Canine ACL Injuries and How We Manage Them

Anterior Cruciate Ligament (ACL) injuries, also known as Cranial Cruciate Ligament (CCL) injuries in dogs, are among the most common orthopedic problems we treat at Santa Ynez Pet Hospital. These injuries can occur for various reasons, including hyperextension of the knee, sudden pivots, steep Tibial Plateau Angles (TPA), and genetic predisposition. Large breeds and overweight dogs are especially prone to these injuries. While some ACL injuries happen suddenly, most cases involve gradual, chronic tearing, particularly in medium to large breed dogs.

Understanding the Role of the ACL

The ACL plays a crucial role in stabilizing the knee joint by preventing the tibia (shin bone) from moving forward relative to the femur (thigh bone). It also limits rotational forces, preventing internal rotation of the knee. When the ACL is damaged, the knee becomes unstable, leading to pain, swelling, and secondary injuries such as:

  1. Osteoarthritis
  2. Tears to the medial meniscus

Managing ACL Injuries

Conservative Management

In some cases, conservative treatment such as rest, pain medications, and rehabilitation exercises may be appropriate. However, surgery is often the recommended approach to effectively address ACL injuries and prevent further complications. Note: External braces are not recommended, as they can cause additional damage to the leg.

Surgical Intervention

Modern veterinary surgery provides a variety of advanced techniques to stabilize the knee joint, with recommendations tailored to each dog’s unique anatomy, activity level, and specific condition, as well as the owner’s preferences and budget. At Santa Ynez Pet Hospital, we combine expert assessment with personalized care to determine the most suitable surgical approach for your pet, ensuring optimal outcomes and long-term joint health. Key elements of ACL surgery include:

  • Joint Exploration: Examining internal structures to address issues like meniscus tears and removing frayed ACL fragments that cause inflammation.
  • Stabilization Surgery: Employing various techniques to restore knee stability

Surgical Techniques

Extracapsular Stabilization

This technique and its variants involve anchoring a synthetic suture-like material outside the joint capsule to stabilize the knee. By attaching this material to specific biomechanical points on the femur and tibia, it effectively mimics the ACL’s function from outside the joint. This method is particularly suitable for smaller dogs with mild tibial plateau angles, as their lower body weight and reduced joint stress make the procedure more effective and less prone to complications. While cost-effective, it is best suited for small dogs (under 40 lbs) with mild tibial plateau angles. Larger dogs or those with steep TPAs may experience faster joint degeneration with this method, and it is therefore not recommended in these cases..

Tibial Plateau Leveling Osteotomy (TPLO)

When a dog bears weight on a damaged or torn ACL, the femur tends to slide down the back slope of the tibia, causing instability and discomfort. The TPLO procedure addresses this by altering the tibial plateau angle, stabilizing the joint and potentially preserving any remaining healthy ACL fibers. This involves performing an osteotomy (bone cut) to rotate the tibial plateau into a more stable position. Over the last 30 years, TPLO has become the gold standard in specialty ACL surgery for dogs, boasting a high success rate of 90-95% and reliably restoring knee stability and mobility. We have had good success with this technique at Santa Ynez Pet Hospital.

Tibial Tuberosity Advancement (TTA)

The TTA technique moves the tibial tuberosity forward (this is the crest at the front of the shin bone), thereby pulling on the thigh muscles. This effectively pulls the femur forward and reduces stress on the ACL (if partially torn). TTA has limitations in cases with severe slopes or additional joint issues, but is a widely acceptable surgical technique for many cases. We do not perform this surgery at Santa Ynez Pet Hospital, as we do not believe it holds any advantages over TPLO and CBLO.

CORA-Based Leveling Osteotomy (CBLO)

CORA-Based Leveling Osteotomy (CBLO) is a specialized surgical procedure designed to treat ACL injuries in dogs with precision and effectiveness by combining the best aspects of the TPLO and TTA techniques. CORA stands for Center of Rotation of Angulation, a key principle in orthopedic surgery and joint geometry. By pinpointing the CORA, the surgeon can adjust the tibial plateau angle while aligning both the mechanical and anatomic axes of the tibia (this does not occur with any other method). In simpler terms, the CBLO procedure modifies the biomechanics of your dog’s knee to compensate for the damaged ACL. It does this not only by altering the angle of the tibial plateau, but also by pulling the patellar tendon and collateral ligaments slightly forward, enhancing stability and alleviating pain.

Why Choose CBLO for Your Dog?

