Affecting both dogs and cats, patellar luxation is dislocation of the kneecap (patella). It is a complex part of their body, with bones, tendons and muscles all working in unison to keep the patella in the right place. If there is a malalignment in the bones above or below the knee, or an injury, then the patella can dislocate. This might be intermittent, causing the common scenario of an intermittent ‘skipping’ lameness. In more severe cases the patella may be permanently dislocated. Either way, the condition can cause discomfort and will predispose to osteoarthritis of the knee.

Patellar luxation is common in small breeds such as terriers and miniature poodles, but can also affect larger breeds such as Labradors. Most, but not all, cases will benefit from surgical stabilisation of the patella.

Patellar luxation is often considered a relatively straight-forward condition to correct by vets, but in order to minimise further damage to the knee and to maximise the chances of a good outcome it is important that the correct procedure is chosen and that it is executed well, which is not always straight-forward. Many patients are treated with a combination of procedures to deepen the groove the patella sits in (femoral trochlear sulcoplasty) and realign the patella tendon (tibial crest transposition). The latter procedure is particularly important to avoid recurrence, but is sometimes neglected. More complicated cases may require straightening (corrective osteotomy) of the femur (thigh bone) and/or the tibia (shin bone). Rarely, patients with severe damage to their femoral trochlear may need a femoral trochlear joint replacement. Choosing the right procedure for each patient requires experience and in some cases a CT scan.