# ACL Tears: Symptoms, Diagnosis, and Corrective Surgery



## Sarah Hall (Apr 12, 2006)

*ACL Injuries: How they Happen and Symptoms*
An ACL (Anterior Cruciate Ligament) injury often occurs when there is just the right amount of force impacts the knee joint. There are actually two cruciate ligaments in a canine knee, however the one most often torn is the cranial cruciate ligament, and this article is mainly going to talk about the repair of this common injury. This, in humans, is most often see with NFL players. They call the ACL injury "football knee" sometimes. With canines, this most often occurs in overweight pet dogs. It also occurs in large breeds, and any breed that gets hit by a car. When the anterior cruciate ligament is torn, instead of moving like a hinge, the knee joint will actually make a sliding motion. This abnormal motion and instability creates trauma within the joint that leads to wearing of cartilage, increased synovial fluid production and inflammation. Eventually, the dog will develope degenerative joint disease.
*Diagnosis*
Vets usually use x-rays and physical examination under sedation (or anesthesia) to diagnose an ACL tear. The vet will perfom ROM (range of motion) tests on the dog, and will also test joint stability. A definite abnormal movement will be felt on palpation, and x-rays will show any swelling of the joint and if arthritis is already present.
There is also a newly device develped by the University of Wisconsin School of Veterinary Medicine called the "DGY2000". The DGY2000 is being used to diagnose partially torn and stretched ACLs.
Dogs (and people) can also stretch their ACL, causing very temporary lameness and pain. These dogs should be confined for at least 2 weeks to let the ligament heal. If these dogs continue to stretch/strain their ACL, eventually it will tear.
*Corrective Surgery*
The recommended treatment for a torn ACL is corrective surgery. There are two surgeries that are offered: Tibial Plateau Leveling Osteotomy (TPLO) and lateral imbrication, the more common surgery. 
*Lateral Imbrication: The Most Common ACL Repair Surgery*
The placement of an artificial tendon is a major surgery involving the removal of the torn ligament and the placement of an artificial tendon made of nylon strands of 80 pound tensile strength. An incision is made in the lateral side of the knee joint. Just below the kneecap, at the top of the tibia where the patellar tendon inserts on the tibia, a hole is drilled through the bone. Heavy sutures will be passed through this hole as an anchor point for the new artificial tendon. The surgeon will then look for any degenerative damage such as arthritis in the knee besides the torn ligament. The surgeon will drill a hole called a tibial tuberosity (a hole in the front part of the tibia bone) to serve as an anchor for the suture material which will serve as the new ligament. Then, a needle and suture material will be passed through the tibial tuberosity. A large needle is then passed behind a small bone (called a fabella) behind the knee. The needle helps the surgeon pass the suture behind the fabella as an anchor point. The tibial tuberosity is the other anchor point for the suture material (which takes the place of the original cruciate ligament).
*Recovery*
After the surgery, the dog must be strictly confined (crated) for 2 weeks. By day 10 after surgery, most dogs touch the toe of the affected leg to the ground and will start bearing minimal weight on the leg. Once the dog has reached this point, it is often very difficult to keep the dog quiet until complete healing has taken place. The dog generally has to be restricted to only leash walking for a minimum of 4-6 more weeks, although the exact amount of time depends upon the extent of the injury.
*Tibial Plateau Leveling Osteotomy (TPLO)*
The less common of the two surgeries to repair an ACL injury is the Tibial Plateau Leveling Osteotomy (TPLO). This surgery requires special and exact training for veterinarians to succesfully perform. Although currently unpopular with smaller vet practices, this surgery is becoming the favorite for many orthopedic vets for large breed dogs. The TPLO surgery involves making a curved cut in the top of the tibia bone (osteotomy) to include the tibial plateau. The tibial plateau is then rotated along the curved osteotomy in order to level the slope. A plate and screws are used to hold the tibial plateau in place so that the bone can heal well.
*Recovery*
About 50% of the dogs will start to walk on the limb within 24 hours after surgery. Within 5 days after surgery most dogs will begin weight-bearing on the operated limb. 
By 2 weeks after surgery, a moderate amount of weight-bearing can be expected. Dogs with partial tears tend to recover quicker than dogs having complete ligament tears.
Radiographs taken at 6 to 8 weeks post-op should reveal healing of the osteotomy site. At this time most dogs have mild or no lameness and the average time for the lameness to resolve was 10 weeks. 
At 2 months after surgery, exercise in the form of leash walks should be gradually increased each week. Increasing the number of walks per day tends to be better than just increasing the duration of each period. 
Complete recovery may take 3 to 5 months. 
At 4 months after surgery most restrictions of exercise can be lifted. Full working activities (hunting, agility, etc) can begin at 6 months after surgery. Unconstrained activity prior to this time can cause spraining of the soft tissues of the stifle (patellar ligament sprain) resulting in a prolonged recovery. 
Yearly radiographs of the stifle should be taken to evaluate the degree of arthritis. The TPLO procedure should minimize the progression of degenerative joint disease.
*Please Note: This article is not to serve as a diagnosis. Please take you dog to the vet if he/she is limping for more than 3 days without ANY improvment if he/she is young. If you have an older dog, 2 days is the maximum recommended.*


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