During the past decade, complete or partial rupture of the cranial cruciate ligament in dogs has become one of the preeminent topics of interest in small animal orthopedic surgery. The high incidence of cranial cruciate ligament injury and the treatment methods for the CCL deficient stifle joint have been a focus of interest for over 50 years. In the past decade, Slocum's tibial plateau leveling osteotomy (TPLO) is, by a broad consensus, a state-of-the-art repair method. In 2002, Montavon and Tepic described their technique, called tibial tuberosity advancement (TTA), which became established for clinical use in early 2004. Tibial plateau leveling osteotomy is a surgical technique which converts cranial tibial thrust in the CCL deficient stifle joint to a caudal tibial thrust. In doing so the caudal cruciate ligament then stabilizes the joint against abnormal cranial caudal translation. Controversy exists as to whether rotational or varus-valgus stability returns. The majority of clinical reports indicate successful improvement in limb function following TPLO surgery. However, return to normal function is only achieved in a minority of cases as determined by owners and gait analysis. Nevertheless, greatly improved function is reported by most surgeons in retrospective studies. For example, Jandi et al reported on the effect of Tibial Plateau Leveling Osteotomy on lameness, OA, ROM, postliminary meniscal injury in dogs with CCLD 2 yr following surgery. They concluded that TPLO leads to minimal progression of OA, minimal arthrofibrosis, minimal post operative meniscal damage and resolution of lameness. Sixty-nine per cent of the cases had normal or near normal gait 6 months after surgery whereas 94% exhibit near normal or normal gait 12 months after surgery.

Tibial tuberosity advancement is a surgical technique designed to neutralize cranial tibial thrust in the CCL deficient stifle by aligning the patella tendon perpendicular to the tibial plateau in the extended weight bearing position. In the cadaver in vitro experiment, TTA is successful in neutralizing cranial tibial thrust at a PTA angle of 90 degrees. However in a separate experiment, cranial tibial thrust, internal foot rotation, stifle angle and hock angle only partially returned with 12mm advancement in large breed dogs. TTA may not be achieving the surgical goals of the technique. A prospective clinical study on 36 dogs indicated that overall outcome showed TTA to be a practical technique capable of restoring full function of the CCLD stifle joint with low morbidity. A separate study examined the results of TTA surgery performed in 57 dogs with CCLD. Overall outcome is good to excellent in 90% of replies (75% excellent). Activity level greatly improved in 72% and improved or greatly improved in 90%. Sixty-seven (67%) showed an increase in radiographic OA at 8 week follow up. The authors concluded that TTA appears to be a useful alternative in the management of CCLD. Another group believes that the results of the TTA procedure are at least as comparable to the TPLO procedure, with a quicker (subjectively assessed) return to postoperative weight bearing. The procedure also is relatively simple to perform with a very short learning curve, and we have observed relatively few complications. Vezzoni compared the results of TPLO and TTA in his practice and concluded that TPLO may be the preferred method of treatment in heavy dogs with a tibial slope of >25°.