Ongoing research in simulated vehicle crash environments utilizes postmortem
human subjects (PMHS) as the closest approximation to live human response.
Lumbar spine injuries are common in vehicle crashes, necessitating accurate
assessment methods of lumbar loads. This study evaluates the effectiveness of
lumbar intervertebral disc (IVD) pressure sensors in detecting various loading
conditions on component PMHS lumbar spines, aiming to develop a reliable
insertion method and assess sensor performance under different loading
scenarios. The pressure sensor insertion method development involved selecting a
suitable sensor, using a customized needle-insertion technique, and precisely
placing sensors into the center of lumbar IVDs. Computed tomography (CT) scans
were utilized to determine insertion depth and location, ensuring minimal tissue
disruption during sensor insertion. Tests were conducted on PMHS lumbar spines
using a robotic test system for controlled loading in flexion, compression, and
a combination, while monitoring pressure changes. The compression force, flexion
angle, and sensor-recorded IVD fluid pressure were recorded during tests. CT
images were analyzed to assess sensor placement and its impact on sensing
ability. Pressure readings during various loading conditions were examined for
different specimens, with data reported from the beginning of tests through
relevant loading phases. The study successfully established a methodology for
inserting pressure sensors into the IVD and assessed their ability to detect
changes in flexion angle, compression, and combined loading. Sensors accurately
tracked compression force and detected changes in flexion angle, although with
some differences in response. Sensors placed optimally showed expected
responses, while those placed suboptimally exhibited variability, particularly
in detecting changes during flexion. This variability underscores the importance
of sensor placement for accurate detection of loading states. Overall, the study
provides a foundation for utilizing pressure sensors to monitor loading states
in sled tests, with future work focusing on refining differentiation between
loading types.
