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Ruptured Cranial Cruciate in Dogs (Torn ACL)

Posted 05.27.19 by Bart E. Madison, DVM

A ruptured cranial cruciate ligament (CCL), also known as a torn ACL, is one of the most common causes of acute and chronic hind limb lameness we see in clinic practice. The CCL in dogs, much like humans, is one of the major ligaments that connect the upper leg bone (the femur) to the lower leg bone (the tibia). Often, the dog becomes suddenly painful and unable to walk on the affected leg after playing outside or jumping off furniture. Other dogs present with a longer history of mild weakness or knee soreness that gets worse with exercise. Some will suffer from knee injuries that would make it hard to walk, jump, or even play.

Checking for laxity in the knee

Dr. Newman checking for instability in the knee.

Many owners come in worried that their dog’s hips are painful. We see 2-3 patients with a ruptured CCL for every patient with a hip problem as a cause of their pain.

Diagnosis of a torn ACL is usually made by physical examination. The majority of the time, the doctor is able to feel instability in the joint and diagnose the condition. Sometimes, if the tear is very acute and the knee joint is swollen, or if the dog is very tense or fractious, sedation may be needed to relax them enough to feel the tear. We can also make a diagnosis based on radiographic signs. Inflammation in the knee joint along with degenerative changes suggest the CCL is the cause of the lameness. Many dogs already have arthritic changes in the joint at the time of diagnosis, which correlates to research that suggest CCL tears are a degenerative process that occurs over several months before the cruciate ligament finally tears.

Dr. Madison cruciate surgery
Checking the knee joint.

Treatment for CCL disease typically involves surgery. Some dogs will recover without ACL surgery, but this option is usually limited to very small patients and sometimes leads to severe arthritis and disappointing outcomes.

When performing ACL surgery, we make a small incision into the knee joint and remove the remnants of the torn ACL. We also check for damage to each of the meniscus, which are small C-shaped cartilage like shock absorbers between the bones. About 60-70% of the dogs treated in our practice have a torn medial meniscus along with the torn CCL.

Torn meniscus in the knee joint
Remnants of a torn CCL inside the joint capsule.

One option we give to all of our patients is to be referred to a specialist for a procedure known as TPLO, where the tibia is surically cut in a circular pattern and a bone plate is applied after rotating the cut bone segment into a position that redirects the forces that were previously applied to the CCL onto other structures in the knee.

For small dogs in our practice, we typically treat with extra-articular or extracapsular stabilization. In this procedure, synthetic material is placed outside the joint and anchored to the bones to stabilize the joint while preserving all other motion.

TTA tibial tuberosity advancement
Cutting the bone during a TTA or tibial tuberosity advancement.

In medium to larger dogs, we perform a procedure known as Orthomed MMP for CCL repair. This is a version of a bone cutting procedure known as TTA or tibial tuberosity advancement. This procedure redirects the forces on the CCL to the patellar tendon and other muscles and ligaments used when the limb is used.

A small cut is made on the lower leg bone using a bone saw. An implant is then place in the gap created by the bone cut. It is then secured with a compression staple and orthopedic wire. Recovery from an ACL surgery usually involves 6-8 weeks of cage rest and leash walks.

No matter what method of repair is chosen, knee rehabilitation is crucial. Many leash walks are involved. Professional physical therapy is also recommended to improve outcome.

The goal of surgery is to return the dog to full athletic function.

Dogs playing at daycare

If you suspect your dog may have injured their knee, contact us or use our Chat function to make an appointment with any of our doctors and we will be happy to check them out!

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