Knee Dislocations - Everything You Need To Know - Dr. Nabil Ebraheim

Educational video describing the types and treatment available for knee dislocations and possible vascular or nerve injuries.
The knee joint allows for flexion and extension. These functions allow the body to perform activities like walking, running and sitting.
Knee dislocations occur as a result of violent trauma. The femur and tibia are not articulating with each other.
The bones of the knee are held together by strong ligaments. For a knee dislocation to occur, 3 out of 4 of these ligaments have to become ruptured.
Types of knee joint dislocations:
•Anterior
•Posterior
•Medial-lateral
•Rotary: usually posterolateral. The medial femoral condyle can button-hole through the medial soft tissues resulting in a “dimple sign”. It is often irreducible.
Posterior dislocation/ dashboard injury
Most common mechanism of injury includes exaggerated hyperextension of the knee and dashboard injuries. Posteriorly directed force with the knee flexed in 90 degrees.
The peroneal nerve is tethered at the fibular neck. The incidence of nerve injury ranges from 14% to 35%.
Arterial injury
•Vascular damage is most common in anterior and posterior dislocations in approximately 40% of the cases. Arterial damage in approximately 20-40% of all knee dislocations. Knee dislocation is associated with a high incidence of popliteal artery injury.
•With an established popliteal artery and resultant ischemia, blood flow must be restored within 6 hours.
•Posterior tibial and dorsalis pedis pulses should be carefully evaluated and compared to the other side in any patient with a knee dislocation.
•Look for any evidence of ischemia, diminished blood flow, or compartment syndrome.
•Urgent reduction of the knee dislocation is mandatory
•Be aware of spontaneously reduced knee dislocations and its associated pathology.
•Reevaluate circulation after reduction, if pulses are normal, serial follow-up up to 48 hours with clinical examination and non-invasive studies (ABI). If ABI is 0.9 or more, then the patient will not have an arterial injury. If pulses are abnormal or different, do arteriography. If no pulses then do an immediate exploration in the OR.
Treatment
•Arterial injury is treated with excision of the damaged segment and reanastmosis with a reverse saphenous vein graft and prophylactic fasciotomy.
•Early surgery if ligament avulsion is present- important ligament to reconstruct is the PCL- if posterolateral corner disruption.
•After reduction, the patient is placed into a knee immobilizer or external fixator.
•Delayed elective reconstruction of the knee ligaments is usually done at a later date.
•The PCL is an important ligament to reconstruct.