuff tears: Between 14 and 63% of anterior dislocations are associated with rotator cuff tears, with increasing frequency in older individuals. Often the subscapularis muscle with anterior dislocation.
Fractures: Humeral head and neck (significant displacement may be a contraindication to closed reduction), glenoid rim, and greater tuberosity avulsions. Seen especially with traumatic etiology.
Hill-Sachs lesion: Depression fracture of posterolateral humeral head. More than 50% of anterior dislocations in patients younger than 40 yrs old are associated with this type of lesion. Presence of a Hills-Sachs lesion associated with recurrent dislocation.
Neurologic injury: Common complication with 10% suffering injury to the axillary nerve. Less frequently injured are the brachial plexus or musculocutaneous nerve.
Vascular injury: Infrequent complication (1–2%), axillary artery most frequently injured in anterior dislocation, higher incidence in older individuals given the loss of arterial elasticity secondary to atherosclerosis.
Recurrent dislocation: Rate varies inversely with age, with up to 95% recurrence in athletic patients, with initial dislocation at younger than 20 yrs old without surgical intervention.

Diagnosis

West Point view (reverse axillary lateral) helps in showing bony Bankart lesions.
Styker notch (anteroposterior internal rotation of humerus) good to demonstrate Hill-Sachs deformity

History

Often occurs after a fall on the outstretched arm or with reaching (making a tackle) and having arm forcibly abducted
1st time event vs recurrence (may affect ease of reduction and long-term treatment plan)
Amount of trauma involved (traumatic vs atraumatic) can give clues as to whether there is a component of ligamentous instability.
Duration shoulder has been dislocated (helps in decision concerning analgesia)

Physical Exam

Anterior fullness of the shoulder
Forearm of affected arm often cradled with shoulder in externally rotated, partially abducted position
Patient usually guarding and very uncomfortable
Sulcus sign (depression in the skin below the acromion)
Perform neurovascular exam, both before and after reduction, to check for previously mentioned nerve injuries.
Check deltoid muscle strength and lateral shoulder sensation to assess axillary nerve function (former not always practical prior to reduction of dislocated shoulder).
Check proximal and distal muscle function and range of motion before and after relocation.
No crepitus should be felt or heard during relocation.

Diagnostic Tests & Interpretation

Imaging

At least 2 views orthogonal to each other are required.
Normally acute traumatic shoulder dislocations are evaluated with a trauma series that includes an axillary view, a trans-scapular (Y) lateral view, and a true shoulder anterior-posterior view
Standard anteroposterior: Head of humerus displaced medially on glenoid; difficult to distinguish anterior from posterior dislocations
True lateral (trans-scapular, Y) view: Humeral head displaced toward coracoid process
Axillary view: Allows easier visualization of associated injuries, but requires movement of an already uncomfortable patient

Diagnostic Procedures/Surgery

May utilize advanced imaging, such as CT scan, MRI, or musculoskeletal US, to assess if associated injuries suspected

Differential Diagnosis

Acute subluxation
Acromioclavicular joint separation
Fractures of humeral head, coracoid, acromion, proximal humerus, clavicle, rib
Rotator cuff injury
Posterior dislocation

Treatment

Analgesia often not needed if reduction is performed immediately after dislocation.
Verbal coaching to relax the patient is helpful.
Narcotic and benzodiazepine medications may be required, if reductions are not performed early, to relax spasm and ease relocation.
Some sources recommend local glenohumeral joint anesthesia using 10–20 mL of 1% lidocaine.
Intra-articular lidocaine has been shown to have similar relocation success rates vs IV analgesia and sedation, and a significant decrease in cost and length of stay in the emergency department, although patient satisfaction tends to be higher with the use of IV agents [A].

