Aims. To develop and internally validate a preoperative clinical prediction model for acute adjacent vertebral fracture (AVF) after vertebral augmentation to support preoperative decision-making, named the after vertebral augmentation (AVA) score. Methods. In this prognostic study, a multicentre, retrospective single-level vertebral augmentation cohort of 377 patients from six Japanese hospitals was used to derive an AVF prediction model. Backward stepwise selection (p < 0.05) was used to select preoperative clinical and imaging predictors for acute AVF after vertebral augmentation for up to one month, from 14 predictors. We assigned a score to each selected variable based on the regression coefficient and developed the AVA scoring system. We evaluated sensitivity and specificity for each cut-off, area under the curve (AUC), and calibration as diagnostic performance. Internal validation was conducted using bootstrapping to correct the optimism. Results. Of the 377 patients used for model derivation, 58 (15%) had an acute AVF postoperatively. The following preoperative measures on multivariable analysis were summarized in the five-point AVA score: intravertebral instability (≥ 5 mm), focal kyphosis (≥ 10°), duration of symptoms (≥ 30 days), intravertebral cleft, and previous history of vertebral fracture. Internal validation showed a mean optimism of 0.019 with a corrected AUC of 0.77. A cut-off of ≤ one point was chosen to classify a low risk of AVF, for which only four of 137 patients (3%) had AVF with 92.5% sensitivity and 45.6% specificity. A cut-off of ≥ four points was chosen to classify a high risk of AVF, for which 22 of 38 (58%) had AVF with 41.5% sensitivity and 94.5% specificity. Conclusion. In this study, the AVA score was found to be a simple preoperative method for the identification of patients at low and high risk of postoperative acute AVF. This model could be applied to individual patients and could aid in the decision-making before vertebral augmentation. Cite this article: Bone Joint J 2022;104-B(1):97–102

Introduction. The aim of this study was to assess patients and healthcare professionals (HCPs) opinions on the validity of using a biopsychosocial model rather than a biomedical model in alleviating patient symptoms/pain. Method. We constructed a questionnaire to assess beliefs on the effectiveness of using a biopsychosocial or biomedical model to develop a treatment plan to optimise patient symptoms/pain. We distributed the questionnaire to new and follow-up patients and healthcare professional in the orthopaedic department. Results. 246 questionnaires were completed - 183 patients and 63 HCPs. The patient group consisted of 77 males and 106 females, the HCP group of 27 males and 36 females. 77(42%) of patients and 9(14%) of HCPs agree the biomedical model is best suited to treat symptoms. 81(44%) of patients and 62(98%) of HCPs agree the biopsychosocial model is best suited to treat symptoms. 70(38%) of patients and 61 (97%) of HCPs agree stress can increase pain. 87(48%) of patients and 62(98%) of HCPs agree distress can increase pain. 83(45%) of patients and 56(89%) of HCPs agree stress can increase disability. 81(44%) of patients and 56(89%) of HCPs agree distress can increase disability. 39(21%) of patients and 43(68%) of HCPs agree if all investigations show no abnormality in explaining symptoms, the main contributor is stress, distress or psychological/socioeconomic factor. Conclusion. HCPs recognise the biopsychosocial model as a useful tool in managing patients pain/symptoms which not recognised by patients. HCPs believe that stress, distress, psychological/socioeconomic factors have a significant impact on a patients pain and disability when compared to patients. No conflicts of interest. No funding obtained

Purpose of study and background. Low back pain affects 80% of the population at some point in their lives with 40% of cases attributed to intervertebral disc (IVD) degeneration. A number of potential regenerative approaches are under investigation worldwide, however their translation to clinic is currently hampered by an appropriate model for testing prior to clinical trials. Therefore, a more representative large animal model for IVD degeneration is needed to mimic human degeneration. Here we investigate a caprine IVD degeneration model in a loaded disc culture system which can mimic the native loading environment of the disc. Methods and Results. Goat discs were excised and cultured in a bioreactor under diurnal, simulated-physiological loading (SPL) conditions, following 3 days pre load, IVDs were degenerated enzymatically for 2hrs and subsequently loaded for 10 days under physiological loading. A PBS injected group was used as controls. Disc deformation was continuously monitored and changes in disc height recovery quantified using stretched-exponential fitting. Histological staining was performed on caprine discs to assess extracellular matrix production and immunohistochemistry performed to determine expression of catabolic protein expression. The injection of collagenase and cABC induced mechanical behavior akin to that seen in human degeneration. A decrease in collagens and glycosaminoglycans (GAGs) was seen in enzyme injected discs, which was accompanied by increased cellular expression for degradative enzymes and catabolic cytokines. Conclusion. This model provides a reproducible model of IVD degeneration which mimics human degeneration. This model allows the testing of biomaterials and other potential treatments of IVD degeneration on a scale more representative of the human disc. There are no conflicts of interest. Funded by MRC and Versus Arthritis

