Aims. Gram-negative infections are associated with comorbid patients, but outcomes are less well understood. This study reviewed diagnosis, management, and treatment for a cohort treated in a tertiary spinal centre. Methods. A retrospective review was performed of all gram-negative spinal infections (n = 32; median age 71 years; interquartile range 60 to 78), excluding surgical site infections, at a single centre between 2015 to 2020 with two- to six-year follow-up. Information regarding organism identification, antibiotic regime, and treatment outcomes (including clinical, radiological, and biochemical) were collected from clinical notes. Results. All patients had comorbidities and/or non-spinal procedures within the previous year. Most infections affected lumbar segments (20/32), with Escherichia coli the commonest organism (17/32). Causative organisms were identified by blood culture (23/32), biopsy/aspiration (7/32), or intraoperative samples (2/32). There were 56 different antibiotic regimes, with oral (PO) ciprofloxacin being the most prevalent (13/56; 17.6%). Multilevel, contiguous infections were common (8/32; 25%), usually resulting in bone destruction and collapse. Epidural collections were seen in 13/32 (40.6%). In total, five patients required surgery, three for neurological deterioration. Overall, 24 patients improved or recovered with a mean halving of CRP at 8.5 days (SD 6). At the time of review (two to six years post-diagnosis), 16 patients (50%) were deceased. Conclusion. This is the largest published cohort of gram-negative spinal infections. In older patients with comorbidities and/or previous interventions in the last year, a high level of suspicion must be given to gram-negative infection with blood cultures and biopsy essential. Early organism identification permits targeted treatment and good initial clinical outcomes; however, mortality is 50% in this cohort at a mean of 4.2 years (2 to 6) after diagnosis. Cite this article: Bone Jt Open 2024;5(5):435–443

Aims. Lumbar spinal stenosis (LSS) is a common skeletal system disease that has been partly attributed to genetic variation. However, the correlation between genetic variation and pathological changes in LSS is insufficient, and it is difficult to provide a reference for the early diagnosis and treatment of the disease. Methods. We conducted a transcriptome-wide association study (TWAS) of spinal canal stenosis by integrating genome-wide association study summary statistics (including 661 cases and 178,065 controls) derived from Biobank Japan, and pre-computed gene expression weights of skeletal muscle and whole blood implemented in FUSION software. To verify the TWAS results, the candidate genes were furthered compared with messenger RNA (mRNA) expression profiles of LSS to screen for common genes. Finally, Metascape software was used to perform enrichment analysis of the candidate genes and common genes. Results. TWAS identified 295 genes with permutation p-values < 0.05 for skeletal muscle and 79 genes associated for the whole blood, such as RCHY1 (PTWAS = 0.001). Those genes were enriched in 112 gene ontology (GO) terms and five Kyoto Encyclopedia of Genes and Genomes pathways, such as ‘chemical carcinogenesis - reactive oxygen species’ (LogP value = −2.139). Further comparing the TWAS significant genes with the differentially expressed genes identified by mRNA expression profiles of LSS found 18 overlapped genes, such as interleukin 15 receptor subunit alpha (IL15RA) (PTWAS = 0.040, PmRNA = 0.010). Moreover, 71 common GO terms were detected for the enrichment results of TWAS and mRNA expression profiles, such as negative regulation of cell differentiation (LogP value = −2.811). Conclusion. This study revealed the genetic mechanism behind the pathological changes in LSS, and may provide novel insights for the early diagnosis and intervention of LSS. Cite this article: Bone Joint Res 2023;12(6):387–396

