Cranial Cruciate Ligament Rupture (CrCLR)

The stifle, or knee joint, is made up of the bones of the upper leg (femur) and the lower leg (tibia), as well as the supporting ligaments. Four major ligaments support and stabilize the stifle in the dog. The external stabilizers are the medial and lateral collateral ligaments. The two important internal stabilizers are the cranial and caudal cruciate ligaments. The two ligaments are the same as the anterior (ACL) and posterior (PCL) cruciate ligaments in people. These ligaments allow for normal range of motion while they prevent abnormal forward and backward sliding and internal rotation of the tibia with respect to the femur. These abnormal movements are called “drawer motion” or “cranial tibial thrust”, and it is by palpation or feeling of this motion that a veterinarian can diagnose a cruciate ligament tear.

Deterioration and tearing of the cranial cruciate ligament is one of the most common causes of hind limb lameness, pain and degenerative joint disease (osteoarthrosis) of the stifle in dogs. The condition is a degenerative one in dogs, with daily wear and tear resulting in damage to the ligament that cannot properly heal. Often a minor injury such as occurs after a twist and accelerate or hyperextension activity causes a partial or complete rupture of the cranial cruciate ligament. Once the cranial cruciate has even a partial tear (sprain), the daily strains on the stifle with any weight bearing activity will eventually result in complete cranial cruciate ligament rupture.

There are several procedures that may be engaged to repair the stifle joint following a rupture. Which procedure is most appropriate for your dog depends on a myriad of factors.  Many veterinarians know one procedure or another to treat Cranial Cruciate Rupture, but a given procedure may not be appropriate or effective for your dog. Board-Certified Surgeons know all of the available techniques of repair. A Board-Certified Surgeon is most qualified to discuss the best-customized treatment for your dog based on upon its size, bone morphology (shape of the bone), age, other damage to the joint, and activity level. .

Whenever your pet is showing signs of a health issue your first step is to contact your primary care veterinarian. If it is indicated that your pet may suffer from cranial cruciate ligament rupture or another serious condition, a veterinary specialist is available at an ExpertVet certified hospital.


The stifle has two very important ligaments called the cranial (CrCL) and caudal (CaCL) cruciate ligaments (cruciate means a cross or crucifix) that cross in the center of the joint. The CrCL (known as the ACL in humans) restrains the backward and forward motion of the joint, in addition to inward twisting and hyperextension of the joint. It is the ligament that is most commonly injured in dogs.

The stifle also has two half-moon shaped cartilage structures between the weight-bearing bone ends called menisci. There are two menisci in each stifle, one on the inner side of the joint called the medial meniscus and one on the outer side of the joint called the lateral meniscus. The menisci add support to the stifle and also serve as shock absorbers by spreading the weight load.