Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 149790

149790 - Variability of the Femoral Neck Axis Through Three-Dimensional Measurements in Infant Femur 

Introduction: Quantifying the femoral neck axis in pediatric populations is crucial for diagnosing pathological conditions in the hip joint [1], such as hip dysplasia in infants or cerebral palsy in older children [2]. Precisely defining the position and orientation of the femoral neck axis is crucial for measuring the femoral neck-shaft angle (NSA) and the femoral anteversion (FAV). Clinically, these metrics are obtained using two-dimensional measurements from radiographs, which may vary depending on the positioning of the patient. We hypothesized that volumetric measurements would minimize the errors associated with two-dimensional measurements using radiographs and may allow for more detailed, repeatable measurements. For this study, we investigated the variability of the femoral neck axis in the infant femur using medical images through two measurements: the NSA and FAV.

 

Materials and Methods: For our study, we developed anatomical volumetric models using computed tomography (CT) images from a small historical collection of post-mortem infant specimens with an average age of 5 months. All measurements were performed using Simpleware ScanIP (Synopsys), a commercial medical image processing software. The NSA was computed as the angle between the femoral neck and femoral shaft axes [3]. The femoral neck axis was defined by a line connecting the centers of the femoral head (FHC) and the center of the femoral neck (FNC). The femoral shaft axis was defined as the line connecting the center of two spheres created along the femoral shaft (FS1 & FS2). The FAV was computed as the angle between the femoral neck axis and the posterior condylar axis of the knee. The femoral neck axis created for the NSA was maintained for the FAV. The posterior condylar axis was defined by two points denoting the most posterior points on the medial (ME) and lateral condyles (LE). The angles were measured by two observers who followed the same protocol.

 

Results:  In this study, a total of 8 femurs (4 left, 4 right) were used to test the variability in the femoral neck axis. A total of 10 measurements were taken for each femur (20 per decedent) for the NSA and FAV. The average NSA for all femurs was 128 +/- 4.92 degrees. The average FAV for all femurs was 35.56 +/- 11.68 degrees. The NSA values were consistent with those found in literature between 115 and 140 degrees for second- and third-trimester fetuses [1], [4]. The FAV findings also align with those reported in [5] of 35.8 +/- 6.5 degrees.

 

Conclusion: Our study investigates the repeatability of pediatric metrics using volumetric data and provides a comparison against the “gold-standard” two-dimensional measurements. Isolating this region of interest is challenging in infant populations where the femoral neck has not yet developed or is still developing. Overall, our findings align with existing literature values and demonstrate the accuracy and reliability of our 3D methodology. Future work includes potential application to infant musculoskeletal models. Learning how to effectively take these measurements can allow us to investigate the effects of femoral geometry on infant biomechanics when developing infant musculoskeletal models.

Presenting Author: Victoria Melendez Embry-Riddle Aeronautical University

Presenting Author Biography: Mechanical Engineering student working as an undergraduate research assistant in pediatric anatomical image segmentation with Dr. Huayamave and PhD student Tamara Chambers. Long term goals include becoming proficient in computational software such MATLAB and OpenSim for applications in biomechanics and biomechanical modeling. I hope to further my understanding of the mechanics of the human body in everyday movement and possible applications in pediatrics.

Authors:

Victoria Melendez Embry-Riddle Aeronautical University
Tamara Chambers Embry-Riddle Aeronautical University
Victor Huayamave Embry-Riddle Aeronautical University