Structural health monitoring (vibration) as a tool for identifying structural alterations of the lumbar spine: a twin control study

Abstract

Structural health monitoring (SHM) is an engineering technique used to identify mechanical abnormalities not readily apparent through other means. Recently, SHM has been adapted for use in biological systems, but its invasive nature limits its clinical application. As such, the purpose of this project was to determine if a non-invasive form of SHM could identify structural alterations in the spines of living human subjects. Lumbar spines of 10 twin pairs were visualized by magnetic resonance imaging then assessed by a blinded radiologist to determine whether twin pairs were structurally concordant or discordant. Vibration was then applied to each subject’s spine and the resulting response recorded from sensors overlying lumbar spinous processes. The peak frequency, area under the curve and the root mean square were computed from the frequency response function of each sensor. Statistical analysis demonstrated that in twins whose structural appearance was discordant, peak frequency was significantly different between twin pairs while in concordant twins, no outcomes were significantly different. From these results, we conclude that structural changes within the spine can alter its vibration response. As such, further investigation of SHM to identify spinal abnormalities in larger human populations is warranted.

A 3D finite element model updating of spinal lumber segment applying experimental modal data and particle swarm optimization algorithm

“…In another study, Van Engelen et al (2012) performed a quasi-static test to assess the quasi-static stiffness of six cadaver human spines and a modal test to determine the Eigen frequencies of the samples for flexion-extension, lateroflexion, and axial rotation. Kawchuk et al (2016) executed an experimental modal test on living human subjects to recognize structural alterations in their spines. Mondal and Arunachalam (2020) proposed a 3D FE model of a seated human driver inside a vehicle simulating the human segments with ellipsoidal portions in Abaqus.…”

Age-related changes in shock absorption capacity of the human spinal column

“…Given the above, there is a significant inability to quantify shock absorption properties using diagnostic methods commonly applied in health care. 11 …”

“…To fill this void, several authors have identified established engineering techniques used in evaluating mechanical assemblies and adapted them for use in the analysis of human locomotor system function. 11 – 14 It seems that the spine shock absorption properties can be directly expressed in the frequency domain as the transmissibility of vibration through the spinal column. 15 These vibrations can be measured with accelerometers attached to the skin over the spine bony prominence, which has been previously validated against pins inserted directly into the bone, with promising results.…”

Non-invasive spinal vibration testing using ultrafast ultrasound imaging: A new way to measure spine function

“…Unfortunately, this invasive approach has limited clinical application. In addition to model experiments, a previous clinical study using surface-based accelerometers was able to demonstrate that signals from different pathologies are unique in human twins 12 . In this study, five sets of discordant twins showed unique vibration signals in contrast to five sets of concordant twins, where signals overlapped.…”