Purposes and Background. Musculoskeletal disorders are leading causes of work disability. Our purpose was to develop a predictive model in a cohort from 2012 and validate the model in 2016 data. Methods and Results. Prospectively collected data was used to identify inception cohorts in 2012 (n=1652) and 2016 (n=199). Data from back pain claimants receiving treatment in physiotherapy clinics and the Ontario workers' compensation database were linked. Patients were followed for 1 year. Variables from a back pain questionnaire and clinical, demographic and administrative factors were assessed for predictive value. The outcome was cumulative number of calendar days receiving wage-replacement benefits. Cox regression revealed 8 significant predictors of shorter time on benefits in the 2012 cohort: early intervention (HR=1.51), symptom duration < 31 days (HR=0.88), not in construction industry (HR=1.89), high Low Back Outcome Score (HR=1.03), younger age (HR=0.99), higher benefit rate (HR=1.00), intermittent pain (HR=1.15), no sleep disturbance (HR=1.15). The 2012 model c-statistic was 0.73 with a calibration slope of 0.90 (SE=0.19, p=0.61) in the 2016 data, meaning not significantly different. The c-statistic in the 2016 data was 0.69. Median duration on benefits of those with a high risk score was 129 days in 2012 and 45 days in 2016. Conclusion. The 2012 model had a good fit and calibrated well in the 2016 data. Changes in case management by the WSIB might have resulted in significant differences between the 2012 and 2106 cohort. The difference in duration on benefits could affect treatment decision making in future. Conflicts of interest: IWH is funded by the Ministry of Labour in Ontario. Sources of funding: Funding was provided by the Canadian Institute for Health Research

Introduction. Low back pain (LBP) is the top leading global cause of years lived with disability. In order to examine LBP, researchers have typically viewed the spine in isolation. Clinically, it is imperative that the lower limbs are also considered. The aim of this study was to design a holistic and reliable multi-segmental kinematic model of the spine and lower limbs. Method. The spine was modelled according to easily identifiable anatomical landmarks, including upper thoracic (T1-T6), lower thoracic (T7-T12) and lumbar (L1-L5) segments. Pelvis, thigh, shank and foot segments were included. A 10-camera 3D motion capture system was used to track retro-reflective markers, which were used to define each segment of 10 healthy participants as they walked 3 times at a comfortable speed over a 6km walkway. The relative peak angles between each segment were calculated using the Joint Coordinate System convention and Intraclass Correlation Coefficients (ICCs) were used to determine intra-rater and inter-rater reliability (between an experienced clinician and biomechanical scientist). Results. Intra-rater and inter-rater ICCs were good to excellent (0.6–0.99). This implies that the system could be used reliably by one tester or by testers with limited anatomical expertise. Subjective participant reports implied that the system was acceptable and suitable for patient use (average application time of 10 minutes). Conclusion. The ‘Imperial Spinal Model’ is a holistic and reliable multi-segmental model. It is suitable for the kinematic assessment of the spine and could be used to enhance our understanding of a variety of spinal conditions. No conflicts of interest. Funding: Janet Deane is funded by an Allied Health Professional Doctoral Fellowship awarded by Arthritis Research U.K. (ARUK). Enrica Papi is funded by the National Centre of Excellence for Musculoskeletal Health and Work funded by ARUK and the Medical Research Council

