What is a Cranial Cruciate Ligament  

The cranial cruciate ligament (CCL) is a crucial stabilizing structure within the knee (also known as the "stifle") joint, which is located in the middle of the back leg. In humans, this ligament is referred to as the anterior cruciate ligament (ACL). Another key component of the joint is the meniscus, a cartilage-like structure positioned between the shin and thigh bones. The meniscus plays a vital role in shock absorption, proprioception, and load distribution, but it is often damaged when the CCL is injured. 

Cranial Cruciate Injury 

A CCL rupture is one of the leading causes of hind limb lameness, pain, and the eventual development of arthritis in dogs. Unlike in humans, the progression of this condition in dogs is more complex, as they can experience varying degrees of ligament damage, ranging from partial to complete tears. Due to this variability, the condition is commonly referred to as "cranial cruciate disease" (CCLD) rather than simply a "cranial cruciate ligament rupture" (CCLR). While the severity of lameness associated with CCLD differs from case to case, it inevitably leads to arthritis over time 

In humans, ACL injuries are most commonly caused by trauma, such as those sustained during sports. While a similar “traumatic” rupture can occur in dogs, it is relatively rare. Instead, cranial cruciate ligament disease (CCLD) in dogs typically results from a combination of factors, including ligament degeneration due to aging, obesity, poor physical condition, conformation, and breed predisposition. Rather than a sudden injury to a healthy ligament, most cases of CCLD develop gradually over months or even years due to ongoing wear and weakening of the ligament. 

This fundamental difference between human and canine cruciate injuries leads to two key characteristics of CCLD: 

  • Dogs that develop a cruciate ligament issue in one knee have a high likelihood—at least 50%—of experiencing a similar problem in the other knee at some point. 
  • Partial tearing of the CCL is common in dogs and often progresses to a full rupture over time. 

Diagnosis 

Diagnosing a complete cranial cruciate ligament (CCL) tear is typically straightforward and involves assessing your pet’s gait, palpating the knee, and taking radiographs (X-rays). However, detecting early partial tears can be more challenging and may require advanced imaging, such as an MRI. 

X-rays are commonly used to confirm joint effusion (fluid buildup in the joint, indicating an underlying problem), assess the degree of arthritis, aid in surgical planning, and rule out other conditions like bone cancer. Certain surgical procedures, including tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA), require specific X-rays, and in some cases, your surgeon may need to take additional radiographs even if your veterinarian has already obtained some. 

A key diagnostic technique used by veterinarians to confirm CCL damage is the cranial drawer test, which evaluates abnormal knee movement and can indicate ligament rupture. However, X-rays do not directly show the condition of the CCL or the meniscus, as these structures are not visible on radiographs. For this reason, a thorough evaluation of both the ligament and meniscus during surgery is essential to ensure proper treatment. 

Treatment Options 

There are several treatment options for cranial cruciate ligament disease (CCLD), but the first key decision is whether to pursue surgical or non-surgical (also called conservative or medical) management. The best approach for your pet depends on various factors, including their activity level, size, age, conformation, and the degree of knee instability. 

In most cases, surgical treatment is recommended because it is the only way to permanently stabilize the stifle joint and directly assess the structures within it. Surgery addresses the two primary issues caused by CCLD: joint instability due to ligament loss and potential meniscal damage, which commonly occurs alongside CCLD. If the meniscus is affected, the surgeon will remove the damaged portions during the procedure to ensure proper joint function. 

To restore stability to the knee, several surgical techniques are available. These procedures generally fall into two main categories, each based on a different approach to stabilizing the joint: 

Osteotomy techniques involve making a controlled bone cut (osteotomy) to alter the way the quadriceps muscles interact with the top of the shin bone (tibial plateau). Rather than replacing the damaged cranial cruciate ligament (CCL), these procedures stabilize the stifle joint by changing the biomechanics of the knee. 

This can be achieved through two primary methods: 

  • Tibial Tuberosity Advancement (TTA): Moves the attachment point of the quadriceps muscle forward. 
  • Tibial Plateau Leveling Osteotomy (TPLO): Rotates the slope of the shin bone (tibial plateau) to reduce instability. 

