Introduction. Transosseous flexion-distraction injuries of the spine typically require surgical intervention by stabilizing the fractured vertebra during healing with a pedicle-screw-rod constructs. As healing is taking place the load shifts from the implant back to the spine. Monitoring the load-induced deflection of the rods over time would allow quantifiable postoperative assessment of healing progress without the need for radiation exposure or frequent hospital visits. This approach, previously demonstrated to be effective in assessing fracture healing in long bones and monitoring posterolateral spinal fusion in sheep, is now being investigated for its potential in evaluating lumbar vertebra transosseous fracture healing. Method. Six human cadaveric spines were instrumented with pedicle-screws and rods spanning L3 vertebra. The spine was loaded in Flexion-Extension (FE), Lateral-Bending (LB) and Axial-Rotation (AR) with an intact L3 vertebra (representing a healed vertebra) and after transosseous disruption, creating an AO type B1 fracture. The implant load on the rod was measured using an implantable strain sensor (Monitor) on one rod and on the contralateral rod by a strain gauge to validate the Monitor's measurements. In parallel the range of motion (ROM) was assessed. Result. The ROM increased significantly in all directions in the fractured model (p≤0.049). The Monitor measured a significant increase in implant load in FE (p=0.002) and LB (p=0.045), however, not in AR. The strain gauge detected an increased implant load not only in FE (p=0.001) and LB (p=0.016), but also in AR (p=0.047). The highest strain signal was found during LB for both, the Monitor, and the strain gauge. Conclusion. After a complete transosseous disruption of L3 vertebra the load on the implants was significantly higher than in the intact respectively healed state. Innovative implantable sensors could be used to monitor those changes allowing the assessment of healing progression based on quantifiable data rather than CT-imaging

To investigate and compare the biomechanical characteristics of Bipedicular versus Unipedicular Vertebroplasty in cadaveric vertebra. Cadaveric single level vertebra were used to evaluate Bipedicular versus Unipedicular Vertebroplasty as an intervention for vertebral compression fractures. Cadaveric vertebra were assigned to two arms: Arm A simulated a wedge fracture followed by bipedicular cement augmentation; Arm B simulated a wedge fracture followed by unipedicular cement augmentation. Micro-CT imaging was performed to assess vertebral dimension, cement fill volumes and bone mineral density. All augmented specimens were then compressed under a static eccentric flexion load to failure. Pre and post augmentation failure load and stiffness were used to compare the two groups. Results suggest, when compared with actual failure strength, that the product of bone mineral density and endplate surface area gave a good prediction of failure strength for specimens in both arms. The mean cement volume fill of augmented vertebral bodies was 22.8% ± 7.21%. The bipedicular group showed a reduction in stiffness but an increase in post augmentation failure load of 1.09. The unipedicular group also showed a reduction in stiffness but showed a much greater increase in post augmentation failure load of 1.68. Preliminary data from this study suggests there is a significant reduction in stiffness following both bipedicular and unipedicular vertebroplasty. There is a significant increase in failure load post augmentation in the unipedicular group

