Background

The glenohumeral joint is the most commonly dislocated large joint.

Over 95% of shoulder dislocations are anterior, with the humeral head becoming situated anterior to the glenoid fossa.

     - This is because of the relatively weak anterior support of the inferior glenohumeral ligament.

     - Posterior dislocation is much less common because of the stronger posterior support of the scapula and multiple muscles posterior to the humeral head.

Mechanism

Usually a combination of abduction, external rotation, and extension.

If patients have had recurrent dislocations, they are more likely to have dislocation with surprisingly benign mechanism (i.e. rolling over in bed).

Patients are more likely to have recurrent dislocations if they are younger (<20 yo) at time of first dislocation.

Feared Complications (Important to assess for and document!)

     - Fractures. Assess with pre and post-reduction XR.

     - Axillary nerve injury. Check for sensation over the deltoid (sensory function) and ability to abduct the arm (motor function). Ability to abduct arm may be limited by pain pre-reduction.

     - Axillary artery injury. Check radial pulse and look for rapidly enlarging hematoma.

     - Rotator cuff injury. Assess for displaced fractures on post-reduction film.

Assessment

Physical exam usually shows loss of normal rounded shape of the shoulder, with indentation at lateral aspect of shoulder (empty GH fossa), and fullness anteriorly, below the clavicle (displaced humeral head).

Be sure to complete (and document) careful neurovascular exam.

Obtain pre and post-reduction XR to confirm dislocation, visualize displaced humeral head, and assess for fractures.

Pain Control

Decisions about level of pre-medication/sedation should be made in conjunction with the patient. A patient who has had multiple dislocations and reductions may require little or even no pre-medication, while a patient with significant pain and/or anxiety about reduction may require conscious sedation.

Alternatives to conscious sedation and/or IV pain medication include:

     - Intra-articular injection. Use anatomic landmarks (empty glenoid fossa) or US guidance to inject lidocaine into the GH joint. Allow up to 20 minutes for full analgesic effect.

     - Nerve blocks. Suprascapular or scalene under US guidance.

These have the benefit of avoiding placement of IV if adequate analgesia achieved.

Reduction

Many approaches to reducing an anterior shoulder dislocation. It is helpful to feel comfortable with a few, as they require varying amounts of time, provider involvement, and patient cooperation. Here are a few methods:

Traction/Counter-traction

     - With patient supine, traction on affected arm applied by provider, with counter traction applied by assistant using sheet wrapped around patient’s torso.

     - Often very uncomfortable for patient - probably best to be used only with sedated patient

     - Requires at least two operators

Stimson Technique

     - Patient prone on stretcher, affected shoulder hanging off the side of the stretcher with fingers dangling toward floor. Suspend weights (bags of saline) from patient’s wrist. Maintain this position for up to 20-30 minutes.

     - Requires little active manipulation by provider. Risks include patient rolling off stretcher and airway compromise while proned (for example if significantly intoxicated or sedated).

Cunningham Technique

     - Patient sitting up on side of stretcher with arm adducted and elbow flexed, hand pointing straight out in front of them. Provider facing the patient applies gentle, steady downward traction on the flexed forearm. With other hand (or an assistant), massage the trapezius. Continue until reduction achieved.

     - May require two operators if traction requires both of provider’s hands. Usually comfortable for patient and well-tolerated without sedation.

FARES Technique

     - Patient supine on stretcher, affected arm at side with forearm extended, palm facing down. Provider holds hand on affected side, provides simultaneous gentle longitudinal traction, slow abduction of arm, and small vertical oscillating movements (toward floor and ceiling, only about 5cm above/below horizontal plane of patient’s body). When at 90 degrees of abduction, gently externally rotate to bring palm facing up. Continue abduction, traction, oscillation. Reduction is usually achieved at about 120 degrees of abduction.

     - Requires only one provider. Generally very well tolerated without sedation.

Post Reduction

     - If patient can touch unaffected shoulder with palm on affected side, reduction is likely successful.

     - Repeat XR to assess for adequate reduction and fractures.

     - Repeat neurovascular exam.

     - Immobilize in sling to prevent repeat dislocation. Patient should follow-up with orthopedics within 1-2 weeks. 

References

     - Cunningham, Neil. A New Drug Free Technique for Reducing Anterior Shoulder Dislocations. Emergency medicine. 15:521–524.

     - Roberts, JR, Custalow, CB, Thomsen, TW. Chapter 49: Management of Common Dislocations in Roberts’ and Hedges’ Clinical Procedures in Emergency Medicine and Acute Care. 7th ed. 2019. Elsevier.

     - Tsoi, LCH, Wong, MCK. FARES Method to Reduce Acute Anterior Shoulder Dislocation: A Case Series and an Efficacy Analysis. Hong Kong Journal of Emergency Medicine. 2012. 19(1): 65-69.