Objectives. Loss of motion following spine segment fusion results in increased strain in the adjacent motion segments. However, to date, studies on the biomechanics of the cervical spine have not assessed the role of coupled motions in the lumbar spine. Accordingly, we investigated the biomechanics of the cervical spine following cervical fusion and lumbar fusion during simulated whiplash using a whole-human finite element (FE) model to simulate coupled motions of the spine. Methods. A previously validated FE model of the human body in the driver-occupant position was used to investigate cervical hyperextension injury. The cervical spine was subjected to simulated whiplash exposure in accordance with Euro NCAP (the European New Car Assessment Programme) testing using the whole human FE model. The coupled motions between the cervical spine and lumbar spine were assessed by evaluating the biomechanical effects of simulated cervical fusion and lumbar fusion. Results. Peak anterior longitudinal ligament (ALL) strain ranged from 0.106 to 0.382 in a normal spine, and from 0.116 to 0.399 in a fused cervical spine. Strain increased from cranial to caudal levels. The mean strain increase in the motion segment immediately adjacent to the site of fusion from C2-C3 through C5-C6 was 26.1% and 50.8% following single- and two-level cervical fusion, respectively (p = 0.03, unpaired two-way t-test). Peak cervical strains following various lumbar-fusion procedures were 1.0% less than those seen in a healthy spine (p = 0.61, two-way ANOVA). Conclusion. Cervical arthrodesis increases peak ALL strain in the adjacent motion segments. C3-4 experiences greater changes in strain than C6-7. Lumbar fusion did not have a significant effect on cervical spine strain. Cite this article: H. Huang, R. W. Nightingale, A. B. C. Dang. Biomechanics of coupled motion in the cervical spine during simulated whiplash in patients with pre-existing cervical or lumbar spinal fusion: A Finite Element Study. Bone Joint Res 2018;7:28–35. DOI: 10.1302/2046-3758.71.BJR-2017-0100.R1

Objectives

Understanding lumbar facet joint involvement and biomechanical changes post spinal fusion is limited. This study aimed to establish an in vitro model assessing mechanical effects of fusion on human lumbar facet joints, employing synchronized motion, pressure, and stiffness analysis.

Purpose of the study and background. The preliminary study aimed to establish clinical and research expert opinion with regards to the key components of an assessment of a person with Mechanical Low Back Pain (MLBP). We aimed to identify the key subjective questions and objective tests which would be helpful for clinicians to develop the most appropriate self-management exercise programme. This is the first part of the study to develop the ‘Back-to-Fit’ digital tool offering personalised self-management exercise solutions for people with MLBP. Summary of the methods. A Bristol online survey which included a questionnaire with a series of open and closed questions was developed using the literature and was distributed among clinicians/researchers with a background in the clinical management of MLBP. The questionnaire included 6 demographic questions followed by sections related to subjective questions and objective tests of the MLBP assessment. 71 participants responded to the survey. Results. In the subjective assessment component, ≥80% level of agreement was obtained for 17 of 26 proposed subjective questions and 05 of the 21 suggested objective tests. Two more questions and two objective tests to be included in the assessment had been suggested by the partcipants. Conclusion. These expert agreements on questions and opinions provides an indication of the key subjective and objective components to be included in a self-assessment tool in a personalised self-management platform for MLBP. Further testing with a multiple round Delphi study in a large sample of experts is now required to obtain consensus for the above findings. Conflicts of interest: No conflicts of interest. Sources of funding: Biomechanics and Bioengineering Research Centre Versus Arthritis, Cardiff University, UK

Aims

The aim of this study was to investigate the impact of the level of upper instrumented vertebra (UIV) in frail patients undergoing surgery for adult spine deformity (ASD).

Spinal Biomechanics Lab, Baylor College of Medicine, Houston, Texas, USA. Documenting the patterns and frequency of collapse in non-operatively managed spine fractures, using a motion analysis software. Retrospective analysis of prospective case series. 105 patients with thoracic or lumbar fractures, were neurologically intact, and treated non-operatively for the ‘stable’ injury at our unit between June 2003 and May 2006. The mean age of the cohort was 46.9 yrs. Serial radiographs (mean 4 radiographs/patient; range 2 – 9) were analysed using motion analysis software for collapse at the fracture site. We defined collapse as a reduction of anterior or posterior vertebral body height greater than 15% of the endplate AP width, or a change in the angle between the inferior and superior endplates > 5°. The changes were assessed on serial radiographs performed at a mean of 5.6 mo (95% CI 4.1 – 7.1 mo) after the initial injury. 11% showed anterior collapse, 7.6% had posterior collapse, 14% had collapse apparent as vertebral body wedging, and 17% had any form of collapse. ODI scores were obtained in 35 patients at the time of the last available radiograph. There were no significant differences in ODI scores that could be associated with the presence of any form of collapse (p > 0.8 for anterior collapse; and p = 0.18 for posterior collapse). This pilot study with the motion analysis software demonstrates that some fractures are more likely to collapse with time. We hope to carry this work forward by way of a prospective study with a control on other variables that are likely to affect the pattern and probability of post-fracture collapse, including age, bone density, vertebral level, activity level, fracture type

Aims

Postoperative complication rates remain relatively high after adult spinal deformity (ASD) surgery. The extent to which modifiable patient-related factors influence complication rates in patients with ASD has not been effectively evaluated. The aim of this retrospective cohort study was to evaluate the association between modifiable patient-related factors and complications after corrective surgery for ASD.