Your pet's knee (stifle) is the joint that bridges the upper and lower leg bones, the femur and tibia. It is a very complex joint that moves in many directions. To add stability to the joint there are very strong ligaments attached in a crosswise fashion that are present within it. The names of these ligaments are the anterior and posterior cruciate ligaments, so named as they form a cross or X. These ligaments acting with two outer bands of fibrous ligament called the lateral collateral ligaments maintain your pet's knee stability through a wide range of motion.
A small group of dogs suffer torn cruciates as a true sports injury. These are athletic dogs that test the physical limits of their bodies through over-exertion, agility trials, roughhousing, dock jumping, and Frisbee catching. But veterinarians see cruciate ligament damage much more frequently in overweight, spayed/neutered, middle-aged dogs.
A cruciate tear is diagnosed through examination of a painful stifle (knee) in your pet. This procedure is best done under anesthesia or heavy sedation due to pain and spasm of muscles surrounding the joint. After the pet is relaxed, palpation of the limb is performed to move the knee in directions that intact cruciate ligaments would normally disallow. Most commonly it is the anterior cruciate ligament (ACL) that is torn.
X-rays may also be recommended. These will not detect the damaged ligaments in your pet when they occur, but can show instability of the joint and pick up later arthritic changes as they develop in the unstable joint.
Surgical repair of the torn ligament is indicated to reduce the incidence of arthritis later in life. This procedure is done by inspecting the knee joint via a small incision (arthrotomy). The torn remnants of the ACL are removed and the other structures are in the knee are examined.
One type of repair, called an extra-capsular repair, is done by placing a strong, non-absorbable suture (nylon band) is passed around a small bone on the back of the knee and then placed through a small hole made in the front of the tibia bone. The suture is then tightened which serves to prevent inappropriate motion, effectively taking over the job of the torn cruciate ligament. Over time, scar tissue forms around the suture helping to stabilize the joint. This surgical option is typically reserved for small patients that are of healthy weight.
The second type of repair is called a tibial tuberosity advancement or TTA. This procedure involves the surgical advancement of the tibial tuberosity of the tibia bone using a specially designed bone plate and spring. The procedure allows the patellar ligament and quadricep muscle to block the abnormal movement that is occurring with the torn ACL ligament. Currently this is the procedure of choice of most orthopedic surgeons as research as shown that there is less arthritic change that occurs using this method. The procedure can be done on any dog of any size and is highly recommended for medium to large sized dogs.
The third type of repair is called a tibial plateau leveling osteotomy or TPLO. This repair requires a surgeon that has completed speciality training to perform this procedure. Like a TTA a TPLO requires manipulation of the joint by repositioning the bone and using special bone plates to hold it in place. This procedure can also be performed on any sized dogs and would be recommended in medium to large beed dogs.
About 85% of patients show a significant improvement after surgery and are able to resume pre-injury activities. To schedule an appointment for a surgical consultation please call our office at 715-268-8131.