Instantaneous helical axis estimation from 3-D video data in neck kinematics for whiplash diagnostics

Area of Science:

• Biomechanics
• Orthopedics
• Medical Imaging

Background:

• Current whiplash injury diagnosis relies heavily on subjective clinical assessment.
• Finite helical axes (FHAs) show potential for objective neck mobility assessment.
• FHAs require large angular intervals for accuracy with noisy data.

Purpose of the Study:

• To investigate the use of instantaneous helical axes (IHAs) for objective neck mobility assessment.
• To overcome limitations of FHAs in analyzing microstructure of neck movement.
• To validate IHAs using marker-based motion capture and compare with FHA approaches.

Main Methods:

• Estimated IHAs from low-pass smoothed video data of head-trunk motion.
• Utilized marker clusters on head and trunk for technical system validation.
• Derived planar models relating instantaneous centers of rotation to neck kinematics.
• Analyzed preliminary data from asymptomatic and pathological subjects.

Main Results:

• IHAs demonstrated low dispersion (approx. 1 degree for direction, 1 mm for position) with validated technical systems.
• Low-pass filtering enabled IHA estimation even with small rotation velocities.
• Preliminary results show distinct IHA patterns for asymptomatic versus pathological subjects during neck movement.

Conclusions:

• IHAs offer a more precise method for analyzing neck movement microstructure compared to FHAs.
• IHA analysis holds promise for objective diagnosis of conditions affecting cervical joint mobility.
• Further investigation with IHAs can improve the objective assessment of whiplash and related injuries.