Cranial Cruciate Ligament Disease

Cranial cruciate ligament disease (CCLD) is the term used in veterinary medicine to describe any disruption to the cranial cruciate ligament in the knee. There are three possible syndromes:

• Chronic degeneration of the ligament

• Injury to the ligament

• Fracture of the bone to which the ligament is attached

In dogs CCLD is almost always due to chronic degeneration and only rarely due to injury or fracture.

Pets with CCLD have life-long arthritis in their knees. No matter what is done medically or surgically, it is impossible to reverse or halt the degeneration of the ligament and the progression of arthritis. With proper care, however, most dogs ultimately have very little observable lameness and a very good quality of life.

DOGS VS. PEOPLE
Human and dog knees are very similar in structure and function. The ligament known as the anterior cruciate ligament (ACL) in people is known as the cranial cruciate ligament (CCL) in dogs. Tears of the cruciate ligament are common in people and dogs.

In people, the most common cause of an ACL tear is a traumatic event. In dogs, this cause is rare. The most common cause of torn CCL in dogs is slow degeneration of the ligament over a long period of time - cruciate ligament disease.

Largely because of the two very different causes, recovery from a torn ACL is relatively predictable in people and much less predictable in dogs.

CAUSES
There are four primary factors that contribute to the degenerative syndrome of CCLD. These factors combine in a complex way that is not completely understood.

• Age - Most dogs with CCLD are 3 to 7 years old when they become obviously lame.

• Body weight - Most dogs with CCLD are overweight to some degree.

• Genetics - Many breeds are predisposed to CCLD. In our experience, Lab Retrievers, Pit Bulls, and Rottweilers are the most common CCLD patients, and some Labs and Newfoundlands have the most severe trouble with CCLD.

The degeneration itself becomes a vicious cycle - As the ligament deteriorates the knee becomes more inflamed and structurally abnormal, which leads to more degeneration.

SIGNS
Lameness in one hind leg is the most common sign of CCLD.

Many dogs with CCLD become lame suddenly, so it might appear that trauma was the cause. What has actually happened in the vast majority of cases, however, is the dog has had no lameness, or very subtle lameness, for an extended period of time while the ligament is degenerating. Then it becomes obviously lame when the problem suddenly reaches a critical point.

Dogs with the degenerative syndrome of CCLD always have both knees affected, but usually to different levels of severity. In our experience, the most common progression of the problem is for the dog to become obviously lame in one leg and have surgery, followed 6 to 24 months later by lameness in, and surgery for the other leg.

DIAGNOSIS
We can usually diagnose CCLD based on the pet’s history and physical exam. Occasionally an anesthetized physical exam is necessary. We take x-rays, not to confirm the diagnosis, but to get a better idea of the extent of the problem and rule out other, much less common causes of lameness, such as fractures in the knee.

MEDICAL MANAGEMENT OF CCLD
Surgery is appropriate for many dogs with CCLD and is discussed below. However, medical management of cruciate disease is essential for all dogs and, with modifications over time, it should be life-long.

At YVC we create a treatment plan using choices from the following options, with the goal of determining what works best for the individual pet and owner. (We will provide more detailed information if you are interested in any of these options.)

Weight control - Establishing and maintaining a healthy, lean weight is the most valuable medical treatment option for all CCLD patients. Feeding Prescription Diet Mobility/Metabolic can be very helpful with weight management and it has significant anti-inflammatory benefits (see omega 3s, below).

Exercise - Walking and running are excellent at-home physical therapy. It varies varies from pet to pet, ranging from simply walking room-to-room and around the yard, to long walks and runs. We can combine this with specific exercise and massage.

Anti-inflammatory / pain medication(s) - We use it daily for 2 weeks to 2 months to get the arthritis under control, then taper to as-needed use; use of laser therapy and supplements helps to minimize the need for medications.

Omega 3s (fish oils, fatty acids) - These have significant anti-inflammatory effects for arthritis when given at high doses. "High dose" means two to four times the dose on the label. They must be given long-term as a daily supplement, and will not work if given intermittently or for a short time. Fish oil products vary dramatically in quality. Two prescription diets, J/D and Mobility/Metabolic have high-quality fish oil in a high-dose amount, so that a supplement is not needed. The veterinary products Free Form (by Bayer) and Welactin are the best options when one of these diets is not used and an omega 3 supplement is given instead.

Glucosamine/chondroitin supplement - This promotes health of joint tissues and joint fluid when used as a daily supplement. As with fish oil, the quality varies dramatically between products; the Nutramax products, in particular Dasuquin Advanced, are clearly the best. PSGAG (polysulfated glycosaminoglycans) is a similar supplement that can be used instead of, or along with glucosamine/chondroitin. PSGAG is given by injection (under the skin, not in the joint).

Laser therapy is the use of laser light as anti-inflammatory therapy. At YVC we have extensive experience with laser therapy, and we are equipped with the best therapy laser devices.

Joint injections - This is the same procedure, using the same medications used for people. We can inject hyaluronate (artificial joint fluid), PRP (platelet-rich plasma, or cortisone. We usually combine two of these medications.

SURGICAL MANAGEMENT OF CCLD: IS SURGERY NECESSARY?
When they are presented with the diagnosis of CCLD, the first thought some owners have is that they want to schedule surgery as soon as possible and get their pet on the road to recovery. Unfortunately, this problem does not have a simple solution.

