One of the most common injuries to the stifle (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. For more information on these ligaments and how they can become damaged, see the handout "Cranial Ligament Rupture in Dogs."
When the CCL is torn or injured, the tibia (shin bone) slides forward with respect to the femur (thigh bone), which is known as a positive 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 soon as possible to reduce permanent, irreversible joint damage and relieve pain.
"Surgery is generally recommended as soon 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 handout covers two types of CCL surgery: external capsular or extracapsular lateral suture (ECLS) stabilization and the TightRope® procedure.
For information on other types of surgery used to correct CCL injuries in dogs, see the handouts "Cranial Cruciate Ligament Repair: Tibial Plateau Leveling Osteotomy (TPLO)" and "Cranial Cruciate Ligament Repair: Tibial Tuberosity Advancement (TTA)".
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 looking 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.
“If the meniscus is torn or damaged, that part will be removed.”
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.
"New materials, anchoring devices, and tools have allowed veterinary surgeons to perform extracapsular repair 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 or TTA procedures (see handouts on 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 two bone channels (resulting in four holes); one from side to side through the tibia and the other from side to side through the femur, 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?
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."
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 or TTA procedures. In most cases, any surgery is better than none, especially in medium- to large-breed dogs.
What is my takeaway message?
Your veterinarian will discuss your dog's condition and which procedure is best. There is no right or wrong answer when it comes to choosing your pet's surgery, only what is most likely to achieve the desired outcome.
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 postoperatively will speed healing. Ask your veterinarian about incorporating rehabilitation into your dog's recovery plan.