Aims. To investigate the correlations among cytokines and regulatory T cells (T-regs) in ankylosing spondylitis (AS) patients, and their changes after anti-tumour necrosis factor-α (TNF-α) treatment. Methods. We included 72 AS patients with detailed medical records, disease activity score (Bath Ankylosing Spondylitis Disease Activity Index), functional index (Bath Ankylosing Spondylitis Functional Index), and laboratory data (interleukin (IL)-2, IL-4, IL-10, TNF-α, interferon (IFN)-γ, transforming growth factor (TGF)-β, ESR, and CRP). Their peripheral blood mononuclear cells (PBMCs) were marked with anti-CD4, anti-CD25, and anti-FoxP3 antibodies, and triple positive T cells were gated by flow cytometry as T-regs. Their correlations were calculated and the changes after anti-TNF-α therapy were compared. Results. The frequency of T-regs in PBMCs was positively correlated to ESR and CRP in AS (r = 0.35 and 0.43; p = 0.032 and 0.027, respectively), and there was also a significant correlation between serum level of TNF-α and CRP (p = 0.041). The frequency of T-regs in PBMCs positively correlated to serum levels of TNF-α, IL-10, and TGF-β, while IL-2, IL-4, and IFN-γ showed opposite results. After anti-TNF-α treatment, there were significantly lower serum levels of TNF-α, IL-10, TGF-β, and frequency of T-regs in PBMCs among these AS patients (p = 0.026, 0.032, 0.029, and 0.037, respectively). Conclusion. In AS patients, proinflammatory cytokine may give positive feedback to induce more T-reg production and anti-inflammatory cytokine secretion to suppress this inflammatory status, and they can be reversed by anti-TNF-α therapy. However, the detailed interactions among T-regs and complex cytokine networks in autoinflammatory diseases still need more studies and further functional assay. Cite this article: Bone Joint Res 2023;12(2):133–137

Aims. Degenerative cervical spondylosis (DCS) is a common musculoskeletal disease that encompasses a wide range of progressive degenerative changes and affects all components of the cervical spine. DCS imposes very large social and economic burdens. However, its genetic basis remains elusive. Methods. Predicted whole-blood and skeletal muscle gene expression and genome-wide association study (GWAS) data from a DCS database were integrated, and functional summary-based imputation (FUSION) software was used on the integrated data. A transcriptome-wide association study (TWAS) was conducted using FUSION software to assess the association between predicted gene expression and DCS risk. The TWAS-identified genes were verified via comparison with differentially expressed genes (DEGs) in DCS RNA expression profiles in the Gene Expression Omnibus (GEO) (Accession Number: GSE153761). The Functional Mapping and Annotation (FUMA) tool for genome-wide association studies and Meta tools were used for gene functional enrichment and annotation analysis. Results. The TWAS detected 420 DCS genes with p < 0.05 in skeletal muscle, such as ribosomal protein S15A (RPS15A) (PTWAS = 0.001), and 110 genes in whole blood, such as selectin L (SELL) (PTWAS = 0.001). Comparison with the DCS RNA expression profile identified 12 common genes, including Apelin Receptor (APLNR) (PTWAS = 0.001, PDEG = 0.025). In total, 148 DCS-enriched Gene Ontology (GO) terms were identified, such as mast cell degranulation (GO:0043303); 15 DCS-enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were identified, such as the sphingolipid signalling pathway (ko04071). Nine terms, such as degradation of the extracellular matrix (R-HSA-1474228), were common to the TWAS enrichment results and the RNA expression profile. Conclusion. Our results identify putative susceptibility genes; these findings provide new ideas for exploration of the genetic mechanism of DCS development and new targets for preclinical intervention and clinical treatment. Cite this article: Bone Joint Res 2023;12(1):80–90

