What is a knee dislocation?
A knee dislocation is different and much more severe than a kneecap (patella) dislocation. A knee dislocation is a medical emergency due to the risk of injury to the nerves and blood vessels behind the knee that supply blood to the lower leg. The thigh bone (femur) completely disassociates from the shin bone (tibia). In order for this amount of instability to occur, multiple ligaments that stabilize the knee are torn and this results in significant dysfunction of the knee.
What are the causes?
The most common cause of a knee dislocation is a high-energy trauma (motor vehicle accident, being hit by a car, fall from height, etc.). Less common causes are collisions during sports, a lower energy twist or hyperextension of the knee.
What are the symptoms?
A knee dislocation results in immediate pain and inability to walk on the leg. Swelling, numbness, and tingling may occur depending on the extent of the injury.
How is it diagnosed?
Patients with these injuries are almost always initially managed by the emergency department due to the severity of the injury. The leg should be immediately reduced and stabilized, followed by X-rays to confirm that the knee is not still dislocated. Nerve and blood flow studies will be performed to evaluate potentially limb threatening injuries. MRI is performed to evaluate the cartilage and ligaments surrounding the knee. In most situations, the orthopedic surgeon will become involved at this point.
How is it treated?
Non-operative treatment is rare due to the severity of these injuries and the persistent dysfunction, instability, and pain that results without surgery. Even long term brace use and extensive physical therapy are often insufficient to provide a functional knee.
Immediate vascular surgery is indicated to repair a damaged blood vessel. Regarding the ligament repairs and reconstructions, Dr. Burrus often waits approximately 1-2 weeks to allow for some soft tissue healing. For some severe injuries, the knee may need multiple surgeries. Due to the complexity of these injuries, it is imperative to see someone trained and skilled at these knee surgeries.