CCLR - Cranial Cruciate Ligament

What is the CCL (cranial cruciate ligament)?
The cranial cruciate ligament in dogs is equivalent to the anterior cruciate ligament (ACL) in people. The CCL has 3 main stabilizing functions during weight bearing: 1) prevent cranial displacement (cranial drawer) of the tibia (shin bone) in relation to the femur (thigh bone), 2) prevent hyperextension, 3) prevent internal rotation.

Why does the CCL rupture?
Unlike in human athletes where the ACL ruptures due to trauma, CCL rupture in dogs is due to a degenerative process that results in weakening of the ligament over time. This weakening can lead to rupture with normal activity, such as chasing a ball, playing, or running in the yard. We suspect there are multiple components to this degeneration, including genetics, conformational, environmental, and immune-mediated causes. Because of this degenerative process, 50% of dogs with a diagnosis of CCL rupture will rupture their contralateral ligament within 1 year of diagnosis.

Are there other parts of the joint that are affected?
The meniscus is a fibrous structure on top of the tibia that acts as a cushion during weight bearing. Without the CCL, there is abnormal motion of the femur that can result in a tear of the meniscus. This is identified and treated during surgery to correct the CCL rupture.

What are signs I will see if my dog has a CCL rupture?
There can be three different presentations of a dog with a CCL rupture: acute, chronic, or partial.

1. An acute rupture will result in acute non-weight bearing lameness that may improve with some time and/or pain medications. There can be waxing and waning signs of pain and lameness that may or may not be related to a meniscal tear.

2. A chronic rupture will result in long-term lameness and thickening or swelling around the affected knee joint. There may be decreased range of motion due to the thickening or from arthritis that forms secondary to the chronic instability.

3. A partial rupture may be difficult to diagnose although there may be a waxing and waning low-grade lameness that responds to restricted activity and pain medications. Eventually, this will lead to a more acute rupture and no resolution of lameness.

How will my doctor diagnose a CCL rupture?
The most common method of diagnosis is a physical examination; the most common finding is a “cranial drawer sign” or “tibial thrust” that is determined by manipulating the knee joint. You pet may need to be placed on his/her side to manipulate the knee or may even require sedation if they are too tense to perform this portion of the examination. X-rays may be taken during your initial appointment to rule out any other causes for lameness; the cruciate ligament is not visible on x-rays but signs consistent with a CCL rupture are easily found.

What treatment options are available?
Surgical treatment is recommended to provide stability to the knee joint. Conservative treatment can also result in stabilization but can lead to significant arthritis and life-long lameness.

There are multiple surgical procedures that have been attempted to restore the stabilizing functions of the ruptured ligament. There are three procedures that offer a greater than 90% success rate at stabilization of the stifle with minimal complications: lateral fabellar extracapsular suture, tibial plateau leveling osteotomy, and the tibial tuberosity advancement.

* Lateral fabellar extracapsular suture: A heavy gauge synthetic suture is used outside the joint to mimic the direction and force of the cruciate ligament. Unfortunately, due to the size of the suture, this

procedure is limited to dogs less than 40 pounds or patients who have decreased activity levels due to other medical conditions.

* Tibial plateau leveling osteotomy (TPLO): This procedure changes the biomechanics in the knee by making a semicircular cut in the back of the tibia and rotating it so that the surface of the tibia is flat, like a human knee. The cut tibia is held together with a stainless steel plate and screws and requires at least 8 weeks of recovery before the bone is healed. This procedure reduces the tibial thrust and is the most widely performed procedure to stabilize a CCL rupture. Most dogs following this procedure are able to return to normal function within 3-4 months of surgery.

* Tibial tuberosity advancement (TTA): This procedure also adjusts the biomechanics of the knee by making a straight cut at the front of the tibia and advancing it forward to put the patellar tendon at a 90 degree angle to the weight bearing surface of the knee. The cut tibial is held together with a titanium plate, cage, and screws. Most dogs following this procedure are able to return to normal function within 6 months of surgery.

What are the potential complications following surgical treatment?
Complications from these procedures include implant failure, infection (requiring implant removal), incisional complications (swelling, infection, loss of sutures), delayed/post-liminary meniscal tear, fibular fracture, pivot shift, delayed/reduced healing, and osteoarthritis. Most of these complications can be reduced by following activity restriction and discharge instructions. Licking or chewing at the incision is a common cause of infection that would require implant removal. Increased activity can lead to implant failure or increase risks for infection, menisal tears, or fibular fracture.

All patients will develop arthritis. Surgical stabilization decreases the progression of arthritis, thus early surgical intervention will improve your pet’s outcome. Arthritis progression can be minimized in the long-term by maintaining a lean body weight, regular low-impact activity, and using joint health supplements. As time progresses and if lameness returns, anti-inflammatory medications or other pain medications may be necessary.

What should be expected during the recovery period?
Orthopedic procedures, such as TPLO/TTA or fracture repairs, require at least 8 weeks of activity restriction. This means no running, jumping, playing, or stair-climbing is allowed. We recommend keeping your pet confined to a small space, such as a dog kennel, x-pen, or small room, for the duration of their recovery. Only leashed walks for eliminations for short periods of time are allowed. Off-leash activity both inside and outside the house are discouraged.

We recommend using an e-collar (not an inflatable collar) during the first 2 weeks of recovery to protect your pet’s incision. We understand that this is not always a desirable accessory but it is very important to your pet’s recovery. Any disruption to the incision from biting, chewing, or licking can lead to complications that may require further testing and treatment. These types of complications are not included in your original surgical price and will therefore require further costs.

Is physical therapy recommended following surgery?
Physical therapy can be instrumental in your pet’s recovery if it is done correctly and under the supervision of a Certified Canine Rehabilitation Therapist (CCRT) or your pet’s attending surgeon. Physical therapy typically begins about 4 weeks after surgery and any program can improve your pet’s flexibility, muscle mass, and comfort during their recovery. Please call to ask about prices and availability schedule for our Rehabilitation Service.