Surgery of the spine is associated with blood loss and frequently transfusion, with consequent risk of infection and reactions. It also costly, and puts a strain on national blood banks. A new blood salvage device works by ‘washing’ and centrifuging the blood lost during surgery; which can then be re-transfused into the patient. In a retrospective study 46 consecutive spinal surgeries with Cell Saver were compared with 39 matched surgeries without. Blood loss and units transfused was obtained from the transfusion database and the anaesthetic record. Average blood loss in the Cell saver group was 1382ml compared to 1405ml in the pre-Cell Saver group. Average allogenic transfusion was 1.30 units with cell saver compared to 2.78 units without. An average 2.3 units of lost blood were re-infused in the Cell Saver group. 26 (57%) of the Cell Saver group require no allogenic blood at all, whereas only 10 (26%) of patients in the pre-Cell Saver group had no transfusions. One unit of blood costs £130.52, and the Cell saver device costs £100 per patient. The average cost per patient in the Cell saver group was £270 (any transfusion plus cost of Cell Saver), compared to an average of £368.50 in the pre-Cell Saver group: a saving of £92.50. The Cell Saver decreased blood transfusions by 46% per patient and by 40% overall, a saving of £92.50 per patient. The number of patients receiving no allogenic blood increased by 31%

We studied 70 consecutive patients with adolescent idiopathic scoliosis who underwent corrective surgery. They were divided into two groups. In the study group of 38 patients one or more modern blood-conservation measures was used peri-operatively. The 32 patients in the control group did not have these measures. Both groups were similar in regard to age, body-weight, the number of levels fused and the type of surgery. Only two patients in the study group were transfused with homologous blood and these transfusions were ‘off-protocol’. Wastage of autologous pre-donated units was minimal (6 of 83 units). By contrast, all patients in the control group were transfused with homologous blood. In the study group there was a significant decrease (p = 0.005) in the estimated blood loss when all the blood-conservation methods were used. The use of blood-conservation measures, the lowering of the haemoglobin trigger for transfusion and the education of the entire team involved in the care of the patient can prevent the need for homologous blood transfusion in patients undergoing surgery for adolescent idiopathic scoliosis

Purpose. To evaluate efficacy of blood conservation strategies on transfusion requirements in adult scoliosis surgery and establish a protocol for cross matching. Methods and Results. Retrospective review of 50 consecutive adult scoliosis patients treated using anterior only(14,28%), posterior only(19,38%) or combined(17,34%) approaches. All patients were anaesthetised by the same anaesthetist implementing a standard protocol using cell salvage, controlled hypotension and antifibrinolytics. Mean age was 24.6 years. BMI was 21.9. On an average 9.5(6-15) levels were fused, with an average duration of surgery of 284.6(130-550) minutes. Antifibrinolytics were used in 31(62%) of the patients which included Aprotinin in 21(42%) and Tranexamic acid in 10(20%). Patients on antifibrinolytics had a significantly (p<0.05) lower blood loss (530ml) as compared to other patients (672ml). Mean volume of the cell saved blood re-transfused was 693.8 ml and mean postoperative HB level dropped to 10.7 g/dl(7.7-15) from a mean preoperative of 13.3 g/dl(10-17). 7(42%) with combined approaches and 3(15.8%) with posterior only approach required blood transfusion, 4/50(8%) of which required intra while 6/50(12%) required intra and postoperative transfusion. None of the patients having anterior surgery alone required blood transfusion. Conclusion. Use of antifibrinolytics reduces the need for blood transfusion in scoliosis surgery. For anterior surgery alone, we do not cross match

To compare the effect of intraoperative red cell salvage on blood transfusion and cost in patients undergoing idiopathic scoliosis surgery. Retrospective. 37 patients (36 females, 1 male) underwent scoliosis surgery from February 2007 to October 2008. Intraoperative red cell salvage (Group 1) was used. They were compared with 28 patients (23 females, 5 males) operated from January 2005 to December 2006 without the use of cell salvage (Group 2). 36 patients in group 1 had posterior surgery and 1 had anterior surgery. In Group 2, 20 patients had posterior surgery, 7 anterior and 1 patient had anterior and posterior surgery. Both groups were comparable for age, number of levels fused, preoperative haemoglobin and haematocrit values. Amount of perioperative blood transfusion, costs. 14 patients (50%) in group 2 had blood transfusion whereas only 6 (16%) were transfused blood in group 1. Average blood loss in group 1 was 1076 mls (range 315-3000) and 1626mls (419-4275) in group 2. An average of 2 units of packed red blood cells per patient was processed by the cell salvage system. Postoperative haemoglobin, haematocrit and hospital stay were comparable in both groups. Cost analysis shows the use of cell salvage is cost beneficial by £116.60 per case. The use of red blood cell salvage reduces the amount of blood transfusion and is cost beneficial

