Effect of Plate Type on Tibial Plateau Levelling and Medialization Osteotomy for Treatment of Cranial Cruciate Ligament Rupture and Concomitant Medial Patellar Luxation in Small Breed Dogs: An In Vitro Study.

OBJECTIVE:  The main aim of this study was to determine the effective magnitude of proximal tibial segment medialization achievable during tibial plateau levelling and medialization osteotomy (TPLO-M) with Fixin 1.9-2.5 mm pre-contoured T plates with three different offsets.

METHODS:  In this in vitro study, 36 tibia bone models reconstructed using stereolithography from hindlimb CT scans of a 5 kg dog and a 10 kg dog without orthopaedic disease were used. TPLO-M was performed using plates with three different offsets (2, 4 and 6 mm). Post-osteotomy radiographic and bone models measurements were performed.

RESULTS:  Regardless of patient weight, the +4 mm offset plates provided a translation of 2.93mm (± 0.51) while the +6 mm offset plates provided a translation of 5.03mm (± 0.47). In the 5kg dog bone model group limited bone contact at the osteotomy site was documented when using the +6mm offset plate.

CONCLUSION:  The +4mm and +6mm offset Fixin plates may be considered for TPLO-M in dogs weighing between 5 and 10 kg. The +6mm offset plate should be used cautiously in dogs weighing less than 10 kg since this plate may result in insufficient postoperative bone apposition at the osteotomy site.