The patella is located in the front of the knee joint, in the groove formed by the
femur and tibia bones, and is able to slide along the length of this groove. As a
result of trauma, lateral impacts or sliding outside the groove during an abnormal
movement or sudden twist or turn, the patella can become partially displaced,
resulting in subluxation, or fully displaced, causing dislocation.
Some factors such as patella femoral dysplasia, patella alta or trauma can
predispose to subluxation or dislocation, which can occur proximally or
mediolaterally, the latter being the most common.
By relaxing the quadriceps with the leg in extension, it is possible to achieve
reduction with relative ease.
Subluxations cause pain and functional disability, with the pain reduced in cases
of recurrent injury, although these episodes can damage the knee joint.
The same goes for patellar dislocations, in which the pain is greater and
incapacitating, and can be associated with damage to the cartilage or other tissue
in the joint itself.
The presence of oedema may be evident, in which case the patient should remain
at rest with the leg elevated.
The immediate application of cold compresses, ice packs or knee orthoses with
internal pockets designed for such a purpose can provide immediate relief by
Subsequent use of an open kneecap orthosis after reducing the dislocation
enables the patella to be centred and stabilised. Rehabilitation techniques to
strengthen the knee muscles, together with the use of a knee orthosis, will help
the patient to recover quickly, and it is advisable to continue using orthoses
during sport as a method of prevention, especially in recurrent dislocations.