Decision making for pets with ACL (Cranial Cruciate Ligament) tears

Anterior (Cranial) Cruciate Ligament Tears

Tears of the anterior (also called “cranial” in pets) cruciate ligament or ACL are the most common orthopedic injury in dogs. They also occur in cats, with less frequency. The reason for this common injury is not entirely known, but genetics, patient weight, and activity all likely play a role.

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Treatment for ACL Injury in Cats

Anyone who shares a home with a cat knows they are unique creatures. Their recovery from ACL injury differs from dogs, and our approach to their treatment is equally different. Cats actually do better without surgery in most cases. For most cats, the goals are to treat their pain, limit activity, and limit calories to allow weight loss for those cats that need it. Surgery is performed if these techniques do not resolve their lameness after a couple of months. The extracapsular repair (described in the next section) is the surgery of choice for cats that need a repair.

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Treatment for ACL injury- Extracapsular Repair

City of Lakes Veterinary Surgery performs three techniques for pets with a torn ACL. For small dogs (less than 25-30 pounds), and sometimes in cats, a surgery called an extracapsular technique (also called a fishing line repair or lateral suture imbrication) works well. This surgery involves placement of one or two heavy monofilament sutures that hold the knee in the correct position, preventing the abnormal movement that occurs when the ACL is torn. Proper recovery from this surgery relies on the body creating fibrous or scar tissue to hold the knee stable long-term. The scar tissue has to form before the suture is stretched for it to work. Essentially, this becomes a race between scar tissue formation and the repair stretching out or failing. But for small dogs, we generally win the race. For larger dogs who may stretch the repair out before enough scar tissue forms, we recommend a different approach. That brings us to the other two options:

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TTA and TPLO- An Overview

TPLO, or tibial plateau leveling osteotomy, and TTA, or tibial tuberosity advancement, are two biomechanically similar surgical techniques used to treat medium and large dogs (more than 25-30 pounds, depending on breed and body conformation), with a torn cranial cruciate ligament (CrCL or ACL). Both the TPLO and TTA create stability within the dog stifle by altering the forces in the knee. They both involve making a surgical cut in the tibia (shin bone) and using implants to hold the bone in place while the it heals in a new position. The new position allows knee stability to be provided by other knee structures, without the need to create a new ACL or repair the old one. The ACL is no longer needed once surgery is performed. The TTA procedure is essentially a modified version of the TPLO procedure, using a different location for the bone cut that is less invasive. Both TTA and TPLO are great procedures that have a very high rate of success, and each is likely to return the patient to normal or near-normal function.

 

So which is better, TPLO or TTA?

Most dogs are candidates for either TTA or TPLO. Dr. Hammel performs both TPLO and TTA. Recent literature favors the long-term outcome for TPLO, due to more normal mechanics and slowed progression of arthritis. TTA has the advantage of a quicker return to use of the leg following surgery, and less frequent need to remove the metal implants later in life. The most important factor for a good outcome is that your pet’s surgeon is experienced in the technique chosen. Dr. Hammel is a board-certified surgeon and has been performing TPLO since 2003, and TTA since the procedure was developed in 2005. He has performed over 10,000 of each of these procedures during this period of time.

 

Which has a shorter recovery time?

Both surgeries rely on the bone for healing, so exercise restrictions are similar- in most cases, 8 weeks. However, because it is a less invasive surgical process, TTA usually allows weight bearing earlier than TPLO. This means less time losing muscle and more time building it during the recovery period. While most TTA and TPLO dogs can begin weight bearing within the first 24 to 48 hours after surgery, TTA dogs tend to weight bear a bit earlier. Physical therapy will speed the use of the leg and improve long-term outcomes with either surgery.

 

Which has less risk of complications?

TTA uses titanium implants, which carry less risk of infection and rejection than the stainless steel implants used in TPLO. However, with recent advances in TPLO implant technology, the risks are now nearly equal between the procedures.