A Posterior Elbow Dislocation often occurs when a person falls on an outstretched hand, posteriorly directed force at the elbow joint causes dislocation at the ulnohumeral and radiocapitellar articulations. Valgus force may induce the commonly seen posterolateral elbow dislocation. [rx][rx][rx] Anterior elbow dislocations occur when the elbow is flexed, and there is a direct blow on the posterior aspect of the elbow.
Pathophysiology
Considering elbow anatomy and the likely mechanism of injury causing an elbow dislocation can help one understand the pathophysiology associated with this particular injury. During a posterior elbow dislocation, the shearing forces causing the injury may cause associated radial head, radial neck or coronoid process fractures. The medial collateral and lateral collateral ligaments provide support to the elbow joint in addition to its bony anatomy. The LCL is often disrupted when an elbow dislocation occurs; the MCL is the last soft tissue structure injured as the ulna is displaced. Often, the flexor-pronator mass may be ruptured, and occasionally the brachialis may be injured.
The anterior compartment of the elbow encompasses the brachial artery and ulnar and median nerves. These structures are particularly vulnerable to injury because the anterior compartment is often disrupted during posterior dislocation. The ulnar nerve may become entrapped as it passes posteriorly around the medial epicondyle. The brachial artery and median nerve travel closely to one another and injuries are often seen in both these structures simultaneously.
Anterior dislocations are often associated with olecranon fractures. These dislocations may also disrupt the posterior elbow compartment which contains the radial nerve and insertion of the triceps muscle.
Causes Of Posterior Elbow Dislocation
In general, elbow trauma can subdivide into the following categories:
Traumatic injuries
- Soft tissue injuries range from mild, superficial soft tissue injuries (e.g., simple contusions, strains, or sprains) to traumatic arthrotomies following gunshot wounds or penetrating lacerations
- The osseoligamentous spectrum of injury encompasses fractures, fracture-dislocations, ligamentous injuries, and simple versus complex dislocation patterns
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“Simple” referring to no associated fracture accompanying the dislocation
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“Complex” refers to an associated fracture accompanying the dislocation
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Terrible triad elbow injuries
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Elbow dislocation – Typically posterolateral direction with associated LCL complex injury. Elbow dislocation is the two most common dislocated joint after the shoulder – most are posterior dislocations
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A radial head/neck fracture
- Coronoid fracture
- Attritional injuries – Encompasses subacute or chronic presentations following various repetitive motion mechanisms
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Often seen in athletes involved in any upper extremity sport-related activity requiring repetitive motions (e.g., overhead throwers/baseball pitchers, tennis)
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Manual laborers with analogous occupational repetitive demands
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Traumatic injuries
- Traumatic injuries range from simple contusions to more complex osseoligamentous fracture-dislocation patterns. The latter is often seen following a fall on an outstretched hand while the forearm is supinated and the elbow is either partially flexed or fully extended
Attritional injuries
- Another form of elbow injuries consists of the subacute-to-chronic variety that occurs secondary to repetitive motions, eventually leading to various tendinosis conditions. These can include but are not limited to, lateral epicondylitis (tennis elbow), and chronic partial UCL injuries or strains.[rx][rx]
Pediatric considerations
- Elbow trauma in children most commonly occurs via sport or following falls. Moreover, careful attention during the assessment is necessary, given the characteristic sequence of ossification center appearance and fusion, which can make the radiographic assessment rather challenging. Commonly encountered pediatric elbow fractures include (but are not limited to)[rx]
Supracondylar fractures
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Most common in children peak ages 5 to 10 years, rarely occurs at greater than 15 years
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Extension type (98%) – fall on an outstretched hand with fully extended or hyperextended armType 1: minimal or no displacement type 2: slightly displaced fracture, posterior cortex intact type 3: totally displaced fracture, the posterior cortex is broken.
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Flexion type – blow directly to a flexed elbowType 1: minimal or no displacement type 2: slightly displaced fracture, anterior cortex intact type 3: totally displaced fracture, the anterior cortex is broken
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Lateral condyle fractures
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Medial epicondyle fractures
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Radial head and neck fractures – Usually indirect mechanism (such as fall on an outstretched hand), and the radial head being driven into capitellum
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Olecranon fractures
Another common elbow injury in children
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Subluxated radial head (nursemaid’s elbow)
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Accounts for 20% of all upper extremity injuries in children
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Peak age 1 to 4 years; occurs more frequently in females than males
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Mechanism of injury: sudden longitudinal pull on the forearm with forearm pronated
Signs And Symptoms Of Posterior Elbow Dislocation
Symptoms include:
- The child stops using the arm, which is held in extension (or slightly bent) and palm down.[6]
- Minimal swelling.
