Comparing the kinematics related to inflicted head injury between violent shaking of a 6-week-old and a 1-year-old infant surrogate

Kim Hutchinson ¹, Arne Stray-Pedersen ^2,3, Jenny Dankelman ¹

⁰Department of BioMechanical Engineering, Delft University of Technology, Delft, Zuid-Holland, The Netherlands.

Royal Society Open Science +

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November 27, 2025

View abstract on PubMed

Summary

Violently shaking smaller infants generates higher head and torso accelerations, increasing the risk of inflicted head injury by shaking trauma (IHI-ST). This biomechanical study highlights the vulnerability of younger infants to severe injury.

Area Of Science

Biomechanics
Pediatric Injury Prevention
Forensic Science

Background

Inflicted head injury by shaking trauma (IHI-ST) is a significant cause of infant injury and disability.
The incidence of IHI-ST is highest in younger infants, potentially due to age-related physical differences.

Purpose Of The Study

To compare the biomechanical kinematics of shaking a smaller infant dummy versus a larger infant dummy.
To investigate how infant size influences the forces and motion patterns during violent shaking.

Main Methods

Utilized two infant dummies, simulating a 6-week-old and a 1-year-old.
Recorded kinematic data, including accelerations and angular velocities, as volunteers violently shook the dummies.

Main Results

Higher head and torso accelerations were recorded when shaking the smaller (6-week-old) dummy compared to the larger (1-year-old) dummy.
Smaller infants exhibited higher peak sagittal angular accelerations with smaller radii of rotation, factors linked to IHI-ST.

Conclusions

Shaking smaller infants generates kinematic forces more likely to cause severe head injuries associated with IHI-ST.
These findings underscore the increased vulnerability of younger infants to shaking-related trauma due to their physical characteristics.

Keywords:

abusive head trauma biomechanical model child abuse head kinematics inflicted head injury by shaking trauma