CRANIAL CRUCIATE LIGAMENT (ACL) TEARS AND CRUCIATE DISEASE
There are two reasons dogs become lame due to cranial cruciate ligament (ACL) tears:
~ The knee is inflamed (arthritis) and the cranial cruciate ligament is degenerating; inflammation and degeneration results in pain, which results in lameness. This is true for every dog with a cruciate tear.
~ The knee is unstable. When the patient attempts to bear weight on a leg with a torn cruciate the upper and lower bones in the joint slide back and forth over each other. These abnormal mechanics add to the pain of arthritis and contribute to lameness. Not every dog with a torn cruciate has an unstable joint; stability of the knee is important when considering treatment options.
The arthritis and degeneration is sometimes called cruciate disease. Cruciate disease is life-long and progressive; no matter what is done medically and surgically it is impossible to reverse it, or even to completely halt its progression. With proper care, however, many dogs with cruciate disease ultimately have no, or very little, observable lameness and an excellent quality of life.
The vast majority of dogs that are diagnosed with a cruciate tear had cruciate disease first; as the inflammation and degeneration in the knee progressed the cruciate ligament became weaker and eventually it tore.
Only a very small percentage of dogs have completely normal knees and suffer a cruciate tear purely as an injury. For these dogs, cruciate disease starts when the injury occurs and continues for life. Medical and surgical treatment will not prevent it.
More than 50% of dogs that tear one cruciate ligament ultimately tear the opposite one.
MEDICAL MANAGEMENT OF CRUCIATE DISEASE
Surgery is appropriate for most dogs with cruciate disease and cruciate ligament tears. However, because of the nature of the problem, medical management of cruciate disease is essential and, with modifications over time, it should be life-long.
Most dogs respond best to management using a combination of treatments. At YVC we tailor this for each pet, using some combination of the following options.
~ Weight control - Establishing and maintaining a healthy, lean weight is essential for all cruciate disease patients. converting to Prescription Diet Mobility/Metabolic can be very helpful with weight management and have significant anti-inflammatory benefits (see below).
~ Exercise - This is at-home physical therapy. It varies based on the ability of the pet, ranging from simply walking room-to-room and around the yard, to long walks and runs. It is essential for all cruciate disease patients. It can be combined with specifically prescribed exercises and massage.
~ Anti-inflammatory / pain medication(s) - We use them 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.
~ Fatty acids (fish oils, omega 3s) - These have significant anti-inflammatory effect for arthritis when given at high doses. "High dose" means two to four times the recommended dose (we can calculate this for individual patients). 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 a supplement will be 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.
~ Laser therapy - At YVC we offer a unique range of laser therapy options (please see the YVC Laser Therapy tab on the yarmouthvetcenter.com home page). It can be very helpful at reducing or eliminating the need for medications.
~ Joint injections - This is the same procedure and medications used for people. We can inject "artificial joint fluid" (hyaluronate), PRP, IRAP, and/or cortisone.
~ Stem cell therapy - This is a special type of joint injection. When an owner is considering this for their pet we recommend a trial joint injection of something other than stem cells first. This allows us to gauge the potential response to a stem cell injection without the much greater expense or more involved procedure of a stem cell injection.
SURGICAL OPTIONS FOR THE UNSTABLE JOINT
In order to directly address the instability associated with a cranial cruciate ligament tear we almost always recommend surgery. There are several different surgical procedures available. They can be divided into two basic types:
~ Lateral suture, aka extracapsular stabilization. In the version of this surgery that we perform at Yarmouth Vet Center a very heavy nylon suture (it looks like ultra-thick fishing line) is surgically placed in a loop around the joint, outside of the joint capsule (the heavy sleeve of the joint). The position of the loop allows it to do the job of the damaged ligament. The suture is held in a loop by a single titanium crimp that is about the size of a large grain of rice. The crimp is attached only to the line and not to the bones or soft tissues of the patient.
~ Geometry-modifying surgery, usually tibial plateau leveling osteotomy (TPLO). The tibia (the lower bone in the knee) is cut, repositioned, and held in its new location by a bone plate. The theory behind this approach is that, in addition to restabilizing the joint, the mechanics of the knee are changed in a way that minimizes the forces that led to the cruciate ligament tear. Another type of osteotomy is trans-tibial advancement (TTA).