CBLO combines the benefits of various techniques while minimizing their drawbacks. Its versatility, enhanced stability, and improved recovery outcomes make it an excellent choice for treating ACL injuries. While TPLO and CBLO are both excellent surgeries, there are several small advantages to the CBLO procedure:

  1. Versatility for All Sizes and Ages: CBLO is suitable for dogs of all sizes and breeds, from small companions to large working dogs. One advantage of CBLO is that the osteotomy (cut through the bone) does not extend into the joint, as it does in a TPLO. For this reason, the CBLO technique can even be used in young animals that are still growing, as it does not jeopardize the growth plates.
  2. Enhanced Stability: CBLO changes the angle of the tibial plateau to reduce the forces exerted on the damaged ACL. By stabilizing the knee joint, it allows your dog to regain full mobility without relying on the torn ligament. This is the same principle used in the TPLO procedure. As an added bonus, CBLO nearly eliminates the “pivot shift” often observed in patients post-TPLO surgery and places less stress on the Posterior Cruciate Ligament (the counterpart to the ACL, which pulls in the opposite direction and is important in preserving joint health and stability).
  3. Faster Recovery Time: Many dogs undergoing CBLO show quicker recovery times compared to other procedures, including TPLO. This is due to a much larger surface area of cancellous bone-to-bone contact when the surgery is completed. CBLO creates a more stable construct at the osteotomy site, which improves early function and promotes faster healing.
  4. Reduced Risk of Arthritis and Delayed Meniscus Injury: ACL injuries often lead to secondary joint issues like arthritis. CBLO’s biomechanical approach minimizes abnormal joint motion, reducing the risk of arthritis development over time. As an added bonus, it has a lower incidence of delayed meniscus injuries when compared to other surgical techniques.
  5. Preservation of Articular Cartilage: Studies have shown that CBLO better preserves the articular cartilage within the knee joint compared to Tibial Plateau Leveling Osteotomy (TPLO) over the long run. This preservation is critical for long-term joint health and function, as it helps delay the onset of arthritis and other degenerative joint conditions.
  6. An Improved Osteotomy: Both TPLO and CBLO elegantly employ a crescentic saw blade to create a curved osteotomy with which bone fragments can be rotated into position. The CBLO uses a dome-shaped or convex crescentic osteotomy through the shaft of the tibia and does not affect the joint nor damage growth plates in young animals. Conversely, the TPLO involves creating a scoop-shaped crescentic osteotomy which starts inside the knee joint and exits through the back of the tibia. This increases the risk of bacterial contamination through the osteotomy (you can never truly close the joint), and carries a risk of leaving a thin stalk of bone at the front of the tibia which can – on rare occasions – fracture despite taking precautions.
  7. Correction of Complex Conditions: CBLO is particularly effective for dogs with excessive tibial plateau angles and can be performed simultaneously with corrections for luxating patellas.

 

Other Surgical Techniques

Cranial Closing Wedge Osteotomy (CCWO)

This is the predecessor to the modern day TPLO. It involves making a wedge shaped osteotomy so as to tilt the tibial head forward and change the angle of the plateau. With the advent of the TPLO, it fell out of favor, but is occasionally still combined with a TPLO for more severe tibial plateau angles. A slightly improved variation of this technique is the Neutral Wedge Osteotomy.

Modified Maquet Procedure (MMP)

Similar to TTA, MMP uses an implant to stabilize the knee. This newer technique offers promising results for specific cases, particularly in dogs with mild to moderate tibial plateau angles.

Fibular Head Transposition (FHT)

This method involves altering the fibular head to restore stability. While less commonly performed, it can be a viable option for certain dogs with ACL injuries.

Primary Ligament Repair and Grafting

Techniques such as autografts (using the dog’s tendon) or allografts (donor tissue) aim to reconstruct the ACL. These advanced procedures are typically performed in specialty or research settings and are less common in routine veterinary practice.

The TPLO and CBLO Procedures at Santa Ynez Pet Hospital

Our TPLO/CBLO approach involves:

  1. Pre-Surgical Assessment: Comprehensive examination and X-rays to determine the severity of the injury.
  2. Surgery: Precision adjustment of the tibial plateau angle to restore knee stability.
  3. Post-Surgical Care: Individualized recovery plans with pain management, physical therapy, and follow-up visits.

Partnering in Your Pet’s Recovery

At Santa Ynez Pet Hospital, your pet’s well-being is our priority. Our team provides expert guidance and compassionate care throughout the treatment process. With our advanced surgical techniques and dedicated support, we’ll help your dog return to an active, happy life.

If your dog is dealing with an ACL injury, contact us today to schedule a consultation and explore the best options for their recovery. Let’s work together to get your furry friend back on their paws!