An ACL rupture is serious: without treatment your dog is likely to develop arthritis and chronic joint pain and stiffness that will affect him the rest of his life. Numerous treatment options are available, such as physical and hydrotherapy, but surgery is necessary in many cases. Surgery is intended to stabilize the joint, and can do this in different ways.
Your dog's ACL, or anterior cruciate ligament, is one of two major ligaments that hold his knee, or stifle, in place. It is technically known as the cranial cruciate ligament, but even among veterinarians the terms ACL and CCL are used interchangeably for this same tendon. If this ligament is torn or ruptured, your dog's knee becomes unstable. If your dog ruptures his ACL in one knee, the other is at increased risk of rupturing also. The most common treatment is surgery to stabilize the knee joint.
Extracapsular repair is the surgical method used most frequently for a ruptured ACL. It takes less time than other surgeries and no special instruments are necessary. With this type of repair, the damaged ligament is removed entirely. The veterinarian drills a hole in the tibia (one of the bones of the leg) and uses a tough thread, or suture, to stabilize the knee and take the place of the cruciate ligament. Over time, tissue around the knee strengthens enough to keep the joint in place and the thread breaks or dissolves.
Intracapsular repair used to be the most common surgery method, but has fallen out of favor since other methods seem to produce better results. Intracapsular repair is similar to the extracapsular method, except that after the damaged ligament is removed, the veterinarian uses a piece of connective tissue from another area on your dog's leg to replace the ACL. The tissue is sewn in place and after a healing period of about two months should fully function in the same manner as the cruciate ligament.
Tibial Tuberosity Advancement and Tibia Plateau Leveling Osteotomy
These two types of surgeries, often referred to as TTA and TPLO, involve reshaping the entire knee joint instead of using tissue or sutures to stabilize it. With TTA, your dog's tibia and patellar ligament are repositioned so that they form a 90-degree angle, and then anchored in place by a metal plate. With TPLO, the tibia is cut and rotated in such a way that the weight of the dog holds the knee joint in place. Both procedures are more expensive than extra- or intra-capsular repair, and there is controversy regarding their effectiveness.