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Jonathan Miller, DVM, MS, Diplomate American College of Veterinary Surgeons

             Tearing of the cranial (or anterior) cruciate ligament (CrCL) in dogs commonly occurs in middle aged, overweight dogs, but we have seen it in dogs as young as 10 months old.  The limp or lameness can happen suddenly or it can wax and wane for months.  Anti-inflammatory medications will help the patient to feel better, but in dogs over 15 to 20 pounds, surgery is required to achieve the best possible outcome.  In medium to large breed dogs the treatment of choice at Oradell Animal Hospital is tibial tuberosity advancement (TTA).  At the time of surgery, the “knee joint” (in dogs called the stifle joint) is examined either in the traditional open method or with arthroscopy to assess the integrity of the CrCL and remove any damaged portion.  The joint is also inspected for degree of arthritis and the medial meniscus (cartilage) is examined because 1/3 of dogs with a CrCL tear will also tear the meniscus.  Then, instead of trying to replace the ligament, the forces around the knee are adjusted by moving the front of the lower bone (tibia) forward to stabilize the joint.  This action eliminates the force pushing the tibia forward when the CrCL is not functioning properly (See Figures 1 and 2).  This involves cutting the bone and placing a titanium spacer in order to keep the bone in its new position.  Additionally, a plate is applied to reinforce the repair.  

            Following surgery, the knee needs to be protected from overuse by restricting the dog from running, jumping, rough play, or fast stairs.  Walking is encouraged as part of a detailed postoperative rehabilitation plan.  Pain medications and antibiotics are routinely used following orthopedic surgery.  Typically, the patient is seen at 2 weeks for staple or suture removal and again at 2 months for recheck x-rays of the stifle to assess bone healing (See Figure 3).  At this time an increase in activity back to a normal level is expected.  Many dogs will eventually tear their other CrCL, so keeping them lean and active to improve muscle strength is important.

Figure 1 showing a force vector diagram of instability caused by CrCL tear.

Figure 2 showing the balancing of the stifle’s forces following TTA surgery.

Figure 3 demonstrating typical bone healing seen at two months after TTA surgery.

 Dr. Miller has successfully performed TTA surgery in hundreds of dogs.  He received his master’s degree evaluating the biomechanics of TTA in dogs which he presented at a national surgery conference and has published two scientific articles on the subject:

 Miller JM, Shires PK, Lanz OI, Martin RA, Grant JW. Effect of 9mm tibial tuberosity advancement on the canine cranial cruciate deficient stifle. Vet Surg 2007;36:335-340.

 Hoffmann DE, Miller JM, Ober CP, Lanz OI, Martin RA, Shires PK. Tibial tuberosity advancement in 65 canine stifles. Vet Comp Orthop Traumatol 2006;19:219-227.