Retrospective review of blood loss during posterior instrumented fusion in Adult Deformity Surgery before and after the introduction of the ultrasonic bone cutter into routine surgical technique. We retrospectively reviewed a large series of adult patients undergoing four or more levels of posterior instrumented fusion (+/− osteotomies/decompressions) over an eight year period. The senior surgeon (SM) switched to using the ultrasonic bone cutter instead of conventional cutting techniques at a specific point in time. We reviewed the clinical records of cases performed both before and after this time point and were able to identify blood loss from the clinical records. We reviewed actual blood loss by evaluating several aspects, including suction volumes, swab weights, re-infusion volumes, pre- and post- operative haemoglobin values and the type and amount of haemostatic agents used. We demonstrated that a significant reduction in blood loss intra-operatively occurred with reduced use of haemostatic agents following introduction of the ultrasonic bone cutter as the method of bone removal. Significant reductions in blood loss were achieved with implications in terms of patient mortality and morbidity, improved surgical field and reduced amount and cost of haemostatic agents

To review blood transfusion practices during elective spinal surgery procedures. Prospective clinical audit. All patients who underwent elective spinal surgery between January 2009 and March 2009. Crossmatch: Transfusion ratio (C: T ratio); Transfusion index (TI) (Evaluates cost-effective crossmatch). British Haematological society standards are C:T ratio= 2.5:1 and TI>0.5. Data was collected from electronic records of blood bank, pathology system (NOTIS) and review of patient notes. A total of 194 patients underwent elective spinal surgery in our unit. (Cervical spine = 15, Thoracic spine = 3, Vertebroplasty = 10, Lumbar spine = 142, Deformity = 31, other = 8). Of these, 62 patients had 197 blood products crossmatched but only 37 units were used. C:T ratio in lumbar spine surgery was 22:1. However C: T ratio in cervical spine procedures, thoracic spine and deformity correction were 6:1, 11:0 and 4:1 respectively. TI was <0.5 in all procedures except deformity surgery (TI=1). Over- ordering of blood products is still common in spinal surgery as routine blood transfusion may not be required in most elective procedures. Therefore implementing Electronic Issue (EI) of blood products for elective spinal procedures for non deformity procedures can be a cost effective and safe practice

Purpose. Comparison between Aprotinin and Tranexamic acid on blood conservation in scoliosis surgery. Null hypothesis. There is no difference in the control of blood loss between 2 drugs. Methods and results. Medical records of 40 (20 received Aprotinin and 20 Received Tranexamic acid) patients that underwent posterior correction of scoliosis were evaluated for age, weight, aetiology, Cobb angle, levels instrumented, cell saver use, pre and post-operative HB levels. The results are as under. Conclusion. Both drugs appears to be equally effective in controlling the blood loss. The study is limited by small numbers and retrospective design, but available data does not prove superiority of one over the other drug

