A three‐dimensional axis for the study of femoral neck orientation

Abstract

A common problem in the quantification of the orientation of the femoral neck is the difficulty to determine its true axis; however, this axis is typically estimated visually only. Moreover, the orientation of the femoral neck is commonly analysed using angles that are dependent on anatomical planes of reference and only quantify the orientation in two dimensions. The purpose of this study is to establish a method to determine the three-dimensional orientation of the femoral neck using a three-dimensional model. An accurate determination of the femoral neck axis requires a reconsideration of the complex architecture of the proximal femur. The morphology of the femoral neck results from both the medial and arcuate trabecular systems, and the asymmetry of the cortical bone. Given these considerations, two alternative models, in addition to the cylindrical one frequently assumed, were tested. The surface geometry of the femoral neck was subsequently used to fit one cylinder, two cylinders and successive cross-sectional ellipses. The model based on successive ellipses provided a significantly smaller average deviation than the two other models (P < 0.001) and reduced the observer-induced measurement error. Comparisons with traditional measurements and analyses on a sample of 91 femora were also performed to assess the validity of the model based on successive ellipses. This study provides a semi-automatic and accurate method for the determination of the functional threedimensional femoral neck orientation avoiding the use of a reference plane. This innovative method has important implications for future studies that aim to document and understand the change in the orientation of the femoral neck associated with the acquisition of a bipedal gait in humans. Moreover, the precise determination of the three-dimensional orientation has implications in current research involved in developing clinical applications in diagnosis, hip surgery and rehabilitation.

Can Femoral Rotation Be Localized and Quantified Using Standard CT Measures?

“…dimensional (2-D) CT to obtain accurate rotational profiles despite complex femoral neck anatomy [1,3,9], it has been noted that variability in the traditional method is minimized with more experienced observers (attending physicians versus residents) and the use of predefined cut levels [9]. In our investigation, both the traditional and Kim methods (2-D) provided excellent inter-and intraobserver reliability as did the volumetric (3-D) technique.…”

“…CT allowed for direct superimposition of a single neck and condylar axis, which remains the basis for most measurements to this day [18]. However, the femoral neck is neither uniplanar nor cylindrical and can be best approximated by a series of ellipses that create a unique composite neck axis, which deviates from the shaft axis by an average 5 mm and the center of the femoral head by 2.5 mm [3]. As a result of this complex proximal femoral anatomy, some authors have suggested that the traditional methods of axial CT-derived femoral profiles are inaccurate and underestimate true anatomic measurements.…”

Temporal trends in femoral diaphyseal torsional asymmetry among the Arikara associated with postural behavior

“…Compared to Europeans, African populations exhibit greater anteversion and South Asian populations from the Republic of India (hereafter referred to as "Indian") exhibit less anteversion (Eckhoff et al, 1994;Jain et al, 2003;Zalawadia et al, 2010;Srimathi et al, 2012). While sexual dimorphism in femoral anteversion is not statistically significant in all populations, females in most populations have greater anteversion angles than males (Davivongs, 1963;Kate, 1976;Tamari et al, 2006;Bonneau et al, 2012). While sexual dimorphism in femoral anteversion is not statistically significant in all populations, females in most populations have greater anteversion angles than males (Davivongs, 1963;Kate, 1976;Tamari et al, 2006;Bonneau et al, 2012).…”

“…While sexual dimorphism in femoral anteversion is not statistically significant in all populations, females in most populations have greater anteversion angles than males (Davivongs, 1963;Kate, 1976;Tamari et al, 2006;Bonneau et al, 2012). Some studies have found no significant asymmetry in femoral torsion (Parsons, 1914;Bonneau et al, 2012), while others have (Kingsley and Olmstead, 1948;Kate, 1976;Young, 2004;Basgall, 2008). Some studies have found no significant asymmetry in femoral torsion (Parsons, 1914;Bonneau et al, 2012), while others have (Kingsley and Olmstead, 1948;Kate, 1976;Young, 2004;Basgall, 2008).…”

An innovative method for the three-dimensional study of hip joint motion

“…This allows an exact determination of the axis of the acetabulum as described by Bonneau et al (2012a). The 3D axis of the femoral neck was semi-automatically calculated by our model based on successive ellipses (Bonneau et al 2012b). …”