The lumbar spine consists of a mobile segment of 5 vertebrae, which are located between the relatively immobile segments of the thoracic and sacral segments. The bodies are wider and have shorter and heavier pedicles, and the transverse processes project somewhat more laterally and ventrally than other spinal segments. The laminae are shorter vertically than are the bodies and are bridged by strong ligaments. The spinous processes are broader and stronger than are those in the thoracic and cervical spine. Internal fixation as an adjunct to spinal fusion has become increasingly popular in recent years. Stainless steel or titanium plates or rods are longitudinally anchored to the spine by hooks or pedicle screws. Powerful forces can be applied to the spine through these implants to correct deformity. Implants provide immediate rigid spinal immobilization, which allows for early patient mobilization, and provides a more optimal environment for bone graft incorporation. Numerous clinical and experimental studies demonstrate higher fusion rates in patients with rigid internal fixation than in controls without instrumentation. Although various implants are available, pedicle fixation systems are the most commonly used implant type in the lumbosacral spine. The large size of the lumbar pedicles minimizes the number of instrumented motion segments required to achieve adequate stabilization. Many authors have reported loss of postoperative deformity correction after transpedicular screw fixation, ranging from 2.5 degrees to 7.1 degrees. The general preference is to stabilize the fractured vertebra by fusing one level above and one level below. With this technique, the rate of loss of correction is high. At our institution, we routinely stabilize the unstable thoracolumbar fractures by fusing one level above and one level below. In addition, we put screws into the pedicle(s) of fractured vertebrae. The reason for this is the following:. To correct the deformed body of the fractured vertebra for better load sharing. To make use of the pedicles of the fractured vertebra for superior rotatory stabilization. To avoid the need for the inclusion of additional levels, thereby preserving motion segments. To avoid the need for possible anterior spinal fusion and instrumentation. To obtain a better correction of a kyphotic deformity. Plain radiographs were analysed post operatively and compared for reduction of the fracture fragments and correction of kyphotic deformity to pre-operative films. 74 Patients were admitted with thoracolumbar spine fractures to our hospital. 48 Patients were surgically treated, and 34 patients were available for follow up. We found that inserting the pedicle screws into the fractured vertebra provided good stabilization for very unstable fractures. No loss of correction was seen in the follow up x-rays. We conclude that including the fractured vertebra into the fracture fixation device not only provides better fracture reduction, but also gives improved rotatory stability

Purpose: The purpose of this work was to study the reliability and the precision of a lumber vertebra reconstruction method using images obtained from a 3D statistical model and two calibrated radiograms. The technique is designed for surgical approach to the lumbar spine and implantation of osteosynthesis material using enhanced-reality technology. Material and methods: A lumbar vertebra was reconstructed on several specimens using images issuing from a 3D statistical model and two calibrated radiograms. The images obtained from the model of this lumbar vertebra to be reconstructed constituted the preoperative images. Intra-operative images corresponded to two calibrated radiograms acquired with a fluoroscope using advanced technology (silicium receptor). The model was equipped with reflecting patches which can be detected in space using a 3D optical system. Correspondence between the 3D statistical model and the two calibrated radiograms was achieved with appropriate software. Navigation views were displayed on the screen to guide surgical tools at the vertebral level. Pedicular screws were implanted into several anatomic specimens to evaluate the reliability and precision of the system. The exact position of the implanted screws was established with computed tomography. Results: This system demonstrated its reliability and precision for the reconstruction of a lumbar vertebra from a 3D statistical model and two calibrated radiograms. All the implanted screws were perfectly positioned in the pedicles. Precision was to the order of 1 mm. Discussion: This method is a passive system not requiring intraoperative intervention. Reconstruction of a lumbar vertebra from a preoperative 3D statistical model and two intra-operative calibrated radiograms avoids the need to identify anatomic landmarks and/or surface points on the vertebra to be reconstructed. The level of precision is very similar to that obtained with CT-based systems. Preoperative CT is not needed for navigation. Conclusion: With this system, new generation fluoroscopic equipment should appear in the operating room, allowing acquisition of successive calibrated images. The digital data could then be matched with statistical anatomic data, avoiding the need for preoperative imaging (CT or MRI). Progressive introduction of intra-operative ultrasound to replace the calibrated radiograms should open a new approach for percutaneous surgery of the lumbar spine

