Analysis of pelvic rotation on the standard hip ventrodorsal extended radiographic view

Abstract

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.

Effects of pelvis rotation on the projected radiographic position of the femoral head in relationship to the acetabulum

“…In this study using a cadaveric model, the normal VDHE view showed a very low mean IHD asymmetry (less than 1°), similar to a previous study (Martins et al 2016) and the mean NA did not show statistically significant changes with pelvis rotation (2° to 6°), either on the dependent or nondependent side, which is not in agreement with some other studies (Genevois et al 2007;Skurkova et al 2010). In fact, the NA showed a consistent tendency to increase on the non-dependent side and greater degrees of rotation may result in statistically significant NA differences.…”

“…Therefore, proper positioning and optimal exposure technique are essential prerequisites for radiographs of sufficient diagnostic quality to allow accurate HD assessment (Genevois et al 2007;Thompson et al 2007;Bausman and Wendelburg 2010). Pelvic rotation over the longitudinal axis changes hip radiographic morphology (Genevois et al 2007;Volta et al 2013;Martins et al 2016). Previously published works have reported the relationship between pelvis rotation and the projected DAE and NA on the dependent side and non-dependent side (Genevois et al 2007;Skurkova et al 2010), although not always with a sound scientific basis.…”

“…The weights ranged from 20 to 45 kg (32.2 ± 7.8 kg) and were evaluated at the Veterinary Teaching Hospital of the University of Trás-os-Montes e Alto Douro. The cadavers were positioned and immobilised on an X-ray table in the standard VDHE view using a special holder device and pins applied to each femoral diaphysis and fixed in a transverse strip of wood, as described in a previous study (Martins et al 2016). The first radiographic view of the pelvis was performed to evaluate the technical quality of the positioning and used as a reference, once acceptable positioning was achieved, i.e.…”

“…In each animal, six more VDHE views with pelvis rotation along the long axis of 2°, 4° and 6° on the right and left sides were obtained. These grades of rotation were achieved by raising the special cadaver holder device on the right or left side with three firm wedges of different thicknesses; evaluation was carried out using a manual inclinometer (Figure 1) as described in a previous study (Martins et al 2016). Only normal hips or those with slight signs of HD (based on the FCI scheme) were included in the study, and all included hips allowed an unequivocal identification of essential radiographic landmarks.…”

“…All measurements were performed by the same examiner, an experienced radiologist (MMDG). First, in the normal hip extended view pelvis symmetry was evaluated; the iliac horizontal diameter (IHD) was measured by drawing a straight line between the dorsal and ventral iliac spines at the level of the cranial aspect of the sacroiliac joint (Martins et al 2016); then, in two independent sessions measurements of NA, PT, SI, SC and FAD in the left and right sides were performed to evaluate repeatability; finally, in six more sessions these variables were measured for each degree of rotation (series of 2°, 4° and 6° of rotation for right and left side). The NA was determined in degrees as the angle formed by a line joining the centre of the femoral heads and a line joining the centre of the femoral head and the craniolateral aspect of the ipsilateral acetabular rim ( Figure 2) (Vandekerckhove et al 2003;Ginja et al 2008;Comhaire et al 2009;Bausman and Wendelburg 2010).…”