Comparison of canine femoral torsion measurements using the axial and biplanar methods on three‐dimensional volumetric reconstructions of computed tomography images

Abstract

Objective To compare the results of the measurement of femoral torsion using the axial measurement method on three‐dimensional (3D) volumetric reconstructions of computed tomography images AMM(CT), the biplanar measurement method on 3D volumetric reconstructions of computed tomography images BMM(CT) and a reference standard using the axial measurement method on stereolithographic bone models AMM (SBM). Study design Ex vivo study. Sample populations Three‐dimensional volumetric reconstructions of computed tomography images and stereolithographic bone models from 23 femurs of 14 dogs with hind limb lameness presented for orthopedic evaluation. Methods Three‐dimensional volumetric reconstructions of computed tomography images and stereolithographic bone models of each femur were created from computed tomography data. Femoral torsion was measured using the AMM (CT) and the BMM (CT) and compared with a reference standard, the AMM (SBM). Results No differences were noted among the measurement methods (P = .0863). Median measurement of femoral torsion using the AMM (CT) was 34.2°, the BMM (CT) was 36.7°, and the AMM (SBM) was 32.3°. Conclusion No differences existed among the AMM (CT), the BMM (CT), and the AMM (SBM). Clinical significance Both AMM (CT) and BMM (CT) can be used to measure femoral torsion in dogs with orthopedic disease.

Three‐dimensional volume rendering planning, surgical treatment, and clinical outcomes for femoral and tibial detorsional osteotomies in dogs

“…The preoperative biplanar and CT FTA measurements were in agreement. Our results are in agreement with a recent study that reported no difference for the measurement of FTA using biplanar or CT axial method 33 …”

“…Our results are in agreement with a recent study that reported no difference for the measurement of FTA using biplanar or CT axial method. 33 With regards to the tibia, there are no wellestablished radiographic methods to quantify tibial torsion. 8,25 It has been anecdotally suggested that in a straight caudocranial view the tibial tuberosity width should be at the center of the proximal tibial width.…”

Introduction of a bone-centered three-dimensional coordinate system enables computed tomographic canine femoral angle measurements independent of positioning

“…VR CT allows free rotation of bones resembling virtual radiographic positioning, which is considered three-dimensionality ( 13 , 14 , 17 , 21 , 22 , 25 , 43 , 46 , 47 , 55 – 57 , 59 – 63 ). The operator visually selects a 3D VR bone position and view to finally measure an angle within a flat image that lacks the third dimension.…”

“…Computed tomography (CT) generates true three-dimensional information and is used to overcome the limitations of two-dimensional radiographic projection errors ( 13 , 14 , 17 , 19 , 21 , 22 , 24 , 25 , 30 , 40 – 43 , 45 , 47 , 53 , 55 , 57 , 59 – 65 ). As with radiography, precise and standardized positioning is also required for various CT-based measurement methods ( 21 , 39 , 40 , 59 ).…”

“…Usually, the reference points for angular measurements are located in different CT images, so postprocessing of cross-sectional images is required. CT measurements are performed in a single CT image or images generated by image fusion or overlay in a single superimposed image ( 24 , 63 , 66 , 67 ), using multiplanar reconstruction (MPR) ( 21 , 22 , 40 , 53 ), maximum intensity projection (MIP) ( 21 ), or volume rendering technique (VR) ( 13 , 14 , 17 , 21 , 22 , 25 , 43 , 46 , 47 , 55 – 57 , 59 – 63 ). MPR, MIP, or VR allow free choice of plane, rotation, and perspective, but after the final post-processing, the result is a flat 2D image that lacks the third dimension.…”