Background. Low back pain (LBP) with or without leg pain, is one of the most common causes of pain and disability and a frequent cause of attendance to emergency departments (ED). Increasing numbers of patients create a difficult challenge for clinicians to effectively and appropriately manage patients with LBP in an urgent care setting. Purpose. To improve the management of atraumatic spinal pain patients admitted onto the emergency assessment unit (EAU) thus improving quality of care, reducing bed stay and facilitating appropriate discharge and follow-up within an interdisciplinary model. Method. From January 2014, consultant physiotherapists, led a 7-day service to assess and manage patients admitted to the EAU with atraumatic back pain. Patients are referred for appropriately and timely investigations. Non-medical prescribing skills allow physiotherapists to offer pharmacological review and prescribing in line with best practice guidelines. All care is delivered within a framework of inter-professional care with involvement of emergency medicine, spinal orthopaedic, neurosurgical, pain management and pharmacy teams. Results. Length of stay has reduced by 25% in two years (potential saving £411,726 per annum). Official patient complaints have reduced to zero. Readmission within 30 days has fallen from 1.2% of the total number of admissions with atraumatic back pain to 0.8% despite earlier discharge. Cost of bed stay has fallen from. Conclusion. Highly skilled physiotherapists are ideally placed to lead and deliver safe and effective care for patients presenting with atraumatic back pain within an urgent care setting. This has resulted in improved care at lower cost. No conflicts of interest. No funding obtained

Background:. Identification of nerve root involvement (NRI) in patients with low back-related leg pain (LBLP) can be challenging. Diagnostic models have mainly been developed in secondary care with conflicting reference standards and predictor selection. This study aims to ascertain which cluster of items from clinical assessment best identify NRI in primary care consulters with LBLP. Methods:. Cross-sectional data on 395 LBLP consulters were analysed. Potential NRI indicators were seven clinical assessment items. Two definitions of NRI formed the reference standards: (i) high confidence (≥80%) NRI clinical diagnosis (ii) high confidence (≥80%) NRI clinical diagnosis with confirmatory magnetic resonance imaging (MRI) findings. Multivariable logistic regression models were constructed and compared for both reference standards. Model performances were summarised using the Hosmer-Lemeshow statistic and area under the curve (AUC). Bootstrapping assessed internal validity. Results:. NRI clinical diagnosis model retained five items. The model with MRI in the reference standard retained six items. Four items remained in both models: below knee pain, leg pain worse than back pain, positive neural tension tests, neurological deficit (myotome, reflex or sensory). NRI clinical diagnosis model was well calibrated (p=0.17) and discrimination was AUC 0.96 (95%CI: 0.93, 0.98). Performance measures for clinical diagnosis plus confirmatory MRI model showed good discrimination (AUC 0.83, 95% CI: 0.78, 0.86) but poor calibration (p=0.01). Bootstrapping revealed minimal overfitting in both models. Conclusion:. A cluster of items identified NRI in LBLP consulters. These criteria could be used clinically and in research to improve accuracy of identification and homogeneity of this subgroup of low back pain patients

Costoplasty remains useful in the treatment of adolescent idiopathic scoliosis, rib hump and associated chest wall deformities. However traditional costoplasty increases morbidity and blood loss. We examine the feasibility and possible effectiveness of a more conservative costoplasty using an animal model. 4 fresh half Ovine rib cages from separate animals were obtained, stored at +4 °C and warmed to room temperature before testing. Each rib cage was randomly assigned to group 1, 2, 3 or 4. Ribs 2–10 were dissected out for testing. The ribs then underwent stepwise deconstruction according to their group. Beginning at the convexity, removing first the convex cortex, then the cancellous, then the cranial and caudal cortices to leave just the concave cortex. Testing for stiffness was by three-point bending on the concave side of each rib with the rib fixed at the head of the rib and 5 cm from the resected area. The ribs were deformed at a constant rate of 0.5 mm.sec . −. 1 up to a maximum load of 9.99 kg or until fracturing. Then stress was plotted against strain to find the Young's modulus of each group and statistics carried out with an ANOVA test. The ribs in each group were as follows: Group 1= control, group 2= 30 mm long convex side cortical bone removed 10 mm from lateral tubercle, group 3= convex, cortical and cancellous bone removal and group 4= removal of convex, caudal and cranial cortices with cancellous removal. The Young's Modulus of the groups were: 1= 3.38 N-m (+/− 0.84), 2= 2.65 N-m (+/− 1.58), 3= 1.55 N-m (+/− 0.55) and 4= 0.74 N-m (+/− 0.55). Groups 3 and 4 were significantly less stiff than group 1 (p< 0.01.) No ribs in groups 1, 2 and 4 fractured under the maximum load. 5/8 ribs in group 3 fractured before the maximum load was administered. By deconstructing the rib down to only the concave side it becomes significantly more flexible by approximately 4.5 times than the control Ribs. Coupled with its increase in flexibility it still retains its ability to withstand up to 10 kg of load without fracture. It may be possible to perform a costoplasty whilst preserving ventilatory integrity. This may improve rib hump correction, and curve correction due to increased flexibility of the stiff thoracic cage