Percutaneous vertebroplasty (PVP) is an emerging interventional technique for treatment of vertebral compression fractures. Bone cement is introduced to mechanically augment fracture and pain relief is almost immediate. Recent clinical and biomechanical studies have outlined the phenomenon of fractures occurring in adjacent vertebrae following PVP [. 1. ,. 2. ]. It is widely believed that rigid cement augmentation may cause a shift in the normal loading pattern of the spine thereby resulting in adjacent fractures. However, very few studies have attempted to quantify this effect [. 3. ]. Most biomechanical studies adopt a single vertebral body as a model for PVP analysis. With this approach it is not possible to determine the effect of load distribution on adjacent structures. Where multi-segment vertebrae have been used there is little documentation of the fracture characteristics produced or their repeatability. The purpose of this study was to develop a 3-vertebra model for the biomechanical analysis of PVP. The particular focus was on developing a robust technique for generating repeatable level of fracture severity from specimen to specimen. An alignment device was developed to fit into standard materials testing machine, which allowed constant axial compression without causing lateral bending or flexion-extension of the specimen’s ends. Porcine 3-segment specimens (T8-L2) were mechanically compressed to failure at a rate of 5mm/min applied vertically at a distance of 35% to the anterior edge of the specimen’s anterior-posterior length. During the test load-displacement data was displayed in real time on a PC. In order to generate uniform fractures, a protocol was devised in which the specimens were compressed for a further 6mm after initial yield point. After the initial fracture the segments were augmented with 3ml of PMMA cement injected through each pedicle and then recompressed. The fracture characteristics generated under these conditions were analysed using quantitative microcomputer tomogragy (μCT). μCT images showed that fractures were generated in the central vertebra, with some propagation towards adjacent vertebra. The results support the use of a 3-segment specimen as a better representation for PVP analysis. The method will enables the load shift and fracture progression on either side of the augmented vertebra to be observed, thereby providing a more complete picture of load-bearing kinetics. Secondly, the middle, augmented motion segment remains unconstrained by platens and cement impressions; hence its anatomical boundary conditions are less compromised. Although longer segments have been shown to be more anatomically appropriate, it is difficult to apply physiologic levels of load without causing the specimen to buckle. We were able to minimise buckling effect by incorporating an alignment device to position the specimen without constraint. Given the preceding observations, the concepts of 3-segment specimen in PVP biomechanical tests provides a suitable compromise in choosing an appropriate clinical setting for in-vitro testing of biological spine specimens

Considerable numbers of authors have reported the change in periprothetic bone mineral density (BMD) after hip arthroplasty. However, there have been few reports concerning the BMD in the lumbar vertebra, especially for dysplastic hips. Since 1998, we have been measuring the BMD mineral density for 2016 patients by DXA (Dual-energy X-Ray Absorptionmetry method). Among them, we evaluated the BMD in 66 postmenopausal patients with the single side primary arthroplasty, with five years or more follow-up, and also aged 60 or more. We used a DXA densitometer (DPX-IQ, GE Healthcare, Madison, WI, USA). The diagnosis at the surgery was dysplastic osteoarthritis in all patients. The average age at the surgery was 66 (60–81). All patients were female. No patients had the systematic diseases which contributed to the secondary osteoporosis. No patients had received the pharmacotherapy for osteoporosis in the whole therapeutic process. The bed rest was seven from two days after the surgery (different by the operation date). The average follow-up was 7.0 (five to ten) years. The average BMD in the lumbar vertebra before the surgery was 0.996 (0.612 to 1.712) g/cm2. The BMD was 0.971 (0.637 to 1.402) at six month postoperatively, 0.972 (0.552 to 1.740) at one year, 1.004 (0.573 to 1.733) at two years, 1.032 (0.633 to 1.670) at three years, 1.035(0.724 to 1.688) at four years, 1.031 (0.564 to 1.679) at five years, 1.027 (0.734 to 1.647) at six years, 1.042 (0.589 to 1.389) at seven years. At the final follow-up, the BMD was 1.054 (0.589 to 1.647). In 53 patients (80%), the density at the final follow-up increased in comparison to that before the surgery. In 27 patients (41%), the density once decreased six month postoperatively. The density increased at 3 years (t=−1.919, p=0.030), four years (t=−2.523, p=0.015), five years (t=−2.381, p=0.021), seven years (t=−2.822, p=0,007), and at the final-follow-up (−4.076, p= 0.000) in comparison to that before the surgery. The activity of the patients was evaluated by the hip score. The average score was 54.5 (21 to 76) before the surgery. The average score was 88.0 (66 to 100) and increased at the final follow-up in comparison to that before the surgery (t=−13.04, p 0.000). Some authors (eg. Bergström I, 2008, Espar I, 2008, etc.) have pointed out that the appropriate activity may increase the bone density. Presumed from the literatures, the increase of activity after the arthroplasty may have increased the BMD, though the direct correlation was not obvious between the BMD and the amount of hip score (at the final follow-up: r=0.005, p=0.972) in this study

