Surgical Treatment Of Cranial Cruciate Rupture In Dogs
Last week we discussed Cranial Cruciate Ligament (CCL) disease, causes and predispositions. Click here to read that post.
The American College of Veterinary Surgeons (ACVS) suggests that pet owners not consider conservative, medical treatment, as patients with complete rupture of the CCL cannot have stabilization of the knee joint by non-surgical means. Also, when the CCL ruptures, a cushioning structure in the knee called medial meniscus is also frequently damaged, and often requires surgical removal. A torn medial meniscus is very painful, and failure to remove damaged portions of the structure will prevent the patient from returning to full function.
In people, cranial (anterior) cruciate ligament (ACL) rupture is repaired with an intra-articular device that literally replaces the torn ligament. Because of the different conformation and structure of the canine knee joint (also called stifle), intra-articular methods of repair have been disappointing. Research into better methods is ongoing and promising.
EXTRA-CAPSULAR SUTURE TECHNIQUE
Extra-capsular surgical techniques (and there are several variations) generally utilize a strong, heavy suture material to mimic the function of the cranial cruciate ligament. Eventually this suture fails, but most patients have, by then, generated sufficient scar tissue around the outside of the knee joint. That scar tissue will prevent the abnormal relative motion of the tibia (lower leg) in relation to the femur (thigh bone). The disadvantages of this approach include suture failure (breakage), which is more likely to happen in active, large-breed dogs, and arthritis progression resulting from failure to completely stabilize the joint. It also has a lower cost when compared to bone-reshaping surgical techniques, discussed below.
TPLO: TIBIAL PLATEAU LEVELING OSTEOTOMY
Newer, more advanced and more technical surgical techniques are also available. TPLO is one, and stands for Tibial Plateau Leveling Osteotomy. Osteotomy means “to cut bone.” The tibial plateau is the top of the shinbone, upon which the femur (thigh bone) sits. After the top of the tibia is cut, the bone fragment is rotated until its top surface is “level,” or 90 degrees to the insertion of the quadriceps muscles, the major muscle group on the front of the femur. Now, normal body weight applied to the leg keeps the knee joint stable, even in the absence of a CCL. The cut bone is secured with a special bone plate that joins the bone fragment back to the tibia. The appliance is usually left in place, where it causes no harm.
Compared to the suture technique, TPLO provides considerably more stabilization of the stifle joint, leading to better leg functionality, less arthritis and a better long-term outcome. The greatest advantage is with the large, young dog.
Disadvantages include the need to cut the bone, which can sometimes lead to failure to heal and additional surgery(s). Rarely, implants can fail (break) before bone healing is complete, necessitating replacement. Few veterinarians who are not board-certified surgeons will tackle this surgery, but there are currently so many boarded surgeons pet owners should not have to travel far to find one. Your general practitioner will refer you to a surgeon.
TTA: TIBIAL TUBEROSITY ADVANCEMENT
TTA, Tibial Tuberosity Advancement, also seeks to create a 90-degree relationship between the quadriceps tendon and the top of the tibia. However, it accomplishes its end by a different means. The tibial tuberosity is a protrusion on the top, front of the shinbone. It is sliced off of the bone, then moved forward (advanced) until the correct angle is achieved. As with TPLO, a special bone appliance is used to stabilize the bone until it heals. The surgeon will help you make the decision between the two procedures. Some dogs’ preexisting knee problems can prevent the use of TTA.
EXTRA-CAPSULAR TIGHTROPE® TECHNIQUE
Tightrope® is the trade name of a device and technique of stabilizing the knee joint with a suture provided by the Arthrex Vet Systems company. Their suture is passed through a specific place in the femur, then a specific place in the tibia. Tightrope® provides a much more stable outcome for the knee than the traditional suture technique. In a study comparing Tightrope® and TPLO, no significant difference in outcome was detected six months postoperatively. Tightrope® has the advantage of being far less invasive.
We refer to non-surgical methods of addressing CCL injuries as “treatment” because failing to stabilize the knee joint rarely prevents ongoing pain and arthritis, which may become crippling. However, anything is better than nothing, and surgical repair may still help to improve your dog’s condition at a later date.
Weight loss is a crucial factor for the overweight patient, regardless of whether your dog has surgical repair. Simple dynamics of excess weight pounding on the knee joint will result in aggravation of arthritis.
Rest is crucial. The more times the knee joint is flexed and extended under pressure, the more wear and tear occurs. If the knee is used vigorously, such as running, the damage is compounded. Short walks on-leash are the most activity your dog should have (separate from rehabilitation, discussed below).
Antiinflammatories. Please note: aspirin causes many of the same problems in dogs that it does in people. Please avoid it. Your pet’s doctor will advise you on safe antiinflammatories.
Chondroprotectives. These are nutraceuticals that will help your dog save the cartilage he has, as well as help that cartilage to heal, be better lubricated, and less inflamed. Nutramax is the brand trusted by the most veterinarians.
Physical therapy and rehabilitation are proven techniques to help dogs after cranial cruciate ligament surgery of any type. Rehab should begin immediately after surgery according to your surgeon’s direction. According to studies, 85-90% of operated knees are improved after surgery. This percentage can be even higher with professional physical rehabilitation.
Unfortunately, even operated knee joints are not quite normal, so arthritis will proceed, although much more slowly than in un-operated knees with CCL rupture.
Remember, also, approximately half of the dogs who rupture one CCL will rupture the ligament in the opposite leg, also.
See you next week, Dr. Randolph.