To assess the effectiveness of unilateral sublaminar and concave rib tethering with convex rib resection through the period of peak growth in lambs. Morphometric growth data from 10 experimental Scottish Blackface sheep were compared to those from 5 control animals (no intervention) over 12 months. Standardized AP and Lateral radiographs were taken before and at monthly intervals after scoliosis creation. The Cobb angle was measured in the coronal and sagittal planes. Rotational mal-alignment was assessed by axial CT 7 months post surgery. In the supine position the control animals had no coronal plane deformity and a mean 5° lordosis (T4-T12). These figures did not alter with growth (doubling of body weight). Tethering (at age 5 weeks) produced an immediate scoliosis of 22±11° and a lordosis of 24±8° (means(sd). The degree of scoliosis was maintained over 7 months (at 20°) but lordosis increased (to 59±11°, p<0.01). There was an associated change in vertebral rotation. Surgery had no influence on rate of growth or animal development. Two animals died from Clostridium associated enterocolitis. There were no deaths associated with the surgical intervention. This ovine model gives a progressive spinal deformity in the sheep but primarily in the sagittal plane. This fact should be considered in studies designed to evaluate the effectiveness of surgical implants

We evaluated the efficacy of Escherichia coli-derived recombinant human bone morphogenetic protein-2 (E-BMP-2) in a mini-pig model of spinal anterior interbody fusion. A total of 14 male mini-pigs underwent three-level anterior lumbar interbody fusion using polyether etherketone (PEEK) cages containing porous hydroxyapatite (HA). Four groups of cages were prepared: 1) control (n = 10 segments); 2) 50 μg E-BMP-2 (n = 9); 3) 200 μg E-BMP-2 (n = 10); and 4) 800 μg E-BMP-2 (n = 9). At eight weeks after surgery the mini-pigs were killed and the specimens were evaluated by gross inspection and manual palpation, radiological evaluation including plain radiographs and micro-CT scans, and histological analysis. Rates of fusion within PEEK cages and overall union rates were calculated, and bone formation outside vertebrae was evaluated. One animal died post-operatively and was excluded, and one section was lost and also excluded, leaving 38 sites for assessment. This rate of fusion within cages was 30.0% (three of ten) in the control group, 44.4% (four of nine) in the 50 μg E-BMP-2 group, 60.0% (six of ten) in the 200 μg E-BMP-2 group, and 77.8% (seven of nine) in the 800 μg E-BMP-2 group. Fusion rate was significantly increased by the addition of E-BMP-2 and with increasing E-BMP-2 dose (p = 0.046). In a mini-pig spinal anterior interbody fusion model using porous HA as a carrier, the implantation of E-BMP-2-loaded PEEK cages improved the fusion rate compared with PEEK cages alone, an effect that was significantly increased with increasing E-BMP-2 dosage. Cite this article: Bone Joint J 2013;95-B:217–23

Scoliosis school screening is either mandatory or recommended in 32 states in the USA. The remaining states having either got voluntary screening or no recommendations. The four primary care providers for adolescents with idiopathic scoliosis in the USA do not support any recommendation against scoliosis screening, given the available literature. In Australia a national self detection program is implemented but in the UK school screening has been abolished since the 1980's. Opponents to scoliosis screening have focused on concerns about a low predictive value of screening, the cost effectiveness of referral, the possibility of unnecessary brace treatment and the effect of exposure to radiation when radiographs are obtained. The purpose of this review was to evaluate the evidence for and against scoliosis screening. The following databases were searched: Cochrane Library, ARIF, TRIP, MEDLINE, EMBASE and CINAHL. Reference lists of articles were searched for relevant systematic reviews and research articles. One systematic review (2008). 1. suggests that there is evidence (level 1B) that intensive scoliosis specific exercise methods can reduce the progression of mild scoliosis (<30 degrees Cobb). Further a Cochrane review (2010) suggests that there is low quality evidence for the effectiveness of bracing. Based on the evidence of this review, a 4 tier model for school screening is proposed that addresses the “opponents” concerns. The model includes the distribution of information leaflets, screening by a school nurse, topographical assessment, referral to the primary care doctor and finally if the patient is still screening positive, referral to a scoliosis surgeon. Exercises reduce the progression rate of adolescent idiopathic scoliosis:

Introduction. Forelimb and tail amputations of 3-week-old C57BL/6 mice are known to yield spinal curves similar to adolescent idiopathic scoliosis (AIS). Our previous work showed that tamoxifen produces a significant decrease in severity of these curves. Vertebral osteoporosis was thought to be related to AIS. Interestingly, a histological pilot study has shown that scoliotic mice given tamoxifen were less osteoporotic than were controls. Raloxifene is an oestrogen receptor modulator (SERM) similar to tamoxifen with a more specific effect on bone and is commonly used to treat osteoporosis. We aimed to study and compare the effects of tamoxifen and raloxifene on the rate and magnitude of scoliosis on a C57BL/6 mice model. Methods. 90 female 3-week-old C57BL/6 mice underwent amputations of forelimbs and tails. 78 were available for analysis and were grouped as control (no medications; n=24), TMX group (10 mg tamoxifen/L drinking water; n=30), and RLX group (10 mg raloxifene/L drinking water; n=241). Seven mice from each group (including scoliotic ones) were killed for histological study at week 20 after posteroanterior (PA) scoliosis radiograph examinations. The rest were killed at the end of week 40 after PA radiographs were obtained. Radiographs were assessed for presence and magnitude of spinal curves. Results. Week 20 analysis showed that lower thoracic curve rate (LTr) was higher in RLX group (p=0·029) and thoracolomber rate (TLr) was higher in TMX group (p=0·33) than in the control group. TMX group had higher upper thoracic (UT) curve magnitudes than did the control group (p=0·021). Week analysis showed similar curve rates in all groups. The RLX group had significantly decreased upper (p<0·0001) and lower (p=0·014) thoracic curve magnitudes compared with the control group. The TMX group had significantly lower UT curve magnitudes than did the control group (p=0·014). Conclusions. Raloxifene is shown to be as effective as tamoxifen in decreasing the magnitude of spinal deformities in C57BL/6 mice model. These results suggest that SERMs might be useful to prevent progression of scoliotic curves. Models of higher animals may be warranted

Introduction. Orthopaedic Spinal Rapid Access Service (OSRAS) was developed in our institute to provide a structured pathway for management of urgent spinal pathologies during working hours of Monday to Friday. It was delivered through a published rota by a multi displinary team of Extended Scope Practitioner carrying a bleep and a Spinal Surgeon. Aim. To evaluate the efficacy of OSRAS through a prospective audit. Results. From Nov 2013 till April 2014, 177 patients (48 Male: 119 Females) with an average age of 50 (17–95) years were referred to OSRAS. Wednesday was the busiest day with 26% referral in AM and 74% in PM. Main source of referrals were: Regional MSK services (50), Triage (34), ED (27) and GPs (20). The reasons were: suspected CESI (n=100), Acute LBP (n=30), pathological fractures (n=23), progressive neurology (n=16), discitis (n=5) and spinal stenosis (n=2). Depending on clinical need 29 patients were seen on same day, 33 next day, 53 with in 2–5 days and 31 more than 5 days. Eighty patients were discharged, 36 listed for surgery, 27 required further follow up and 31 were given telephone advise only. High user satisfaction rating was obtained. Conclusion. We propose an OSRAS model as an alternate to often un satisfactory current emergency department model, that can provide a structured pathway for timely expert management of serious spinal pathologies therefore prevent potential consequences whilst avoid unnecessary admissions. Conflicts of interest: No conflicts of interest. Sources of funding: No funding obtained

