cranial cruciate ligament

This diagram shows the anatomy of the stifle or knee of a dog. Injuries to the cranial cruciate ligament are similar to ACL tears in humans.

The anterior cruciate ligament (ACL) in people is analogous with the cranial cruciate ligament (CrCL) in dogs. Like with people, CrCL injuries are common. Here we discuss how these injuries happen and the treatment options.

Where is the CrCL?

The cranial cruciate ligament is in the stifle (knee) which is in the back legs. Its purpose is to stabilize the stifle by keeping the femur and tibia in place.

How do dogs tear their CrCL?

People have ACL tears most commonly with traumatic injuries, whereas dogs most commonly have CrCL tears due to degeneration.

Genetic predispositions for degeneration of the ligament exist in Newfoundlands and boxers. CrCL ligament injuries also occur commonly in large breeds such as Labs and Rottweilers.

Straight-legged conformation may predispose the dog to CrCL injury. Dogs are also more prone to tearing their CrCL if they are overweight.

What are the signs of CrCL injury?

Dogs typically present with acute (quick) or progressive (worsening with time) lameness of one or both of the hind limbs.

They can be three-legged lame after exercise but lameness may improve with rest. Sometimes with time, the limb will become more weight bearing. If they can use the leg, they tend to walk with it rotated out and keep it more flexed than normal. Dogs will sit sideways and may have stifle swelling.

I have seen varying degrees of pain levels in these dogs from very little pain to extreme pain when motioning the joint.

How is a CrCL injury diagnosed?

The stifle joint is usually palpated (felt) for instability using a cranial drawer sign which is when the tibia is moved cranial (more forward) to the femur. Radiographs (X-rays) may be taken to look for signs of degeneration.

How is a CrCL injury treated?

About half of small dogs and 20 percent of large dogs will return to function with conservative treatment such as pain medications and rest.

If the conservative treatment does not work, dogs have to go to surgery which has over an 85 percent success rate and return to full weight bearing is much faster.

What are the surgical options?

There are several different options varying in cost and effectivity. The most common is the tibial plateau leveling osteotomy (TPLO) in which the tibia is moved to a position that makes the patellar tendon perpendicular to the tibial plateau.

The second most common is the extracapsular suture stabilization that limits the cranial motion and internal rotation of the tibia.

There are several other options too. Your surgeon will be able to discuss which is the best option for your dog.

How are CrCL injuries prevented?

As of right now, there is no prevention for cranial cruciate ligament injuries besides keeping your dog at a healthy weight.

Questions? Send email to Eric Knock, DVM, at or send mail to 321 E. 14th St., Miller, SD 57362.

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