Aims

The aim of this study was to compare the peak pull-out force (PPF) of pedicle-lengthening screws (PLS) and traditional pedicle screws (TPS) using instant and cyclic fatigue testing.

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. Methods and Results. Seven human lumbar spinal units (age 54 to 92, ethics 15/YH/0096) underwent fusion via a partial nucleotomy model mimicking a lateral cage approach with PMMA cement injection. Mechanical testing pre and post-fusion included measuring compressive displacement and load, local motion capture, and pressure mapping at the facet joints. pQCT imaging (82 microns isotropic) was carried out at each stage to assess the integrity of the vertebral endplates and quantify the amount of cement injected. Before fusion, relative facet joint displacement (6.5 ± 4.1 mm) at maximum load (1.1 kN) exceeded crosshead displacement (3.9 ± 1.5 mm), with loads transferred across both facet joints. After fusion, facet displacement (2.0 ± 1.2 mm) reduced compared to pre-fusion, as was the crosshead displacement (2.2 ± 0.6 mm). Post-fusion loads (71.4 ± 73.2 N) transferred were reduced compared to pre-fusion levels (194.5 ± 125.4 N). Analysis of CT images showed no endplate damage post-fusion, whilst the IVD tissue: cement volume ratio did not correlate with the post-fusion behaviour of the specimens. Conclusion. An in vitro model showed significant facet movement reduction with stand-alone interbody cage placement. This technique identifies changes in facet movement post-fusion, potentially contributing to subsequent spinal degeneration, highlighting its utility in biomechanical assessment. Conflicts of interest. None. Sources of funding. This work was funded by EPSRC, under grant EP/W015617/1

Background. We have previously reported an injectable hydrogel (NPgel), which could deliver patients own stem cells, via small bore needles, decreasing damage to the annulus fibrosus. NPgel drives differentiation to NP cells and can inhibit the degenerate niche. However, clinical success of NPgel is dependent on the capacity to inject NPgel into naturally degenerate human discs, restore mechanical function to the IVD, prevent extrusion during loading and induce regeneration. This study assessed injectability of NPgel into human IVD, influence on mechanical properties, regeneration ability in an ex vivo culture system and retention under failure testing. Methodology. Cadaveric human discs were used to calculate disc height and to determine Youngs Modulus during simulated walking pre and post injection of NPgel, extrusion testing performed. Whole human IVDs were injected with NPgel +/− human BMPCs and maintained in culture under physiological loading regime for 4 weeks. Pre and post culture MRI imaging and in line biomechanical characteristics determined. Histology and immunochemistry performed for anabolic and catabolic factors. Results. NPgel injection significantly increased disc height and Youngs modulus with no extrusion observed during failure testing. T1ρ intensity was increased during culture in those injected with NPgel +/− cells compared to non-injected discs, and biomechanical restoration. Histological analysis has demonstrated excellent tissue attachment to the injected gel, and cellular migration into acellular gel systems. With increased matrix production and decreased catabolic factor expression. Conclusion. These results provide essential proof of concept data supporting the use of NPgel as an injectable therapy for disc regeneration. Conflict of interest: C Le Maitre & C Sammon are inventors on the hydrogel discussed. Funding: This work was funded by MRC and Versus Arthritis

Background. Chronic low back pain is strongly linked to degeneration of the intervertebral disc (IVD), which currently lacks any targeted treatments. This study explores NPgel, a biomaterial combined with notochordal cells (NC), developmental precursor cells, as a potential solution. NCs, known for anti-catabolic effects on IVD cells, present a promising avenue for regenerating damaged IVD tissue. Methods. Bovine IVDs underwent enzymatic degeneration before NPgel (+/- NC) injection. Degenerated bovine IVDs were cultured under biomechanical loading for 21 days. Histology and immunohistochemistry assessed NC survival, phenotype, and matrix production. Within an in vivo sheep pilot study, NPgel (+/- NC) was injected into degenerated IVDs, blood was taken, and immune cell activation was monitored via flow cytometry over three months post-injection. Results. Within the ex vivo model, IVDs injected with NPgel (+/- NC) exhibited increased matrix expression and deposition. Viable NCs were detected post-culture, indicating survival and matrix production. In the in vivo model, NPgel injection into sheep IVDs did not significantly increase activation of immune cells compared to controls, suggesting no systemic inflammatory effects. Conclusion. NPgel, combined with NCs, shows promise for IVD regeneration. Ex vivo findings indicate NPgel supports NC survival and matrix production. Moreover, in vivo results demonstrate the absence of systemic immunogenic responses post-NPgel injection. This suggests NPgel's potential as a carrier for NCs in IVD regeneration therapy. These findings underscore NPgel's candidacy for further investigation in addressing chronic low back pain associated with IVD degeneration. Subsequent research, including long-term efficacy and safety evaluations, is imperative for clinical translation. Conflicts of interest. There are no conflicts of interest. Sources of funding. iPSpine, grant # 825925, Horizon 2020

