Combined Tibial Plateau Levelling Osteotomy and Tibial Tuberosity Transposition: An Ex Vivo Mechanical Study.

OBJECTIVES: The purpose of this study is to compare the load at failure and mode of failure between (1) tibial plateau levelling osteotomy (TPLO) and combined TPLO and tibial tuberosity transposition (TPLO-TTT) (Phase I) and (2) TPLO-TTT and tibial tuberosity transposition (TTT) (Phase II). METHODS: Seven pairs of cadaveric tibiae were tested in each of the Phase I (TPLO vs. TPLO-TTT) and Phase II (TPLO-TTT vs. TTT) experiments. One limb of each pair was randomly assigned to one of two groups for each experimental phase. A tensile force was applied to the patellar ligament until construct failure occurred. RESULTS: There was a significant difference in mean load at failure between TPLO (2092.8 N) and TPLO-TTT (1067.8 N), p = 0.004. All TPLO constructs failed by fracture of the tibial crest. The TPLO-TTT constructs failed by cranial displacement of the distal tibial crest. Additionally, the tibial plateau was displaced in the majority of limbs. There was a significant difference in mean load at failure between TPLO-TTT (1157.6 N) and TTT (1394.0 N), p = 0.025. The TTT constructs demonstrated a similar mode of failure as TPLO-TTT. CLINICAL SIGNIFICANCE: Although ex vivo mechanical testing does not replicate the postoperative clinical scenario, these results demonstrate reduced construct strength of the combined TPLO-TTT technique compared with TPLO or TTT alone. When performing TPLO-TTT, meticulous technique and implants of adequate strength must be employed to create a robust construct and minimize postoperative tibial crest fixation failure.

Breed-Specific Vertebral Heart Scale for the Dachshund.

The objectives of this study were to determine a breed-specific vertebral heart scale (VHS) range for the dachshund and compare results to the established reference range of 9.7 ± 0.5, calculate inter-observer variability, and correlate VHS with echocardiography. Fifty-one normal dachshunds had radiographs and an echocardiogram performed. Five observers measured VHS to the nearest 0.25 vertebra. The data was analyzed using one-way analysis of variance, Wilcoxon Rank Sum test, Mann-Whitney rank sum test, calculation of reference and confidence intervals, Spearman rank-order correlations, and generation of intra-class correlations and confidence intervals. P < .05 was considered significant. The median for right lateral VHS was significantly larger than left (10.3 [range 9.25-11.55] versus 10.1 [range, 8.7-11.31], p < .0001). VHS for females was significantly larger than for males (left: 10.56 [9.2-11.31] versus 9.74 [8.7-10.88] and right: 10.8 [9.5-11.55] versus 9.99 [9.25-10.8], p = .0002). Observer consistency was high with an intra-class correlation coefficient of 0.95. No significant correlation was found between left atrial echocardiographic parameters and VHS. Results indicate normal dachshunds have a median VHS above the published generic canine reference range, and VHS can be reliably performed by observers with varying degrees of clinical experience.