Introduction. Calmodulin probably has a regulatory role in muscle contraction and its antagonism may decrease the magnitude and progression of scoliosis. A separate study has shown that tamoxifen (TMX), a known antagonist, is effective in altering the natural history in an avian model; however, whether the same effect is conceivable in mammals is unknown. We aimed to analyse whether the natural course of scoliosis in mice may be altered by the administration of TMX. Methods. 60 female, 3-week-old, C57BL/6 mice underwent amputations of forelimbs and tails. 57 mice were assigned to three groups: control group, no medications; TMX group, 10 mg TMX/L drinking water; and combined group, 10 mg TMX plus 10 mg trifluoperazine (TFP)/L drinking water. PA scoliosis radiographs were taken at 20 and 40 weeks and evaluated for presence and magnitude of spinal curves. Results. Four mice were lost to follow-up in the TMX group. Overall scoliosis rate was significantly lower in the TMX group (33%) than in the control (90%) and combined (68%) groups (p=0·001) at week 40. Similarly, upper thoracic scoliosis rate was lower in the TMX group (27%) than in control (74%) and combined (47%) groups (p=0·01). The thoracic scoliosis rate was also lower in the TMX group (7%) group than in control (63%) and combined (26%) groups (p=0·001). Combined drug group had lower thoracic and lumbar Cobb angles (17·50° [□}3·45]) than did the control group (29·40° [□}5·98]; p=0·031). Furthermore, double curve incidence at week 40 was lower in TMX group (12%) than in control (74%) and combined (47%) groups (p=0·001). Triple curve incidence was lower in combined (0%) and TMX (6%) groups than in the control group (15%), but this result was not significant (p=0·167). Conclusions. TMX effectively decreased the incidence and magnitude of the scoliotic curves in C57BL/6 mice scoliosis model. This is a novel finding, and could be very important in opening a pathway for the conservative treatment of idiopathic scoliosis by oral drugs

Background. In the USA more than half the states have legislated scoliosis school screening with the remaining states having either voluntary screening or no recommendations. The four primary care providers for adolescents with idiopathic scoliosis in the USA (AAOS, SRS, POSNA, AAP) do not support any recommendation against scoliosis screening, given the available literature. In Australia a national self detection program is implemented but in the UK school screening has been abolished since the 1980's. Opponents to scoliosis screening have focused on concerns about a low predictive value of screening, the cost effectiveness of referral, the possibility of unnecessary brace treatment and the effect of exposure to radiation when radiographs are obtained. Objectives. The purpose of this review was to evaluate the evidence for and against scoliosis screening. Methods. The following databases were searched: Cochrane Library, ARIF, TRIP, MEDLINE, EMBASE and CINAHL. Reference lists of articles were searched for relevant systematic reviews and research articles. Results. One systematic review (2008). 1. suggests that there is evidence (level 1B) that intensive scoliosis specific exercise methods can reduce the progression of mild scoliosis (<30 degrees Cobb). Further a Cochrane review (2010). 2. suggests that there is low quality evidence for the effectiveness of bracing. Conclusions. Based on the evidence of this review, a 4 tier model for school screening is proposed that includes the distribution of information leaflets, screening by a school nurse, topographical assessment, referral to the primary care doctor and finally if the patient is still screening positive, referral to a scoliosis surgeon. Category: Deformity/screening. Ethics approval: none needed for a review. Interest statement: none

Background. For bone grafting procedures, the use of autologous bone is considered the gold standard, as it is has a better healing capacity compared to other alternatives as allograft and synthetic bone substitutes. However, as there are several drawbacks related to autografting (infection, nerve- or vascular damage, chronic pain problems, abdominal herniation), there has been a targeted effort to improve the healing capacities of synthetic bone substitutes. Aim. To evaluate the performance of a carbonated osteoionductive hydroxyapatite (CHA) scaffold of clinical relevant size (Ø=15mm, H=50mm) in a sheep model of multi level posterolateral intertransverse lumbar spine fusion after activation with autologous bone marrow nuclear cells (BMNC) in a flow perfusion bioreactor. Method. Two groups were included in the study, autograft (n=6) and CHA scaffold (n=6) CHA. A paired design was used between and within the groups as lumbar posterolateral arthrodesis was performed in sheep on two levels (L2-L3, L5-L6) +/− BMNC, respectively. Before implantation, the CHA scaffold was cultured in a flow perfusion bioreactor system with BMNC for 21 days, and the autograft group was supplemented with isolated BMNC during the procedure. Micro tomography was used to evaluate fusion rate and the microarchitectural properties of the explants after an observation period of four months. Results. In the autograft group, the healing rate was 83.3% irrespective of the presence BMNC, and in the CHA group, 66.7% fused in the presence of BMNC, and 33.3% without. The microarchitectural data suggested the autograft group to be superior to the CHA scaffold regarding mechanical properties, however porosity decreased significantly (p=0.001) in the CHA scaffold group suggesting deposition of mineralized bone matrix. Conclusion. Based on the fusion rate and micro architectural properties, we consider the CHA scaffold fully capable of new bone formation, and that the presence of BMNC has a positive effect on the fusion rate in a challenging model of bone healing

