The patella is the medical term for the knee cap. It is located in a bony groove (called the trochlear groove) which lies in the lower end of the femur (thigh bone). In a normal animal, the patella slides smoothly along the groove during flexion and extension of the knee.

Medial patellar luxation (MPL) is the condition where the patella displaces (or luxates) towards the inside of the leg from the groove, temporarily or permanently. The patella can also luxate laterally (towards the outside of the leg from the groove), but this is quite uncommon. MPL is usually not a very painful condition but in some cases can be painful and uncomfortable. If this condition is left uncorrected a period of time, ligament and cartilage injury may occur. This will then predispose the animal to arthritis in the knee joint. Dogs commonly present with a “skipping” gait where they will lift up the affected leg for a few steps and skip and then return back to a normal gait.

MPL is graded from I to IV where IV is the most severe. Grades are determined by the amount of time the patella spends out of the trochlear groove. In Grade I luxations, the patella only luxates occasionally and slides back into place not long after, while in Grade IV luxations the patella is permanently out of position. The more severe the grade of luxation, the more extensive and complex and the surgical treatment becomes.

MPL is a common condition in small dogs (less than 10 kg). MPL can occur in one or both legs, and is prevalent in breeds with “bowed” hind limbs. The cause of MPL can be generally classified into two groups: developmental or traumatic. Developmental or congenital cause of

of MPL is multifactorial and may involve complex skeletal abnormalities affecting the overall alignment of the limb. Traumatic causes are more common in larger dogs. The condition does occur in cats, but only rarely.

Treatment

Surgery is required to correct and stabilize the patella. As part of the surgical planning each knee is evaluated by the surgeon while the patient is fully anesthetized. Radiographs (X-rays) are taken at the same time to assess for the presence, type and severity of bone
deformity. An individual surgical plan is made from this assessment. Surgical correction may include remodelling of the bony groove, repositioning of the ligament of the patella or complete realignment of the stifle. These surgeries may involve cutting and repositioning of bone and placement of surgical implants.

During surgery, and for the first few days post-operatively, your pet will receive appropriate pain control medications (epidurals, pain-patches, injections and oral medication) as indicated. All dogs must remain in hospital until they are comfortable and able to walk. The duration your pet remains in hospital will depend on his/her size, whether one or both legs or operated on, and the presence of other injuries/conditions. This can take from two to five days.

The repair of MPL can be a technically demanding surgery. While complications during diagnosis or surgery are uncommon, they may occur and may alter the chances of a good outcome or the requirement for additional procedures. Higher grade luxations tend to have a higher incidence of complications than lower grade luxations.

Post-operative Care

Strict confinement and supervised activity is required at home after surgery. Activity restriction is essential until bone healing is adequate to avoid complications. Adequate healing usually occurs at about eight weeks post injury and is confirmed by radiographs (X-rays).

Medication is required for pain control during the early part of the post-op period. The frequency of post-operative rechecks determined on an individual basis. Typically they occur at two weeks postoperatively for suture removal, and at eight weeks for radiographs.

Early controlled activity and professional physiotherapy is strongly recommended to help maximise recovery and return to normal function. This typically requires weekly visits until healing is confirmed. You can learn more the animal physiotherapy service provided by BVSC by visiting the service page listed on the left hand side of our webpage.

Most animals with MPL heal well after treatment. However, it can be quite difficult to cure MPL but it can definitely be improved in grade. Normal comfort and activity is almost always achieved, however it can take up to six months for a complete return to vigorous activities like ball chasing.

Financing Surgical Treatment For Your Pet

BVSC understands that surgical treatments are both unexpected and costly. We can assist your access to third party external finance companies working with us to help spread your payments. To make an appointment for your pet ask your veterinarian for a referral and contact our friendly reception staff on (07) 3264 9400.