Purpose and background. Work-related musculoskeletal disorders, particularly back pain, are a significant issue for healthcare workers, with patient handling being the most frequently reported risk factor. Patient handling is often performed without assistive devices or equipment, which can cause healthcare staff to maintain awkward postures or experience high loads. This review aimed to comprehensively map the literature surrounding manual patient handling (without assistive devices) by healthcare practitioners to identify the current evidence-base on moving and handling of patients and explore what primary research had been conducted. Methods and results. JBI methodology for scoping reviews and an a priori registered protocol (DOI 10.17605/OSF.IO/8PR7A) was followed and AMED, CINAHL, MEDLINE, SPORTDiscus and EMBASE databases were searched. Literature published in English between 2002 and 2021 was included. Forty-nine records were included: 36 primary research studies, 1 systematic review and 12 ‘other’ including narrative and government reports. Primary research predominantly used observational cross-sectional designs (n = 21 studies). Most studies took place in hospitals (n = 13) and laboratories (n = 12). Nurses formed the largest population group (n = 13), with very little research on physiotherapists and other allied health professionals. Conclusion. This scoping review comprehensively reviewed the available literature in the area. Most of the included primary research was observational. Nurses were often investigated in hospitals and laboratories. Qualitative research investigating moving and handling and further biomechanical investigation into therapeutic handling by healthcare staff were identified as areas for further research. Conflicts of interest. None. Sources of funding. None. This work has been published in Physiotherapy: Johnson, K., Swinton, P., Pavlova, A. and Cooper, K., 2023. Manual patient handling in the healthcare setting: a scoping review. Physiotherapy. (120) 60–77 . https://doi.org/10.1016/j.physio.2023.06.003

Background. Osteopathy has been shown to be effective in the management of chronic low back pain. Guidelines recommend biopsychosocial care for chronic, complex musculoskeletal conditions, including non-specific low back pain but there is a lack of evidence comparing standard osteopathic care, which has traditionally been based on dated and disputed biomechanical theories of dysfunction, with more contemporary biopsychosocial approaches. Methods and results. A multiple baseline single case experimental design trial with 11 UK osteopaths and 60 patients is currently assessing effectiveness of osteopathic treatment for patients with non-specific low back pain of more than 12 weeks’ duration. Patients are randomised to early, middle, or late treatment start dates to increase the validity of inferences about the effects of treatment. Osteopaths have participated in one course on the study protocol and processes pre-participation and will take an e-learning course on the biopsychosocial management of patients with low back pain after the first patient recruitment stage. Statistical analysis will assess the degree and rate of change between baseline, intervention and follow-up periods, and whether differences in effect are observed after the osteopaths have completed the biopsychosocial patient management training course. Primary outcomes will be the Numeric Pain Rating and Patient Specific Function Scales, measured daily at baseline and for 6 weeks during the intervention stage, and weekly or fortnightly during a 12-week follow-up period. Conclusion. This experimental design will offer osteopaths in practice the opportunity to engage in research evaluating the effectiveness of osteopathic care and the influence of a training programme to augment biopsychosocial osteopathic care. Study registration: . https://clinicaltrials.gov/ct2/show/NCT05120921. Sources of funding: The Osteopathic Foundation. Conflict of interest: The authors declare no competing interests. Previous publication of work: This protocol is under review with a peer-reviewed journal

Background. Low back pain (LBP) is a major problem across the globe and is the leading cause worldwide of years lost to disability. Self-management is considered an important component the treatment of people with non-specific LBP. However, it seems that the self-management support for people with non-specific LBP provided by physiotherapists can be improved. Moreover, the way exercise therapists (ET) address self-management in practice is unknown. Purpose. To investigate the ideas, opinions and methods used by physiotherapists and ET with regard to self-management and providing self-management support to patients with non-specific LBP. Methods. This study was a qualitative survey. An online questionnaire with open-ended questions was developed. The survey was conducted among physiotherapists and ET working in the Netherlands. Data was analysed using thematic analysis. Results. Respondents considered self-management support an important topic in physiotherapy and exercise therapy for people with non-specific LBP. In the self-management support provided by the respondents, providing information and advice were frequently mentioned. The topics included in the support given by the respondents covered a broad range of important factors. The topics frequently focused on biomechanical factors. Therapists mainly provided patient education rather than self-management support. Moreover, important self-management skills were generally not addressed sufficiently. The majority of respondents had a need with regard to self-management or providing self-management support. These needs include having more knowledge, skills and tools aimed at facilitating self-management. Conclusion. The way physiotherapists and ET address self-management in people with non-specific LBP is not optimal and should be improved. Conflicts of interest: No conflicts of interest. Sources of funding: No funding obtained. Previous publication: This work was published in a scientific journal: Hutting N, Oswald W, Staal JB, Heerkens YF. Self-management support for people with non-specific low back pain: A qualitative survey among physiotherapists and exercise therapists. Musculoskelet Sci Pract. 2020 Dec; 50:102269. doi: 10.1016/j.msksp.2020.102269. This work was never presented at a conference

