Rupture of the cruciate ligament in a dog's knee often requires surgical repair. This is a common injury among dogs, and is characterised by sudden lameness or swelling of the affected rear leg. A cruciate ligament injury may improve without surgery, however, arthritis will quickly set in making it difficult for the dog to walk or run.
A dog's knee is comprised of the femur, which is the bone above the knee, the kneecap in front and the fabellae in the back of the knee. Cartilage fits between the femur and tibia, forming a cushion, and ligaments hold everything in the knee in place. There are two cruciate ligaments, the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). The ACL keeps the tibia in the knee from moving forward. A rupture of the ACL causes severe soreness and the dog may not be able to walk.
One test that is performed by veterinarians to determine if the cruciate ligament in dogs is ruptured is the drawer sign. This involves the veterinarian stabilising the femur with one hand while he manipulates the tibia with the other. If the tibia moves forward (as a drawer moves forward when opened), the cruciate ligament is ruptured. The anatomy of a dog's knee does not allow for this movement on a healthy knee. The tibial compression test is another test that veterinarians may use to determine if the cruciate ligament is ruptured. The veterinarian stabilises the femur and flexes the ankle at the same time. If the tibia moves forward, the cruciate ligament is ruptured.
If a dog's cruciate ligament is not intact, the knee is not stable. Therefore, most veterinarians recommend the surgical repair of a ruptured cruciate ligament in dogs. There are three surgical techniques that are most commonly used in the repair of the cruciate ligament. These are the extracapsular repair, tibial plateau levelling osteotomy and the tibial tuberosity advancement. Most veterinarians use the extracapsular repair, due to the fact that it has a shorter surgery time and does not require the use of special surgical equipment.
After the surgery to repair the cruciate ligament in dogs, it may be necessary for the dog to receive rehabilitation such as physiotherapy. If the extracapsular repair is used, this may begin as soon as the dog goes home. Ice should be applied to the affected knee, for approximately 10 minutes two or three times a day. Passive range-of-motion exercises may help the dog to increase mobility in the knee. No matter which type of surgical repair is performed, the dog should not climb stairs, jump or run for several weeks.
If a dog has a ruptured cruciate ligament, surgical repair is the best option to regain range-of-motion in the knee. Dogs that do not have surgery may be at an increased risk for arthritis, bone spurs and chronic pain in the leg.