In Silico Meta-Analysis of Boundary Conditions for Experimental Tests on the Lumbar Spine

Abstract

The study of the spine range of motion under given external load has been the object of many studies in literature, finalised to a better understanding of the spine biomechanics, its physiology, eventual pathologic conditions and possible rehabilitation strategies. However, the huge amount of experimental work performed so far cannot be straightforwardly analysed due to significant differences among loading set-ups. This work performs a meta-analysis of various boundary conditions in literature, focusing on the flexion/extension behaviour of the lumbar spine. The comparison among range of motions is performed virtually through a validated multibody model. Results clearly illustrated the effect of various boundary conditions which can be met in literature, so justifying differences of biomechanical behaviours reported by authors implementing different set-up: for example, a higher value of the follower load can indeed result in a stiffer behaviour; the application of force producing spurious moments results in an apparently more deformable behaviour, however the respective effects change at various segments along the spine due to its natural curvature. These outcomes are reported not only in qualitative, but also in quantitative terms. The numerical approach here followed to perform the meta-analysis is original and it proved to be effective thanks to the bypass of the natural variability among specimens which might completely or partially hinder the effect of some boundary conditions. In addition, it can provide very complete information since the behaviour of each functional spinal unit can be recorded. On the whole, the work provided an extensive review of lumbar spine loading in flexion/extension.

Cross-link augmentation enhances CFR-PEEK short fixation in lumbar metastasis stabilization

“…Two aspects support this position: firstly, the compressive stress state caused by the longitudinal load reached the highest magnitude in the case of the long configuration (being stiffer, a higher load was necessary to reach the same ROM at parity of arm); secondly, both in extension and in lateral bending on the intact side, the arm of the longitudinal force was smaller, and this could have heightened the secondary effect of the compression summed to the moment (Borrelli et al, 2022). In closing, this comparative analysis assessed that CFR-PEEK cross-links in short stabilizations embrace the biomechanical advantages assessed in the literature of metallic cross-links in multi-level stabilizations and have the potential to become an effective surgical solution in the management of spinal stabilization, exploiting its radio-transparency characteristics, which is cardinal in imaging and radiotherapy (Ringel et al, 2017).…”

Multibody Models of the Thoracolumbar Spine: A Review on Applications, Limitations, and Challenges

“…Furthermore, a systematic model-based analysis can help standardize clinical procedures, such as the classification of spinal shapes [116] or to define boundary conditions for experimental protocols [24].…”

“…After filtering a total of 2592 articles, 81 articles remained, which were included in this review. Focusing on extensive musculoskeletal models of the thoracolumbar spine, we discuss models with reduced complexity, such as abstracted models [12][13][14][15][16], skeletal models neglecting muscular effects [17,18] or models of the lumbar spine [19][20][21][22][23][24][25][26][27][28][29] only in passing.…”

Annals of Biomedical Engineering 2022 Year in Review

“…One common trend among the review articles was the need for standardization. In particular, there is a need for standardized assessments of insulin infusion pump accuracy [24] and upper body industrial exoskeletons [12] as well as standardized boundary conditions for experimental testing of the lumbar spine [2] and closed head impact models for traumatic brain injury [23]. Additional review articles highlighted emerging research topics in biomedical engineering.…”