In vivo femorotibial subluxation during weight-bearing and clinical outcome following tibial tuberosity advancement for cranial cruciate ligament insufficiency in dogs

Long Term Functional Outcome of Tibial Tuberosity Advancement vs. Tibial Plateau Leveling Osteotomy and Extracapsular Repair in a Heterogeneous Population of Dogs

“…Experimentally, the neutral point at which cranial shear forces are eliminated or converted to caudal shear forces occurs at a PLA of 90° . Clinically though, the majority of dogs with a mean PLA CT of 89° remained unstable on standing radiographic evaluation . The results of experimental ex vivo studies and clinical in vivo studies may not correlate, as is the case with the TPLO …”

“…Several ex vivo studies have validated this alteration of tibiofemoral shear forces as a result of the PLA change associated with TTA . An in vivo study showed that the TTA does not stabilize sagittal femorotibial motion at a standing PLA of 90° as measured by the common tangent method …”

Effect of proximal translation of the osteotomized tibial tuberosity during tibial tuberosity advancement on patellar position and patellar ligament angle

“…The difference between each of the measurements was as high as 11° within one specimen in this study. A recent study demonstrated that 70% of dogs that had undergone a TTA and had a mean postoperative PLAtangent of 89° continue to have cranial tibial subluxation when weight-bearing, suggesting that further in vivo studies need to be performed to determine which of the measurements would result in optimal clinical outcomes [34]. Certainly, our results suggest that if an MMP type procedure is performed using the same pre-operative planning techniques [33] to those recommended for the original TTA procedure [8, 10], this may result in under-advancement of the tibial tuberosity.…”

Canine Stifle Biomechanics Associated With Tibial Tuberosity Advancement Predicted Using a Computer Model

“…In vitro biomechanical assessment has indicated that TTA limits cranial tibial translation, and this stabilizing effect is influenced by the extent of cranial displacement of the tibial tuberosity and the corresponding change in sagittal plane patellar ligament angle . In vivo assessment of dogs with TTA during weight‐bearing has indicated that cranial tibial translation is reduced but not eliminated . Previous studies have found cranial tibial translation may be either reduced, neutralized, or converted to caudal tibial translation following TTA .…”

“…Recently, the common tangent technique has been used and accounts for the anatomic relationship between the femoral condyles and tibial plateau. The common tangent technique re‐orients the patellar ligament so that it is perpendicular to the common tangent, defined as the line that is perpendicular to the line joining the centers of the circles with circumferences coincident to the medial femoral condyle and medial tibial plateau articulation . Neither the tibial plateau slope nor the common tangent planning technique for TTA has demonstrated superiority .…”