One of the most common injuries to the knee in dogs is tearing of the cranial cruciate ligament (CCL). This ligament is like the anterior cruciate ligament (ACL) in humans. There are actually two cruciate ligaments inside the knee: the cranial cruciate ligament and caudal cruciate ligament. They are called cruciate because they cross over each other inside the middle of the knee. For more information about these ligaments and how they can become damaged, see the handout "Cruciate Ligament Rupture in Dogs".
"Most dogs with this injury cannot walk normally and they experience pain."
When the CCL is torn or injured, the shin bone (tibia) slides forward with respect to the thigh bone (femur). This movement is known as a positive drawer sign. Most dogs with this injury cannot walk normally and they experience pain. The resulting instability damages the cartilage and surrounding bones and leads to osteoarthritis.
What options are there for repairing my dog's torn CCL?
When the cranial cruciate ligament is torn, surgical stabilization of the knee joint is often required, especially in larger or more active dogs. Surgery is generally recommended as soon as possible to reduce permanent, irreversible joint damage and to relieve pain.
Several surgical techniques are currently used to correct CCL rupture. Each procedure has unique advantages and potential drawbacks. Your veterinarian will guide you through the decision-making process and advise you on the best surgical option for your pet.
This handout describes tibial plateau leveling osteotomy (TPLO) surgery. For information about other types of surgery used to correct CCL injuries in dogs, see the handouts "Cranial Cruciate Ligament Repair: Tibial Tuberosity Advancement (TTA)" and "Cranial Cruciate Ligament Repair: Extracapsular Repair".
My veterinarian has suggested surgically fixing my dog’s CCL using a tibial plateau leveling osteotomy. What does this surgery involve?
The development of tibial plateau leveling osteotomy (TPLO) was a major advancement in the treatment of CCL rupture. This surgery changes the angle and relationship between the thigh bone (femur) and the shin bone (tibia).
The overall intent of the surgery is to reduce the amount that the tibia shifts forward during a stride. This is accomplished by making a semicircular cut through the top of the tibia, rotating the top of the tibia, and using a bone plate to allow the tibia to heal.
This realignment of the surfaces within the knee (stifle) helps to provide stability during a stride and helps to reduce future joint inflammation and osteoarthritis. By carefully adjusting the angle or slope of the top of the tibia, surgeons can create a more normal configuration of the knee joint and reduce mechanical stress.
To better understand the purpose of leveling the tibia, we often use the analogy of a wagon on a hill. Imagine a wagon tied to a post on the slope of a hill. If the rope holds, the wagon does not roll downhill. If we add excess weight (or downward force) to the wagon, the rope could break, and the wagon will roll down the hill. However, if the wagon is on level ground, it will not roll with added weight, even if the rope is broken.
"By carefully adjusting the angle or slope of the top of the tibia, surgeons can create a more normal configuration of the knee joint and reduce mechanical stress."
In this example, the wagon is the femur, and it slides down the slope of the tibia when the CCL is ruptured. This instability leads to damage and destruction of the cartilage and bones of the knee joint. TPLO surgery levels the tibia to prevent the femur from sliding forward, thereby stabilizing the joint.
TPLO surgery involves making a curved cut in the tibia from the front to the back, much like half a smiley face. The top section of the tibia is then rotated backward until the angle between the tibia and femur is deemed appropriately level, typically between 2 and 14 degrees, with 5 degrees being the ideal angle. A metal bone plate is then used to set the two sections of tibia in the desired positions, allowing the tibia to heal in its new position.
How long will it take for my dog to recover from TPLO surgery?
Healing from TPLO surgery is generally rapid.
- About half of all canine patients begin walking on their injured leg within 24 hours of surgery.
- Two weeks after the operation, most dogs bear moderate to complete weight on the affected leg.
- By ten weeks, most dogs do not have an appreciable limp or gait abnormality.
- Four months after the operation, most dogs can begin walking and playing normally, with only the most stressful activities restricted.
- Within six months, most dogs can resume full physical activity.
Pain management during and after knee surgery is critical, so be sure to give all medications as prescribed and use them until they are gone. Post-operative physical rehabilitation can improve healing and speed the time it takes for your dog to return to normal activity. Ask your veterinarian about incorporating rehabilitation into your dog's recovery plan.
The most common complication after TPLO is infection. Studies assessing outcome have shown various rates of complications, with an average of roughly 10%-30%, with smaller dogs tending to show fewer postoperative problems. Your dog will need several recheck examinations and X-rays (radiographs) to ensure the area is healing properly.