2022 Undergraduate Research Showcase


Comparing Infant Hip Joint Center Estimations Between Manual and Digital Measures

Document Type

Student Presentation

Presentation Date


Faculty Sponsor

Dr. Erin Mannen


Comparing Infant Hip Joint Center Estimations Between Manual and Digital MeasuresDespite the high prevalence of developmental hip disorders in infants, there has been little research on understanding infant hip anatomy. The hip joint center (HJC) is the center of rotation of the hip joint, usually assumed to be the center of the femoral head, and it is the critical location for calculating moments and forces about the hip joint. The HJC cannot be externally identified, and thus localization requires diagnostic imaging or approximation when using motion capture systems. Approximations are calculated from regression equations dependent on anthropometric data and anatomical landmarks. None of the current regression equations are based on infant anatomy. The purpose of this study was to determine whether the HJC estimation equations recommended by the International Society of Biomechanics yield comparable results when tested on a 3-dimensional (3D) digital model and a 3D physical model of the infant hip. Anatomical positions needed for the computation of the HJC were identified in the digital and physical models. Ten measures were collected on each model and the HJC was estimated using the four Bell methods. An independent samples T-test was performed for each dataset. No significant differences in HJC estimations were found between the manual and digital measures for each method. This indicates that anatomical landmarks utilized in a digital model are comparable to a physical model and supports that the use of manual measurements may be viable for estimating the infant HJC in clinical settings where diagnostic imaging is unavailable. The lack of significant findings may partially be due to the fact that only one model was tested, thus we were unable to compare between subjects. Additionally, the current models were bone-only and lacked representation of soft-tissue, which may have altered our results. Further testing with more robust models and methods are needed to confirm the results. This study serves as preliminary research in the development of HJC estimation standards for infants.

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