Torn Knee Ligament in Dogs

The equivalent of the anterior cruciate ligament (ACL) in humans, the cranial cruciate ligament (CrCL) is vital to stabilizing the middle joint in the back of a canine leg (referred to as a knee or stifle joint). When the cranial cruciate ligament ruptures, it can cause damage to the meniscus—responsible for helping the joint to absorb shock, sense position and carry weight. A rupture of the canine cruciate ligament is a common cause of hind limb problems, such as lameness, pain, and knee arthritis. Cranial cruciate ligament tears are most common in larger dogs, where there is more weight being placed on the joint. It is common for dogs that develop a cranial cruciate ligament tear in one knee to also develop a similar problem in the other knee. The most prevalent risk factors for cranial cruciate ligament tears are poor physical body condition and obesity. The correlation between a genetic link and a torn knee ligament has not been defined. The majority, if not all, breeds have the painful possibility of a cranial cruciate ligament, with some breeds seeing an increase in chance.

Symptoms of a cranial cruciate ligament tear in canines are similar to those of an ACL tear in humans. Symptoms are usually more noticeable for acute cases, in which the tear occurs quickly, as opposed to progressively. Some common symptoms of cranial cruciate ligament tears include:

• Difficulty standing from a sitting position
• Hesitance to put weight on the limb, resulting in only the toe touching the ground
• Trouble jumping
• A decrease in activity
• Limping
• Muscle atrophy
• A decrease in the knee’s range of motion
• A popping sound (this sound may indicate a tear in the meniscus, which is responsible for a range of the knee’s capabilities)
• Swelling near the shin bone
• Pain
• Lessened desire to play
• Stiffness

Types

There are two primary distinctions when it comes to cranial cruciate ligament tears. These two categories are identified primarily by the progression of the cranial cruciate ligament tearing:

• Chronic - Just as it sounds, chronic cranial cruciate ligament tears occur in dogs that experience ongoing problems, usually mild. This form may improve with pain relief and rest. Over time, however, the condition worsens and is less responsive to pain relief treatments.
• Acute - Contrary to chronic cranial cruciate ligament tears, acute cases exhibit sudden onset of problems. Because the onset is sudden and typically more severe, this form is usually more painful, and signs of your dog experiencing pain are more obvious.

Cranial cruciate ligament tears are often a combination of multiple causes that are putting excessive force and wear on the ligament. Some of these possible causes include:

• Degeneration of the ligament, sometimes linked to excessive wear and tear or normal aging
• Obesity, which causes an increase of the weight put on the joint
• Poor physical condition also linked to obesity
• Genetics – Specifically for Newfoundlands and Labrador Retrievers
• Skeletal makeup
• Breed – Dogs that exhibit a higher likelihood of cranial cruciate ligament disease are Rottweilers, Newfoundlands, Staffordshire Terriers, Mastiffs, Akitas, Saint Bernards, Chesapeake Bay Retrievers and Labrador Retrievers.

On average, it is easier to diagnose a complete tear of the cranial cruciate ligament than a partial tear. However, the following diagnostic tests can help your veterinarian form a diagnosis:

• Physical exam
• X-Rays
• Palpation techniques, such as the cranial drawer test and tibial compression test, in which the veterinarian will place their hands in a specific way near the cranial cruciate ligament to assess the damage and aid in diagnosis.

Treatment for tears of the cranial cruciate ligament depends on a number of factors, including your pet’s activity levels, size, age, skeletal makeup and severity of the injury, as well as any other individualized health factors your veterinarian or surgical specialist may find. There are both surgical and non-surgical treatment options available. In most cases, a well thought out combination of the two may yield better results.

• Surgery - In most cases, surgical treatment is the best option for your pet’s improvement and quality of life. The cranial cruciate ligament is ultimately unable to heal once it has started to tear, so surgery takes a different approach. Surgery will vary depending on the degree of injury and if there is any additional damage to the meniscus, in which case the damaged parts of the meniscus will be removed. Possible surgical treatments can be categorized into two sections:
  • Bone cut-based techniques - which ultimately changes the way the knee works by manipulating the relationship between the quadriceps muscles and the skin bone. This technique is often most effective for large, active dogs. Surgeries that fall into this category include tibial plateau leveling and tibial tuberosity advancement.
  • Suture-based techniques - which are most commonly performed outside of the joint, uses a suture material to work similarly to how the cranial cruciate ligament functioned before tearing. Surgeries that fall into this category include extracapsular suture stabilization and the tightrope technique. This technique is more suited to smaller, less active dogs.
• While surgery is most often viewed as the best treatment of cranial cruciate ligament tears, there are non-surgical treatment options. These include activity restriction, anti-inflammatories, rehab, and custom knee braces.

While recovery and management depend largely on the treatment, the overall prognosis is good. It’s important to limit activity following surgical procedures. If your pet is overly active, it can reverse the effects of surgery and may require additional surgeries to repair the damage. Rehab, while offered as a non-surgical remedy, can also aid in the improvement and management following surgery. Rehabilitation should include passive range of motion, balance exercises and controlled walks on leashes. It is possible that your pet will develop arthritis as a result of the cranial cruciate ligament tear; this occurs less rapidly if surgery is used to treat the problem. If your pet is overweight, weight loss is an important part of recovery. Identifying and addressing causes of the condition can aid in avoiding future problems with the same knee and other knees as well.

The total estimated cost for diagnostic tests, which includes a physical exam, x-rays, and palpitation techniques, is $425 - $800 Treatment may include surgery (tibial plateau leveling, tibial tuberosity advancement, extracapsular suture stabilization, tightrope technique), activity restriction, anti-inflammatories, rehabilitation, and custom knee braces. These costs will depend on the condition of the canine and specialists required treatment. The cost will vary between $1,850 to $5,800.