Dislocation of the knee

The more common types (remember this is a rare condition) are anterior knee dislocation and posterior knee dislocation.

Anterior dislocation may be the result of forceful hyper-extension - bending the knee the wrong way. The lower leg bones (tibia and fibula) are dislocated forwards. Posterior dislocation may follow a severe sudden force on the lower legs when the knee is bent - eg. a dashboard injury in a car impact.

The more straightforward dislocations like the two above can be reduced often by pulling the legs downward from the thighs, of course after adequate pain relief and muscle relaxation. If there are no pulses, reduction is generally attempted immediately without delaying for X-rays. More complicated dislocations may require open reduction in the operating theatre (OR).

Blood vessels and nerves are at extreme risk and it is generally considered extremely important to order an angiogram as early as possible after reduction to check the arterial supply. Soft tissue damage, eg ligaments, are likely to require surgery once the immediate problem is over.