Cranial Cruciate Ligament Rupture in Dogs

CHF-Funded Researcher Hopes to Develop More Effective Surgical Treatment for CCL Injuries in Dogs

Cranial Cruciate Ligament rupture (CCL) is one of the most common orthopedic injuries in dogs. This injury, similar to a torn ACL in humans, can come on suddenly or can appear gradually over a longer period. The cranial cruciate ligament helps the stifle (knee) function as a hinge joint. When it ruptures, abnormal movement of the joint occurs, resulting in pain and lameness. CCL injury is diagnosed through a physical exam and a Cranial Drawer Test, which functions to elicit instability of the joint.  And while the ligament is not visible, an x-ray is often taken enabling veterinarians to look at the joint for signs consistent with injury and to rule out other possible causes of lameness.

CCL injury can occur in many breeds of dogs, although large breed, active dogs like Labrador Retrievers, Rottweilers,Newfoundlands, and American Staffordshire Terriers seem predisposed. Researchers have looked at the factors that may predispose these breeds to CCL injury, and current evidence points to a complex interplay between conformation, genetics, and the mechanics of how a dog moves. CCL injury can occur in athletic dogs who participate in agility or hunting activities, but it can also occur with a family pet who accompanies his owner on regular walks or runs.

Jeffery Biskup, DVM at the University of Minnesota Veterinary Medical Center in St. Paul, MN is an AKC Canine Health Foundation-funded researcher who is looking at alternative surgical techniques for CCL rupture. According to Dr. Biskup, three common surgeries for dogs with CCL rupture are the Tibial Plateau Leveling Osteotomy (TPLO), Tibial Tuberosity Advancement (TTA), and Lateral Fabellotibial Surgery (LFS). While these surgeries have high rates of success, Biskup notes that these surgeries change the mechanics of the knee and normal function of the CCL cannot be replaced. In looking at the long-term success rates of these surgeries, there is high owner satisfaction one year post-surgery. However, as CCL surgeries have become more common and patients are tracked, researchers have seen osteoarthritis (OA) and pain in many dogs 3 -5 years post-surgery. Through his research, Biskup hopes to develop a surgical technique that better replicates the normal anatomy of the stifle join in dogs.

Interestingly, the technique used to repair a torn ACL in humans was first performed on dogs with the goal to develop an effective surgery in human medicine. In humans, 1/3 of the patellar ligament is commonly used to repair the torn ACL. In dogs, 1/3 of this ligament is not strong enough to repair a CCL rupture. Biskup points out that humans are able to use crutches and put a percent of their weigh on the injured leg during healing, while in dogs, he said, “Our repairs need to be strong from day one.”

Biskup’s research looks at the possibility of more closely mimicking normal function in dogs by taking an entire patellar ligament from donor dogs and placing it in a dog with a ruptured CCL. This provides the additional graft strength needed.  Determining a strong enough ligament replacement is only half the battle, though. Biskup notes that in his research, the donor ligament must be secured to the dog’s stifle and also be strong while the ligament is incorporated into the knee. To address this concern, Biskup looked to human medicine where bioabsorbable screws have been implemented. They are used in the repair of human ankles and wrists, are the appropriate size, and just like their name sounds, the screws disintegrate and are absorbed by the body. As with any surgical procedure, when a foreign tissue is introduced into the body, there is always a risk for rejection or infection that must be overcome.

When asked about the new findings from Dr. Benjamin Hart’s (University of California, Davis) early spay and neuter research on the prevention of CCL injury and its impact on the field of CCL injury repair, Biskup indicated that while the findings would not necessarily impact the surgical technique he is working to perfect, “The research is important because an original CCL is better than anything research can develop,” he said. He pointed out that he has seen plenty of dog owners follow all the recommendations to prevent CCL rupture, including maintaining an ideal body weight and getting regular exercise, and their dog still sustains an injury. He said that Dr. Hart’s study may play a role in the recommendations of timing for spaying and neutering in these predisposed breeds to aid in CCL injury prevention, but that these findings do not address the additional factors that many researchers believe contribute to CCL rupture in certain breeds.

If an owner notices a sudden or gradual lameness in their dog, Biskup recommends taking the dog to their family veterinarian. “CCL injury is common and veterinarians are adequately equipped to make a diagnosis,” said Biskup. Typically, after diagnosis is made surgery to repair the CCL occurs within one to two weeks. “A small percentage of dogs improve without surgery. These dogs respond to medical management which includes anti-inflammatory medications, rehab, and rest,” said Biskup. “In cases where patients improve with medical management alone, surgery may be delayed. However, surgery should not be postponed too long because muscle atrophy and arthritis can progress, in addition to the pain associated with this type of injury.” Following surgery there is a period of 6 – 12 weeks of recovery, which includes rehab, followed by six additional weeks of gradual return to normal activity.

Ideally, prevention is the best defense against CCL rupture. Dr. Biskup estimates that it will take at least another 6 – 12 months to perfect the CCL surgery technique he is researching before it is tested in dogs. And while he is passionate about perfecting his surgical technique utilizing the patellar ligament from donor dogs, he said that whether his technique becomes the standard, or pre-existing techniques are refined, the goal is working toward a model that is as close to normal anatomy as possible.