Dog ACL Surgery (CCL)

Your dog’s stifle joint (knee) consists of 3 bones: the femur (upper leg), tibia (lower leg) and patella (knee cap), which moves up and down in a groove on the femur during movement of the joint. A meniscus, the shock-absorbing cushion in the joint, is attached to either side of the inner tibia. Stability of the joint is predominantly maintained by ligaments, bands of fibrous tissue that run from one bone to the other. The most important ligament in the dog’s stifle is the cranial cruciate ligament (Dog ACL), called the ACL in humans – known to be a common place of injury in athletes.

1 - Femur
2 - Tibia
3 - Fibula
4 - Cranial Cruciate Ligament (Dog ACL)
5 - Caudal Cruciate Ligament
6 - Lateral Meniscus

What causes a CCL (Dog ACL) rupture / tear?

The rupture of a CCL (Dog ACL) is usually a two-fold process. It has been determined recently that preexisting deterioration of the ligament itself is likely needed for this injury to occur. Unfortunately,
ligament deterioration is very common in medium to large breed dogs, the most commonly affected by a torn CCL. It is thought that the ligament, being weakened by the deterioration, is then put under
stress during activity, such as playing ball, Frisbee, running outside, or even as simple as a slip off of a stair. This weakened ligament will then rupture, creating a severely unstable stifle joint.

What are the signs of a CCL (Dog ACL) rupture / tear?

The dogs are initially unable to put weight on the leg, gradually becoming less lame. The lameness, however, does persist, even with rest. If the inciting injury is severe, there may be significant joint
swelling in the first 24 hours. Pain in movement of the stifle is a common sign, but if the injury occurred long enough before examination by a veterinarian, the pain may not be obvious. A common
second injury associated with a CCL tear is a medial meniscal tear, which can often be detected as a click on flexion of the stifle.

How do you diagnose a CCL(Dog ACL) rupture / tear?

A veterinarian will perform a complete physical and orthopedic examination of your dog, focusing ultimately on the leg in question. During the course of this examination, they may need to administer a
sedative to help your dog relax – in medium and large dogs, the thigh muscles are so strong that they can obscure any evidence of joint instability. Many times, the main focus for diagnosis of a CCL rupture is called
the “cranial drawer” test. If the CCL is intact, it keeps the femur and tibia from moving in an inappropriate front-to-back motion. However, in the cases of ligament rupture, the tibia can be slid out
from the femur like pulling out a drawer. Radiographs of your dog’s stifle are usually taken to determine if any other abnormalities are present, such as pre-existing arthritis.

How is a CCL(Dog ACL) rupture treated?

In smaller dogs, medical management with anti-inflammatory painkillers and cage rest (usually at least 6 weeks) is often sufficient to allow scarring down of the joint structures and return of some stability to the joint. However, the dogs will still very likely develop significant arthritis in that stifle. Physical therapy can be used after the rest period to help strengthen the thigh muscles that have atrophied during that time and improve the dog’s use of that leg.

For bigger dogs, medical management may not be an option. The length of time of cage rest required, and the subsequent arthritis development sometimes makes surgery more feasible.

What are my surgical options?

There are three types common surgeries, both with pros and cons, depending on the size of the dog.

Lateral suture (EXTRACAPSULAR) repair:

This type of surgery takes a thick filament similar to fishing line, and places it in a manner to mimic the action of the CCL. (Dog ACL) This provides the needed joint stability while the stifle heals from the initial injury.
The knee joint is opened and inspected. The torn or partly torn cruciate ligament is removed. Any bone spurs of significant size are bitten away with an instrument called a “rongeur.” If the meniscus is torn, the damaged portion is removed. A large, strong suture is passed around the fabella behind the knee and through a hole drilled in the front of the tibia. This tightens the joint to prevent the drawer motion, effectively taking over the job of the cruciate ligament.

• Typically, the dog may carry the leg up for a good 2 weeks after surgery but will increase knee use over the next 2 months eventually returning to normal

• Typically, the dog will require 8 weeks of exercise restriction after surgery (no running, outside on a leash only including the backyard)

• The suture placed will break 2-12 months after surgery and the dog’s own healed tissue will “hold” the knee.

This procedure is usually recommended for small to medium sized dogs.

Tibia Plateau Leveling Osteotomy (TPLO):

This procedure is usually recommended for all large dogs. It involves cutting the tibia, changing the joint angle, then placing a metal plate and screws across the cut to alter the joint mechanics and eliminate the need for a CCL to maintain stability.