Study Design: A retrospective review of the functional outcome of neurologically intact patients with burst fractures of the first lumbar vertebra. Objective: To assess the functional outcome of patients treated either surgically or conservatively following burst fractures of L1. Methods: A retrospective review of 38 neurologically intact patients with burst fractures of L1 was performed. Follow-up clinical evaluation was obtained from 26 patients, eleven of whom were treated surgically and fifteen of whom were managed conservatively. Patients were assessed with regard to pain, employment status, ability to partake in recreational activities and their overall satisfaction with treatment. Radiographic evaluation of anterior body compression and vertebral kyphosis was performed at the time of injury. Computed tomography scanning of spinal canal compromise was also recorded at the time of injury. Subsequent recordings of vertebral kyphosis were assessed at the time of remobilisation and at 3-month follow-up evaluation. Results: Mean follow-up time for the 26 patients was 43.02 months. At final clinical follow-up of the fifteen patients managed conservatively, 6 patients (40%) had little or no pain; 12 patients (80%) had returned to work with 6 (40%) stating that they had little or no restrictions in their ability to work; 8 patients (53%) had returned to the same level of recreational activity as prior to their injury with 7 (47%) stating they had little or no restrictions in their ability to participate in recreational activities. One patient (9%) reported being very dissatisfied with the operative treatment of their spine fracture. No correlation was found between kyphotic deformity, extent of canal compromise and clinical outcome. Conclusions: Non-operative management of burst fractures of the first lumbar vertebra is a very safe and effective method of treatment. It reduces hospitalisation time and avoids the costs and risk of surgery. Patients return to the functional activities of daily living quickly and have a better clinical outcome when compared with operative management

Purpose: There is scant literature with respect to reproducibility in radiological measurements of vertebral morphology. The purpose was to determine the reliability of measurement of various parameters of vertebral morphology in idiopathic scoliosis. Method: Ten patients with AIS were investigated with standardised low dose multi-slice helical CT. Axial reconstructions in the plane of the T8 (apical) vertebra were performed prone, as per Jamieson et al (2008). Antero-posterior (AP) canal diameter, left and right pedicle width, canal width, left and right mid-point to medial pedicle length, left and right pedicle length, and cord length, left and right transverse angles, and left and right canal area were measured by our spine surgeons and spine surgery fellow. Statistical analysis for intra-class coefficients (ICC) for intra and inter observer reliability was then performed. Results: Intra-observer reliability was excellent, with a mean ICC score of 0.930 (range 0.608–0.996), across all fourteen variables. Inter-observer reliability was very good with a mean ICC score of 0.890 (range 0.360–0.987), across all variables. There was poor inter-observer reliability for measurement of the transverse pedicle angles (0.360 – 0.446). The intra-observer reliability for transverse pedicle angles, whilst good (0.608–0.861), was worse than any of the other intra-observer reliabilities. Conclusion: We demonstrate excellent intra, and inter observer reliability for measurement of apical vertebrae morphology in AIS. This tool can be utilized in the further study of pedicle dysplasia. Measurement of transverse pedicle angle was less reliable than any of the other measurement variables. A standardised measurement of the morphology of vertebral canal, pedicles and vertebral body morphology is reliable both within individual observers, and across a group of observers. A standardised measure for further investigation has been validated which will enable study of the evolution of pedicle dysplasia over time. This will lead to a better understanding of the etiology of pedicle dysplasia in scoliosis

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.

