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ASG Specialties:

  • Hip Dysplasia
  • Patella Luxation
  • Medial Patella Luxation
  • Elbow Dysplasia
  • Fragmented Coronoid Process
  • OCD Osteochondritis Dissecans Fractures
  • Arthritis
  • Ruptured Cruciate Ligament
  • Ruptured Cranial Cruciate Ligament
  • Ruptured Anterior Cruciate Ligament

Cranial Cruciate Ligament Disease

TPLO postop - Cranial Cruciate Ligament Disease

Injury to the cranial cruciate ligament (CrCL), also known as the ACL in people, is one of the most common orthopedic diseases seen by veterinary surgeons. Although occasional cases present after some form of trauma, like human athletes, the majority of cases occur during normal activities without any abnormal stress on the knee.

by Michael Huber, DVM, MS,
Diplomate American College of Veterinary Surgeons

Cranial Cruciate Ligament

Much like the human ACL, this ligament is one of the primary stabilizers of the canine knee. The cranial cruciate ligament runs across the joint in a diagonal direction and prevents forward translation of the tibia. When the cranial cruciate ligament is deficient, the femur will slide down the top of the tibia with every step taken by the pet. This abnormal movement, if allowed to continue, will lead to arthritis and meniscal damage.

Affected Pets

Cranial cruciate ruptures occur in dogs of all sizes and ages, but most commonly middle aged, medium to large breed pets are affected. Certain breeds, such as Neapolitan mastiffs, Newfoundlands, Akitas, St. Bernards, Rottweilers, Chesapeake Bay retrievers, and American Staffordshire terriers have been reported to be particularly at risk. Cats can also present for lameness of the back legs due to cruciate ligament rupture.

Common Signs of a Cranial Cruciate Ligament Rupture

Signs associated with a ruptured cranial cruciate ligament can vary greatly. Pets can have mild signs, usually associated with a partial tear, such as not wanting to jump into the car, sitting off to the side, or stiffness after exercise. However, most commonly there is a history of acutely becoming non-weight bearing on a back leg, which will gradually improve over several weeks.

Other Causes

Any stifle (knee) pathology can cause very similar signs. Patellar luxations (medial or lateral), osteochondritis dessicans (OCD) of the stifle, caudal cruciate ligament rupture, tumors of the bone, or joint and immune-mediated diseases can all cause similar signs.

Cranial Cruciate Ligament Rupture Diagnosis

Diagnosis of a ruptured cranial cruciate ligament is generally straightforward. With complete ruptures, your veterinarian can elicit a cranial drawer or tibial thrust sign. These tests demonstrate the abnormal forward movement of the tibia that the cranial cruciate ligament is supposed to prevent. In partial tears, the diagnosis is a little more difficult, but most dogs have pain on hyperextension and more laxity in flexion. Chronic tears are usually accompanied by a firm swelling associated with the inner part of the knee, known as medial buttress.

Treatments for a Ruptured Cranial Cruciate Ligament

Unlike in humans, a torn cranial cruciate ligament is a surgical disease. Surgery speeds the rate of recovery, decreases progression of osteoarthritis, and enhances function. Without some form of surgery to stabilize the knee, continual damage to the cartilage and menisci will lead to severe arthritis. Medical management is often employed concurrently, and consists of activity restriction, weight loss, anti-inflammatories and joint supplements. It is important to note that medical management alone is not a treatment, as it does not provide any stability to the knee, but hopefully provides subsidence of inflammation and symptoms of lameness with return to normal function usually limited by progression of osteoarthritis.

There are several surgical options available for the treatment of ruptured cranial cruciate ligament. They are divided into two main categories: recreating the function of the ligament and altering the forces within the knee.

Recreating the Function of the Ligament: The most common procedure done to recreate the function of the cruciate ligament is an extracapsular stabilization or lateral fabellotibial suture. This procedure uses a heavy nylon suture to stabilize the knee and is placed in the same direction as the normal ligament. This procedure depends on the pet developing scar tissue, which will ultimately keep the knee stable.

Altering the Forces Within the Knee: A tibial plateau leveling osteotomy (TPLO) is one of the procedures that alters the forces applied to the knee to neutralize the forward translation thus stabilizing the knee. The top of the tibia is flat and slants backwards in the dog. This slope is what the femur slides down during weight bearing. In this surgery, a circular saw blade is used to cut the top part of the tibia. The bone is then rotated to eliminate the slope and repaired with a bone plate and screws. This surgery essentially eliminates the “need” for a cranial cruciate ligament. This surgery is generally advocated over the suture technique especially in large breed, active pets.

Possible Surgical Complications

As with any surgery or anesthesia there are potential complications. Pre-operative blood tests are performed to eliminate any metabolic conditions that may complicate anesthesia. Mild incisional infections and seroma (fluid pocket under the skin) formations occur infrequently. Occasionally, an infection may require plate removal once healing is complete. If the postoperative instructions are followed, complications are not common.

It should be noted that approximately 30-50% of pets will rupture the opposite leg cruciate ligament within two years.

Postoperative Care

For the first two weeks after surgery the incision will need to be evaluated daily for increased swelling or redness, bleeding or discharge, or missing sutures. Any mild bruising or swelling can be treated with a warm compress applied to the incision for 10-15 minutes two to three times daily.

Activity restriction is the MOST IMPORTANT aspect of postoperative care. The pet should be STRICTLY CONFINED for the two months after surgery. When not under your direct supervision, your pet should be confined in an airline kennel, crate, small room with non-slip floors, or equivalent. No running, jumping or playing is allowed. Short (10-minute) leash walks to urinate and defecate are allowed. Additionally, we send home a sling, which should be used under the belly to help support the back legs (keep them from slipping or trying to run).

Re-check examinations are usually performed at two, four and eight weeks after surgery. At these re-checks the knee is examined for stability, and if a TPLO was performed, radiographs (x-rays) are taken to assess healing.

Animal Specialty Group

DVM, MS, Diplomate American College of Veterinary Surgeons

After Dr. Michael Huber received his Doctor of Veterinary Medicine degree in 1993 from Purdue University, he completed an internship at the University of Minnesota (in small animal medicine, surgery, and emergency medicine), followed by a three-year residency at Auburn University.

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