The Problem

A simple elbow dislocation is a soft tissue injury with no associated fractures. A complex elbow dislocation is defined as a dislocation coupled with a fracture. The elbow is the most commonly dislocated joint in children and the second most dislocated joint in adults, the shoulder being the first. The incidence of elbow dislocations in the United States is estimated to be 5.21 per 100,000 people. The injury most commonly occurs in adolescent males during sports-related activities. Simple elbow dislocations are classified based on the direction of the dislocation. The direction of the elbow dislocation is described based on the position of the proximal ulna and radius relative to the distal humerus. Simple elbow dislocations are most commonly posterior or posterolateral. Anterior and divergent dislocations are rare. Divergent dislocations are due to high-energy trauma and involve a dislocation of the elbow with dissociation of the radius from the ulna.

Clinical Presentation

Posterior elbow dislocations typically occur from a fall on outstretched hand. Sports related falls accounts for 45% of acute elbow dislocations. A fall on an outstretched hand results in a posterolateral rotatory displacement of the elbow. The axial load on the elbow causes the elbow to flex and the body internally rotates on the fixed hand as it falls towards the ground. This results in supination, external rotation and valgus moments on the elbow. The tensile forces disrupt the capsuloligamentous structures of the elbow allowing the dislocation to occur.

The ulnohumeral articulation is the primary stabilizer of the elbow in the flexion-extension. The other primary stabilizers of the elbow are the lateral collateral ligament and medial collateral ligament. The lateral ulnar collateral ligament provides varus and posterolateral stability. The anterior bundle of the medial collateral ligament provides valgus and posteromedial stability. The secondary stabilizers of the elbow are the joint capsule, radial head, and the common flexor and extensor masses. The injury to the circle of soft tissue around the elbow (Horii circle) starts on the lateral side of the elbow and progresses to the medial side in three stages:

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Stage 1 involves injury to the lateral ulnar collateral ligament and results in posterolateral rotatory instability.

Stage 2 is comprised of Stage 1 as well as anterior and posterior capsule disruption.

In stage 3A, the lateral side of the elbow, anterior capsule, posterior capsule and posterior medial collateral ligament are disrupted. The anterior bundle of the medial collateral ligament is intact and the elbow pivots around this structure.

Stage 3B is when the entire medial collateral ligament complex is damaged.

Stage 3C is when the distal humerus is stripped of all soft tissue and the elbow is severely unstable and requires at least 90 degrees of flexion to maintain reduction.

Diagnostic Workup

The patient presents acutely with pain, swelling, decreased range of motion and a gross deformity of the elbow. A thorough neurovascular exam must be performed pre and post reduction. Neurologic injuries occur in 20% of dislocations and most commonly the ulnar nerve is affected due to a valgus stretching. An examination of the entire upper extremity should be performed and documented prior to any reduction maneuver as well as corresponding radiographs. Associated injuries occur in 12 – 15% of elbow dislocations. Most commonly the injuries occur on the same upper extremity and include distal radius fractures, perilunate dislocations and shoulder trauma. The forearm and wrist should be examined for tenderness at the interosseous membrane and instability of the distal radial ulnar joint to evaluate for an interosseous membrane injury (Essex-Lopresti variant).

Radiographs of the elbow including posteroanterior, lateral and oblique views should be evaluated for the direction of the dislocation and any associated fractures. Radiographs of the forearm and wrist should be obtained to evaluate for an injury at the distal radioulnar joint.

Non–Operative Management

Reduction can be performed in the emergency room with adequate muscular relaxation and pain medication using intramuscular or intravenous medications. If muscular relaxation is not obtained with the pain medication then conscious sedation can be performed in the emergency room. The reduction technique involves the patient in the supine position. Longitudinal traction is applied to the forearm with the forearm in a supinated and extended position. Counter traction is applied to the arm as the arm is brought from an extended to a flexed position. The goal is to clear the coronoid from the trochlea. To further facilitate reduction, firm pressure is applied posteriorly to the olecranon to direct it distally and anteriorly as the forearm is slowly flexed. The reduction is confirmed with an audible “clunk” or palpable reduction. After the elbow is reduced, the stable range of motion arc must be checked and noted. If the elbow requires more than 50 – 60 degrees of flexion to maintain reduction then the elbow is deemed unstable.

A post-reduction well-padded posterior splint should be applied to the elbow with the elbow placed in 90 degrees of flexion and full pronation. Pronation prevents posterolateral rotatory instability because the intact medial soft tissues are used as a fulcrum. Post-reduction radiographs of the elbow in two planes should be evaluated for joint congruency, joint widening and fractures. A true lateral radiograph of the elbow joint is key. If adequate radiographs are unable to be obtained then fluoroscopy or CT scan imaging can be used. Post-reduction a thorough neurovascular exam of the upper extremity must be performed. The patient should be reexamined in 5 – 7 days.