Some dogs with CCLD do well with medical treatment only, and no surgery; the problem is, veterinarians have no reliable way of determining who these dogs are. With all of the current knowledge of CCLD, the best answers we have to this question are:

If the knee is unstable (a positive cranial drawer test) on our (awake or anesthetized) physical exam, surgery is usually worthwhile.

If the patient is not exceptionally painful, we will often try medical management for 2 to 4 weeks first, to see if there is significant, sustained improvement. If so, we can then continue medical management indefinitely; if not, we can do surgery.

Small dogs with CCLD do not usually need surgery; they require medical management only.

When we encounter evidence of a CCL tear or CCLD in a dog of a breed that is not predisposed to these problems we hesitate to recommend surgery. We start with an anesthetized physical exam and x-rays and then, if the diagnosis is CCL tear/CCLD, we recommend at least one month of medical management before considering surgery. We have found that many of these dogs do very well with medical management, and, on the other hand, many of them do not respond to surgery well.

SURGICAL MANAGEMENT OF CCLD: THE OPTIONS
There are two basic options, each with some variations, for CCLD surgery:

• LATERAL SUTURE (AKA EXTRACAPSULAR STABILIZATION) We regularly perform this surgery at YVC. In our version, a heavy nylon suture (it looks like very thick fishing line) is surgically placed in a loop around the knee, under the skin and outside of the joint capsule (the heavy fibrous sleeve of the joint). The position of the loop allows it to stabilize the knee the same way that the CCL does. The suture is held in the loop by a titanium crimp about the size of a large grain of rice. The crimp is attached only to the suture and not to the bones and soft tissues of the patient.

• GEOMETRY-MODIFYING SURGERY (USUALLY TPLO - TIBIAL PLATEAU LEVELING OSTEOTOMY) The tibia (the lower bone of the knee) is cut, repositioned, and held in place with a bone plate. The theory behind this surgery is that, in addition to stabilizing the joint, the mechanics of the knee are changed in a way that minimizes the mechanical forces that led to the cruciate ligament tear.

SURGICAL MANAGEMENT OF CCLD: LATERAL SUTURE VS. TPLO
Both lateral suture and TPLO are effective surgeries. At YVC we usually recommend lateral suture over TPLO surgery. Some factors worth considering, when making the choice between the surgeries:

If you review the previous section CAUSES, you will see that neither surgery is capable of directly curing or reversing any of the causes of CCLD. The hope with either lateral suture or TPLO is that re-stabilizing the knee will minimize the disease.

We have done lateral suture surgeries at YVC for over 30 years. There have been several variations on the procedure over this time. We have been performing the current version, with some minor modifications, for over 20 years. Our success rate is very good, and very similar to the success rates reported for all types of CCLD surgery, including TPLO, in the veterinary literature in general.

The lateral suture implants (the suture and crimp) are small. Lateral suture surgery can accurately be described as the "minimally invasive" version of CCLD surgery.

We perform lateral suture surgery at YVC, and the cost is $1500. TPLO is available at YVC and at local veterinary referral practices. At YVC, TPLO is performed by a travelling veterinary surgical specialist, and the cost is about $3500. At local specialty practices the cost is considerably more, about $5000.

Many veterinarians believe that TPLO is the most appropriate procedure for athletic dogs and large dogs; some veterinarians believe it is the most appropriate surgery for any dog with a torn cruciate ligament. Some of these veterinarians will not even mention lateral suture surgery when discussing treatment options for CCLD. However, extensive veterinary research has failed to prove that TPLO is superior to lateral suture surgery. At YVC, we have performed lateral suture surgery on all types of dogs, including giant breeds and very athletic patients, with the same results for all.

TPLO involves much more surgical trauma than lateral suture. For TPLO a bone is cut and re-positioned, and held in its new position with a plate that is screwed to the bone. Our lateral sutures are positioned outside of the joint, no bone is cut and nothing is attached to bone. The only metallic implant is a tiny titanium crimp.

Post-operative recovery, including exercise restriction, is more strict and prolonged with TPLO than lateral suture. TPLO patients typically need two months of severe restriction to allow the plated bone to heal, before they can begin gradually increasing recovery activities. YVC lateral suture patients need two weeks of short leash walks, and then begin a gradual increase in controlled activities for the next two months.

Complications at the bone plate site of TPLO are uncommon, but they do occur. One of these possible complications is bone cancer in the proximal tibia, the site of the plate. A veterinary study published in 2018 found that dogs with a history of TPLO were 40 times more likely to develop bone cancer in this region than dogs that did not have a TPLO. There is no reliable cure for bone cancer; it is always very painful and most patients die or are euthanized within 3 to 6 months of diagnosis.

Complications involving lateral suture surgery are very uncommon. We have seen a very small number of patients that reacted adversely to the nylon line and had to have it removed.  We have not seen any reactions to the titanium crimp. There are no reports in the veterinary literature of bone cancer, or any other cancer, associated with the line or crimp.

If a lateral suture surgery is done and the results are poor or the pet reacts to the line, the line can be removed and TPLO is still an option. If TPLO is performed and the results are poor, the bone plate can be removed, but lateral suture is not a follow-up option.