Analysis of Hip Joint Mechanics in Infants with Developmental Dysplasia of the Hip
Faculty Mentor Information
Dr. Clare Fitzpatrick, Boise State University
Presentation Date
7-16-2026
Abstract
Developmental dysplasia of the hip (DDH) is a common musculoskeletal condition in neonates - approximately 1 in 100 infants need treatment for DDH. It is characterized by an abnormal anatomic relationship between the femoral head and the acetabulum. Untreated DDH can cause irreversible joint damage, chronic hip pain, and early onset osteoarthritis and current treatments, such as the Pavlik harness, are not always effective. The objective of this research was to develop an infant musculoskeletal model that can be used for analyzing infant hip mechanics.
An existing musculoskeletal hip model (2398Hip_LaiArnold2017_hiptorso_OS40) was adapted to represent an infant hip. This model was scaled to infant size using experimental data collected using a motion capture system. This data was then used for inverse kinematics, estimating joint angles and body segment positions over time. Muscle strength parameters were also scaled to better match those of an infant. External forces were then applied to simulate Pavlik harness resistance and static optimization was performed to estimate muscle force requirements of the infant.
This research provides a framework for infant hip modeling. Outputs such as hip joint reaction forces and muscle fiber forces could be used in finite element models to analyze stress, strain, and contact mechanics between the acetabulum and femoral head. Future research will focus on improving Pavlik harness representation and model fidelity, as well as study the effects of how Pavlik harness positions and tensions can affect hip biomechanics.
Analysis of Hip Joint Mechanics in Infants with Developmental Dysplasia of the Hip
Developmental dysplasia of the hip (DDH) is a common musculoskeletal condition in neonates - approximately 1 in 100 infants need treatment for DDH. It is characterized by an abnormal anatomic relationship between the femoral head and the acetabulum. Untreated DDH can cause irreversible joint damage, chronic hip pain, and early onset osteoarthritis and current treatments, such as the Pavlik harness, are not always effective. The objective of this research was to develop an infant musculoskeletal model that can be used for analyzing infant hip mechanics.
An existing musculoskeletal hip model (2398Hip_LaiArnold2017_hiptorso_OS40) was adapted to represent an infant hip. This model was scaled to infant size using experimental data collected using a motion capture system. This data was then used for inverse kinematics, estimating joint angles and body segment positions over time. Muscle strength parameters were also scaled to better match those of an infant. External forces were then applied to simulate Pavlik harness resistance and static optimization was performed to estimate muscle force requirements of the infant.
This research provides a framework for infant hip modeling. Outputs such as hip joint reaction forces and muscle fiber forces could be used in finite element models to analyze stress, strain, and contact mechanics between the acetabulum and femoral head. Future research will focus on improving Pavlik harness representation and model fidelity, as well as study the effects of how Pavlik harness positions and tensions can affect hip biomechanics.