Posterior Elbow Dislocation

Definition/Description

Posterior elbow dislocation (PED) occurs when the radius and ulna are forcefully driven posteriorly to the humerus.

Specifically, the olecranon process of the ulna moves into the olecranon fossa of the humerus and the trochlea of the humerus is displaced over the coronoid process of the ulna. PED is classified as simple or complex and staged according to severity.

Epidemiology /Etiology

In children under 10 years, PEDs are the most common type of joint dislocation. 

In adults, they are the second most commonly dislocated joint proceeded by shoulder dislocations.

Elbow dislocations annually affect between 6 and 7 people per 100,000. Approximately 90% of all elbow dislocations are directionally classified as posterior or posterolateral and are more commonly seen in the non-dominant upper limb. 

Typically, elbow dislocation is caused by a traumatic fall onto an outstretched hand resulting in an hyper-extension injury. However, more recent research has suggested that axial compression, elbow flexion, valgus stress, and forearm supination lead to a rotational displacement of the ulna on the distal humerus. 

Most commonly, the dislocation is associated with a damaged or torn anterior capsule.

Classification

PED can be classified as simple or complex.

1. A simple dislocation is classified as a dislocation without the presence of a fracture.
2. A complex dislocation has related fractures. 
   • Fractures may exist on the radial head, coronoid process, olecranon, humeral condyles, or capitellum. 
   • These fractures may lead to disruption of the medial collateral ligament (MCL), lateral collateral ligament (LCL), or interosseous membrane. 
   • 'Terrible triad' is a term used to describe a severe complex dislocation with intra-articular fractures of the radial head and coronoid process. Elbow dislocations are staged depending on the disruption of the following stabilizers: the ulnohumeral articulation, MCL, and LCL.

Characteristics/Clinical Presentation

The clinical presentation may include:

• Instability
• Popping sensation on immediate injury
• Pain
• Weakness
• Reduced AROM
• Swelling - the olecranon may be prominent creating a divot over distal triceps
• Joint line tenderness on palpation
• Recurrent dislocations can occur if a ligament injury is also sustained

Differential Diagnosis

To diagnose PED, radiographs in the anterior, posterior, and lateral views with valgus stress are obtained.

Table 1: below depicts other injuries that should be considered when suspecting PED.

Diagnosis	Cause	Examination Findings
Posterolateral Rotary Instability	Insufficiency of the ulnar LCL	Valgus instability Positive lateral pivot-shift test Recurrent dislocations
Associated Fracture	Traumatic forces through radial head, humeral condyles, coronoid process, olecranon, or capitellum	Radiographic diagnostics Tenderness over fracture sight. Positive Elbow Extension Sign
Compartment Syndrome	Fractures, swelling, casting, trauma	Pain out of proportion to the injury Absent pulse Pallor Paresthesia Paralysis
Complex Regional Pain Syndrome (CRPS)	Unknown	Persistent pain after injury, Swelling Hypersensitivity Change in skin colour/texture, Reduced ROM Weakness

Examination

Physiotherapy Examination

Physical therapy examination should include:

• Observation - specifically deformities
• Vascular screen - palpation of brachial, radial and ulnar arteries
• Neuromuscular screen - dermatomes, myotomes and reflexes including upper limb neuro-tension tests (if tolerated by patient)
• Palpation - It is essential to palpate for associated fractures in the elbow complex. The elbow extension sign can be used to rule out a fracture.
• ROM
• Muscle testing
• Ligament integrity tests - varus and valgus stress test, the lateral pivot-shift test/ apprehension test (Posterolateral Rotational Instability Test).

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Medical Management (current best evidence)

Before surgery is considered, research indicates reduction under local or general anesthesia as the primary treatment for PED. Patient presentation including elbow stiffness and pain are key factors when considering the need for surgery along with irreducible dislocation, gross instability, neurovascular injuries, and associated fractures. The most common surgical options include an open procedure, with or without Speed's procedure, and excision or closed arthroplasty.
                                         

An open procedure, more commonly seen in neglected PED < three months, involves ulnar nerve release, humeroulnar and humeroradial reduction, possible triceps lengthening using Speed's procedure, and wires and/or screws placed in the olecranon for stabilizing the joint. In the Elzohairy study, within two weeks the wires were removed and active motion was initiated, while the screws were removed six months after surgery. Excision arthroplasty is also used when patients present with neglected PED, but studies suggest high reoccurrences of pain and instability. In other studies, surgery was indicated only when concomitant fractures occurred with PED. Ligaments injured with fractures or dislocations are repaired via sutures attaching them back to the bone. Once surgery is complete, the patient is immobilized with time frames varying based on the individual and the surgeon's protocol. Hinged braces, fixators, plaster casts, and slings are utilized to keep the elbow in a position of approximately 70-80^o of flexion and slight pronation. Active movement is usually initiated between three to fourteen days, with slow, gradual supination. When treating a post-surgical PED patient, physical therapists should be cautious of pin site infection. A patient is able to return to functional activities around twelve weeks and sports around six months. While much of the research highlights general dislocation of the elbow with some positive outcomes following surgery, there is not enough evidence to support surgical interventions for PED. Also a disadvantage in studies that report positive outcomes post-surgery is the lack of comparison against non-surgical interventions, such as physical therapy.