We previously reported that osteoblasts at the curve apex in adolescent idiopathic scoliosis (AIS) exhibit a differential phenotype, compared to non-curve osteoblasts(1). However, the Hueter-Volkmann principle on vertebral body growth in spinal deformities (2) suggests this could be secondary to altered biomechanics. This study examined whether non-curve osteoblasts subjected to mechanical strain resemble the transcriptomic phenotype of curve apex osteoblasts. Facet spinal tissue was collected perioperatively from three sites, (i) the concave and (ii) convex side at the curve apex and (iii) from outside the curve (non-curve) from six AIS female patients (age 13–18 years; NRES 19/WM/0083). Non-curve osteoblasts were subjected to strain using a 4-point bending device. Osteoblast phenotype was determined by RNA sequencing and bioinformatic pathway analysis. RNAseq revealed that curve apex osteoblasts exhibited a differential transcriptome, with 1014 and 1301 differentially expressed genes (DEGs; p<0.05, fold-change >1.5) between convex/non-curve and concave/non-curve sites respectively. Non-curve osteoblasts subjected to strain showed increased protein expression of the mechanoresponsive biomarkers COX2 and C-Fos. Comparing unstimulated vs strain-induced non-curve osteoblasts, 423 DEGs were identified (p<0.05, fold-change >1.5). Of these DEGs, only 5% and 6% were common to the DEGs found at either side of the curve apex, compared to non-curve cells. Bioinformatic analysis of these strain-induced DEGs revealed a different array of canonical signalling pathways and cellular processes, to those significantly affected in cells at the curve apex. Mechanical strain of AIS osteoblasts in vitro did not induce the differential transcriptomic phenotype of AIS osteoblasts at the curve apex

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

Aims

To determine the major risk factors for unplanned reoperations (UROs) following corrective surgery for adult spinal deformity (ASD) and their interactions, using machine learning-based prediction algorithms and game theory.

Aims

Symptomatic spinal stenosis is a very common problem, and decompression surgery has been shown to be superior to nonoperative treatment in selected patient groups. However, performing an instrumented fusion in addition to decompression may avoid revision and improve outcomes. The aim of the SpInOuT feasibility study was to establish whether a definitive randomized controlled trial (RCT) that accounted for the spectrum of pathology contributing to spinal stenosis, including pelvic incidence-lumbar lordosis (PI-LL) mismatch and mobile spondylolisthesis, could be conducted.

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To report the development of the technique for minimally invasive lumbar decompression using robotic-assisted navigation.

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To systematically evaluate whether bracing can effectively achieve curve regression in patients with adolescent idiopathic scoliosis (AIS), and to identify any predictors of curve regression after bracing.

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The aim of this study was to reassess the rate of neurological, psoas-related, and abdominal complications associated with L4-L5 lateral lumbar interbody fusion (LLIF) undertaken using a standardized preoperative assessment and surgical technique.

Purpose and Background. The intervertebral disc is constantly subjected to forces generated by movement. But degeneration can disrupt normal biomechanics, generating uneven and complex loading patterns. Evidence suggests that these forces are converted into voltages through different mechanisms, such as streaming potentials. This implicates voltage-gated ion channels in the biological remodelling response of the disc to loading. These signalling pathways have not been studied, and this incomplete understanding of disc mechanotransduction may hinder regenerative therapies. The purpose of this study is to identify and determine the role of voltage-gated ion channels in the intervertebral disc and to investigate any changes in degeneration. Methods and Results. Primary bovine and human disc cells were cultured in monolayer or alginate beads for experiments. Cells were treated with altered osmolarity alone or in combination with IL-1β. Ion flux was measured through calcium influx and will be further investigated using the xCelligence RTCA CardioECR. Immunohistochemistry was performed on human and bovine discs to evaluate expression levels of ion channels. RNA was extracted from bovine NP cells and will be analysed through PCR/Microarray for gene expression. Conclusions. Preliminary results show that the Ca. v. 2.2 channel is expressed across the human disc, and is altered by degree of degeneration. Treatment with IL-1β may partly hinder the increase in calcium signalling of disc cells in response to lower osmolarity conditions. The presence of voltage-gated ion channels in the disc has been demonstrated for the first time. The role of these channels will be investigated through measuring ion flux with channel inhibitors across different culture treatments. No conflicts of interest exist. This research was supported by funding from the Society for Back Pain Research through the Travel Award 2019 and from the Irish Research Council under the Government of Ireland Postgraduate Scholarship Programme (GOIPG/2018/2416)

