Are the Left and Right Proximal Femurs Symmetric?

Abstract

Background The contralateral femur frequently is used for preoperative templating for THA or hemiarthroplasty when the proximal femur is deformed by degenerative changes or fracture. Although femoral symmetry is assumed in these situations, it is unclear to what degree the contralateral femur is symmetrical. Questions/purpose We therefore defined the degree of asymmetry between left and right proximal femurs and determined whether it was affected by demographics and proximal femoral anatomy. Methods We obtained 160 paired femurs from individuals (20-40 years old), evenly distributed for gender and ethnicity (African-American and Caucasian). The height and weight of the individuals were recorded. We measured the femoral head diameter, minimal femoral neck diameter in the AP and cephalocaudal (CC) planes, and the AP femoral diaphyseal diameter. The absolute and percent differences were determined.Results All femoral measurements showed an absolute difference less than 2 mm and a percent asymmetry and difference less than 2% for the femoral head, less than 4% for the femoral neck, and less than 3.5% for the femoral shaft. We found no correlation or predictive value between absolute differences and asymmetry and age, ethnicity, gender, or weight. Height was negatively associated with femoral head differences and thus increased symmetry of the femoral head. Conclusions Our data support assumptions of substantial symmetry of the proximal femur and highlights that asymmetry is not affected by demographics or the size of the proximal femur. Asymmetry tends not to occur in isolated segments of the femur.

Global point signature for shape analysis of carpal bones

“…These findings agree with those reported by Crisco et al (2005) for the carpal bones of the right and left hand for healthy men and women. There are also reports of insignificant shape differences of the left and right bones of other joints such as those of the knee (Murshed et al 2005, Young et al 2013). …”

What Is Normal Femoral Head/Neck Anatomy? An Analysis of Radial CT Reconstructions in Adolescents

“…Their study was performed with standard radiographs with no calibration template. Young et al examined the symmetry between the right and left femoral heads in a series of 160 paired cadaveric femurs measured using calibrated digital photographs [14]. In their series, the mean femoral head diameter averaged 55.8 mm for males and 48.3 mm for females, and the mean femoral neck diameter was 39.3 and 33.7 mm for males and females respectively in the AP view and 23.9 and 20.1 mm for males and females respectively in the craniocaudal direction.…”

The Etiology of Cam-type Femoroacetabular Impingement: A Cadaveric Study

“…All measurements were performed by the same investigator using established techniques. 15,16,[18][19][20] The a-angle was determined by the method described by Toogood et al 15 The a-angle was defined on the modified axial view as the angle formed between the axis of the femoral neck and a line extending from the center of a best-fit circle inscribed around the femoral head to the point where the anterior cortex of the femoral head/neck junction first exited the circle. Although there is no single universal objective radiographic standard for diagnosing a cam deformity, the a-angle is the most commonly used.…”

“…20 Moreover, the femoral head diameter was described as the diameter of a best-fit circle around the femoral head by which the head did not extend beyond 1 mm outside of the circle on the anteroposterior view. 16,18,19 Finally, the AOR was calculated as the anterior offset divided by the femoral head diameter. 20 Of note, data for the femoral head diameter are not presented in this manuscript as it was not a primary measurement of interest, but rather a means to determining the AOR.…”