What is Posterior Elbow Dislocation?
The elbow joint is generally sturdy, but dislocations, or when the joint slips out of place, are quite frequent. Typically, these injuries occur during sports when someone falls on an outstretched elbow. Usually, a particular part of the ulna bone (semilunar notch) in the elbow moves backwards away from the lower part of the upper arm bone (distal humerus). If the dislocation happens without any associated bone breakage, it’s known as a ‘simple’ dislocation. These types of injuries frequently do not break the skin and do not have any bones sticking out.
Because the structure of the elbow joint is fairly solid, it takes a lot of force to dislocate it. As such, a bone fracture might sometimes accompany a dislocated elbow, making it a ‘complex’ dislocation. Complications involving nerves or blood vessels are rare from simple, closed, posterior (backwards) dislocations. The less common forward (anterior) dislocation of the elbow requires even more force to occur. In such cases, there is usually a higher concern for issues involving nerves or blood vessels. A dislocated elbow requires immediate repositioning to prevent further complications. If the elbow dislocates repeatedly, it indicates a persistent instability of the joint, which might require surgical intervention.
What Causes Posterior Elbow Dislocation?
A posterior elbow dislocation typically happens when someone falls on an outstretched hand. The force directed at the back of the elbow joint can cause a dislocation at the points where the ulna and humerus bones, and the radius and capitellum bones meet. If the arm is twisted outward while under stress, it can commonly lead to a dislocation to the back and side of the elbow.
On the other hand, anterior elbow dislocations take place when the elbow is bent, and a direct hit occurs on the back side of the elbow.
Risk Factors and Frequency for Posterior Elbow Dislocation
Elbow dislocation is a frequent injury, especially among children and young adults. It is the most common joint dislocation seen in kids and the second most common in adults. Each year, there are 6 to 13 cases of elbow dislocation for every 100,000 people. This injury is particularly common in male athletes during their adolescence, with high school football and wrestling participants being especially at risk. Most elbow dislocations (about 90%) involve the back part of the elbow.
Signs and Symptoms of Posterior Elbow Dislocation
When a person has a traumatic injury, the first step is to check from head to toe for any injuries that might be immediately life-threatening or could cause serious harm to a limb. Sometimes, visible bone injuries can distract from more serious, hidden damage. After ensuring there aren’t any other serious injuries, the focus can shift to the injured area.
The doctor will need to know how the injury happened and how long it has been since the injury occurred. They will ask if the person has previously injured their elbow, and if they’ve been experiencing any symptoms that could indicate damage to nerves or blood vessels, like numbness, tingling, or a cool feeling in the hand or lower arm.
The physical examination will start with a look at the elbow for signs of swelling, misshapenness, or bruising. Depending on whether the elbow has been dislocated forwards or backwards, the arm might appear either shorter or longer than usual. It’s also important to check for any open wounds, which could suggest a more complex injury. The doctor will check how well the elbow can move and examine the rest of the arm and nearby joints for any additional injuries. Certain points, such as the joint between two of the forearm bones, will be checked specifically for any signs of pain which could indicate particular types of injury.
Nerve or blood damage is a common complication of elbow dislocations, usually affecting the brachial artery and the ulnar and median nerves. The doctor can check blood flow by feeling the pulses at the wrist and testing how quickly blood re-fills in the fingertips after being squeezed out. Sensation and motor function in the hands are tested by touching certain areas and testing grip strength. The doctor should also be alert to any signs of ‘compartment syndrome,’ a potentially serious condition where pressure within the muscles can cause major tissue damage.
Testing for Posterior Elbow Dislocation
If you think you’ve dislocated your elbow, the first steps in evaluating it will usually involve X-rays from both the front or back (anterior-posterior) and side (lateral) of your elbow. These images help the doctor to check the alignment of the joint and look for any fractures. If the injuries around your joint (periarticular fractures) are difficult to see, special angled (oblique) views may be more helpful.
Sometimes, if the injury seems particularly complicated or if some fractures are not clear on the X-rays, a computed tomography scan (more commonly known as a CT scan) may be considered. This type of imaging is more detailed and can capture injuries that are difficult to identify on regular radiographs.
After your elbow has been manipulated or treated, you should have X-rays again. This is done to ensure that the treatment was successful and the elbow has been properly realigned. Checking the alignment of the radio-capitellar joint (a specific part of the elbow) can help the doctors determine whether your elbow has been adequately restored.
Treatment Options for Posterior Elbow Dislocation
The initial treatment for a simple elbow dislocation, where the joint surfaces get separated, involves a procedure called closed reduction. This means that the elbow is repositioned without the need for surgery. However, in the case of complex elbow dislocations, which often involve fractures and significant tissue damage, the initial treatment can be the same, but they might eventually require surgical intervention for better results. This is because such injuries might cause the joint to remain instable even after the closed reduction. Open dislocations, where the joint is completely visible, would require thorough cleaning (washout) during surgery. It’s crucial to act immediately if the dislocation is accompanied with signs of compromised blood flow or nerve function (neurovascular compromise), as these require immediate closed reduction.
There are two main ways to perform the closed reduction procedure for a dislocated elbow. The first technique suggests that the patient lies prone (face down). The practitioner then holds the patient’s wrist and lifts the arm slightly while gently pulling. This allows a bone (the coronoid process) to become dislodged from the elbow joint indentation (the olecranon fossa). When this is achieved, pressure is applied downward on the elbow, which should reset the dislocation—a sensation described as a confirmatory ‘clunk’. This method may sometimes require two people, one to apply traction at the wrist and the other to apply downward force onto the elbow.
The other technique can be done with the patient sitting or lying on their back. An assistant holds the affected upper arm stable, while the doctor bends the elbow, slightly turns the hand, and applies force downward at the wrist. The doctor uses the other hand to pull slowly and gently along the forearm, until the joint is back in place, indicated by a ‘clunk’ sound.
After the elbow is reset, the doctor should check again for nerve function and blood flow to ensure there are no new symptoms which may have arisen during the procedure. The elbow should then remain bent at a 90-degree angle for the next 5 to 10 days, after which the patient can gradually start moving the joint. Starting movement earlier can lead to better healing. For dislocations that seem unstable, a splint might be necessary for up to 3 weeks, along with a specific motion plan. Lastly, X-rays should be taken after the procedure to confirm that the elbow has returned to its proper position.
What else can Posterior Elbow Dislocation be?
If you’re experiencing discomfort and swelling in your elbow, your doctor might consider several possible causes:
- Olecranon bursitis, an inflammation of the small sac of fluid (bursa) located on the tip of your elbow
- Olecranon stress fracture, a type of broken bone caused by repetitive stress
- Osteoarthritis, a condition that can cause your joints to become painful and stiff
- Posterior impingement, a pinch or squeeze of tissues at the back of your elbow
- Tricep tendinopathy, an issue with the tendon that connects the muscles on the back of your arm to your elbow
Through a thorough examination and possibly some tests, your doctor will be able to tell which of these conditions might be causing your elbow problem.
