Faculty Mentor: Amy Lenz (Biomedical Engineering, University of Utah)

Patients with ankle injuries seek the care of clinicians, scientists, and engineers to help find solutions to improve their pain and injuries that can severely impact their ability to move around and their quality of life. The field of foot and ankle research has been rapidly advancing however, and there are no standards for coordinate systems used by researchers to help patients by understanding motion of the complex area of the body[1]. Accurate anatomical coordinate systems for the foot and ankle are critical for interpreting their complex biomechanics[2]. The tibial superior-inferior axis is crucial for analyzing joint kinematics, influencing bone motion analysis during gait using CT imaging and biplane fluoroscopy. This study investigated various superior-inferior axes using multiple distal tibia lengths to determine the minimal field of view for representing the full tibia long-axis. Twenty human cadaver tibias were imaged and segmented to generate 3D bone models. Axes were calculated based on coordinate definitions that required user manual input, and a gold standard mean superior-inferior axis was calculated based on the population’s principal component analysis axis. Four manually calculated superior-inferior tibial axes groups were established based on landmarks and geometric fittings. Statistical analysis revealed that geometrically fitting a cylinder 1.5 times the mediolateral tibial width, starting 5 cm above the tibial plafond, yielded the smallest angular deviation from the gold standard. Implementing these findings will help improve foot and ankle research generalizability and impact clinical decisions. Using this definition as a standard will allow clinicians such as surgeons to work with engineers and scientists in better understanding the motion of the foot and ankle and help those overcome challenges caused by ankle pain and injury.

For a complete and in depth analysis of this project, please view:  Muhlrad, E, Peterson, A.C., Anderson, A.M., Aragon, K., Lisonbee, R.J., MacWilliams, B.A., Kruger, K.M & Lenz, A.L. “Recommendation of minimal distal tibial length for long axis coordinate system definitions,” Journal of biomechanics, vol. 170, p. 112153, Jun. 2024, doi: https://doi.org/10.1016/j.jbiomech.2024.112153.

References

[1] Wu, G., Siegler, S., Allard, P., Kirtley, C., Leardini, A., Rosenbaum, D., Whittle, M. D’Lima, D., Cristofolini, L., Witte, H., Schmid, S., & Stokes, I.“ISB recommendation on definitions of joint coordinate system of various joints for the reporting of human joint motion—part I: ankle, hip, and spine,” Journal of Biomechanics, vol. 35, no. 4, pp. 543–548, Apr. 2002, doi: https://doi.org/10.1016/s0021-9290(01)00222-6.

[2] Lenz AL, Strobel MA, Anderson AM, Fial AV, MacWilliams BA, Krzak JJ, Kruger KM. Assignment of local coordinate systems and methods to calculate tibiotalar and subtalar kinematics: A systematic review. J Biomech. 2021 May 7;120:110344. doi: 10.1016/j.jbiomech.2021.110344. Epub 2021 Mar 10. PMID: 33744722.