P.271

Traction methods: Stimson (prone traction with weight applied to arm hanging down); supine traction/countertraction (gentle traction at 45 degrees of abduction while countertraction applied with folded sheet under axilla)
Leverage techniques: Hennepin or modified Kocher maneuver (with patient supine, externally rotate arm to 90 degrees; slowly abduct arm until dislocation reduced)
Axillary pressure by assistant's hand may help guide the humeral head over the glenoid.
Scapular manipulation: Patient prone or seated with arm at 90 degrees of flexion with mild traction applied (10–15 lbs), apply medially directed force to inferolateral border of scapula; may also do when patient is supine to assist with other techniques.
Combinations
Experience, familiarity, and available resources (time and help) are important considerations when deciding which technique to use.
More than 2 dozen different described techniques, but only 1 randomized controlled trial exists that compared Kocher and Milch techniques. In this study, the authors did not detect a statistically significant different success rate between the 2 techniques. They did, however, find a greater relocation success rate in those under 40 yrs old vs those older than 40 yrs (1)[A].
Recheck neurovascular exam and rotator cuff; post-reduction radiographs
Controversy exists as to best approach to postdislocation management, but many authors at this time would recommend immobilization in a sling for comfort about 1 wk (2)[A], followed by range-of-motion exercises and then progression to strengthening exercises, with an emphasis placed on periscapular muscle strengthening. Shorter immobilization period decreases the risk of adhesive capsulitis in the older patient (age over 30).
Recent reports have suggested that immobilization in external rotation instead of traditional internal rotation may be associated with a lower rate of recurrence. In clinical practice, patients may find it difficult to function with their arm immobilized in external rotation (3)[B].
Immobilization theoretically allows time for “scarring” of injured anterior structures and healing of pathologic lesions.
Humeral head and neck fractures contraindications to closed reduction, as are:
- Significantly displaced (<1 cm) greater tuberosity fractures
- Severe scapula fractures
- Intrathoracic humeral head fractures

Additional Treatment

Additional Therapies

Early range of motion in older patients (age >30) to prevent adhesive capsulitis
Strengthening of rotator cuff muscles and scapular stabilizers help in maintaining dynamic stability.
Most helpful in nontraumatic dislocations in patients who have multidirectional instability or generalized ligamentous laxity (TUBS [traumatic unilateral Bankart lesions] vs AMBRI [atraumatic, multidirectional, bilateral shoulders])
Immobilization and postimmobilization rehabilitation have not been shown to be effective in preventing recurrence in young, traumatic, 1st-time dislocators.

Surgery/Other Procedures

Surgical stabilization recommended for many athletic 1st-time disclocators, especially if “throwing shoulder.”
Surgery recommended for those with recurrent dislocations, especially if the episodes appear to require less “trauma” than prior episodes.

Ongoing Care

Little data exist as to when it is safe for an athlete to return to play after sustaining a dislocation.
Most experts would recommend waiting until athlete has full range of motion and strength before their return (4)[C].
Athletes returning to play with history of instability are at risk for recurrence, with 1 study showing 37% incidence of repeat dislocation during the ongoing season (4)[B].

Follow-Up Recommendations

Growing consensus for early arthroscopic stabilization after primary anterior shoulder dislocation in young athletic patients unwilling to modify their risk factors, as numerous studies have shown a high rate of recurrence in nonoperative treated subjects in this group. When surgically stabilized, athletes show significant decreased rates or dislocation recurrence (2)[A].
Recurrent instability patients likely to benefit from orthopedic referral for arthroscopic or open surgical repair as warranted
Patients with multidirectional instability should be treated with traditional methods, although surgical repair is often necessary with recurrences.
Early orthopedic referral indicated for all except uncomplicated, recurrent anterior dislocations.
Orthopedic referral with humeral head or neck fractures and irreducible dislocations

References

1. Cox CL, Kuhn JE. Operative versus nonoperative treatment of acute shoulder dislocation in the athlete. Curr Sports Med Rep. 2008;7:263–268.

2. Dodson CC, Cordasco FA. Anterior glenohumeral joint dislocations. Orthop Clin North Am. 2008;39:507–518, vii.

3. Kuhn JE. Treating the initial anterior shoulder dislocation—an evidence-based medicine approach. Sports Med Arthrosc. 2006;14:192–198.

4. Cutts S, Prempeh M, Drew S. Anterior shoulder dislocation. Ann R Coll Surg Engl. 2009;91:2–7.

Additional Reading

Arciero RA, St Pierre P. Acute shoulder dislocation. Indications and techniques for operative management. Clin Sports Med. 1995;14:937–953.

Wen DY. Current concepts in the treatment of anterior shoulder dislocations. Am J Emerg Med. 1999;17:401–407.

Codes

ICD9

831.01 Closed anterior dislocation of humerus