CCL vs ACL Injuries in Dogs. What's the Difference?

Table of Contents

Introduction

The cranial cruciate ligament (CCL) and the anterior cruciate ligament (ACL) refer to the same ligament in a dog’s knee. This ligament is one of the major stabilizing ligaments in the canine knee joint and is commonly torn or ruptured in dogs.

A CCL or ACL injury involves partial or complete tearing of this ligament, which leads to joint instability and osteoarthritis over time. It is one of the most common orthopedic injuries in dogs.

While CCL and ACL technically refer to the same ligament, CCL is more commonly used in veterinary medicine to describe the dog’s knee anatomy, while ACL is used in human medicine. But the terms are often interchangeable when discussing knee injuries in dogs.

A CCL/ACL rupture is a severe injury that will significantly impact normal function and quality of life if left untreated. But various treatment options are available to help stabilize the joint and manage pain. With proper treatment, many dogs can return to an active lifestyle after a CCL/ACL tear.

Anatomy

The cranial cruciate ligament (CCL) in dogs is analogous to the anterior cruciate ligament (ACL) in humans. Both ligaments are located within the stifle (knee) joint and have the important function of providing stability and preventing excessive forward movement of the tibia on the femur (Veterinary Teaching Hospital, https://vetmedbiosci.colostate.edu/vth/services/orthopedic-medicine/canine-cruciate-ligament-injury/).

Specifically, the CCL crosses diagonally from the front of the femur to the back of the tibia, forming a cross or “cruciate” shape. It prevents the tibia from sliding forward away from the femur and provides rotational stability to the stifle joint. The ACL serves the same stabilizing function within the human knee (TPLO Austin, https://tploaustin.com/6-steps/step-2-about-ccl-acl-injuries/).

When the CCL/ACL is torn or ruptured, the stability of the knee/stifle joint is compromised, leading to abnormal motion and instability.

Causes

Common causes of both CCL and ACL tears in dogs include:

High-impact activities like jumping or running can put strain on the ligaments and cause tears, especially as dogs age. Older dogs are more prone to ligament tears due to natural weakening and deterioration that occurs over time.

Obesity is a major risk factor, as excess weight puts increased stress on joints and ligaments. According to the AVMA, overweight dogs have a greater than 1 in 5 chance of rupturing a CCL.

Traumatic injuries from things like falls or accidents can also damage CCLs and ACLs. However, the majority of cruciate ligament tears in dogs occur over time without a specific traumatic cause, especially in larger breed dogs.

Other predisposing factors include anatomical variations like a shallow knee joint or malformation of the femur, as well as diseases like diabetes that may weaken connective tissue.

Overall, CCL tears are primarily attributed to long-term wear and tear, while ACL tears in humans more frequently involve sudden trauma and impacts from sports or accidents. But obesity, aging, and anatomical issues raise risk for cruciate ligament ruptures in both dogs and people.

Source: https://vetmedbiosci.colostate.edu/vth/services/orthopedic-medicine/canine-cruciate-ligament-injury/

Symptoms

The most common symptoms of CCL and ACL injuries in dogs include limping, difficulty bearing weight, swelling, stiffness, and lameness in the affected leg ^[1]. Dogs with partial tears may show mild lameness that worsens with exercise. More severe injuries can result in the dog being unable to put any weight on the injured leg. Swelling around the knee joint within the first 24 hours is also indicative of significant ligament damage^[2].

Additional symptoms of CCL/ACL tears include difficulty standing up, abnormal sitting posture with the injured leg extended out, muscle wasting in the affected leg, and stiffness after resting. Dog owners may also notice their pet suddenly yelp or vocalize from pain. Some dogs will avoid stairs and jump down from furniture. Lameness that persists for more than a day warrants veterinary examination^[1].

Diagnosis

Diagnosing a torn CCL or ACL in dogs usually begins with a physical examination by the veterinarian. They will manipulate the dog’s knee joint and perform drawer and tibial compression tests to check for laxity and pain response, which are indicative of ligament tears (Canine Cruciate Ligament Injury).

Imaging tests like X-rays, CT scans, and MRI can help confirm the diagnosis and assess the extent of injury. X-rays may reveal signs of osteoarthritis and bone changes consistent with a chronic ACL/CCL injury. However, ACL/CCL tears don’t show up directly on X-rays, so MRI or CT scans can provide more definitive confirmation by visualizing the ligament itself (Diagnosing rupture of the cranial cruciate ligament).

While some ACL/CCL tears can be partial, most diagnosed clinically are complete ruptures. Since these ligaments provide major stability for the knee joint, complete tears significantly destabilize the joint and require treatment.

Treatment

Treatment for CCL injuries in dogs usually involves a combination of conservative management, surgical repair, and rehabilitation. Conservative management focuses on restricting activity, anti-inflammatory medications, joint supplements, and other alternative therapies to control pain and inflammation while allowing the knee to rest and heal. According to CCL Injuries in Dogs: What They Are, How to Fix Them, the goal is to “make the patient comfortable while healing occurs.” This approach may be suitable for small dogs or those with partial tears.