Lumbar spondylolysis is a stress fracture of the pars interarticularis. We have evaluated the site of origin of the fracture clinically and biomechanically. Ten adolescents with incomplete stress fractures of the pars (four bilateral) were included in our study. There were seven boys and three girls aged between 11 and 17 years. The site of the fracture was confirmed by axial and sagittal reconstructed CT. The maximum principal tensile stresses and their locations in the L5 pars during lumbar movement were calculated using a three-dimensional finite-element model of the L3-S1 segment. In all ten patients the fracture line was seen only at the caudal-ventral aspect of the pars and did not spread completely to the craniodorsal aspect. According to the finite-element analysis, the higher stresses were found at the caudal-ventral aspect in all loading modes. In extension, the stress was twofold higher in the ventral than in the dorsal aspect. Our radiological and biomechanical results were in agreement with our clinical observations

Aims

The aim of this study was to assess the ability of morphological spinal parameters to predict the outcome of bracing in patients with adolescent idiopathic scoliosis (AIS) and to establish a novel supine correction index (SCI) for guiding bracing treatment.

To evaluate the current biomechanical and clinical evidence available on the use and effectiveness of lumbar interspinous devices. Literature review. A PubMed search was done using the following key words: interspinous implants, interspinous devices, interspinous spacers, dynamic stabilization, X-stop, Coflex, Wallis, DIAM. The abstracts of all the articles were reviewed. Further critical analysis was done of the relevant articles. Special emphasis was given to those articles pertaining to biomechanical and clinical results. A total of 50 articles were found, 18 of them also related to the effect of spacers on the biomechanics of the spine. 25 articles were on the X-stop device. However, level I evidence is lacking. Only two prospective randomized controlled trials have been done and these were on the X-Stop device. Analysis of current evidence suggests a potential beneficial effect of lumbar interspinous spacers in select group of patients. However, further level I evidence is required to justify their widespread use for all the proposed indications. The results of the ongoing trials are keenly awaited

Aims

Vertebral body tethering (VBT) is a non-fusion technique to correct scoliosis. It allows correction of scoliosis through growth modulation (GM) by tethering the convex side to allow concave unrestricted growth similar to the hemiepiphysiodesis concept. The other modality is anterior scoliosis correction (ASC) where the tether is able to perform most of the correction immediately where limited growth is expected.

Objectives. Cement augmentation of pedicle screws could be used to improve screw stability, especially in osteoporotic vertebrae. However, little is known concerning the influence of different screw types and amount of cement applied. Therefore, the aim of this biomechanical in vitro study was to evaluate the effect of cement augmentation on the screw pull-out force in osteoporotic vertebrae, comparing different pedicle screws (solid and fenestrated) and cement volumes (0 mL, 1 mL or 3 mL). Materials and Methods. A total of 54 osteoporotic human cadaver thoracic and lumbar vertebrae were instrumented with pedicle screws (uncemented, solid cemented or fenestrated cemented) and augmented with high-viscosity PMMA cement (0 mL, 1 mL or 3 mL). The insertion torque and bone mineral density were determined. Radiographs and CT scans were undertaken to evaluate cement distribution and cement leakage. Pull-out testing was performed with a material testing machine to measure failure load and stiffness. The paired t-test was used to compare the two screws within each vertebra. Results. Mean failure load was significantly greater for fenestrated cemented screws (+622 N; p ⩽ 0.001) and solid cemented screws (+460 N; p ⩽ 0.001) than for uncemented screws. There was no significant difference between the solid and fenestrated cemented screws (p = 0.5). In the lower thoracic vertebrae, 1 mL cement was enough to significantly increase failure load, while 3 mL led to further significant improvement in the upper thoracic, lower thoracic and lumbar regions. Conclusion. Conventional, solid pedicle screws augmented with high-viscosity cement provided comparable screw stability in pull-out testing to that of sophisticated and more expensive fenestrated screws. In terms of cement volume, we recommend the use of at least 1 mL in the thoracic and 3 mL in the lumbar spine. Cite this article: C. I. Leichtle, A. Lorenz, S. Rothstock, J. Happel, F. Walter, T. Shiozawa, U. G. Leichtle. Pull-out strength of cemented solid versus fenestrated pedicle screws in osteoporotic vertebrae. Bone Joint Res 2016;5:419–426