CVMA-ACMV

Cruciate Surgery: What You Need to Know

October 23, 2012

Just like our football and basketball stars, our athletic furry four-legged friends will jump and run around fine until one day, they may damage ligaments that hold the stifle joint in place (the knee joint in people). There are two cruciate ligaments that cross over the top of the tibia plateau, which is the flat part at the top of the tibia bone, and these ligaments act to stabilize the joint during motion. Usually, it is the CCL or cranial cruciate ligament (ACL in people) that is torn or broken. This condition is more common in dogs than cats. Frisbee or ball catching is one of the risk sports for dogs

Unfortunately, once the ligament snaps, the joint surface moves around (is unstable), so the pet almost always needs surgery to stabilize the joint to allow pain-free function. Without surgery, the excess movement will lead to severe lameness and arthritis which can cause pain and joint destruction. Sometimes, milder signs are noted.

According to Dr. Turpel, “instability” (commonly referred to as a positive drawer sign or positive tibial compression test) is often times absent since the ligament may be only partially torn at the time of evaluation”. It should be noted that a partial tear can progress to a complete rupture of the ligament especially if athletic activities continue without support. Torn ligaments must be distinguished from hip problems by your veterinarian, and x-rays (radiographs) will be recommended.

Some community veterinarians perform this surgery, while many refer to a board-certified orthopaedic surgeon—these latter specialists can be found at larger referral clinics and veterinary colleges. Dr Turpel advises his clients that surgical treatment of torn cranial cruciate ligaments, depending upon the technique employed and skill of the surgeon, typically have excellent outcomes.

There are different surgical techniques the surgeon may elect:

  • TTA (tibial tuberosity/tubercle advancement)
  • TPLO (tibial plateau levelling osteotomy)
  • Extracapsular repair (imbrication and plication, or Securos, TightRope™ )

TTA

The TTA has come into favour with many surgeons in the last decade according to Dr. Turpel, for reasons including “excellent long-term results, lower complication rates, more rapid return to normal function, and the TTA being a less invasive surgical procedure “.

TTA counteracts the rotational instability and cranial tibial thrust force which generate arthritis changes. The procedure involves placing titanium implants in the bone below the joint to hold the front aspect out ahead of the previous position. The “bionic” dog will now be ready to return to exercise gradually. Weight bearing returns in the first few days post-op, and frequently physiotherapy or other modalities are used to enhance healing.

TPLO

The TPLO is typically used for large dogs and according to Dr. Turpel, is referred to as the gold standard surgical treatment, and has been used on millions of dogs over the last 25 years.

Extracapsular

This is more than one technique. Different variations of surgery all share the goal of providing stabilization by supporting the joint outside the capsule.

The TightRope™ procedure is used in over 40 pounds but less than 130 pound dogs, and involves drilling holes into the bones to anchor a Kevlar-braided strong rope outside the joint capsule. In smaller dogs a thin Kevlar wire can be used to perform this technique, using smaller diameter anchors and smaller holes in the bones.

Other extracapsular techniques are described. According to Dr. Turpel, extracapsular surgery is “generally viewed as a good procedure for smaller dogs and cats, however the success decreases significantly with the increased size (weight) of the patient”.

Summary

The stifle (knee) joint is an important one to maintain normal limb function, since this joint is required to flex and extend with each stride. Return to athleticism is a goal that each caregiver hopes for. Costs for the procedure vary, and your veterinarian can provide you an estimate of costs involved. Unfortunately, sometimes active pets break first one hind leg cruciate ligament, then the other hind leg cruciate weeks to years later. To minimize the likelihood of a CCL injury, good fitness, muscle tone and lean body condition should be maintained. Turpel cites obesity as a major risk factor, and reinforces the fact that while many people with torn ACLs function fine without surgery, our pets require surgery if normal pain-free function is desired.

Note that veterinary orthotics and prosthetics are now available. These are external braces made of plastics or high density carbon that can help support an injured leg, and provide an adjunct to surgery treatments. They can be custom fit just like athletic splints for people! Sometimes they are used for support while one leg is repaired, because the other one is loaded more heavily and is at increased risk for injury until healing is complete on the surgery limb; this apparatus can be used to support the limb pre-op as well.

If your pet appears lame take him (or her) to your veterinarian for a thorough evaluation.

(Thank-you to Dr. Jim Turpel of Upper Canada Animal Hospital, Niagara-on-the-Lake for his comments)