Background. Fissures in the anulus fibrosus are common in disc degeneration, and are associated with discogenic pain. We hypothesise that anulus fissures are conducive to the ingrowth of blood vessels and nerves. Purpose. To investigate the mechanical and chemical micro-environment of anulus fissures. Methods. Six thoracolumbar spine specimens, comprising three vertebrae and two discs, were obtained from cadavers aged 68-83 yr. Discs were injected with blue dye to reveal the location of complete anulus fissures. Each specimen was then subjected to 1000 N compression, while intradiscal compressive stress was investigated by pulling a miniature pressure transducer through the disc, in planes likely to cross the anulus fissures. Some additional disc fragments were removed at surgery from patients with discogenic back pain, and examined histologically to gauge the concentration of collagen and proteoglycans within radial fissures, using a qualitative method. Results. Stress profiles were obtained perpendicular to major anulus fissures in seven discs. A marked local reduction in vertically-acting compressive stress usually coincided with fissure location (confirmed at dissection), and stress reductions were inversely proportional to average pressure in the nucleus (r. 2. =0.56, p<0.05). Surgical disc samples showed local depletion of proteoglycans around the margins of radial and circumferential fissures, leaving a collagen-rich scaffold of the type known to support nerve and blood vessel growth. Conclusion. Compressive stresses within anulus fissures are reduced most when the disc nucleus is decompressed, because this facilitates internal displacements of disrupted tissue. Anulus fissures provide a micro-environment that is mechanically and chemically conducive to the ingrowth of blood vessels and nerves

The systemic arterial pressure has been used as a guide for determining the susceptibility to surgical bleeding during controlled hypotensive anaesthesia. Arterial hypotension is not, however, necessarily accompanied by venous or intraosseous hypotension. The main source of bleeding during posterior spinal surgery is the bone and is venous rather than arterial. The intraoperative blood loss, the intraosseous pressure (IOP) within the first thoracic vertebral body, and the systemic arterial pressure were measured in 27 patients during cervical laminoplasty for spondylotic myelopathy. The intraoperative blood loss correlated significantly with the vertebral IOP (p = 0.0073, r = 0.499), but not with systemic arterial pressure, age, or body-weight. The systemic arterial pressure did not correlate with the vertebral IOP. The mean value of the mean arterial pressure throughout the operation varied between 74 and 110 mmHg. The findings suggest that the vertebral IOP parallels surgical bleeding during posterior spinal surgery under normotensive anaesthesia and that patients with a low arterial pressure do not necessarily have a low IOP

Aims. A variety of surgical methods and strategies have been demonstrated for Andersson lesion (AL) therapy. In 2011, we proposed and identified the feasibility of stabilizing the spine without curettaging the vertebral or discovertebral lesion to cure non-kyphotic AL. Additionally, due to the excellent reunion ability of ankylosing spondylitis, we further came up with minimally invasive spinal surgery (MIS) to avoid the need for both bone graft and lesion curettage in AL surgery. However, there is a paucity of research into the comparison between open spinal fusion (OSF) and early MIS in the treatment of AL. The purpose of this study was to investigate and compare the clinical outcomes and radiological evaluation of our early MIS approach and OSF for AL. Methods. A total of 39 patients diagnosed with AL who underwent surgery from January 2004 to December 2022 were retrospectively screened for eligibility. Patients with AL were divided into an MIS group and an OSF group. The primary outcomes were union of the lesion on radiograph and CT, as well as the visual analogue scale (VAS) and Oswestry Disability Index (ODI) scores immediately after surgery, and at the follow-up (mean 29 months (standard error (SE) 9)). The secondary outcomes were total blood loss during surgery, operating time, and improvement in the radiological parameters: global and local kyphosis, sagittal vertical axis, sagittal alignment, and chin-brow vertical angle immediately after surgery and at the follow-up. Results. Data for 30 patients with AL were evaluated: 14 in the MIS group and 16 in the OSF group. All patients were followed up after surgery; no nonunion complications or instrumentation failures were observed in either group. No significant differences in the VAS and ODI scores were identified between the two groups. Mean ODI improved from 51 (SE 5) to 17 (SE 5) in the MIS group and from 52 (SE 6) to 19 (SE 5) in the OSF group at the follow-up. There were significant improvements in total blood loss (p = 0.025) and operating time (p < 0.001) between the groups. There was also no significant difference in local kyphosis six months postoperatively (p = 0.119). Conclusion. Early MIS is an effective treatment for AL. MIS provides comparable clinical outcomes to those treated with OSF, with less total blood loss and shorter operating time. Our results support and identify the feasibility of solid immobilization achieved by posterior instrumentation without bone graft via MIS for the treatment of AL. Cite this article: Bone Jt Open 2024;5(10):886–893

