Technical note: Measuring bicondylar length in computed tomography data

ObjectivesWith the increased use of 3D-generated images in biological research, there is a critical need to adapt classical anatomical measurements, traditionally conducted with calipers, to a virtual environment. We present detailed protocols for measuring bicondylar length, a critical dimension of the femur, using three different imaging software programs-3D Slicer (TM), Amira (TM), and Simpleware (TM). These protocols provide researchers and practitioners in radiology, orthopedics, biomechanics, and biological anthropology with accurate and reproducible measurement techniques. The objective is to standardize and support virtual osteology in biomechanical research, stature estimation, and related medical and anthropological studies.Materials and MethodsAdhering to standardized protocols, we adapted femoral bicondylar length measurements for computed tomography images from a New Mexican collection (n = 10). The method was designed for applicability and reproducibility across three software platforms. By comparing measurements from the same sample across different observers and different platforms, this study validates the accuracy and consistency of the adapted protocol, demonstrating its utility for research and clinical assessments.ResultsWe present a step-by-step guide for each program, detailing bone alignment and measurement. We illustrate each step and provide video tutorials via links for an enhanced understanding of the process.DiscussionBicondylar length can be measured effectively in each software program following the provided instructions. However, ease of measurement varied among the programs, with some offering a more straightforward process. This variability underscores the importance of choosing appropriate software for the user's needs and proficiency. It also suggests areas for improvement and standardization in software design and instructional clarity. The study introduces a detailed protocol for measuring femoral bicondylar length in 3D bone renderings using three different software programs: 3D Slicer (TM), Amira (TM), and Simpleware (TM). Comprehensive step-by-step descriptions, accompanied by illustrative images and video tutorials, are available to researchers to replicate the measurement process easily. Error testing across all three software programs and among different observers on the same software program demonstrated low variability, indicating that this measurement protocol is precise and reliable across all three platforms and with different observers.