EM@3AM: Anterior Shoulder Dislocation
- Apr 4th, 2020
- Brit Long
Author: Brit Long, MD (@long_brit, EM Attending Physician, San Antonio, TX) // Reviewed by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital)
Welcome to EM@3AM, an emDOCs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.
A 35-year-old male presents with right shoulder pain. He was playing football with some friends, and as he was in the midst of throwing the football, a friend hit his throwing arm. He is right-handed and has no medical history. He has never had a shoulder injury in the past. He is holding his arm in an internally rotated and abducted position. You are able to detect an ulnar and radial pulse in the hand of the affected arm, and his median, ulnar, and radial motor and sensory function is normal in the right hand.
What’s the next step in your evaluation and treatment?
Answer: Anterior shoulder dislocation
- The shoulder is the most commonly dislocated joint (over half of all dislocations).
- There are three primary types of dislocation: anterior, posterior, and inferior. Anterior is the most common (97%, followed by posterior at 3%).
- Young males are the most commonly affected population, with trauma the most common cause of anterior dislocation.
- The shoulder is stabilized via soft tissues and is thus relatively unstable. Only 30% of the humeral head articulates within the glenoid fossa.
- The axillary nerve is the most common nerve injured, as it wraps around the surgical neck of the humerus.
- The axillary nerve provides motor to the deltoid muscle and sensory to the anterolateral shoulder, similar to a “patch”.
- Mechanisms differ and affect the type of dislocation:
- Anterior – Fall onto an outstretched hand, or an applied force to an abducted and externally rotated or extended arm.
- Posterior – Often due to an awkward fall, blow to anterior shoulder, forceful internal rotation and adduction (seizure, shock, alcohol withdrawal).
- Inferior – Usually due to hyperabduction; often with soft tissue injury or fracture (80%).
- Severe pain and limited mobility.
- Anterior: Arm held internal rotated and abducted
- Posterior: Arm is internally rotated, adducted, fixed.
- Inferior: Abducted position, arm held over the head, fixed.
- See CanadiEM for a guide to the shoulder exam.
- Perform history and exam, primary and secondary survey, looking for other injuries if trauma was involved.
- Ask about mechanism and prior arm trauma, injuries, dislocations. One dislocation significantly increases risk of subsequent dislocations.
- Assess axillary nerve status (motor – deltoid, sensory – patch distribution). Assess neurovascular status of radial, median, and ulnar nerves/vessels.
- Inspect, palpate, assess passive and active range of motion (will be limited), neurovascular status.
- Neurovascular status should be assessed before and after reduction.
- For suspected dislocation, obtain x-ray with AP, scapula Y, and axillary views if possible. See this Core EM post for more.
- Anterior dislocation will show the following:
- AP: Anterior dislocation of the humeral head, resting under the coracoid process.
- Scapula Y: Medial displacement of humeral head.
- Axillary: Anterior displacement of the humeral head in front of coracoid process.
- Anterior dislocation will show the following:
- Findings on X-ray
- Hill Sachs Lesion: Humeral head impaction fracture against glenoid rim. For anterior dislocations, this may occur in 40-90% of dislocations against the posterolateral surface.
- Bankart Lesion: Anterior inferior labrum detachment from glenoid. A “soft” lesion is the labrum only, while “bony” is an impaction fracture involving the glenoid margin.
- Ultrasound: High sensitivity and specificity (approaching 100%) for diagnosis of dislocation. See this emDOCs post and Brown EM Blog post for how to perform ultrasound for diagnosis and assessing reduction.
- Process: Start from behind the affected shoulder and support the affect arm’s elbow inferiorly with the humerus adducted. Find the scapular spine and palpate laterally not the glenohumeral space is reached. Place the curvilinear or linear probe in the transverse position parallel and inferior to the scapular spine. Move laterally until the glenoid is visualized and you see the humeral head.
- Anterior dislocation is present with a humeral head deep on the screen.
- After initial stabilization, analgesia is often required. US can be utilized for intraarticular lidocaine, as well as blocks. See this ALiEM post for the intraarticular injection and this emDocs post for the interscalene block.
- The greater the muscle tension, the more difficult the reduction. Procedural sedation may be needed.
- Be comfortable with a variety of techniques.
- There are many different techniques for reduction. The processes described are several of the more commonly used techniques. See this post from NUEM Blog and this great video from Larry Mellick.
- May not require sedation:
- Cunningham: Sit facing the patient, patient moves shoulders up and back (shrug), massage patient biceps as the patient holds arm adducted and elbow flexed.
- FARES: Patient lies supine or prone, grasp affected arm’s wrist, gently oscillate arm up and down, apply gentle traction to arm and slowly abduct, once abducted to 90 degrees then externally rotate, continue with oscillation and traction until reduced (usually 120 degrees abduction).
- Davos: Patient is seated with ipsilateral knee flexed, patient holds wrist of affect arm with hand of unaffected arm and both looped around fully flexed knee (stabilize/tie wrists with tape), sit on patient’s foot for stabilization, as the elbows are adducted have patient slowly lean back and let shoulder roll forward.