Objective: To present the clinical features, radiological findings and differential diagnosis of this rare benign condition. Design: Melorheostosis (Leri’s Disease) is a rare mesenchymal dysplasia commonly exhibiting hyperostosis on the internal and external aspect of tubular bones in a sclerodermal distribution. It usually occurs in the limbs, frequently crosses joints and there is often ossification in local soft tissues. Presenting features may include pain, restricted joint movement and skin thickening. It very rarely affects the spine and its cause is unknown. Subject: A 40-year-old female presented with insidious onset of mild mid thoracic back pain. There was no history of trauma and she had no past medical or family history. She underwent a six-month course of physiotherapy but this failed to help her symptoms. She developed a small lump over the area of pain and her GP arranged an X-Ray. This showed an irregular area of high attenuation over the right side of the tenth thoracic vertebra. A CT demonstrated a “dripping candle wax” appearance of densely calcified cortical bone undulating over the right side of the body and posterior elements of T10. The ossification crossed the synovial zygoapophyseal joint but not the intervertebral disc and a diagnosis of melorheostosis was suggested. MRI supported the CT findings and confirmed the presence of a soft tissue lesion over the dorsal process of T10. A bone scan verified the solitary nature of the lesion and showed widening of the right side of the body of T10 with increased focal uptake. All blood and urine investigations were normal. Results: The patient underwent an open biopsy to obtain sufficient tissue for histological diagnosis and confirm that the lesion was benign in nature. It was felt that the dense ossification of the lesion would make percutaneous biopsy difficult. The most important differentials to exclude were an osteosclerotic bone metastasis and osteosarcoma. Other differential diagnoses were a parosteal osteoma, a burnt out osteoblastoma and a giant bone island. The soft tissue histology showed a necrotic fibrocartilagenous mass. The bone samples required prolonged decalcification prior to cutting and were composed of compact cortical bone similar to the appearances seen in ivory osteoma and also consistent with melorheostosis. This pathological pattern and the radiological finding of cortical compact bone crossing a synovial joint confirms the diagnosis of melorheostosis. Conclusions: Spinal melorheostosis is a rare condition. The diagnosis should be considered in the differential of atypical osteosclerotic lesions of vertebrae. Adequate histological sampling is essential in order to exclude malignancy

Compressive fracture of osteoporotic vertebrae has been one of the most important health problems in aged societies because severely injured spin might be a reason of bedridden for elderly people. Osteoporosis has been widely assessed by averaged bone mineral density of vertebrae measured using DEXA, however, BMD sometimes does not reflect the strength of vertebrae. CT imaged based finite element method (CT-FEM) has been applied to evaluate the strength of vertebrae based on the biomechanics theory and approved by a part of the highly advanced medical treatment in Japan. In the present study, compressive strength of more than 100 vertebrae were evaluated using CT-FEM, and the correlation between BMD and the strength was thoroughly investigated. It was found that some vertebrae with high BMD could have low strength which may cause fracture easily. Thus, a controversial point of the BMD based diagnosis of osteoporosis was clearly indicated. In this invited talk, some basic theories of CT-FEM and fracture assessment and some key results from the recent study will be presented.

Abstract

A 22-year-old man was admitted to hospital after being assaulted. He complained of a painful neck and upper limbs, with weakness and numbness of his upper limbs.

Initial treatment was skull traction for six weeks, during which the motor power in the upper limbs recovered. CT scan of the cervical spine showed a lytic expanding bone lesion in the atlas. At 10 weeks he was transferred to a Spinal Centre, walking normally, with good bladder and bowel control. He was complaining of intermittent occipital headaches and pain at the cervicothoracic junction. He was wearing a cervical orthosis. His neck movements were guarded and markedly restricted. No neurological deficit was detected. A right-sided brachiocephalic artery angiogram showed no abnormality. MR scan showed definite narrowing of the spinal canal at the C2 vertebral level and stress studies some vertebral instability at the atlanto-axial level. Under general anaesthetic a transoral biopsy, curettage, and bone grafting of the atlas was carried out. The biopsy material comprised white membranous-type material, which had the histological features of hydatid cysts. A posterior spinal fusion with instrumentation was performed over posterior vertebral arches Cl to C3. Postoperatively ultrasound of the abdomen and radiograph of the chest did not reveal any further evidence of hydatid disease. Treatment with albendazole was commenced. The diagnosis was not anticipated preoperatively.

