Summary
Objectives: To study the symmetry of the iliac horizontal diameter (IHD) maximum obturator foramen
width (OFW), ischiatic femoral overlap (IFO), pelvic horizontal radius (PHR), femoral
head diameter (FHD), and obturator foramen area (OFA) parameters in the normal hip
extended radiographic view and to evaluate the correlation of pelvic rotation with
the magnitude of asymmetry of these parameters.
Methods: Nine canine cadavers from adult, large and giant breeds were radiographed in standard
hip extended views and with 2°, 4° and 6° degrees of rotation. The variables IHD,
OFW, IFO, PHR, FHD, and OFA were analysed in radiographs.
Results: The IHD measurements exhibited repeatability, bilateral symmetry and 95% of confidence
interval of asymmetry in different pelvic rotations without superposition (p <0.05);
OFW and IFO exhibited repeatability, bilateral symmetry and a small superposition
in 95% of confidence interval of asymmetry according different pelvic rotations; PHR,
FHD and OFA exhibited repeatability, bilateral symmetry and unacceptable superposition
in 95% of confidence interval of asymmetry depending on pelvic rotation.
Clinical significance: The IHD is the recommended variable and OFW is an acceptable variable in order to
evaluate slight pelvic rotation. The data may be used in qualitative analyses of hip
extended radiographic views. In the future, complementary studies should be performed
to evaluate the impact of degree of pelvic rotation on the hip dysplasia score.
Keywords
Iliac horizontal diameter - pelvic horizontal radius - femoral head diameter - maximum
obturator foramen width - ischiatic overlap - femoral overlap - obturator foramen
area