A strong epidemiological link has been established between the reporting of low back pain, and the development of low back disorders to exposures of vibration in an occupational setting. Specifically, intervertebral disc herniations as a form of low back disorders have been indicated as a possible injury development pathway due to seated occupational vibration exposures. However, very little experimental evidence exists corroborating the strong epidemiological link between intervertebral disc herniations and vibration exposures using basic scientific approaches. The purpose of the current investigation was to provide some basic experimental evidence of the epidemiological link between intervertebral disc damage (herniation) and exposure to vibration.

Partial intervertebral disc herniations were created in a population of in-vitro porcine functional spinal units using a well established herniation protocol of repetitive flexion/extension motions under modest compressive forces. After herniation initiation, functional spinal units were exposed to 8 different vibration and postural constraint loading protocols consisting of two postural conditions (full flexion and neutral) and 4 vibration loading conditions (whole-body vibration, shock loading, static compressive loads, and whole-body vibration in addition to shock loading) to assess the effects of vibration and posture on functional spinal unit damage progression. There were three main outcome variables that were assessed and used to quantify damage progression;​ average stiffness changes, herniation distance progression (distance of tracking changes), and specimen height changes, while cumulative loading factors were considered. Additionally the concordances between two types of contrast enhanced medical imaging (Computed Tomography and Discograms) were qualified to a dissection ‘gold standard’, and an attempt was made to classify disc damage progression via three categorical variables

Concordance to a dissection ‘gold standard’ was higher for the Computed Tomography medical imaging approach than for the Discograms. The categorical criteria used to qualify disc damage progression were insufficiently sensitive to detect damage progressions illustrated through dissection and medical imaging techniques. The partial herniation loading protocol was quantified to be more damaging overall to the functional spinal units compared to the vibration and postural constraint loading protocols. However, the combination of load (vibration) and posture (postural constraint) did provided sufficient mechanical insult to the functional spinal units to progress damage to the intervertebral discs beyond the level illustrated via the partial herniation loading protocol. Vibration loading exposures alone were found to alter specimen height changes and distance of tracking changes, however posture alone had no significant effects on these variables. Neither posture nor vibration loading conditions had any meaningful significant effects on average stiffness changes.

It appeared that the combination of load (vibration) and posture (postural constraint) loading protocols provided sufficient mechanical insult to intervertebral discs to exacerbate preexisting disc herniations. However, load (vibration) loading alone appeared to be more influential in the exacerbation of disc damage than did posture (postural constraints) alone. The current investigation was successful in establishing some basic scientific evidence to further the vibration to disc herniation epidemiological link.