Surgical repair is considered the most effective treatment for complete CCL ruptures as it stabilizes the joint and facilitates quicker healing. Common techniques include extracapsular suture stabilization, tibial plateau leveling osteotomy (TPLO), tibial tuberosity advancement (TTA), and variations involving implants or grafts. According to Canine Cruciate Ligament Injury – Veterinary Teaching Hospital, the type of surgery depends on factors like the dog’s size and activity level. Surgery often requires 8-12 weeks of restricted activity for proper healing.

Rehabilitation is an essential part of recovery following CCL surgery or injury. This typically involves controlled exercise, massage, cryotherapy, hydrotherapy, and other modalities to strengthen the knee, improve range of motion, prevent muscle atrophy, and accelerate healing. Rehab protocols are tailored to each dog’s specific needs. According to ACL (CCL) Injuries in Dogs & Available Treatment Options, the goal is to “maximize function and quality of life.” Regular rehab can lead to better outcomes long-term.

Surgical Options

There are several different surgical procedures that can be performed to repair a torn CCL in dogs. Three of the most common are:

Tibial Plateau Leveling Osteotomy (TPLO)

The TPLO procedure involves cutting and rotating the top of the tibia to change the angle of the tibial plateau, stabilizing the stifle joint. According to the All Animal Clinic, this surgery is more complex but may allow for faster recovery time. Pros of TPLO include early return to function and decreased risk of future arthritis. Cons are the extensive surgery and bone cutting required.

Tibial Tuberosity Advancement (TTA)

In the TTA procedure, a spacer is placed to neutralize the slope of the tibial plateau. The A-Z Animals notes this method also allows for early weight bearing. Pros are the joint stabilization and minimally invasive technique. Cons are the implants required and potential for fracture.

Extracapsular Repair

According to VCA Hospitals, extracapsular repair uses sutures around the knee to stabilize it. This technique does not require bone cutting. Pros are the simplicity and lower cost. Cons are the longer recovery time and higher risk of re-injury.

Recovery

The typical recovery time for dogs after CCL or ACL surgery is 8-12 weeks ¹. During this time, exercise should be restricted and supervised to allow proper healing. Movement such as climbing stairs, jumping on furniture, running, and playing should be limited.

For the first 2 weeks after surgery, dogs should be kept crated or confined when not taken outside on a leash for bathroom breaks. Strenuous activity and free range of motion can damage the surgical repair before it has healed. After 2 weeks, 5-10 minute leash walks can be introduced a few times per day.

At 4-6 weeks, longer and more frequent walks are allowed but running and playing is still restricted. Around 6-8 weeks, supervised off-leash activity in a confined space can be introduced. After 8-12 weeks, dogs can return to normal activity levels as long as they are showing no signs of lameness or pain.

It’s important to follow activity restrictions during recovery as returning to normal activity too soon can damage the repair and require additional surgery. With proper rest and limited activity during the 8-12 week recovery period, most dogs heal successfully after CCL/ACL surgery².

Rehabilitation

Rehabilitation focuses on physical therapy exercises and modalities to help dogs recover from CCL injuries and surgery. Some common exercises include:

Passive range of motion – Gentle bending and extending of the knee joint by a therapist to maintain flexibility. Should be done multiple times a day early in recovery (Source: https://ucah.ca/ccl-rehab-instructions/)
Active range of motion – Having the dog actively bend and straighten the injured leg on their own. This builds muscle strength. (Source: https://www.dvm360.com/view/rehabilitation-of-the-cranial-cruciate-deficient-stifle-and-targeted-therapeutic-exercise)

Controlled walking – Walking on a leash using slings or harnesses to control weight bearing. Speed and duration increases gradually over weeks. (Source: https://www.dvm360.com/view/rehabilitation-of-the-cranial-cruciate-deficient-stifle-and-targeted-therapeutic-exercise)

Modalities like cold laser, therapeutic ultrasound, and neuromuscular electrical stimulation may also aid recovery and control pain/inflammation.

Prevention

There are several ways to help prevent CCL/ACL injuries in dogs:

Exercise – Low impact exercise like swimming and walking can help strengthen muscles around the knee joint without putting too much strain on the ligaments. Avoiding high intensity activities like jumping and rough play can also reduce risk of injury. Physio-Vet

Diet – Ensuring your dog maintains a healthy weight reduces stress on the joints. Some supplements like glucosamine and chondroitin may also help strengthen cartilage and prevent injury.

Prehab – Doing preventative exercises and stretches can strengthen muscles and increase proprioception. This includes things like balancing on unstable surfaces, sideways walking, and hind leg stands.

Body awareness – Paying attention to changes in your dog’s movement and gait can help identify issues early before a full tear occurs. Contact your vet if you notice limping, trouble standing up, or other changes.

Surgical prevention – Some vets may recommend preventative surgery on the other knee after a CCL/ACL tear, as dogs have a high likelihood of tearing the opposite ligament later on. Discuss options with your vet.