Aims. Closed suction subfascial drainage is widely used after instrumented posterior spinal fusion in patients with a spinal deformity. The aim of this study was to determine the effect of this wound drainage on the outcomes in patients with adolescent idiopathic scoliosis (AIS). This was a further analysis of a randomized, multicentre clinical trial reporting on patients after posterior spinal fusion using segmental pedicle screw instrumentation. In this study the incidence of deep surgical site infection (SSI) and chronic postoperative pain at two years’ follow-up are reported. Methods. We conducted a randomized, multicentre clinical trial on adolescents undergoing posterior spinal fusion for AIS using segmental pedicle screw instrumentation. A total of 90 consecutive patients were randomized into a ‘drain’ or ‘no drain’ group at the time of wound closure, using the sealed envelope technique (1:1). The primary outcomes in the initial study were the change in the level of haemoglobin in the blood postoperatively and total blood loss. A secondary outcome was the opioid consumption immediately after surgery. The aim of this further study was to report the rate of deep SSI and persistent postoperative pain, at two years' follow-up. Results. As previously reported, the mean 48-hour opioid consumption was significantly higher in the no drain group (2.0 mg/kg (SD 0.8) vs 1.4 mg/kg (SD 0.7); p = 0.005). There were no delayed deep SSIs. At two years’ follow-up, the mean Scoliosis Research Society 24-item questionnaire (SRS-24) total score did not differ between the groups (4.11 (SD 0.47) vs 4.16 (SD 0.33); p = 0.910). The mean SRS-24 pain score was 4.28 (SD 0.48) in the no drain group compared with 4.33 (SD 0.66) in the drain group (p = 0.245). Seven patients (19%) in the no drain group and six in the drain group (14%) reported moderate to severe pain (numerical rating scale ≥ 4) at two years’ follow-up (p = 0.484). The general self-image domain score was significantly higher in the no drain group compared with the drain group (4.02 (SD 0.74) vs 4.59 (SD 0.54); p < 0.001). Conclusion. The main finding in this study was that more severe pain immediately after surgery did not result in a higher incidence of chronic pain in the no drain group compared with the drain group. Back pain and health-related quality of life at two years’ follow-up did not differ between the groups. The patient-reported self-image domain was significantly better in the no drain group compared with the drain group. Cite this article: Bone Joint J 2024;106-B(10):1176–1181

Aims. Surgical approaches to cervical ossification of the posterior longitudinal ligament (OPLL) remain controversial. The purpose of the present study was to analyze and compare the long-term neurological recovery following anterior decompression with fusion (ADF) and posterior laminectomy and fusion with bone graft and internal fixation (PLF) based on > ten-year follow-up outcomes in a single centre. Methods. Included in this retrospective cohort study were 48 patients (12 females; mean age 55.79 years (SD 8.94)) who were diagnosed with cervical OPLL, received treatment in our centre, and were followed up for 10.22 to 15.25 years. Of them, 24 patients (six females; mean age 52.88 years (SD 8.79)) received ADF, and the other 24 patients (five females; mean age 56.25 years (SD 9.44)) received PLF. Clinical data including age, sex, and the OPLL canal-occupying ratio were analyzed and compared. The primary outcome was Japanese Orthopaedic Association (JOA) score, and the secondary outcome was visual analogue scale neck pain. Results. Compared with the baseline, neurological function improved significantly after surgery in all patients of both groups (p < 0.001). The JOA recovery rate in the ADF group was significantly higher than that in the PLF group (p < 0.001). There was no significant difference in postoperative cervical pain between the two groups (p = 0.387). The operating time was longer and intraoperative blood loss was greater in the PLF group than the ADF group. More complications were observed in the ADF group than in the PLF group, although the difference was not statistically significant. Conclusion. Long-term neurological function improved significantly after surgery in both groups, with the improvement more pronounced in the ADF group. There was no significant difference in postoperative neck pain between the two groups. The operating time was shorter and intraoperative blood loss was lower in the ADF group; however, the incidence of perioperative complications was higher. Cite this article: Bone Jt Open 2024;5(9):768–775

