Knee dislocation is when the bones that come together at the knee joint are thrust out of place with great force. It is very painful and an orthopaedic emergency.
The dislocation usually occurs as the result of a car accident or sports injuries when the knee is bent in an awkward position or over extended.
The area hurts considerably, the leg is swollen and sometimes can look out of place.
During such an injury it is possible to damage the blood vessels running behind the knee joint. The most important one to worry about is the Popliteal artery taking blood to the leg. If this is badly damaged, there is no blood going to the leg and the leg becomes ischaemic and at risk of needing an amputation.
Sometimes the blood vessel is not actually avulsed or transected but the bending damages its lining and clot develops within it having the same effect of reducing blood flow to the leg.
However, although this can occur, it is rare, occurring in about 3% of people who have a full dislocation of the knee. It is far more common in men than ladies, and in the age range 20-40 years old
Although the arteries can be damaged, in a lot of cases surgical intervention is not needed and the leg swelling only needs to be observed to ensure it remain fine. Of those who do have arterial damage, about 13% will need some form of surgical intervention.
The orthopaedic surgeon therefore keeps a very close eye on the blood supply to the leg after such an injury and usually requests a vascular surgeons opinion. There are a number of investigations which can be undertaken such as a Doppler ultrasound, CT angiogram or MRI.
If vascular surgery is needed, a bypass operation around the damaged vessel can be considered. Sometimes it is possible just to tack down the torn area. Only very rarely (<0/1%) does this result in an amputation at the knee.
If you would like any further information, please email me and I will be able to send you recent clinical papers on this.