The Cranial Cruciate Ligament (CrCL) is one of the most important stabilizers inside the canine knee joint, which is the middle joint in the back leg. The CrCL may also be known as the Anterior Cruciate Ligament or ACL because this is the equivalent in humans. In fact, we are most commonly asked about treating a torn ACL.

A ruptured CrCL, or torn ACL, is one of the most common reasons for a dog’s hind leg limping, pain and subsequent knee arthritis.

Causes of a Torn ACL

A combination of factors causes CrCL Disease. Most commonly, your dog will tear his or her ACL due to:

  • Aging and degeneration of the ligament
  • Obesity
  • Poor physical condition
  • Genetics
  • Conformation (skeletal shape and configuration)
  • Breed
    • While CrCL can affect dogs of all sizes, breeds and ages, it rarely affects cats. Certain dog breeds are at higher risk for a torn ACL, including:
      • Rottweiler
      • Newfoundland
      • Staffordshire Terrier
      • Mastiff
      • Akita
      • Saint Bernard
      • Chesapeake Bay Retriever
      • Labrador Retriever

Symptoms of CrCL Disease/Tear

If your dog has torn his or her ACL, he or she will likely exhibit multiple signs of discomfort and immobility. Here are some of the primary clinical signs:

  1. Difficulty standing up
  2. Trouble jumping into the car
  3. Decreased activity level
  4. Lameness or limping (variable severity)
  5. Muscle atrophy (decreased muscle mass in the effected leg)
  6. Decreased range of motion in the knee joint
  7. A popping noise (which may also indicate a meniscal tear)
  8. Swelling on the inside of the shin bone


Surgery is the best way to treat a torn ACL as it is the only way to permanently control the instability and pain associated with the loss of normal CrCL structural support. Depending on the surgeon and the facility, there are many surgical options. However, there are two common surgical procedures: lateral fabellar suture (also known as extra-capsular suture stabilization) and Tibial Plateau Leveling Osteotomy (TPLO).

Extra-capsular suture stabilization (can be referred to as Ex-Cap suture and fishing line technique) is a popular technique. While there are many variations of this method, there is a consistent goal: to place a suture in similar orientation to the original ligament to mimic function prior to tear or deterioration. This method facilitates the formation of organized scar tissue around the joint to provide stability even as the suture gradually stretches or breaks.


  • Lower cost (typically)
  • Lack of specialized training to perform
  • No bone cut

High-Risk Patients:

  • Larger and younger patients have more complications. For this reason, many surgeons reserve suture-based techniques for small breed, older and/or inactive dogs.

Common Complications:

  • Failure of the suture
  • Progressive development of arthritis

TPLO involves cutting and rotating the bone to increase the joint’s stability when a dog has a torn ACL. The surgeon makes a circular cut around the top of the tibia and rotates its contact surface until it attains a perpendicular orientation relative to the attachment of the quadricep muscles. This renders the knee more stable in the absence of CrCL functionality.

The surgeon bridges the cut in the bone with a plate and screws. Once the bone heals, the bone plate and screws are unnecessary, though they are rarely removed unless they cause irritation or infection.


  • Superior outcomes attained in larger dogs
    • Limb function
    • Athletic mobility
  • Less progression of arthritis

Postoperative Care

Postoperative care at home is critical. Premature, uncontrolled or excessive activities risk complete or partial failure of any surgical repair. This failure may require extensive surgery. Your surgeon will explain (in detail) proper postoperative care before and after surgery to repair your pet’s torn ACL.

Regardless of treatment type, the long-term prognosis for animals undergoing ACL surgery is good. Reports signify 85-90% improvement. While arthritis threatens to ail torn ACL patients, it is expected to progress more slowly if surgery is performed. Therefore, we recommend multimodal osteoarthritis management for any dog with CrCL Disease or Tear regardless of treatment. This includes anti-inflammatory medications, weight loss, physical therapy and Omega 3 fatty acid supplementation as directed by your veterinarian.

How To Prevent a Torn ACL

Poor physical body condition and excessive body weight increase a dog’s chances of developing CrCL disease and tearing an ACL. Dog owners definitely influence these factors. As a dog owner, make sure to consistently exercise your furry friend and closely monitor his or her food intake.

How CARE Can Help

If your pet is limping on either back leg, having trouble standing up or showing any other sign mentioned above, schedule an evaluation with your family veterinarian. If a torn ACL or CrCL is suspected, ask your veterinarian for a referral to a board-certified surgeon at CARE. Our number is 704-457-2300.

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