With this surgery the tibia is cut and rotated in such a way that the natural weight-bearing of the dog actually stabilizes the knee joint. As before the knee joint still must be opened and damaged meniscus removed. The cruciate ligament remnants may or may not be removed depending on the degree of damage.

This surgery is complex and involves special training in this specific technique. Many radiographs are necessary to calculate the angle of the osteotomy (the cut in the tibia). At this time the TPLO is felt by many experts to be the best way to repair a cruciate ligament rupture regardless of the size of the dog and is especially appropriate for dogs over 50lbs. This surgery typically costs twice as much as the extracapsular method and requires a specialist.

• Typically, most dogs are touching their toes to the ground by 10 days after surgery although it can take up to 3 weeks.

• As with other techniques, 8 weeks of exercise restriction are needed.

• Full function is generally achieved 3 to 4 months after surgery and the dog may return to normal activity.

TIBIAL TUBEROSITY ADVANCEMENT (TTA)

The TTA represents another take on how to use the biomechanics of the knee to create stabilization. The idea is that when the cruciate ligament is torn, the tibial plateau (the top of the tibia) and the patellar ligament should be repositioned at 90 degrees to one another to combat the shear force generated as the dog walks. To make this happen, the tibial tuberosity (front of the tibia where the patellar ligament attaches) is separated and anchored in its new position by a titanium or steel “cage,” “fork,” and plate. Bone grafts are used to assist healing. This procedure was developed in 2002 at the University of Zurich and since then over 20,000 patients worldwide have have had this surgery. Some experts prefer it to the TPLO while others prefer the TPLO. Both procedures require specialized equipment and expertise.

• Typically the leg is bandaged for a week after surgery.

• The patients activity must be restricted and confinement is a must post-operatively with gradually increasing activity over 3-4 months. Most dogs can return to normal activity by 4 months after surgery.

Regardless of the type of surgical repair chosen by you and your orthopedic surgeon, physical therapy is highly recommended in the post-operative period to regain muscle strength and limb use.

What is involved with post-op care?

Your dog will be placed on strict cage rest after surgery. You should be given instructions on icing the stifle the stifle a few times a day and doing some basic stretching exercises to keep the motion in the stifle. Our "Bella's Hot/Cold Pain Relief Pack for Dogs" is perfect for icing the stifle after surgery! Made from a non-toxic glycerin gel, it remains flexible when frozen, allowing you to wrap it completely around the stifle (knee), icing down the entire stifle.

It is crucial that you follow the surgeon’s instructions in regards to activity level or the surgical procedure may fail. Depending on which surgical procedure is performed, physical therapy should begin a few weeks after surgery. A typical PT program for CCL ruptures takes about 5 weeks, with gradual return to nearly full exercise at that time. This will vary on a case-by-case basis depending on how your dog responds and how diligent you are with the at-home exercise.

What are the chances of this happening in both stifles?

One of the inciting causes of CCL rupture is deterioration of the ligament itself. One can assume that if one CCL has ruptured, there is deterioration of the ligament in the other stifle as well. In fact, about 50-75% of dogs with one torn CCL will rupture the other within a year or so. That is why we feel strongly about physical therapy, to get early return to a proper fitness level, even getting your dog in better physical shape than before surgery. This is your best hope at delaying a second CCL rupture.

MENISCAL INJURY

We mentioned the menisci as part of the knee joint. The bones of all joints are capped with cartilage so as provide a slippery surface where the bones contact each other (if the bones contact each other without cartilage, they grind each other down). In addition to these cartilage caps, the stifle joint has two “blocks” of cartilage in-between the bones. These blocks are called the menisci and serve to distribute approximately 65% of the compressive load delivered to the knee. The only other joint with a meniscus is the jaw (tempero-mandibular joint).

When the crucial ligament ruptures, the medial (on the inner side of the knee) meniscus frequently tears and must either be removed, partly removed, or ideally repaired. This is generally done at the time of cruciate ligament surgery and we would be remiss not to mention it.

Pets with meniscal damage may have an audible clicking sound when they walk or when the knee is examined, but for a definitive diagnosis the menisci must actually be inspected during surgery. It is difficult to access the menisci and thus repairing a tear in the meniscus is problematic; furthermore, poor blood supply to the menisci also makes good healing less likely. For these reasons, removal of the damaged portion of the meniscus is the most common surgical choice. This leaves some meniscus behind to distribute the compression load on the knee but removes the painful, ineffective portion.

Areas of current research include techniques to improve blood supply to the healing meniscus so that repair can be more feasible. If meniscal damage has occurred in a cruciate rupture, arthritis is inevitable and surgery should be considered a palliative procedure.