What And Where Is The Cranial Cruciate Ligament In Pets?
The cranial cruciate ligament (CCL), also known as the anterior cruciate ligament (ACL) in humans, is found in the knee, called the stifle in pets. When this ligament is torn, instability or excessive movement of the joint causes pain, inflammation, and arthritis over time.
What Causes A Cranial Cruciate Ligament Injury In a Dog?
Cruciate ligament tears in a dog’s knee are the most common orthopedic injury in our canine companions. Just like in people, the majority of injuries occur during an "athletic performance" while playing with other dogs, running around in the backyard, or even chasing that neighborhood squirrel. Some ligaments tear due to the shear weight and force administered to the knee by the dog while others can have an underlying disorder that predisposes them to the injury; this can be due to an underlying hormone condition, lyme disease, a luxating patella (kneecap), or a ligament just becomes weaker over time with age and eventually breaks without any significant trauma or activity. In some cases, a "cushion" within the knee, known as the meniscus, is also torn and needs to be repaired. When a partial or complete tear of the cruciate ligament occurs, the knee becomes unstable and this instability can be detected during a physical exam. This abnormal motion in the joint is called “cranial drawer” or "tibial thrust" depending on the method of palpation. In some cases, your pet may need to be sedated in order for the doctor to safely and accurately diagnose the motion in a stifle.
It's worth noting that approximately 50% of dogs that tear one CCL will tear the other, possibly due to weight shifting or a predisposition to ligament injury in the first place.
What Types Of Surgeries Are Available To Repair My Dog’s Cranial Cruciate Ligament?
There are several surgical options to stabilize a dog's knee after they have been diagnosed with a torn cruciate ligament. The most commonly performed surgeries are Tibial Leveling Osteotomy (TPLO), Tibial Tuberosity Advancement (TTA), and Extracapsular Lateral Suture Stabilization, sometimes referred to as lateral suture surgery. Even with surgery arthritis will develop over time, but will be minimal in comparison to opting out of surgery.
The TPLO and TTA surgeries are performed by making a cut into the tibia, the "shin" bone, and placing a metal implant that changes the conformation of the joint in order to prevent the excessive movement that is causing pain and inflammation. This surgery is most commonly performed by board-certified orthopedic surgeons and is the preferred option for large and athletic dogs. Dr. Parker would recommend the TPLO over the TTA as the biomechanical principles are superior in his opinion.
If surgery is not performed, it's crucial to understand that the knee will continue to experience excessive motion, which can result in a more rapid development of arthritis, leading to pain, inflammation, and a decline in the quality of life. Non-surgical medical management can be utilized, but only if surgery is not an option for your pet and to be determined by your veterinarian.
Which Cranial Cruciate Ligament Surgery Is Performed At Howard County Animal Hospital?
Here at Howard County Animal Hospital in Ellicott City, we
offer the Lateral Suture technique, where a strong monofilament (suture) is placed around the outside of the joint to mimic the function of the dog's natural cruciate ligament. This surgery is a great option for small-medium or older and less active dogs as it is less invasive since there is no need for a bone cut. The lateral suture technique is also a good option when the TPLO or TTA procedure is not financially feasible for large dogs, as it is typically more affordable.
What Else Do I Need To Know Before My Dog’s Cranial Cruciate Ligament Surgery?
Prior to surgery, pre-anesthetic bloodwork and x-rays of your pet's hips and knees are required. The blood work we perform helps us screen for health concerns that could increase your pet's risk of undergoing anesthesia, help us tailor the best anesthetic plan for each patient, and rule out co-morbidities(conditions) that could have predisposed your pet to rupture their CCL in the first place.
X-rays will need to be taken to determine if there is evidence of any other orthopedic abnormalities that could complicate surgery and rehabilitation or prevent your pet from regaining the mobility and stability of that limb in the long term. Giving our owners a complete picture of what the outcome of your pet will be is important and we can't do that without these tests.
How Can I Ensure The Best Recovery For My Dog Following Cranial Cruciate Ligament Surgery?
One of the crucial factors to increase the chance of success with this surgery is strict adherence to postoperative rest and recovery protocols. Crate rest is required for the first week, where your pet must stay in the crate, other than to go to the bathroom while on a leash. Once the skin incision has healed and the knee has been re-evaluated by a veterinarian, a very controlled and gradual return to exercise can begin. We will provide specific guidelines after surgery for the first 2 months of recovery and then recommend a gradual return to normal function over an additional 2 months. Failure to properly restrict your pet's activity during the rehabilitation process significantly increases the chance your pet will need additional treatments or surgery.
ADDITIONAL NOTES & SUMMARY
In a dog's knee joint, there are two cruciate ligaments, with the cranial cruciate the one that tends to rupture causing excessive movement leading to pain, inflammation, and chronic arthritis formation.
This tends to be either an "athletic" injury, occurs due to having an underlying disorder, or the pet being overweight. Approximately 50% will have the same problem in the opposite knee. Less commonly we see patients who have been involved in some sort of accident that has caused an acute rupture, this is when other ligaments in the knee could be injured complicating repair.
If left alone, it will appear to improve over a week or two but the knee will be notably swollen and arthritis will set in quickly. More importantly, lameness and pain will persist.
Three different surgical repair techniques are commonly used today: extracapsular repair; tibial plateau levelling osteotomy (TPLO); and tibial tuberosity advancement (TTA).
The extracapsular repair involves using an artificial ligament replacement. TTA and TPLO are much more invasive and require metal plates and screws. These are more expensive as they require specialized equipment, extra personnel and can have more complications. For dogs under 45 lbs, there is no clear advantage to the newer procedures. For larger dogs, the choice of which procedure is best is controversial but Dr. Parker would recommend the TPLO.
Extracapsular repair: The ruptured ligament is "cleaned up" then sutures are put through a hole drilled in the tibia and across the knee to stabilize the joint; the dog needs 8 to 12 weeks of exercise restriction; the suture tends to break 2 to 12 months after surgery and the dog's own healed tissue will stabilize the knee.
TPLO: The tibia is cut and rotated; most dogs are touching their toes to the ground by 10-21 days after surgery; 8-12 weeks of being outside on a leash only including the back yard.
TTA: The tibia is cut and repositioned to stabilize the new angle of the patellar ligament. Most dogs are touching their toes to the ground by 10-21 days after surgery; 8-12 weeks of being outside on a leash only including in the backyard.
After surgery, patients need strict confinement (this cannot be overemphasized), medications, and weight loss if needed. Water treadmills and other physical therapies are helpful. Rehabilitation is important no matter which method is used.
Osteoarthritis will develop in all cases and will cause a degree of lameness but much less compared to opting out of surgery.