Joint Venture: Elbow Dislocation Edition

 

Written By: Khin Oo, MD; Edited by: Timothy Khowong, MD, MSEd

 

Elbow Anatomy: Osseous & Soft tissue:

Osseous Stabilizers: the elbow is a trochoginglymoid (hinged-pivot) joint composed of three articulations:

1. Humeroulnar Joint Structure: A hinge joint between the trochlea of the humerus and the trochlear notch of the ulna.  Responsible for the bending (flexion) and straightening (extension) of the arm

2. Humeroradial Joint Structure: A gliding joint between the rounded capitulum of the humerus and the flattened head of the radius. Assists in flexion, extension, and the rotation required for turning the forearm.

3. Proximal Radioulnar JointStructure: A pivot joint between the rim of the radial head and the radial notch of the ulna. Works exclusively to allow for pronation (turning the palm down) and supination (turning the palm up)

Soft Tissue Stabilizers

  1. Lateral collateral ligament complex (LCL) -  most important component is the lateral ulnar collateral ligament (LUCL), which resists posterolateral rotatory instability

  2. Medial collateral ligament complex (MCL) - the anterior bundle is the primary restraint to valgus stress; most important soft tissue stabilizer of the elbow

  3. Annular Ligament -  Wraps around the radial head, holding it securely against the ulna during forearm rotation

Mechanism of Injury

Most common: fall onto an outstretched hand (FOOSH)

92% occurred at or near full extension, with a valgus moment being the most common deforming force

Clinical Evaluation

History & Physical Examination

  • Mechanism (FOOSH, direct blow, sports injury)

  • Dominant hand, occupation, sport

  • Prior elbow injury or surgery

  • Inspection: Obvious deformity; olecranon prominence posteriorly; swelling

  • Neurovascular assessment (Before AND After reduction):

    • Ulnar nerve — most commonly injured; test finger abduction, sensation to small finger

    •  Median nerve — test thumb opposition, sensation to index finger

    • Anterior interosseous nerve (AIN) — test flexion of thumb IP and index DIP ("OK sign")

    • Brachial artery — palpate radial and ulnar pulses; assess capillary refill

  •   Skin integrity — open dislocations require urgent surgical management

Radiographic Evaluation

Alignment:

  • Anterior humeral line: drawn down the anterior surface of the humerus. It should intersect the middle 1/3 of the capitellum.  If it does not, think distal humeral fracture.

  • Radiocapitellar line: drawn along the radial neck. It  should always intersect the capitellum.  If it does not, think radial head dislocation or subluxation. Check for an accompanying fracture, e.g. Monteggia fracture-dislocation

Effusion: visible posterior fat pad always indicates an elbow effusion

  •  If there is an effusion, think acute intra-articular fracture. Elbow fractures may be occult on x-rays

    • Adult: radial head fracture

    • Child: supracondylar fracture

Bones: look specifically for common fractures

  • Radial head and neck fractures

  • Olecranon fracture

Cortex: trace the cortex of each bone

  • Distal humerus​

  • Radial head, neck and shaft

  • Olecranon, coronoid process and ulnar shaft

Normal Elbow Alignment

Joint Effusion

Bony Anatomy of Elbow

The Horii Circle of Soft Tissue Disruption

The model proposed that elbow dislocation results from posterolateral rotatory instability with soft tissue failure progressing sequentially from lateral to medial in a circle. The classic model describes sequential disruption from lateral to medial: Lateral collateral ligament (LUCL)  Anterior capsule  Posterior capsule  Medial collateral ligament

Mechanism: Axial load + supination + valgus stress → the ulna rotates posterolaterally off the trochlea. However, studies have demonstrated that injury patterns are heterogeneous. Some dislocations show medially predominant injury ("reversed Horii circle")

Takeaway: Always assess both medial and lateral stability after reduction, regardless of the assumed mechanism.