To reduce vertebral fractures, emerging techniques such as vertebroplasty need to be improved by studying cement infiltration and leakage within bone. Thus we investigated samples extracted from lumbar spines using μCT to evaluate morphological parameters (trabecular thickness and separation, structural index). The specific finding is that relevant shifts of the trabecular thickness and separation Gaussian medians associated to sharpened distributions are related to donors’ age. These morphological parameters, correlated to common fluid laws, enable the prediction of bone cement flow within vertebrae and provide new ways for designing biomaterials and estimate key vertebroplasty parameters regarding time, pressure and injection site.

Osteoporosis, a pathological bone decay leading to fractures, is an economical burden on society. A prevalent fracture site is the spine. To avoid vertebral fractures, emerging techniques such as vertebroplasty are used. Nevertheless, the lack of knowledge relating to cement infiltration, distribution and leakage within vertebrae during cement injection interferes with an appropriate medical practice. This study, by assessing morphological parameters, aims at a better understanding of these processes.

The investigation includes size-controlled cylindrical samples (diameter of 18mm and height of 18mm), extracted from five lumbar spines (L1 to L5) of four female donors aged from forty-nine to eighty years old, analysed using micro-Computed Tomography technique (with a voxel size of 18μm*18μm*36μm) and three-dimensional computed reconstructions.

Then morphological parameters such as porosity, trabecular thickness, trabecular separation, tissue surface and structural index were extracted from the reconstructed volume using dedicated software.

The general findings are significant decreases in bone mass and mineral density while porosity increased and bone anisotropy remains unchanged. The specific finding is that relevant shifts of the trabecular thickness and separation Gaussian medians associated to sharpened distributions are related to donors’ age

Previously determined morphological parameters correlated to common fluid laws (Stokes, Reynolds) enable the prediction of bone cement flow, infiltration and leakage during vertebroplasty and thus provide new ways for designing and evaluating biomaterials and estimating key vertebroplasty parameters regarding time, pressure and injection site.

Please contact author for diagrams and graphs.

Introduction

In the previous study regarding the relationship among maximum hip flexion, the pelvis, and the lumbar vertebrae on the sagittal plane, we have found in X-rays that the lumbo lordotic angle (LLA) and the sacral slope angle (SSA) have a large impact on hip flexion angle. We examined hip flexion angles to the various height of the objects (half round plastic tube) placed under the subject's lower back and compared the passive hip flexion angles in the supine position between younger and middle age groups.

Variations in pelvic anatomy are a major risk factor for misplaced percutaneous sacroiliac screws used to treat unstable posterior pelvic ring injuries. A better understanding of pelvic morphology improves preoperative planning and therefore minimises the risk of malpositioned screws, neurological or vascular injuries, failed fixation or malreduction. Hence a classification system which identifies the clinically important anatomical variations of the sacrum would improve communication among pelvic surgeons and inform treatment strategy. 300 Pelvic CT scans from skeletally mature trauma patients that did not have pre-existing posterior pelvic pathology were identified. Axial and coronal transosseous corridor widths at both S1 and S2 were recorded. Additionally, the S1 lateral mass angle were also calculated. Pelvises were classified based upon the sacroiliac joint (SIJ) height using the midpoint of the anterior cortex of L5 as a reference point. Four distinct types could be identified:. Type-A – SIJ height is above the midpoint of the anterior cortex of the L5 vertebra. Type-B – SIJ height is between the midpoint and the lowest point of the anterior cortex of the L5 vertebra. Type-C – SIJ height is below the lowest point of the anterior cortex of the L5 vertebra. Type-D – a subgroup for those with a lumbosacral transitional vertebra, in particular a sacralised L5. Differences in transosseous corridor widths and lateral mass angles between classification types were assessed using two-way ANOVAs. Type-B was the most common pelvic type followed by Type-A, Type-C, and Type-D. Significant differences in the axial and coronal corridors was observed for all pelvic types at each level. Lateral mass angles increased from Types-A to C, but were smaller in Type-D. This classification system offers a guide to surgeons navigating variable pelvic anatomy and understanding how it is associated with the differences in transosseous sacral corridors. It can assist surgeons’ preoperative planning of screw position, choice of fixation or the need for technological assistance

