Part A – Concepts


The cruciate ligaments in the dog knee joint (stifle) play a very important role in stabilising the joint. The cranial cruciate ligament (CrCL) is the most important of these. Its role is to limit the internal rotation (twisting) and extension (straightening) of the stifle. It also controls the cranial movement (cranial “drawer”/ instability) of the tibia bone.

Cranial cruciate ligament disease

Many dogs develop disease of the CrCL. This may be precipitated by an injury or simply arise through the stresses of normal activity. Once the CrCL is damaged, it is usually painful for dogs to bear weight on the leg, so they will appear lame. They may be lame all the time, only when walking or running, or only “off-load” or pick up the leg when standing. If left alone, the CrCL damage will tend to progress to complete rupture of the ligament. Over time, the instability of the stifle and the damaged ligament inside the joint will promote arthritis in the joint. The best results from CrCL surgery in the dog occur when surgery is performed sooner rather than later – before arthritis becomes entrenched.

Fixing the problem Historically, people have used a number of techniques to address CrCL damage in dogs. For many years, veterinary surgeons have used material, either external to the joint (heavy suture materials), or internally in the joint (using the body’s own tissue) to “tighten” and stabilise the joint). These techniques attempted to stabilise the stifle independently to weight-bearing. Results tended to be variable and often disappointing. I was the first surgeon in Western Australia to embrace the concept of tibial osteotomy as a primary means of treating canine cruciate ligament deficiency, back in the mid 1990’s. I have utilised the “TWO” and “TTO” techniques as well as the TPLO technique to help thousands of dogs over the years. I currently find the Tibial Plateau Levelling Osteotomy (TPLO) my preferred technique to provide stability to a CrCL-deficient joint. The tibial osteotomy techniques have given us an improved ability to control the abnormal cranial drawer movement (instability) of the stifle over the long term, especially in larger, boisterous or heavily muscled dogs. The evidence shows this leads to better results in these dogs, leading to happier dogs with less knee joint pain.
TPLO This surgery achieves a levelling of the tibial plateau through a crescentic saw cut. It has the advantage of spreading weight-bearing forces along a crescentic cut in the bone, providing support and speeding healing. It is the first choice for medium and larger-breed dogs and any dog that is boisterous and where an athletic postoperative result is desired.
TWO This surgery removes a wedge of bone from the tibia to level the tibial plateau. This form of surgery is sometimes still chosen for those dogs where the patella is unstable and needs redirecting or where the dog is very small.

These techniques allow us to avoid “tightening” the joint in a static sense with artificial materials. The forces acting through the joint are changed and, in a sense, “neutralised” so that there is much less need for a cranial cruciate ligament. Thus, a joint without a CrCL can still function well. Or a joint with a partially injured CrCL may not suffer any further injury to the ligament, thanks to the greatly reduced “cranial drawer” or cranial tibial shear forces within the joint. We use a bone plate and screws (implants) to hold the bones together while they heal. Bone healing usually takes 6 to 8 weeks. Healing of the soft tissues surrounding the joint often take another month or two. The implants usually do not require removal. The skin incision we make is on the inner side of the stifle and tibia. Scarring is minimal and once the hair grows back, there is generally no obvious sign of the surgery.

Care after surgery

Please read these notes together with any discharge instructions you have been given specifically tailored for your pet.
There are three components to caring for your dog after this surgery – controlling pain, caring for the bone as it heals (preventing disruption of the bone healing) and caring for the joint.

Pain: Is minimised at the time of surgery with powerful painkillers. We favour nerve-blocking techniques (administered by our specialist anaesthetic team) to prevent pain transmission from the operated leg during the surgery. This makes the anaesthetic safer and will minimise pain at home too. We will also usually give you pain-killing tablets to give your pet. Most people are amazed at how comfortable their pet is after the surgery.

Bone healing: The bone will heal to 100% of its former strength, but you must avoid any excessive stresses or force on the bone prior to this time as disruptions to bone healing can be serious. Keep your dog on a lead at all times that they are not closely confined. Walks should be very short (walks to the toilet only) until the go-ahead is given for longer walks. Always use a premium quality balanced dog food to maximise the speed of bone healing.

Joint care: The joint and surrounding ligaments require a little longer than the bone to reach full strength and they often do not reach 100% of their original strength. However, results from these surgeries are usually very good. You can maximise the chances of this by following a very slow progressive return to activity – see Part B “Postoperative Care”.