Introduction

The response of the intervertebral disc to asymmetric forces may accelerate degeneration through changes in the matrix. Macroscopically, the disc sustains structural changes that may play a part in the progression of a scoliotic curve. Molecularly, disc degeneration is the outcome of the action of matrix metalloproteases (MMPs), members of a family of enzymes that bring about the degradation of extracellular matrix components. In this study we measured in vivo the expression of MMPs in a rat scoliotic intervertebral disc and studied the effect of the degree of the deformity on their production.

Aims. In this investigation, we administered oxidative stress to nucleus pulposus cells (NPCs), recognized DNA-damage-inducible transcript 4 (DDIT4) as a component in intervertebral disc degeneration (IVDD), and devised a hydrogel capable of conveying small interfering RNA (siRNA) to IVDD. Methods. An in vitro model for oxidative stress-induced injury in NPCs was developed to elucidate the mechanisms underlying the upregulation of DDIT4 expression, activation of the reactive oxygen species (ROS)-thioredoxin-interacting protein (TXNIP)-NLRP3 signalling pathway, and nucleus pulposus pyroptosis. Furthermore, the mechanism of action of small interfering DDIT4 (siDDIT4) on NPCs in vitro was validated. A triplex hydrogel named siDDIT4@G5-P-HA was created by adsorbing siDDIT4 onto fifth-generation polyamidoamine (PAMAM) dendrimer using van der Waals interactions, and then coating it with hyaluronic acid (HA). In addition, we established a rat puncture IVDD model to decipher the hydrogel’s mechanism in IVDD. Results. A correlation between DDIT4 expression levels and disc degeneration was shown with human nucleus pulposus and needle-punctured rat disc specimens. We confirmed that DDIT4 was responsible for activating the ROS-TXNIP-NLRP3 axis during oxidative stress-induced pyroptosis in rat nucleus pulposus in vitro. Mitochondria were damaged during oxidative stress, and DDIT4 contributed to mitochondrial damage and ROS production. In addition, siDDIT4@G5-P-HA hydrogels showed good delivery activity of siDDIT4 to NPCs. In vitro studies illustrated the potential of the siDDIT4@G5-P-HA hydrogel for alleviating IVDD in rats. Conclusion. DDIT4 is a key player in mediating pyroptosis and IVDD in NPCs through the ROS-TXNIP-NLRP3 axis. Additionally, siDDIT4@G5-P-HA hydrogel has been found to relieve IVDD in rats. Our research offers an innovative treatment option for IVDD. Cite this article: Bone Joint Res 2024;13(5):247–260

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

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. Methods. Patients who underwent surgery for ASD, with a minimum of two-year follow-up, were retrospectively reviewed. In total, 210 patients were included and randomly allocated into training (70% of the sample size) and test (the remaining 30%) sets to develop the machine learning algorithm. Risk factors were included in the analysis, along with clinical characteristics and parameters acquired through diagnostic radiology. Results. Overall, 152 patients without and 58 with a history of surgical revision following surgery for ASD were observed; the mean age was 68.9 years (SD 8.7) and 66.9 years (SD 6.6), respectively. On implementing a random forest model, the classification of URO events resulted in a balanced accuracy of 86.8%. Among machine learning-extracted risk factors, URO, proximal junction failure (PJF), and postoperative distance from the posterosuperior corner of C7 and the vertical axis from the centroid of C2 (SVA) were significant upon Kaplan-Meier survival analysis. Conclusion. The major risk factors for URO following surgery for ASD, i.e. postoperative SVA and PJF, and their interactions were identified using a machine learning algorithm and game theory. Clinical benefits will depend on patient risk profiles. Cite this article: Bone Joint Res 2023;12(4):245–255