Introduction: What is Cruciate Disease
The anterior cruciate ligament (ACL) is a major stabilizing structure in the canine knee. This ligament is responsible for preventing forward movement of the tibia (shin bone). With humans, it is often skiers and football players who tear this ligament. In dogs, we sometimes refer to this ligament as the cranial cruciate ligament, but the word cranial is a directional anatomical term used in dogs that means towards the head. The ligament is the same in humans as it is in dogs despite this directional term and rupture of this ligament is a common and debilitating problem. Unlike in humans where the ligament ruptures due to acute trauma (overloading of the ligament causing tearing), most dogs experience a degenerative process, weakening the ligament which leads to tearing. For this reason, your dog does not need to be an “athlete” to experience this problem.
Clinical Signs: What to Watch For
Pets with cruciate disease show a variety of signs:
- Walking on three legs or “hiking” their leg up
- A simple weight-shift off the painful leg
- Unwillingness to play or exercise
- Sitting with one leg extended out to the side
- Pain when the affected leg is moved
- Stiffness in the morning or while getting up
Diagnosis: Getting to the Bottom of the Problem
Your veterinarian may also notice additional signs including excessive fluid in the knee, clicking during flexion and extension of the knee and/or instability in the knee. Based on these signs, your veterinarian might recommend radiographs (X-Rays) and an evaluation of the knee while your pet is relaxed under mild sedation. At Spry Companions, the surgeons always utilize arthroscopy to confirm the diagnosis of a torn ACL (arrow) and to inspect the remainder of the joint for other injuries.
Prognosis: What to Expect Long Term
Once cruciate disease has been diagnosed, there are several points that are important to understand as treatment options are considered. In dogs, rupture of the ligament is a degenerative process rather than an injury. The ligament deteriorates first, weakening and allowing the ligament to rupture under normal activity. The likelihood of the ACL tearing in the other knee is 40-70% and for this reason, we typically refer to this problem as a “disease” in veterinary medicine rather than an “injury.” All dogs (100%) that have cruciate disease also have osteoarthritis. This osteoarthritis cannot be cured, but its progression can be greatly limited through surgical intervention. The prognosis is considered good to excellent when proper surgery is performed.
Treatment: Joint Exploration – How the Surgeon Looks Inside the Joint Matters
It is absolutely necessary that your surgeon provides some type of inspection of the inside of the joint in order to confirm the diagnosis, remove diseased ligament and identify other common injuries such as meniscal tears (a torn cartilage pad). Joint inspection can be done by open arthrotomy (an incision into the joint) or arthroscopy (exploration of the joint using a tiny camera).
The surgeons at Spry Companions have specialized training in arthroscopy and elect to utilize this method of joint exploration because it is the most minimally invasive option that has several advantages:
- Less invasive
- Reduces pain
- Improves function following surgery
- Minimizes progression of arthritis
- Allows better visualization of other structures within the joint, including the meniscus
Some surgeons utilize arthroscopy only to confirm the diagnosis and then open the joint. Just because a surgeon utilizes a tiny camera does not mean they practice in a truly minimally invasive manner. Should a concurrent meniscal injury be identified on arthroscopy, some surgeons will open the joint with a larger incision. Initial use of a small camera with conversion to a large incision cannot be considered “minimally invasive.” Therefore, it is important to ask your surgeon if all problems identified in the joint will be addressed through the tiny camera in addition to confirming the diagnosis (simply looking in the joint). The surgeons at Spry Companions have advanced arthroscopic training and high-definition equipment, so meniscal tears will always be managed through arthroscopy.
Treatment: Types of Joint Stabilization
There are three main techniques for stabilizing the knee including intracapsular (inside the joint), extracapsular (outside the joint) and high tibial osteotomies (bone cut). Each procedure has advantages and disadvantages. Orthopedic surgeons can help owners make good decisions for their pets regarding these surgical options. Recovery time for all procedures is similar, at approximately 6-8 weeks.
Intracapsular techniques are uncommonly performed today primarily because these techniques often fail. Extracapsular (outside the joint) techniques are sometimes performed but are not preferred by the surgeon at Spry Companions. Lateral Suture Stabilization (LSS) was one of the original techniques developed to treat ACL tears in dogs. This procedure is sometimes referred to as the “fishing line” technique. A suture is placed outside the joint capsule, but under the skin, to stabilize the joint in the same fashion that the ruptured ligament once did. This suture eventually breaks, so it only provides stabilization until scar tissue forms around the knee to provide long-term stability for the knee. Stronger materials have since been developed along with a variety of anchor techniques, but these implants can still fail.
The surgeons at Spry Companions most commonly perform procedures that address abnormal biomechanics following rupture of the ACL. Abnormal biomechanics can be addressed by high tibial osteotomy (bone cutting) techniques. A variety of osteotomy techniques have been developed (TPLO, CCWO, TTA, CBLO), but we prefer Tibial Plateau Leveling Osteotomy (TPLO) for standard ACL tears because we have the best success with this procedure. There are certain instances where another procedure might be better and your surgeons will help determine this. A semicircular cut in the tibia (arrow in picture) allows the top of the tibia to be rotated until it is “flat.” This results in a change in the biomechanics (how a joint functions) within the knee so that it no longer needs the ACL to remain stable. The cut in the bone must be stabilized with a bone plate and screws, but once the bone is healed, the metal plate is no longer required.
Treatment: How to Decide What is Best
Clinical research has not been able to “prove” that one procedure is best. The surgeons at Spry Companions have published research on this problem in dogs and agree about the following recommendations for most patients:
Sometimes unusual circumstances may indicate one procedure has a unique advantage over another. Deciding on one procedure should be based on initial consultation, experience and comfort level of the surgeon, success of the procedure and risk of complications. The surgeons at Spry Companions are board certified through examinations conducted by the American College of Veterinary Surgeons and are the most experienced in the region. The surgeons will most often recommend TPLO, but evaluate each case on an individual basis, creating a tailored plan for surgery and outlined rehabilitation. If your dog has been diagnosed with this problem or even if you suspect the problem, we understand that it can be stressful when considering surgery. We can help you arrive at a decision in which you feel comfortable and confident. If surgery is best for your pet, we will help you navigate the process with a comprehensive surgical and rehabilitation plan.