- All movements are permitted except supination.
- Pain on the outer part of the elbow (lateral epicondyle)
- Point tenderness over the lateral epicondyle—a prominent part of the bone on the outside of the elbow
- Pain from gripping and movements of the wrist, especially wrist extension (e.g. turning a screwdriver) and lifting movements[rx]
- Sudden intense pain at the back of the elbow will be felt at the time of injury.
- The patient will in most cases be unable to straighten the elbow.
- Rapid swelling and bruising may start to appear. Trying to move the elbow will be painful and the back of the elbow will be very tender to touch.
- Caused by longitudinal traction with the wrist in pronation, although in a series only 51% of people were reported to have this mechanism, with 22% reporting falls, and patients less than 6 months of age noted to have the injury after rolling over in bed.
- Symptoms include pain and tenderness on the inside of the elbow. Bruising and swelling may be present for more severe injuries.
- Impact injuries causing damage to the medial ligament usually involves a lateral force (towards the outside) being applied to the forearm, placing the medial (inner) joint under stress.
- The patient presents with swelling over the lateral elbow with a limited range of motion, particularly forearm rotation and elbow extension ± elbow effusion and bruising. Pain is increased with passive rotation.
- The most reliable clinical sign is point tenderness over the radial head.
- Needs careful assessment for nerve and vascular involvement, especially with brachial artery, median and ulnar nerves.
- It is important to detect crepitation or a mechanical blockage of motion from displaced fracture fragments. This often requires aspiration of a haemarthrosis with the installation of local anesthetic for pain relief.
- If there is significant wrist pain and/or central forearm pain, there may be acute longitudinal radioulnar dissociation with disruption of the distal radioulnar joint.
- Overuse injuries of the MCL may also occur. Repetitive motions that place a lot of stress on the inner elbow can cause damage to the ligament. For example, throwers (track and field and ball sports such as baseball) are prone to this injury. Especially if the technique is poor!
Diagnosis Of Posterior Elbow Dislocation
History
All patients experiencing traumatic injury should first be assessed head to toe for any life or limb threatening injuries first. Obvious bony deformities may distract both the patient and the practitioner from more serious traumatic injuries. After the patient has been cleared of other significant injuries, attention can be turned to the affected extremity.
The initial history should consist of the mechanism of injury and the duration of the injury until initial presentation. The patient should be asked if this is a first-time occurrence or if there have been previous elbow injuries in the past. A physician should review associated symptoms suggesting a neurovascular compromise and inquire about numbness, tingling or coolness of the distal extremity.
The physical examination should begin with an inspection of the elbow joint looking for swelling, deformity or bruising. Posterior elbow dislocations often present with an upper extremity that is flexed and appears shortened. Anterior elbow dislocations are held in extension, and the upper extremity appears elongated. Specific attention should be paid to looking for open wounds which would suggest a complex dislocation. The functionality of the elbow joint should be assessed by observing a range of motion. It is also important to evaluate the remainder of the affected extremity and nearby joints for associated injury. Particular attention should be paid to the distal radioulnar joint for tenderness which can indicate disruption of the intraosseous ligament, eponymously referred to as an Essex-Lopresti lesion.
Physical Examination
The examiner should perform and document relevant findings, including:
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Skin integrity
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Critical when assessing for the presence of an open fracture and/or traumatic arthrotomy
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Presence of swelling or effusion
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Comprehensive neurovascular examination
How the patient carries their arm may give clues to the diagnosis.
Bony Injuries
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Supracondylar fracture
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Flexion type
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Patient supports injured forearm with other arm and elbow in 90º flexion
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Loss of olecranon prominence
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Extension type
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Patient hold arm at side in S-type configuration
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Soft Tissue Injuries
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Elbow dislocations:
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Posterior: abnormal prominence of olecranon
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Anterior: loss of olecranon prominence
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Radial head subluxation
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Elbow slightly flexed and forearm pronated resists moving the arm at the elbow
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Sensory And Motor Testing Of The Median And Ulnar Nerves
Median
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Test for sensory function
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Two-point discrimination over the tip of the index finger.
