The Relationship of the Canine Femoral Head to the Femoral Neck: An Anatomic Study with Relevance for Hip Arthroplasty Implant Design and Implantation

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

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.

Femoral and tibial alignments in chihuahuas with patellar luxation by radiograph: Angular values and intra- and inter-observer agreement of measurements

Measurement of fore and pelvic limb alignment in veterinary orthopedics is significant, as it is in human medicine. The establishment of reference ranges for alignments and comparing measured ranges in diseased animals to these reference values would allow veterinarians to specify the quantitative degree of an angular deformity, plan suitable treatments and evaluate treatment outcomes. Patellar luxation is a common orthopedic disease in small animal clinics. Severe grades of MPL may present with bone deformities or abnormal alignments; therefore, evaluation of the measurement methods of femoral and tibial alignment in dogs with different grades of patellar luxation to assess the accuracy and reliability of the measurements could be useful. In this retrospective study radiographs of 21 client-owned Chihuahuas that had been presented to the Small Animal Surgery of Vetmeduni Vienna from 2012-2016 with a diagnose of patellar luxation were selected. The measurements were performed on frontal, lateral and axial view radiographs to determine the femoral and tibial angles and to evaluate the intra- and inter-observer variabilities of the protocol. Radiographs of each dog were investigated by three observers. Intra-observer variability was based on measurements by each observer who repeated the protocol two times to evaluate repeatability. Inter-observer variability was based on the measurements between the three observers to evaluate the reproducibility of the protocol. The results of the study showed that 92.85% of inter-observer ICC (intra-class correlation coefficient) had high correlation, and the remaining 7.15% had good correlation. Intra-observer ICCs for measurements of the first observer were 28.57% high correlation and 50% good correlation. For the second observer, 100% high correlation was recorded, and for the third observer 71.42% high correlation and 14.28% good correlation was recorded. These results show that the selected methods have high correlation and could be used as a reliable method in veterinary orthopedics.

Proximal and distal alignment of normal canine femurs: A morphometric analysis

Many researchers are interested in femoral conformation because most orthopaedic problems of the long bones occur in the femur and its joints. The neck-shaft (NSA) and the anteversion (AVA) angles are good predictors for understanding the orientation of the proximal end of the femur. The varus (aLDFA) and procurvatum (CDFA) angles have also been used to understand the orientation of the distal end of the femur. The purposes of this study were to investigate the relationship between the proximal and distal angles of the femur and to compare the distal femoral angles in male and female dogs in order to investigate the sexual dimorphism. The measurements of normal CDFAs, which have not been previously reported, may also provide a database of canine distal femoral morphology. A total of 75 cleaned healthy femora from different breeds or mixed breed of dogs were used. The three-dimensional images were reconstructed from computed tomographic images. The AVA, NSA, aLDFA and CDFA were measured on the 3D images. The correlation coefficients were calculated among the measured angles. The distal femoral angles were also compared between male and female femora. The 95% confidence intervals of the AVA and the NSA were calculated to be 24.22°-29.50° and 144.97°-147.50°, respectively. The 95% confidence intervals of the aLDFA and the CDFA for all studied dogs were 92.62°-94.08° and 89.09°-91.94°, respectively. The NSA showed no correlation with either the aLDFA or CDFA. There was a weak inverse correlation between the AVA and CDFA and a weak positive correlation between the AVA and aLDFA. The differences in the aLDFA and CDFA measurements between male and female dog were not significant. In conclusion, femoral version, regardless of the plane, might have little influence on distal femoral morphology in normal dogs. Besides this, there is no evidence of a sexual dimorphism in the varus and procurvatum angles of the dog distal femur. The data from this study may be used in both orthopaedic studies and for clinical applications related to the distal femur of dogs.