EXPECTATIONS WITH SURGERY
Regardless of which surgery is done, two important points apply:
~ Lameness is eliminated, or almost eliminated, in most, but not all dogs that have surgery. Beyond saying this, it is not possible to predict how well each patient will respond to surgery.
~ The length of time from surgery to when the pet is using the leg as well as it will ultimately use it varies from patient to patient. In our experience this time frame varies from two months to two years. It is not possible to predict how long it will take any particular patient to use an operated leg well: for example, when a dog has both knees operated at different times, the recovery for each leg is often very different.
LATERAL SUTURE VS. TPLO
At YVC we generally recommend lateral suture over TPLO surgery. It is worth looking at some aspects of the two surgeries before deciding which procedure is best for a pet.
We have done knee surgeries at YVC for over 30 years. There have been several variations on the lateral suture procedure over this time. We have been performing the current version, with some minor modifications, for over 15 years. Our success rate is very good, and very similar to the success rates reported for this surgery in the veterinary literature in general. The implants (the suture and crimp) are small. We believe a lateral suture without an arthrotomy (more on arthrotomy later in this article), can accurately be described as the "minimally invasive" version of canine cruciate surgery.
Lateral suture surgery at YVC is $975 without an arthrotomy and $1200 with an arthrotomy. TPLO is available at YVC and at local veterinary referral practices. It is performed at YVCby a local veterinary surgical specialist. At YVC the cost of TPLO is $2500 to $3500, and at specialty practices it is usually considerably more.
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. However, extensive veterinary research has failed to prove that TPLO is superior to lateral suture surgery. We have performed lateral suture surgery on all types of dogs, including giant breeds and very athletic patients, with excellent results.
TPLO involves much more surgical trauma than lateral suture. For TPLO a bone is cut and repostitioned, and held in it's 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.
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 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 at this site than dogs that did not have a TPLO. In general, bone cancer in this location is less common than bone cancer at other locations, which makes this finding even more striking.
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 (a simple surgical procedure). 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 is difficult or impossible to remove and lateral suture is not a follow-up option.
A meniscus is a cushion on the end of a bone in a joint. Some patients with cruciate disease have meniscal damage. In dogs meniscal tears can be diagnosed in a few different ways:
~ Palpation. Feeling the knee with the patient awake and asleep.
~ Arthroscopy. "Scoping" is commonly done in people but rarely done in dogs, for a number of reasons.
~ Arthrotomy. Making a surgical incision into the joint capsule of the knee.
For many veterinary surgeons arthrotomy is a standard part of surgery for cranial cruciate tears. The surgeon first performs an arthrotomy, inspects the inside of the joint, debrides the torn pieces of cruciate ligament, and removes any damaged meniscal tissue, then proceeds with either lateral suture or TPLO. At YVC, our thinking on this subject, and subsequently our approach to knee surgery, has evolved over the last several years. We no longer routinely perform arthrotomy as part of knee surgery because:
~ Over many years of performing arthrotomies with every knee surgery we found very few patients with a damaged meniscus (and we have looked very carefully). We have also found on arthrotomies of knees with chronic cruciate disease that the damaged, diseased meniscus and cruciate ligament invariably shrink dramatically, so much that they are no longer contributing to arthritis or lameness. In some cases we could not find them at all.
~ Arthrotomy is the most difficult part of knee surgery for a dog to recover from (other than the bone cut in TPLO), in both amount and duration of post-operative pain and lameness.
Recent studies in people have shown no or minimal benefit when meniscal damage is treated surgically.
Our current approach to lateral suture surgery at YVC is to anesthetize the patient and palpate the knee, feeling for evidence of a problem with the meniscus. If none is found, we proceed with surgery without arthrotomy. If we find evidence of meniscal damage then the decision whether or not to perform arthrotomy is made on a case-by-case basis.
Since we have been regularly performing knee surgery without arthrotomy we have found that most patients recover with dramatically less swelling of the operated knee, improved range of motion, earlier weight-bearing, and substantially less post-operative discomfort compared to knee surgery including arthrotomy. We have not encountered any surgical problems or trouble with long term recovery specific to not doing an arthrotomy.
Yarmouth Veterinary Center