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Test for motor function
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“OK” sign with thumb and index finger and abduction of the thumb (recurrent branch)
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Ulnar
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Test for sensory function
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Two-point discrimination of the little finger
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Test for motor function
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Abduct index finger against resistance
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Compartment Syndrome
Acute compartment syndrome can usually develop over a few hours after a serious injury. Some symptoms of acute compartment syndrome are:
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A new persistent deep pain
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Pain that seems greater than expected for the severity of the injury
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Numbness and tingling in the limb
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Swelling, tightness and bruising
Radiological Test
Radiographic studies that are necessary for all patients presenting with varying degrees of elbow trauma include:
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Anteroposterior (AP) elbow
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Lateral elbow
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Oblique views (optional, depending on fracture/injury)
- Traction view (optional, can facilitate the assessment of comminuted fracture patterns)
- Ipsilateral shoulder to wrist orthogonal views
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Especially in the setting of high energy trauma or when exam and evaluation are limited
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- Fat pad sign
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Seen with intra-articular injuries
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Normally, anterior fat pad is a narrow radiolucent strip anterior to humerus
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The posterior fat pad is normally not visible
- Anterior fat pad sign indicates joint effusion/ injury when raised and becomes more perpendicular to the anterior humeral cortex (sail sign)
- Posterior fat pad sign indicates effusion/injury
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In adults, posterior fat pad sign without other obvious fracture implies radial head fracture
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In children, it implies supracondylar fracture
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Pediatric Considerations
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Fractures in children often occur through unossified cartilage, making radiographic interpretation confusing
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A line of mensuration drawn down the anterior surface of the humerus should always bisect the capitellum in lateral view.
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If any bony relationship appears questionable on radiographs, obtain a comparison view of uninvolved elbow.
- Suspect nonaccidental trauma if history does not tip injury.
- Ossification centers: 1 appear: (CRITOE)
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Capitellum 3 to 6 months
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Radial head 3 to 5 years
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Medial (Internal) epicondyle 5 to 7 years
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Trochlea 9 to 10 years
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Olecranon 9 to 10 years
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Lateral Epicondyle
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It is essential to do bilateral radiographic imaging in pediatric cases.
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A nurse’s elbow can reduce spontaneously when the patient supinates the arm.
Advanced Imaging Sequences
Computerized tomography (CT) scans are often a consideration in the setting of comminuted fracture patterns for pre-operative surgical planning. Magnetic resonance imaging (MRI) can be an option in the setting of soft tissue and ligamentous injury evaluation, or when suspecting stress or occult fractures.[rx][rx][rx]
Treatment of Posterior Elbow Dislocation
Initial treatment of simple, closed posterior elbow dislocations is a closed reduction. Some complex elbow dislocations may initially be treated with closed reductions; however, associated fracture implies significant soft tissue damage and likely persistent instability which may require open reduction and internal fixation to improve outcomes. Open dislocations will require extensive washout during an open reduction. Any dislocation with signs of neurovascular compromise requires immediate closed reduction.[rx][rx]
Doctors sometimes recommend very different treatments for both tennis elbow and golfer’s elbow. According to the studies done so far, the following treatments can help:
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Rest, ice
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Physical therapy when appropriate – Eccentric exercises for lateral epicondylitis
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Braces/bandages – These are worn around the elbow or on the forearm to take the strain off the muscles.
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Injections – Injections into the elbow with various substances, such as Botox, hyaluronic acid or autologous blood (the body’s own blood).
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Extracorporeal shockwave therapy (ESWT) – A device generates shock or pressure waves that are transferred to the tissue through the skin. This is supposed to improve the circulation of blood in the tissue and speed up the healing process.
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Laser therapy – The tissue is treated with concentrated beams of light. This is supposed to stimulate the circulation of blood and the body’s cell metabolism.
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Stretching and strengthening exercises: Special exercises that stretch and strengthen the muscles of the arm and wrist.
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Manual therapy – This includes active and passive exercises, as well as massages.
