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Biomedical Imaging and Instrumentation

Biomedical Imaging and Instrumentation - Poster Session A

Poster G9 - Comparison of radiographic and percutaneous measurement techniques for femur and humerus lengths

Thursday, October 24, 2024
10:00 AM - 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  Long bone length measurements have been used for decades to predict human stature. Accurate stature determinations are key for matching remains to identities and for research analyzing stature evolution. There is a strong correlation between stature and long bone lengths in the upper and lower extremities. Traditionally, prediction models gather known stature and long bone lengths from a population with a common demographic and compute a linear regression equation to extrapolate stature. The equation can be used to estimate stature when the long bone length is known. However, validation studies have found that equations are only reliable for the specific population they are created from. Factors such as race, sex, age, and time period of birth can significantly impact the accuracy of estimation equations. Therefore, it is important to apply an equation that was computed from a pool of individuals with the same demographics as the person being studied. Due to the large number of possible demographic combinations, there is a high demand for population-specific stature equations. Thus, many bone measurements need to be obtained from a variety of current, living individuals. Long bones can be measured from x-rays, computed tomography (CT) scans, or percutaneously using a tape measure or calipers. CT scanning is the most definitive means of determining length, as specific landmarks in 3D space can be located, but its accessibility and affordability are suboptimal. This study aims to investigate the validity of percutaneous and x-ray measurements compared to measurements obtained from CT scans.

Materials and

Methods:  Lengths of the right and left femurs and humeri were measured on 4 cadavers with three methods: percutaneously with a tape measure, 3D distance on a CT scan, and 2D distance on an “x-ray” mimicking image from the CT scan. Cadavers 1 and 2 were female, white, and >89 years old. Cadaver 3 was male, black, and 41 years old. Cadaver 4 was male, white, and 82 years old. Some measurements could not be obtained due to scan artifacts and insufficient field of view. All lengths were measured by 2-4 observers and the averages were used to decrease inter-rater bias. Images were viewed using 3D Slicer, the Total Segmentation module was used for segmentation, and “x-ray” measurements were done in Blender. CT lengths were obtained by finding the 3D distance between the following landmarks: femur - superior vertex of the greater trochanter to superior-most point of the inferior condylar divot; humerus - superior vertex of the greater tubercle to inferior vertex of the trochlea. Imitated “x-rays” were created by using the 3D segmentation of each bone in the coronal plane, and lengths determined between the same landmarks. Percutaneous lengths were obtained by measuring the distance between the following landmarks with a tape measure: femur - superior vertex of the greater trochanter to inferior vertex of lateral condyle; humerus - the lateral tip of acromion process to the inferior vertex of the lateral epicondyle [1-5].

Results, Conclusions, and Discussions: The percent errors for all "x-ray" and percutaneous measurements were determined by comparing each length to their corresponding lengths measured with CT, which was considered to be the ground truth. The average percent error for all “x-ray” and percutaneous measurements was 1.18% and 5.71%, respectively (Figure 1). The largest average percent error occurred when measuring the humerus, with 1.33% for “x-ray” and 5.76% for percutaneous. The smallest average percent error occurred when measuring the femur with 1.02% for “x-ray” and 5.65% for percutaneous. Using stature estimation equations from 1952 for a white male [6], a femur length of 41 cm with a 5.65% error or a humerus length of 33 cm with a 5.76% error results in an overestimation of stature by nearly 6 cm, demonstrating the importance of proper measurement technique. The results demonstrate that both x-ray and percutaneous measurements of the femur and humerus generate considerable error when obtaining long bone lengths, but percutaneous is the least suitable method. The large error in percutaneous measurements may be due to issues palpating landmarks through the rigid, embalmed tissue of cadavers, but the amount of fat around the bone was likely the largest contributor to identification difficulty. Further research is needed with more cadavers and assorted bones to confirm the degree of x-ray and percutaneous error. The quantification of error based on the method of measurement allows for the development of new stature equations for a wide range of demographic subsets with the ability to calculate the amount of compounded error due to data collection. Percutaneous measurements will continue to be used in communities with limited access to advanced imaging technologies, however, our quantification of error will aid in identifying the exact degree of data variance that is attributable to other factors. Additionally, determining the lengths of bones throughout the body may facilitate the creation of personalized anatomical models for precise surgical planning, customized prosthetic fittings, and identification of musculoskeletal disorder risk factors.

Acknowledgements (Optional):  Acknowledgments: This work was supported by NIH Stimulating Peripheral Activity to Relieve Conditions programs 75N98022C00018 and Case Western Reserve University. The opinions expressed in this article are the author’s own and do not reflect the view of the National Institutes of Health, the Department of Health and Human Services, or the United States government.

References: [1] Borkar, M. P. (2014). Estimation of height from the length of humerus in western region of Maharashtra.

[2] Chhikara, P., Dhattarwal, S. K., Sharma, R., Soni, J., & Khanna, K. (2014). Comparison of body height and percutaneous femur length among North Indian students. Medico-Legal Update, 14(2), 31-34.

[3] Hegde, A. S., Shetty, C. B., Joseph, N., Mane, P., & Thakkar, S. (2023). Preoperative estimation of humerus intramedullary nail length using clinical landmarks. Chinese Journal of Traumatology, 26(05), 256-260.

[4] Tetteh, J., Appiah, A. K., Abaidoo, C. S., & Adjei-Antwi, C. (2021). The forensic use of percutaneous femur length in height and sex estimation among Ghanaians. Forensic Science International: Reports, 4, 100234.

[5] Tetteh, J., Diby, T., Abaidoo, C. S., Yorke, J., Robertson, J., & Nketsiah, J. (2024). Height and sex estimation using percutaneous humeral length among Ghanaians. Forensic Science International: Reports, 9, 100367.

[6] Jeong, Y., Taylor, R. J., Jung, Y., & Woo, E. J. (2023). Trotter and Gleser’s (1958) equations outperform Trotter and Gleser’s (1952) equations in stature estimation of the US White males. Forensic Sciences Research, 8(1), 16-23.