The tibial plateau leveling osteotomy is chosen by most surgeons for large breed active dogs. This choice is made over concerns for larger heavier dogs damaging an extra- capsular repair resulting in chronic lameness. Many also believe that dogs receiving a TPLO return to function sooner. Another reason to choose this procedure is for dogs with bilateral disease to get them walking as soon as possible. There is no evidence that choosing a TPLO over another procedure will result in less osteoarthritis.
The tibial plateau leveling osteotomy changes the biomechanics to the canine stifle (knee). Normally the knee is stabilized both passively (cruciate ligament, menisci, joint capsule) and actively (muscles & tendons). The cranial cruciate is a passive constraint to cranial tibial translation as well as internal rotation. The cranial tibial translation is tested by cranial tibial thrust test. The severity of cranial tibial thrust is related to the slope of the tibia. The premise of the TPLO is that if you reduce cranial tibial thrust to neutralize the pain associated with cranial tibial translation will resolve.
The tibial plateau leveling osteotomy requires special radiographs that allow the surgeon to measure the slope of the medial plateau. The slope angle is then converted to millimeters depending on the size of the osteotomy. The procedure incorporates the release of meniscus and debridement of remaining cruciate ligament. Once this is completed a jig is placed on the medial aspect of the tibia. A curved saw blade is utilized to make the osteotomy. The osteotomy is then rotated a specified number of millimeters. The osteotomy is then stabilized by a bone plate. Once this is completed cranial tibial thrust should be eliminated.
The tibial plateau leveling osteotomy takes approximately 8 weeks to heal. The osteotomy must go through the process of bone healing just like a fracture. During the healing period your dog should have only controlled exercise. This procedure requires radiographs at the 8 week after surgery to determine if healing is sufficient to allow release back to normal activity.
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Jacqueline J Mair, DVM, Diplomate of the American College of Veterinary Surgeons