Valgus, varus and posterolateral rotatory instability should be assessed at each follow-up evaluation. Valgus and varus stress-testing are both performed when the elbow is in full extension and 30 degrees of flexion. When the elbow is flexed to 30 degrees the olecranon is unlocked from the olecranon fossa. The lateral pivot-shift maneuver is used to assess for posterolateral rotatory instability. The lateral pivot-shift maneuver is typically performed with the patient supine and the affected upper extremity placed in the overheard position with the shoulder flexed to 90 degrees and the forearm supinated. The elbow is then ranged from extension to flexion while a moderate valgus force is applied. The maneuver elicits apprehension, pain, or an audible or visible clunk as the radius subluxates when the elbow is extended and reduces when the elbow is flexed.

Simple elbow dislocations usually do not requireoperative intervention. There is no advantage of early collateralligament repair over early motion for simple elbow dislocations. Surgeryis indicated when the elbow is unstable on follow-up examination andrequires more than 40 degrees of flexion to maintain reduction.Recurrent instability in simple elbow dislocations occurs in less than 1- 2% of cases. Persistent instability of the elbow and jointincongruency post-reduction can indicate soft tissue interposed in thejoint and disruption of the medial and lateral collateral ligaments.

Surgical Technique

Instruments:

  • Bean bag

  • Sterile tourniquet

  • Bone foam

  • Fluoroscopy

  • Suture anchors

  • Hand instruments tray

  • Dynamic hinged external fixator

  • Hinged elbow brace

Positioning:

  • Lateral decubitus position with a bean bag. The operative arm is draped over bone foam or an arm holster.

  • Sterile tourniquet applied to operative upper extremity.

Incision:

  • Posterior midline incision with slight curve around the olecranon process directed towards radial side.

  • Develop lateral and medial full-thickness flaps.

Medial side:

  • Ulnar nerve identified and protected.

  • If patient has persistent ulnar neuropathy, then the ulnar nerve should be anteriorly transposed in either a subcutaneous or submuscular fashion.

  • Origin of flexor/pronator mass usually torn from medial epicondyle and disrupted medial collateral ligament is visualized deep to flexor/pronator mass.

  • Suture anchors placed in medial epicondyle and used to repair MCL and flexor/pronator mass.

Lateral side:

  • Extend the rent in the fascia created by the trauma.

  • If there is no obvious fascial rent then either the Kocher approach (between the anconeus and the extensor carpi ulnaris) or the Kaplan approach (between the extensor digitorum communis and extensor carpi radialis longus) can be utilized.

  • Lateral ulnar collateral ligament is usually torn from the lateral epicondyle.

  • Bone anchor placed in the lateral epicondyle and used to repair the LUCL and extensor mass.

Repair secure and elbow stable:

  • Check the stable elbow range of motion arc.

Soft tissue closure:

  • Repair fascia layers with figure of eight absorbable sutures.

  • Close skin layer with horizontal mattress 4-0 nylon sutures.

Immobilization:

  • Hinged elbow brace.

If the elbow is unstable after repair:

  • Apply dynamic hinged external fixator for 3 to 4 weeks.

Pearls and Pitfalls of Technique

Identify and protect ulnar nerve:

  • Repair lateral ulnar collateral ligament and medial collateral ligament.

  • Check stable range of motion arc after repair and apply adjunct dynamic external fixator if needed.

Potential Complications

Simple elbow dislocations rarely have late elbow instability and stiffness. Potential late complications include post-traumatic stiffness, heterotopic ossification, posterolateral rotatory instability and occult distal radioulnar joint instability. Immobilization of the elbow for more than 3 weeks is associated with a greater range of motion loss and worse outcomes. Most patients with simple elbow dislocations lose 5 – 15 degrees of terminal extension. Other rare complications include neurovascular injuries. A diminished pulse usually returns after joint reduction. Ulnar neuropraxia usually resolves with conservative management.

Post–operative Rehabilitation

If the simple elbow dislocation has a concentric and stable joint after closed reduction then it is splinted for 1 week. After 1 week the patient should begin active overhead range of motion exercises while in the supine position. If the elbow was stable post-reduction then there is no restriction on flexion and extension range of motion exercises. If the elbow was unstable after reduction in terminal extension, then the range of motion exercises is restricted to their stable range of motion arc. A hinged elbow brace with an extension block should be worn. The extension is gradually increased during the 3 – 6 week post-injury period. The patient should be evaluated weekly with elbow radiographs to monitor for subluxation or dislocation during the first 3 weeks. The patient can return to light duty use 2 weeks after injury. The elbow should not be immobilized for more than 3 weeks.

Outcomes/Evidence in the Literature

O’Driscoll, SW, Morrey, BF, Korinek, S, An, KN. “Elbow subluxation and dislocation: A spectrum of instability”. Clin Orthop Related Res. vol. 280. 1992. pp. 186-197. (Dislocation is the final of three sequential stages of elbow instability resulting from posterolateral rotation, with soft-tissue disruption progressing from lateral to medial – in each stage, the pathoanatomy correlated with the pattern and degree of instability. The mechanism of dislocation during a fall on the outstretched hand would involve the body "rotating internally" on the elbow, which experiences an external rotation/valgus moment as it flexes. Posterior dislocations should therefore be reduced in supination.)