Classification – Direction & Complexity


By Direction: 

  1.   Posterior / Posterolateral - Most common; olecranon displaced posteriorly

  2.  Anterior - Rare; direct blow to posterior olecranon

  3.  Medial / Lateral - Uncommon; pure translational displacement

  4. Divergent - Very rare; radius and ulna separate from each other


By Complexity:

  1.  Simple:  No associated fracture

  2. Complex: Associated fracture(s)


Named Complex Patterns:

  1.  Terrible Triad — posterior dislocation + radial head fracture + coronoid fracture

  2. Transolecranon fracture-dislocation — fracture through the olecranon with anterior displacement of the forearm

  3. Monteggia variant — proximal ulna fracture with radial head dislocation


Traction-Countertraction

Reduction Techniques

General Principles

  • Perform under adequate procedural sedation and analgesia

  • Avoid forceful manipulation — gentle, controlled maneuvers reduce iatrogenic injury

  • An assistant is helpful but not always required

Posterolateral Dislocation: 

Technique 1: Traction-Countertraction (Most Common) 

  1.  Patient supine, elbow slightly flexed

  2. Assistant stabilizes the humerus with both hands 

  3.  Operator applies steady longitudinal traction to the forearm

  4. While maintaining traction, gently flex the elbow

  5.  Apply anterior pressure over the olecranon to guide it distally and anteriorly

  6.  A palpable "clunk" confirms reduction

Technique 2: Leverage (No Assistant Needed)

  1. Patient supine, arm on a flat surface

  2. Operator grasps the proximal forearm with one hand and the distal humerus with the other

  3. The forearm is used as a lever — the operator pushes down on the proximal forearm while lifting the distal humerus

  4. This disengages the coronoid from the olecranon fossa without requiring forceful traction

Technique 3: Modified Stimson (Prone)

  1. Patient prone with the affected arm hanging off the side of the bed

  2. Gravity provides traction on the forearm

  3. The operator applies gentle downward traction on the wrist and anterior pressure on the olecranon

  4. Useful when sedation resources are limited

Levarage

Modified Stimson (Prone)

Anterior Dislocation:

Technique: Modified Traction-Counteraction Technique 

Posterior directed force applied on patient’s proximal forearm guides olecranon past distal humerus 

Post-Reduction Assessment (Critical Step)

  • Move the elbow through a full arc of flexion-extension to determine the angle of re-dislocation (instability arc)

  • Apply varus and valgus stress at 30° of flexion to assess collateral ligament integrity

  • Assess forearm pronation/supination

  • Repeat neurovascular examination

  • Short term Immobilzation with posterior/long arm splint

  • Obtain post-reduction radiographs

Clinical Pearls

  • FOOSH is the most common mechanism of elbow dislocation

  • With any elbow dislocation, you need to check  the shoulder  and the wrist for injuries and fractures

  • Always perform and document a neurovascular exam before and after reduction—the ulnar nerve is the most commonly injured nerve.

  • Posterior fat pad sign indicates an occult intra-articular fracture until proven otherwise.

  • Terrible Triad = posterior elbow dislocation + radial head fracture + coronoid fracture is a highly unstable injury that usually requires operative management.

  • Reduce the elbow with gentle traction under adequate procedural sedation to minimize iatrogenic injury.

  • A reduced elbow is not necessarily a stable elbow, always repeat the neurovascular exam, obtain post-reduction radiographs, and assess elbow stability

 
 

Citations:

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2.     O'Driscoll SW, Morrey BF, Korinek S, An KN. Elbow subluxation and dislocation: a spectrum of instability. Clin Orthop Relat Res. 1992;(280):186-197.

3.     Morrey BF, An KN. Articular and ligamentous contributions to the stability of the elbow joint. Am J Sports Med.1983;11(5):315-319.

4.     Morrey BF, An KN. Functional anatomy of the ligaments of the elbow. Clin Orthop Relat Res. 1985;(201):84-90.

5.     O'Driscoll SW, Jupiter JB, King GJ, Hotchkiss RN, Morrey BF. The unstable elbow. J Bone Joint Surg Am.2000;82(5):724-738.

6.     Reichert ILH, Ganeshamoorthy S, Aggarwal S, Arya A, Sinha J. Dislocations of the elbow—An instructional review. J Clin Orthop Trauma. 2021;21:101484. doi:10.1016/j.jcot.2021.101484. Available at: https://www.jsesreviewsreportstech.org/article/S2666-6391(21)00107-3/fulltext

7.     Roberts JR, Custalow CB, Thomsen TW. Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care. 7th ed. Elsevier; 2019.

8.     Tintinalli JE, Ma OJ, Yealy DM, et al., eds. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill; 2020.

9.     Orthobullets. Elbow Dislocation. Available at: https://www.orthobullets.com/trauma/1018/elbow-dislocation

10.  Radiopaedia. Elbow Dislocation. Available at: https://radiopaedia.org/articles/elbow-dislocation?lang=us

11.  Long B, Koyfman A. Elbow Dislocations. REBEL EM. Published November 18, 2021. Available at: https://rebelem.com/elbow-dislocations/

 
Booth EM