Dr. Carlos Rebollón
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Knee dislocation, despite not occurring easily, is considered an emergency because if the arteries or nerves are affected during the dislocation, blood flow to the limb can also be interrupted, risking amputation.
Below, we will provide you with all the details about this injury, how it is classified, its symptoms, and how to treat it…
What is knee dislocation?
Knee dislocation occurs when the bones that form part of the tibiofemoral joint (femur and tibia) undergo a displacement that causes them to lose their natural alignment. Generally, knee dislocation occurs due to a blunt trauma or by forcing the knee into a position that exceeds its limits.
In many cases, knee dislocation causes damage to ligaments, tendons, nerves, and arteries, so doctors must act correctly to restore blood supply and attempt to regain the support and stability the joint needs to perform its functions.
When the problem is not treated promptly or when the treatment applied is inadequate, the consequences can be severe (amputation, permanent instability, dysfunctionality, etc.), which is why we emphasize the importance of seeking immediate medical attention after experiencing a knee dislocation.
Types of knee dislocations
Knee dislocations are classified based on the type of displacement the knee bones have experienced and are as follows:
Anterior dislocation is the most common type (around 40% of cases are of this type) and mainly occurs due to hyperextension of the knee.
It is the result of a direct anteroposterior force on the tibia while the knee remains flexed, causing the tibia to be displaced behind the femur. Posterior dislocation, along with anterior dislocation, poses the greatest risk of arterial damage.
Lateral and medial dislocation
Less frequent, these dislocations are mainly the result of varus or valgus forces.
Symptoms of Knee Dislocation
When a knee dislocates, a cracking or popping sound is often heard at the moment of dislocation. Other characteristic symptoms include:
The limb may also appear pale and numb, indicating the presence of internal arterial or nerve injury, further worsening the patient’s condition.
Since most knee dislocations result from a traumatic event, it is crucial to seek emergency care as soon as possible to avoid severe or permanent damage. Generally, the doctor examines the joint to check for signs of knee dislocation. Additionally, some X-rays will be taken to confirm the diagnosis and rule out fractures.
If there are suspicions of arterial damage, a computed tomography angiography may be performed to assess the current condition of the arteries and nerves. If the examination confirms that the tissues are not receiving sufficient blood, surgical options will be evaluated to quickly repair the damage.
It is worth noting that if the limb loses blood and receives inadequate oxygen for more than 7 or 8 hours, the chances of amputation increase by over 90%.
Causes of knee dislocation
Knee dislocations can occur due to various reasons, including:
Treatments for Knee Dislocation
The treatment generally depends on the severity of the injury. The procedures used in these cases include:
Reduction and immobilization
If the joint damage is mild, the doctor will perform closed reduction maneuvers to put the bones back in place. These maneuvers can be especially painful, so sedatives or analgesics may be administered to make the pain more tolerable. After reduction, it is common to immobilize the area with a splint to promote healing and prevent movement for several weeks.
Surgery should be employed immediately if there is arterial damage. On the other hand, if the arteries were not affected by the injury, surgical intervention to repair any fractures, tears, or sprains can be postponed for a couple of weeks to reduce swelling.
Physical therapy is crucial to regain full mobility of the joint after a knee dislocation.
Knee dislocation causes severe soft tissue damage; therefore, to ensure a return to normal joint function, the patient must go through various stages of recovery.
After surgery, there will be a period of immobilization with orthopedic devices or braces while the tissues heal. Subsequently, physical therapy will aid in rehabilitating the knee. Physical therapy exercises focus on strengthening the muscles in the limb, especially those around the knee, to restore full range of joint mobility.
As mentioned before, the rehabilitation time varies for each person depending on the severity of the injury and the treatment received. However, it can be anticipated that total knee rehabilitation in some cases may take up to 1 year.