Repeatability and reproducibility of measurements of femoral and tibial alignment using computed tomography multiplanar reconstructions.

OBJECTIVES: (1) To describe a protocol for measurement of the anatomic lateral distal femoral angle (aLDFA), angle of anteversion (AA), mechanical medial proximal tibial angle (mMPTA), tibial tuberosity displacement (TTD), and crural torsion angle (CTA) from computed tomography (CT) multiplanar reconstructions of canine hindlimbs. (2) To test the intra-observer variability (repeatability) and inter-observer variability (reproducibility) of the protocol. (3) To assess the proportion of variance in the measurement of each parameter explained by dog, observer, body mass, and medial patellar luxation (MPL). STUDY DESIGN: Anatomic study. ANIMALS: Twenty client-owned dogs. METHODS: A protocol for the measurement of aLDFA, AA, mMPTA, TTD, and CTA was performed by 3 observers, and performed 3 times by 1 observer, on CT multiplanar reconstructions of 20 canine hindlimbs. Intraclass correlation coefficients (ICC) were calculated for each parameter to examine intra-observer variability (repeatability) and inter-observer variability (reproducibility). The proportion of variance in the measurement of each parameter explained by dog, observer, body mass, and MPL was assessed using mixed effect, linear models. RESULTS: Intra-observer and inter-observer ICC were >0.8 for all parameters indicating good repeatability and reproducibility. Most of the variance in the measurement of each parameter was attributable to dog. CONCLUSIONS: The CT protocol, as described, was repeatable and reproducible for assessing the femoral and tibial alignment of dogs.