Worst case scenario, when the ball of the femur pops back into the socket of the hip it can (if you're very unlucky) cause damage to the blood flow around the end of the femur and kill the bone around it. Chronic pain in the hip can result, but with good care and a little luck they can make a full recovery. Best of luck to them!
I take it that's what you meant when the femur dislocated? At the hip, or was it at the knee end?
From what I remember Lawrence has had problems with the hamstring which has been limiting his stride more than anything relating directly to the hip.