Many surgeons favor these techniques for large, active dogs. At Salish Veterinary Hospital, we primarily perform the TTA procedure as our preferred surgical approach 

Tibial Tuberosity Advancement (TTA) 

Tibial tuberosity advancement (TTA) is a surgical procedure that involves making a linear cut along the front of the shin bone (tibia). The tibial tuberosity, the bony prominence where the quadriceps muscle attaches, is moved forward until the muscle's pull is approximately 90 degrees to the tibial plateau. This adjustment achieves the same biomechanical stability as the tibial plateau leveling osteotomy (TPLO) but through a different approach. 

Like the TPLO, the bone cut is stabilized using a specially designed bridging bone plate and screws to ensure proper healing and long-term stability. The choice between TPLO and TTA depends on factors such as surgeon preference, and individual patient anatomy. Some dogs may not have the appropriate knee structure for a safe and effective TTA procedure.  

Extra-Capsular Suture Stabilization 

Extra-capsular suture stabilization has been used for many years to treat cranial cruciate ligament disease (CCLD). While there are various modifications to this technique, including different suture materials, tying methods, and attachment points, the fundamental goal remains the same: to replace the function of the damaged CCL by placing a strong suture outside the joint. 

The suture is positioned in a way that mimics the orientation of the original cruciate ligament, providing stability while still allowing for normal knee movement. Over time, the suture supports the joint until scar tissue develops and assumes the stabilizing role. 

The most common complications following this procedure include suture failure and the progressive development of arthritis. Since suture failure is more likely in larger, more active dogs, this technique is reserved for small breeds. At Salish Veterinary Hospital, extra-capsular suture stabilization is available for patients when deemed appropriate.  

Potential Complications Following Surgical Treatment 

When selecting the best treatment for your dog, it is important to consider potential complications. Any surgical technique carries certain risks, including anesthesia-related complications, wound healing issues, infections, patellar (kneecap) luxation (dislocation), failure to regain full function, and progressive arthritis. 

For osteotomy procedures such as Tibial Tuberosity Advancement (TTA) and Tibial Plateau Leveling Osteotomy (TPLO), additional risks include: 

  • Delayed or non-healing of the bone 
  • Improper bone healing, such as limb rotation 
  • Bone fractures 
  • Failure or breakage of screws/plates 

While some of these complications may require additional surgeries, serious complications are rare when the procedure is performed by an experienced surgeon and post-operative exercise restrictions are followed carefully. 

Aftercare 

Proper postoperative care at home is essential for a successful recovery. Premature, excessive, or uncontrolled activity can lead to partial or complete failure of the surgical repair. The consequences of this failure depend on the procedure performed: 

  • In suture-based repairs, failure may require repeating the surgery. 
  • In osteotomy procedures (TTA or TPLO), failure can result in severe complications that may necessitate a more invasive corrective surgery. 

To promote healing, strict activity restriction is required for eight to twelve weeks. This includes: 

  • Leash walking only (no off-leash activity) 
  • No running, jumping, or rough play 

While limiting activity is crucial, it is equally important to maintain muscle mass and joint function through controlled rehabilitation exercises and range-of-motion activities. Following post-operative guidelines carefully will significantly improve the chances of a smooth recovery. 

Activity Restriction & Anti-Inflammatory Medications (conservative management)  

CCLD-related lameness often fluctuates, with periods of improvement, especially when pain management is implemented. In small dogs or cases involving partial ligament tears, lameness may temporarily resolve with rest and anti-inflammatory medication. However, larger dogs often experience ongoing lameness as arthritis progresses, particularly when attempting to return to normal activity. 

It is important to note that while pain medication and restricted activity can provide symptom relief, they do not stabilize the knee joint or prevent long-term arthritis. For this reason, non-surgical treatment is generally not recommended unless a dog is: 

  • Very small 
  • Sedentary/inactive 
  • Managing other serious health conditions 
  • Unable to undergo surgery due to financial constraints 

Prevention 

As mentioned earlier, obesity and poor physical condition are significant risk factors for the development of cranial cruciate ligament disease (CCLD). If your dog is overweight, implementing a weight loss program can help reduce their risk. 

Regular, daily activity is also crucial for maintaining joint health and preventing CCLD. Routine exercise strengthens the muscles around the knee, providing better support and reducing stress on the ligament. 

While joint supplements may offer benefits for general joint health, there is currently no evidence to suggest that they directly prevent the onset of CCLD.