Stoneback, JW, Owens, BD, Sykes, J, Athwal, GS, Pointer, L, Moriatis, Wolf J. “Incidence of Elbow Dislocations in the United States Population”. J Bone Joint Surg Am. vol. 94. 2012. pp. 240-245. (The estimated incidence of elbow dislocations in the U.S. population is 5.21 per 100,000 person-years, with use of a national database. Adolescent males are at highest risk for dislocation. Nearly half of acute elbow dislocations occurred in sports, with males at highest risk with football, and females at risk with gymnastics and skating activities.)

O’Driscoll, SW, Jupiter, JB, King, GJ, Hotchkiss, RN, Morrey, BF. “The unstable elbow”. Instr Course Lect. vol. 50. 2001. pp. 89-102. (Review article on the evaluation and management of the unstable elbow.)

Morrey, BF, Tanaka, S, An, KN. “Valgus instability of the elbow: A definition of primary and secondary constraints”. Clin Orthop Relat Res. vol. 265. 1991. pp. 187-195. (This study defines the medial collateral ligament (MCL) as the primary constraint of the elbow joint to valgus stress and the radial head as a secondary constraint. In the otherwise intact elbow, absence of the radial head does not significantly alter the three-dimensional characteristics of motion in the elbow joint. The comminuted radial head fracture uncomplicated by MCL insufficiency should be treated by excision without the need for an implant and without concern of altering the normal kinematics of the elbow.)

O’Driscoll, SW, Bell, DF, Morrey, BF. “Posterolateral rotatory instability of the elbow”. J Bone Joint Surg Am. vol. 73. 1991. pp. 440-446. (Describes the posterolateral rotatory-instability test involving supination of the forearm and application of a valgus moment and an axial compression force to the elbow while it is flexed from full extension.)

Dowdy, PA, Bain, GI, King, GJ, Patterson, SD. “The midline posterior elbow incision: An anatomical appraisal”. J Bone Joint Surg Br. vol. 77. 1995. pp. 696-699. (In 18 cadaver arms we made three standard 16 cm incisions in the skin medially, laterally, and posteriorly and explored them using loupe magnification assessing he number of nerves crossing each incision. Cutaneous nerves are at considerable risk of injury when medial or lateral incisions are used to approach the elbow, but the posterior approach carries less hazard.)

Coonrad, RW, Roush, TF, Major, NM, Basamania, CJ. “The drop sign, a radiographic warning sign of elbow instability”. J Shoulder Elbow Surg. vol. 14. 2005. pp. 312-317. (Pre- and post-reduction radiographs of 10 consecutive simple adult elbow dislocations were reviewed and compared with radiographs of 20 consecutive adult elbows without any trauma history. A statistically significant measured increase in static ulnohumeral distance was noted on the routine unstressed post-reduction lateral radiographs of patients sustaining dislocation – The Drop Sign.)

Mehihoff, TL, Noble, PC, Bennett, JB, Tullos, HS. “Simple dislocation of the elbow in the adult. Results after closed treatment”. J Bone Joint Surg Am. vol. 70. 1988. pp. 244-249. (The long-term results after treatment of simple dislocation of the elbow in 52 adults were evaluated with regard to limitation of motion, pain, instability, and residual neurovascular deficit. Despite the generally favorable prognosis for this injury, 60 per cent of the patients reported some symptoms on follow-up. Prolonged immobilization after injury was strongly associated with an unsatisfactory result.)

Cohen, MS, Hastings, H. “Acute elbow dislocation: evaluation and management”. J Am Acad Orthop Surg. vol. 6. 1998. pp. 15-23. (Review article on the evaluation and management of acute elbow dislocations.)

Kuhn, MA, Ross, G. “Acute elbow dislocations”. Orthop Clin North Am. vol. 39. 2008. pp. 155-161. (Review article on the evaluation and management of acute elbow dislocations.)

Josefsson, PO, Gentz, CF, Johnell, O, Wendeberg, B. “Surgical versus non-surgical treatment of ligamentous injuries following dislocation of the elbow joint: A prospective randomized study”. J Bone Joint Surg Am. vol. 69. 1987. pp. 605-608. (Thirty consecutive patients who had dislocation of the elbow without concomitant fracture were randomly assigned to undergo either non-surgical or surgical treatment of the ligamentous injuries. At follow-up, both groups showed generally good results; the differences were not statistically significant. There was no evidence that the results of surgical repair of the ligaments were any better than those of non-surgical treatment.)

O’Driscoll, SW, Morrey, BF, Sanchez-Sotelo, J. “Elbow Dislocations”. The Elbow and its Disorders. 2009. pp. 436-449. (Chapter on the evaluation and management of elbow dislocations.)

Summary

Simple elbow dislocations commonly occur and the majority of these can be treated with closed reduction, brief immobilization and early range of motion. Rarely, the elbow remains unstable after reduction and requires surgical intervention with repair of the medial and lateral collateral ligaments. The most common complication is post-traumatic stiffness. The majority of patients regain a functional range of motion arc; however, terminal elbow extension is commonly lost. Patient outcomes are better for simple elbow dislocations than complex elbow dislocations.

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