Aims. The aim of this study was to evaluate whether, after correction of an adolescent idiopathic scoliosis (AIS), leaving out the subfascial drain gives results that are no worse than using a drain in terms of total blood loss, drop in haemoglobin level, and opioid consumption. Methods. Adolescents (aged between 10 and 21 years) with an idiopathic scoliosis (major curve ≥ 45°) were eligible for inclusion in this randomized controlled noninferiority trial (n = 125). A total of 90 adolescents who had undergone segmental pedicle screw instrumentation were randomized into no-drain or drain groups at the time of wound closure using the sealed envelope technique (1:1). The primary outcome was a drop in the haemoglobin level during first three postoperative days. Secondary outcomes were 48-hour postoperative oxycodone consumption and surgical complications. Results. All 90 patients were included in the primary outcome analysis (no drain = 43; drain = 47). The mean total postoperative blood loss (intraoperative and drain output) was significantly higher in the group with a subfascial drain than in the no-drain group (1,008 ml (SD 520) vs 631 ml (SD 518); p < 0.001). The drop in haemoglobin level did not differ between the study groups over the postoperative timepoints (p = 0.290). The 48-hour opioid consumption was significantly higher in the no-drain group (2.0 mg/kg (SD 0.9) vs 1.4 (SD 0.6); p = 0.005). Two patients in the no-drain and one patient in the drain group developed a surgical site infection. Conclusion. Leaving the subfascial drain out after pedicle screw instrumentation for AIS is not associated with higher postoperative haemoglobin levels. Patients treated without a subfascial drain needed 30% more opioids during the first 48 hours than those who had a drain. Cite this article: Bone Joint J 2022;104-B(9):1067–1072

Aims. Historically, patients undergoing surgery for adolescent idiopathic scoliosis (AIS) have been nursed postoperatively in a critical care (CC) setting because of the challenges posed by prone positioning, extensive exposures, prolonged operating times, significant blood loss, major intraoperative fluid shifts, cardiopulmonary complications, and difficulty in postoperative pain management. The primary aim of this paper was to determine whether a scoring system, which uses Cobb angle, forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and number of levels to be fused, is a valid method of predicting the need for postoperative critical care in AIS patients who are to undergo scoliosis correction with posterior spinal fusion (PSF). Methods. We retrospectively reviewed all AIS patients who had undergone PSF between January 2018 and January 2020 in a specialist tertiary spinal referral centre. All patients were assessed preoperatively in an anaesthetic clinic. Postoperative care was defined as ward-based (WB) or critical care (CC), based on the preoperative FEV1, FVC, major curve Cobb angle, and the planned number of instrumented levels. Results. Overall, 105 patients were enrolled. Their mean age was 15.5 years (11 to 25) with a mean weight of 55 kg (35 to 103). The mean Cobb angle was 68° (38° to 122°). Of these, 38 patients were preoperatively scored to receive postoperative CC. However, only 19% of the cohort (20/105) actually needed CC-level support. Based on these figures, and an average paediatric intensive care unit stay of one day before stepdown to ward-based care, the potential cost-saving on the first postoperative night for this cohort was over £20,000. There was no statistically significant difference between the Total Pathway Score (TPS), the numerical representation of the four factors being assessed, and the actual level of care received (p = 0.052) or the American Society of Anesthesiologists grade (p = 0.187). Binary logistic regression analysis of the TPS variables showed that the preoperative Cobb angle was the only variable which significantly predicted the need for critical care. Conclusion. Most patients undergoing posterior fusion surgery for AIS do not need critical care. Of the readily available preoperative measures, the Cobb angle is the only predictor of the need for higher levels of care, and has a threshold value of 74.5°. Cite this article: Bone Joint J 2024;106-B(7):713–719