- Require Sedation:
- Kocher: Patient is supine, adduct affected arm and flex 90 degrees at elbow, externally rotate shoulder until feel resistance, lift arm anteriorly as far as you can, internally rotate shoulder, and humeral head should reduce.
- Stimson: Patient is prone with limb hanging freely over the edge and a weight (> 10 lb) from the wrist. Traction overcomes the spasm and can often result in reduction within 20 minutes.
- Scapular manipulation: Often used in combination with Stimson technique; provider is behind patient with the superior aspect of the shoulders stabilized; the scapula is manipulated in a counterclockwise motion with superior stabilization and a medial force applied to the inferior angle.
- Milch: The patient is supine and steady downward traction is applied at the elbow combined with slow external rotation and abduction of the limb. Can use free hand to manipulate humeral head laterally and superiorly.
- Traction-Countertraction: Smooth and gradual traction applied to the affected arm while an assistant uses counter traction.
- May not require sedation:
- Relative contraindications to ED reduction:
- Fracture of humeral neck, nerve injury or deficit, major vascular injury, chronic dislocation (over 48 hours the rate of success is low; over several weeks high risk of vascular complication).
- Recurrent dislocation occurs in up to 40-90% of patients (risk factors include age < 40 , male, occupation, bony banker lesion, increased laxity).
- Bony injuries: Hill- Sachs occurs in 40% and Bankart in 10-20%.
- Fracture of the greater tuberosity may occur in older patients.
- Axillary nerve injury can occur in up to 15% of patients.
- Axillary artery injury is rare. Prolonged dislocations may cause vascular injury with attempted reduction.
- Discharge after successful reduction, if pain is controlled, and if recovered from sedation if used.
- Patient should be placed in a shoulder immobilizer. A sling for 3-4 weeks in younger patients and 1-2 weeks for older patients.
- Physical therapy can assist the patient rehab with passive range of motion exercises.
- For anterior dislocations, patients should not externally rotate past neural and not abduct past 90 degrees for up to 6 weeks.
- Complete a full history and exam, looking for neurovascular injuries before and after reduction.
- Carefully assess all views on X-ray. US can assist.
- Know multiple reduction techniques, as one does not work for all.
- Become comfortable with procedural sedation, blocks, and intra-articular injections.
- Sling for several weeks is vital after reduction.
A 28-year-old man presents to the emergency department after a fall while riding his mountain bike. The patient states he went off a six-foot ramp and landed on his right shoulder. On physical exam, he is unable to move his right shoulder, and he holds the right upper extremity in internal rotation. An X-ray of the right shoulder is obtained, as seen above. Which of the following is the most likely diagnosis?
A) Acromioclavicular separation
B) Anterior shoulder dislocation
C) Clavicle fracture
D) Posterior shoulder dislocation
A posterior shoulder dislocation is caused by an axial force applied while the shoulder is internally rotated and abducted or by a direct blow to the anterior shoulder. With this injury, the arm will be held in adduction and internal rotation, and there is mechanical obstruction with active external rotation of the extremity. This injury is frequently missed because it is difficult to identify on radiographs. The subtle “light bulb” sign may be appreciated on the anteroposterior view of the radiograph. The axillary view is most helpful for diagnosis and will show the humeral head posterior to the glenoid fossa. Posterior shoulder dislocations are commonly associated with fractures of the surgical neck of the humerus, reverse Hill–Sachs deformities, and rotator cuff injuries. Procedural sedation should be given for reduction. The technique for reduction includes internal rotation and lateral traction to disimpact the humeral head from the glenoid rim, followed by external rotation. Reduction can be difficult, and orthopedic consultation for operative management may be required. The shoulder should be immobilized in external rotation with slight abduction.
Acromioclavicular separation (A) occurs most commonly from falling directly on the “point” of the shoulder, which causes the clavicle to separate from the scapula. Anterior shoulder dislocation (B) occurs with force on the extremity while in abduction, external rotation, and extension. This is the most common type of shoulder dislocation. The radiograph will show the humeral head anterior, medial, and inferior to the normal location. A clavicle fracture (C) usually occurs from falling onto the lateral shoulder, onto an outstretched arm, or from a direct blow. The majority of fractures occur in the middle third of the clavicle.
Additional FOAM Resources:
- Gottlieb M. Shoulder Dislocations in the Emergency Department: A Comprehensive Review of Reduction Techniques. Journ Emerg Med. 2020. DOI: https://doi.org/10.1016/j.jemermed.2019.11.031
- Youm T et al. Acute Management of Shoulder Dislocations. J Am Acad Orthop Surg. 2014 Dec;22(12):761-771.
- Matsen FA et al. Principles for the evaluation and management of shoulder instability. Instr Course Lect 2007; 56:23-34.
- Guler O, Ekinci S, Akyildiz F, et al. Comparison of four different reduction methods for anterior dislocation of the shoulder. Journal of Orthopaedic Surgery and Research. 2015;10:80.
- Olds, M., Ellis, R., Donaldson, K., Parmar, P., and Kersten, P. (2015) Risk factors which predispose first-time traumatic anterior shoulder dislocations to recurrent instability in adults: A systematic review and meta-analysis. British Journal of Sports Medicine, 49(14).