Total and partial dislocations of the kneecap generally occur as a result of a glancing blow to the front of the knee and are intensely painful. The kneecap is normally seen to lie on the outer side of the knee and often has to be pushed back. Occasionally an anaesthetic may be required to achieve this. the traditional treatment was plaster for 6 weeks but now it is considered better to get the knee moving as soon as possible after the injury. A splint may be worn for the first week or so until the swelling subsides then early active movement is encouraged. If a second dislocation occurs surgery may be required to repair the structures around the kneecap. Sometimes a piece of bone and cartilage is knocked off the kneecap in the injury (osteochondral fracture) and may become a loose body.
In some people the joint behind the kneecap does not develop fully or the leg may develop with a twist in it. Such people may suffer from recurrent dislocations and the treatment of such people may be more problematic and require realignment procedures of the kneecap.