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Ultrasound therapy – The arm is exposed to high-frequency sound waves. This warms the tissue, which improves the circulation of blood.
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Transcutaneous electrical nerve stimulation (TENS) – TENS devices transfer electrical impulses to the nervous system through the skin. These are supposed to keep the pain signals from reaching the brain.
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Acupuncture – The acupuncture needles are inserted into certain points on the surface of the arm. Here, too, the aim is to minimize the perception of pain.
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Cold – The elbow is regularly cooled with ice packs.
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Massages –A massage technique called “transverse friction massage” is often used to treat tennis elbow and golfer’s elbow. It is applied to the tendons and the muscles, using the tips of one or two fingers.
Medication
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Conscious sedation is often necessary to achieve reductions
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Painkillers – especially non-steroidal anti-inflammatory drugs (NSAIDs).
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Injections – Steroid injections.
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Ibuprofen – 600 to 800 mg (pediatric: 5 to 10 mg/kg) PO TID
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Naprosyn – 250 to 500 mg (pediatric: 10 to 20 mg/kg) PO BID
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Tylenol with codeine – 1 or 2 tabs (pediatric 0.5 to 1 mg/kg codeine) PO: do not exceed acetaminophen 4g/24 hours
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Morphine sulfate – 0.1 mg/kg IV
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Hydromorphone 5 mg/acetaminophen 300mg
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Hydrocodone/acetaminophen – 1 to 2 tabs PO
Attritional injuries management modalities
Most of these injections contain one of the following active ingredients. These include but are not limited to[rx][rx][rx]:
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Corticosteroid injection – when applicable
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Platelet-rich plasma (PRP) considerations – 2016 study noted efficacy in managing UCL insufficiency
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Steroids: reduce inflammation. Studies show that steroid injections can temporarily relieve pain. But there is also evidence that they can disrupt the healing process: People who were first given several steroid injections had more pain after a few months than people who didn’t receive any steroid injections. Frequent steroid injections carry the risk of tissue dying (atrophy), for instance, leaving a visible mark on the elbow.
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Hyaluronic acid – A substance made by the body, found in tissue and joints. It is typically used to treat osteoarthritis. One study suggests that hyaluronic acid might be effective in the treatment of tennis elbow. But further research is needed to assess its pros and cons.
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Botox – inhibits the sending of signals between the nerve cells. This has a paralyzing effect on the muscles. According to studies done on this so far, Botox can relieve the pain just a little at most. Also, Botox injections can have side effects like partial paralysis in the fingers that can last several weeks.
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Autologous blood injections – Blood is taken from a vein in the arm and then injected into the elbow. This blood may be treated in different ways before it is injected. One common form of treatment with autologous blood is called platelet-rich plasma (PRP) therapy. It involves separating the blood into its various elements in a centrifuge. Then a concentrated solution of blood platelets is injected into the elbow. There is no evidence that treatment using autologous blood is effective.
Surgery Technique or Approaches to the Reduction
There are two common approaches to the reduction of a posterior elbow dislocation. It is recommended the first technique is attempted in the prone position. With the patient laying down the affected arm is abducted with an elbow on the edge of the cart. The wrist is then grasped and the forearm placed in slight supination while gentle traction is applied. The coronoid process must be distracted and disengaged from the olecranon fossa. Once this has been accomplished downward pressure with the other hand on the olecranon should reduce the dislocation with the operator feeling a confirmatory clunk. A two-person technique is also described where one operator applies downward traction at the wrist, and other applies the downward force onto the olecranon with both their thumbs.
The alternative method is performed with the patient seated or lying supine on the cart. An assistant stabilizes the affected humerus while the operator flexes the elbow, supinates the wrist slightly and applies distal and downward traction at the wrist with one hand. The other hand is placed just distal to the elbow on the volar aspect of the forearm applying slow, gentle inline traction until the confirmatory clunk is appreciated.
Following reduction of the dislocation, a neurovascular examination should be performed to identify improvement in any previous neurovascular symptom or a new symptom that may have manifested following the reduction. The elbow should be held in 90 degrees of flexion for 5 to 10 days followed by an active range of motion. Earlier range of motion has demonstrated better physical outcomes. Dislocations that appear more unstable may require up to 3 weeks of splinting and a specific range of motion plan. Post-reduction films should be obtained.
References
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