Purpose of study and background. Psychological factors are considered to play a role in development and maintenance of chronic low back pain (CLBP). Stress or anxiety can change pain sensitivity; however, this has predominantly been studied in healthy individuals with limited work in individuals with musculoskeletal pain. The objective of this study was to quantify the effect of acute exposure to a psychosocial stressor on mechanical pain sensitivity in individuals with and without CLBP. Summary of methods and results. Six individuals with CLBP and 10 individuals without CLBP performed a 10-minute computer task under conditions of low and high psychosocial stress. Psychosocial stress was manipulated using mental maths and memory tasks combined with social evaluative threat. The effect of the stressor was evaluated using blood pressure, heart rate and the state anxiety component of the Spielberger State-Trait Anxiety Index. Mechanical pressure pain threshold (PPT) was recorded on the tibialis anterior muscle using a handheld digital pressure algometer. The stress manipulation increased self-reported anxiety (p<0.001), but not blood pressure or heart rate (p>0.06). Change in PPT from low to high stress was greater in the CLBP group (median ΔPPT = −0.5 kg/cm. 2. ) than in the control group (−0.15 kg/cm. 2. ; p=0.005). Conclusion. Individuals experienced an increase in pain sensitivity after acute exposure to a stressor designed to mimic low-level workplace stressors, and this increase was greater in individuals with CLBP than asymptomatic individuals. These results indicate that this experimental model can be used to study links between pain sensitivity and psychosocial stressors and increase our understanding of their potential role in CLBP. Conflicts of Interest: No conflicts of interest. Sources of funding: No funding obtained

Aims. Frailty has been gathering attention as a factor to predict surgical outcomes. However, the association of frailty with postoperative complications remains controversial in spinal metastases surgery. We therefore designed a prospective study to elucidate risk factors for postoperative complications with a focus on frailty. Methods. We prospectively analyzed 241 patients with spinal metastasis who underwent palliative surgery from June 2015 to December 2021. Postoperative complications were assessed by the Clavien-Dindo classification; scores of ≥ Grade II were defined as complications. Data were collected regarding demographics (age, sex, BMI, and primary cancer) and preoperative clinical factors (new Katagiri score, Frankel grade, performance status, radiotherapy, chemotherapy, spinal instability neoplastic score, modified Frailty Index-11 (mFI), diabetes, and serum albumin levels). Univariate and multivariate analyses were developed to identify risk factors for postoperative complications (p < 0.05). Results. Overall, 57 postoperative complications occurred in 47 of 241 (19.5%) patients. The most common complications were wound infection/dehiscence, urinary tract infection, and pneumonia. Univariate analysis identified preoperative radiotherapy (p = 0.028), mFI (p < 0.001), blood loss ≥ 500 ml (p = 0.016), and preoperative molecular targeted drugs (p = 0.030) as potential risk factors. From the receiver operating characteristic curve, the clinically optimal cut-off value of mFI was 0.27 (sensitivity, 46.8%; specificity, 79.9%). Multivariate analysis identified mFI ≥ 0.27 (odds ratio (OR) 2.94 (95% CI 1.44 to 5.98); p = 0.003) and preoperative radiotherapy (OR 2.11 (95% CI 1.00 to 4.46); p = 0.049) as significant risk factors. In particular, urinary tract infection (p = 0.012) and pneumonia (p = 0.037) were associated with mFI ≥ 0.27. Furthermore, the severity of postoperative complications was positively correlated with mFI (p < 0.001). Conclusion. The mFI is a useful tool to predict the incidence and the severity of postoperative complications in spinal metastases surgery. Cite this article: Bone Joint J 2024;106-B(12):1469–1476