Ligamentus repair can be indicated when frequent dislocations occur.

Radiographs are indicated when there is no response to care after four weeks of conservative treatment, significant activity restriction for more than four weeks, or non-mechanical pain is present. As with all patients, clinicians should be aware of red flags listed in Table 3 below.

Physical Therapy Management (current best evidence)

While nonsurgical treatment approaches to PED can vary depending on the level of tissue involvement, there are key elements to consider throughout the clinical decision-making process. PED can occur on a continuum of severity; therefore, the treatment must be diverse as well. Treatment can vary from aggressive immediate AROM to traditional plaster immobilization for several days. If a fracture occurs secondary to dislocation, intra-articular bone fragments and fracture position may dictate treatment. Closed or nonsurgical reduction by a physical therapist is only performed if there are no associated fractures. Uhl et al. described one technique for reduction: the patient hangs their affected arm over the back of a chair as the clinician tractions the ulna in a downward direction. After reduction of the joint, instability is evaluated. A splint should be applied and the patient should be referred for radiographs if the joint subluxes or dislocates while assessing instability. If left untreated (unreduced) patients may develop soft tissue contractures and localized osteoporosis.  The following clinical decision-making algorithm for immobilization and surgical options can be used following acute dislocations. 

File:Decision Model.jpg

Decision-Making Algorithm: Adapted from O’Driscoll SW, Jupiter JB, King GJW, Hotchkiss RN, Morrey BF. The unstable elbow. J Bone Joint Surg. 2000;82-A(5):724-738.

File:Sx Model.jpg

Surgical Treatment Algorithm: Adapted from O’Driscoll SW, Jupiter JB, King GJW, Hotchkiss RN, Morrey BF. The unstable elbow. J Bone Joint Surg. 2000;82-A(5):724-738.

Generally following reduction the patient is placed in a posterior splint at 45-90^o of elbow flexion for three days to three weeks. Evidence reveals detrimental effects of prolonged immobilization including flexion contractures, enhanced perception of pain, and increased duration of disability, all of which prolong the rehabilitation process. Throughout the immobilization phase, wrist and shoulder function should be maintained through ROM and strengthening exercises. Inflammation is a common sequela following PED and can be addressed using compression, ice, and effleurage. When the patient no longer requires immobilization, functional treatment begins with gentle AROM and PROM exercises in a pain-free range targeting the entire UE. Research by Haan et al. shows better outcomes when early rehabilitation is functionally-based and pain-free. Multi-angle isometric activities and Proprioceptive Neuromuscular Facilitation patterns for the elbow help decrease pain, increase ROM, and begin to target strengthening components in the preliminary stages of recovery. When pain is no longer a barrier to treatment, functional progressive resistance exercises should be implemented to improve total UE muscle strength and endurance. Although full extension should be a goal of rehabilitation, care must be taken to protect the vulnerable elbow and avoid hyperextension. It is important to be cautious during passive mobilization and ROM. Multiple articles have warned that aggressive PROM (especially into extension) and forceful manipulation may cause myositis ossificans and should be avoided. Also, Uhl et al. suggested that any valgus stress applied to the elbow should be avoided throughout treatment so not to stress the already compromised tissues. Therapeutic goals in the later phase of rehabilitation include attaining full ROM and strength capabilities of the entire affected arm, suppression of pain, and restoration of functional abilities to pre-injury level.

 

Key Research

Haan et al. analyzed treatments for simple elbow dislocations. Included were two RCTs and three observational comparative studies with 342 patients available for follow-up. Between surgical repair of the collateral ligaments and plaster immobilization, no differences were found. Functional treatment provided better functional scores and ROM, shorter treatment and disability, and less pain, when compared to immobilization.

Maripuri et al. found that early mobilization with sling application and physical therapy resulted in better functional outcomes, including higher MEPI scores and lower DASH scores, compared to 14 day plaster of Paris immobilization followed by physical therapy.

Resources

American Academy of Orthopedic Surgeons

eMedicine

Postero-lateral Elbow Instability

Clinical Bottom Line

Since the elbow joint is one of the most commonly dislocated joints, it is imperative that physical therapists are aware of its complications and the best evidence for treatment. It is important to explore the level of severity and degree of complication associated with each PED since this dictates the patients' prognoses. Patients who have had simple PED with early reduction usually have good outcomes. In most cases, there is potential for developing instability and degenerative joint disease. Overall the best treatment for PED is initial short term restricted motion (usually two weeks or less) followed by early mobilization including PROM and progressing to AROM and functional strengthening. Long duration plaster of Paris immobilization has been show to have poorer functional outcomes.