A medially luxating patella (MLP) occurs when the patella (the kneecap) moves from its normal position within the stifle (the knee) to the side of the stifle. A mild MLP will simply move in and out of its normal position, which can lead to wearing of the cartilage under the patella and femur – resulting in pain and lameness. Over time, the majority of luxating patellae are permanently outside of their normal position.
Boo, 3 year old Chihuahua, before MLP surgery
Owners often notice that their pets skip or hop occasionally. They do this after the patella has popped from its place and are trying to flick it back into place. Your pet won’t feel pain until there is cartilage loss and bone to bone contact is occurring – by this stage, the animal will be lame rather than occasionally hopping. Palpation of the knee will reveal whether the kneecap is in the correct position or whether it can be easily moved in and out of the normal position. Crepitus (loss of cartilage and bone on bone contact) may also be occurring.
Chihuahua, Boo, 3 year old, during surgery
In some mild cases (where the dog occasionally hops but is not yet lame) weight loss and no longer partaking in rotational activities like fetching, and the use of medications such as Cartrophen or Zydax to look after the cartilage, may mean that surgery is never required. However, in severe cases where pain and lameness are occurring due to cartilage loss, surgery will be the best option. We treat MLP by chiselling off the tibial crest before moving it laterally and reattaching it with a pin. This redirects the patella tendon, keeping the patella in the correct location. We will also deepen the groove within the femur, making it more difficult for the patella to move in and out of its normal position. We then separate the medial adductor muscles from the thigh muscles to stop them from pulling (often initiating at the hip), allowing for a more normal tracking of the patella at the femur.
We perform this procedure for between $1,200 - $1,350 – we perform this surgery often, and we are very good at it. Surgery to correct MLP in dogs will usually cost between $2,000 - $4,000 at a hospital or referral centre.
Recovery and aftercare
We recommend short walks several times a day following surgery, with rest needed at all other times for the first four weeks. This allows for the tibial crest to reattach and properly heal. After this point, walking can increase, and by six weeks after the surgery off lead activity can begin. We also prescribe Zydax (pentosan polysulphate) to stop the inflammation of the bone and aid in the recovery of the cartilage. We advise using this as a series of four injections per week for six months to avoid arthritis developing in the long term.
Indi, 8 year old Beagle, 4 weeks post MLP surgery
Poppi, 5 year old Shih tzu, 16 weeks post MLP surgery
Meet Dr. Scot Plummer
Since childhood, Dr. Plummer has been passionate about caring for animals, and graduated with Honours in a Bachelor of Veterinary Science from the University of Queensland. He opened the Brisbane Pet Surgery with the aim of making quality pet care affordable for everyone.