Advanced cruciate repair techniques in dogs - TPLO

The cranial cruciate ligament (CCL) is an important structure that provides critical stability to the knee joint. The knee joint is normally a hinge joint with the femur (thigh bone) and tibia (shin bone) being securely fixed together by the cruciate ligaments. When the cranial cruciate ligament ruptures the hinge mechanism is broken and the femur and tibia can move independently; the tibia slides forward and the femur backwards every time weight is placed on the leg causing pain and progressive damage to the cartilage and meniscus of the knee. The goals for treatment of cruciate disease are to alleviate pain and return your pet to normal function. The treatment approach to cruciate disease is multimodal and includes nonsurgical strategies, such as anti-inflammatory medications, weight control, and surgical stabilization techniques.

How does a TPLO work?

The term “TPLO” stands for tibial plateau levelling osteotomy, a surgical procedure which aims to decrease the steep tibial plateau angle (the weight bearing surface at the top of the tibia/shin bone). The dog’s knee is unique, as the tibial plateau typically has an angle of about 25° to 30°, which is much steeper than in humans. Because of the sloped angle of the top of tibia, the forces acting on the stifle during walking cause instability when the cruciate ligament is unable to lock the tibia and femur together.

How is the operation performed?

In order to decrease the angle of the tibial plateau the tibia needs to be cut using a circular oscillating saw. Measurements are taken on pre-operative radiographs to establish where the cut is to be made and how much rotation is required. Ideally the post-operative tibial plateau angle should be close to 5 degrees to neutralise weight bearing instability. Once the tibia has been cut and rotated it needs to be fixed into its new position. A plate and screws, specially designed for this procedure, are used to fix the tibia in its new position. 

Post operative radiographs of a dog that has had a TPLO. The pre-operative tibial plateau angle was 25 degrees (image on the left). The post operative angle is 4 degrees (image on the right) and the circular bone cut and plate can be seen fixing the bone in its new position.

Most dogs will be more comfortable fairly quickly after surgery, often using the leg better within days than prior to the surgery. Studies suggest that greater than 90% of dogs will return to their pre-cruciate rupture limb function.

The osteotomy site (bone cut) takes 6-7weeks to heal so lead only activity is required during this period. Post-operative radiographs at this point are recommended to assess bone healing before patients are allowed to resume normal exercise.