Cranial Cruciate Ligament Repair: Tibial Plateau Leveling Osteotomy (TPLO), Extracapular Repair & Tight Rope®
One of the most common injuries to the knee of dogs is tearing of the cranial cruciate ligament (CCL). This ligament is similar to 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.
When the CCL is torn or injured, the shin bone (tibia) slides forward with respect to the thigh bone (femur), which is known as apositive drawer sign. Most dogs with this injury cannot walk normally and experience pain. The resulting instability damages the cartilage and surrounding bones and leads to osteoarthritis (OA).
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 quickly as possible to reduce permanent, irreversible joint damage and 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 article covers four types of CCL surgery: tibial plateau leveling osteotomy (TPLO), tibial tuberosity advancement (TTA), Extracapular Repair and Tight Rope® procedures.
My veterinarian is recommending a tibial plateau leveling osteotomy (TPLO) to fix my dog’s torn CCL. What does this surgery involve?
A major advancement in the treatment of CCL rupture has been the development of tibial plateau leveling osteotomy or TPLO. This surgery changes the angle and relationship of the femur and the tibia. The overall intent of the surgery is to reduce the amount that 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 stifle helps to provide stability during a stride, and helps to reduce future joint inflammation and OA. By carefully adjusting the angle or slope of the top of the tibia, surgeons are able to replicate 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. As long as the rope holds, the wagon doesn’t 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 forward with added weight, even if the rope is broken.
In this example, the wagon is the femur, and it slides down slope of the top 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 affix the two sections of tibia in the desired positions, allowing the tibia to heal in its new configuration.
How long will it take for my dog to recover from TPLO surgery?
Healing from TPLO is relatively rapid.
- About half of all canine patients will begin walking on the injured leg within 24 hours after surgery.
- At 2 weeks postoperatively, most dogs are bearing moderate to complete amounts of weight on the affected leg.
- By 10 weeks, most dogs do not have an appreciable limp or gait abnormality.
- As mentioned above, at 4 months postoperatively, the majority of dogs can begin walking and playing normally, with only the most stressful activities restricted.
- Within 6 months, most dogs can resume full physical activity.
Pain management during and after stifle surgery is critical, so be sure to give all medications as prescribed and use them until they are gone. Physical rehabilitation post-operatively will speed healing. Ask your veterinarian about incorporating rehabilitation into your dog’s recovery plan.
The most common complication after TPLO is infection. Studies conclude that infection occurs in less than 10% of all patients, with many surgeons reporting much lower complication rates. Your dog will need several recheck examinations and radiographs (x-rays) to ensure that the area is healing properly.
My veterinarian has suggested surgically fixing my dog’s CCL using an external capsular repair technique called ECLS. What does this surgery involve?
The traditional ECLS technique is the oldest surgical correction for cruciate ligament injury in dogs. The name of the procedure originates from the fact that the joint is stabilized outside the joint capsule (externally).
In simplest terms, a loop of a special type of suture material (an artificial ligament) is placed from the back of the knee joint around to the front, where it is anchored just below the knee. This suture material stabilizes the joint and prevents the tibia from slipping back and forth after the cruciate ligament has torn. This procedure typically requires two bone channels (tiny holes) to be drilled — one at the front of the tibia and the other on the outer (lateral) aspect of the femur at the level of the stifle joint —so the artificial ligament can be passed through them.
CCL repair surgery typically consists of an initial examination of the inside of the knee. This examination may either be done by opening the joint capsule and peering inside or by using an arthroscope. Any damaged or torn portions of the CCL are removed. The “shock absorber,” or cartilage meniscus, that cushions the knee and sits between the femur and tibia, is examined. If the meniscus is torn or damaged, that part will be removed. After the joint capsule has been examined and any cartilage or ligament fragments are removed, the joint capsule is sutured closed.
In the ECLS procedure, a suture is passed from the outside/lateral aspect of the knee joint to the front of the tibia. Some surgeons refer to this as “imbricating,” or overlapping the extracapsular tissues to pull the joint tight and create stability to prevent front-to-back sliding of the femur and tibia. Usually, one or two bone channels or holes will be required to pass the suture from back to front.
There have been several innovations in external capsular repair during the past decade. New materials, anchoring devices, and tools have allowed veterinary surgeons to perform this surgery more successfully than ever before.
Several surgical product manufacturers have created advances that make this procedure viable for many dogs, including some large and athletic breeds Larger, more active dogs may do better with TPLO/TTA procedures (see article of TPLO and TTA).
Perhaps the biggest advancement in CCL surgery has been in how the suture material is joined together. In the past, veterinarians relied on bulky knots that could come undone or irritate the surrounding tissues. Today, there is a variety of suture connectors that are much more reliable, effective, and less irritating. The use of bone anchors and modified bone drills and bits for varying sizes of dogs has also improved ECLS. Strong, specialized knee suture materials have also been developed that make the surgery simpler, more effective, and less risky than in the past.
My veterinarian mentioned that she might use the TightRope® procedure to repair my dog’s torn CCL. What does this surgery involve?
Different materials and a slight variation in the traditional extracapsular repair have resulted in the TightRope® procedure. This method uses a customized needle and a special suture material affixed to bone anchors.
The TightRope® procedure requires drilling three holes in bones above and below the knee joint to run the suture material through, thereby stabilizing the joint. The use of these unique bone anchors helps reduce the need for additional suture material in the joint.
Is one of these procedures better than the other?
TPLO offers some benefits over older procedures such as extracapsular repairs (ECLS), especially for larger or athletic dogs. Dogs undergoing TPLO tend to heal faster, resume normal activities quicker, and have a better range of motion in the knee.
Both the traditional ECLS and Tight Rope® procedures are considered extracapsular or external repairs of CCL injury. Both yield similar results with similarly low risks. The two primary risks of extracapsular surgical repairs are infection and failure. With either type of extracapsular repair, success rates have been found to be at least 85% and infection rates reported to be only 1% to 4%. Because both procedures are nearly identical in their respective potential risks, it is up to the surgeon to determine the procedure he or she is most confident will give your dog the best chance of full recovery.
Either traditional ECLS or the TightRope® procedure is considered adequate for most small to medium sized dogs and for cats. Larger dogs may benefit more from TPLO procedures. In most cases, any surgery is better than none, especially in medium- to large-breed dogs.
Your veterinarian will guide you through the decision-making process to determine which procedure provides your dog with the best chance of full recovery.