Aims. The aim of this study was to review the current evidence surrounding curve type and morphology on curve progression risk in adolescent idiopathic scoliosis (AIS). Methods. A comprehensive search was conducted by two independent reviewers on PubMed, Embase, Medline, and Web of Science to obtain all published information on morphological predictors of AIS progression. Search items included ‘adolescent idiopathic scoliosis’, ‘progression’, and ‘imaging’. The inclusion and exclusion criteria were carefully defined. Risk of bias of studies was assessed with the Quality in Prognostic Studies tool, and level of evidence for each predictor was rated with the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. In all, 6,286 publications were identified with 3,598 being subjected to secondary scrutiny. Ultimately, 26 publications (25 datasets) were included in this review. Results. For unbraced patients, high and moderate evidence was found for Cobb angle and curve type as predictors, respectively. Initial Cobb angle > 25° and thoracic curves were predictive of curve progression. For braced patients, flexibility < 28% and limited in-brace correction were factors predictive of progression with high and moderate evidence, respectively. Thoracic curves, high apical vertebral rotation, large rib vertebra angle difference, small rib vertebra angle on the convex side, and low pelvic tilt had weak evidence as predictors of curve progression. Conclusion. For curve progression, strong and consistent evidence is found for Cobb angle, curve type, flexibility, and correction rate. Cobb angle > 25° and flexibility < 28% are found to be important thresholds to guide clinical prognostication. Despite the low evidence, apical vertebral rotation, rib morphology, and pelvic tilt may be promising factors. Cite this article: Bone Joint J 2022;104-B(4):424–432

7% of adolescent idiopathic scoliosis (AIS) patients also present with a pars defect. To date, there are no available data on the results of fusion ending proximal to a spondylolysis in the setting of AIS. The aim of this study was to analyze the outcomes of posterior spinal fusion (PSF) in this patient cohort, to investigate if maintaining the lytic segment unfused represents a safe option. Retrospective review of all patients who received PSF for AIS, presented with a spondylolysis or spondylolisthesis and had a min. 2-years follow-up. Demographic data, instrumented levels and preoperative radiographic data were collected. Mechanical complications, coronal or sagittal parameters, amount of slippage and pain levels were evaluated. Data from 22 patients were available (age 14.4 ± 2.5 years), 18 Lenke 1–2 and four Lenke 3–6. Five patients (24%) had an isthmic spondylolisthesis, all Meyerding I. The mean preoperative Cobb angle of the instrumented curves was 58 ± 13°. For 18 patients the lowest instrumented vertebra (LIV) was the last touched vertebra (LTV); for two LIV was distal to the LTV; for two, LIV was one level proximal to the LTV. The number of segments between the LIV and the lytic vertebra ranged from 1 to 6. At the last follow-up, no complications were observed. The residual curve below the instrumentation measured 8.5 ± 6.4°, the lordosis below the instrumented levels was 51.4 ± 13°. The magnitude of the isthmic spondylolisthesis remained constant for all included patients. Three patients reported minimal occasional low back pain. The LTV can be safely used as LIV when performing PSF for the management of AIS in patients with L5 spondylolysis

Background. Surgical site infection following spine surgery is associated with increased morbidity, mortality and increased cost for the health care system. The reported pooled incidence is 3%. Perioperative antibiotic prophylaxis is a key factor in lowering the risk of acquiring an infection. Previous studies have assessed perioperative cefuroxime concentrations in the anterior column of the cervical spine with an anterior surgical approach. However, the majority of surgeries are performed in the posterior column and often involve the lumbar spine. Accordingly, the objective was to compare the perioperative tissue concentrations of cefuroxime in the anterior and posterior column of the same lumbar vertebra using microdialysis in an experimental porcine model. Method. The lumbar vertebral column was exposed in 8 female pigs. Microdialysis catheters were placed for sampling in the anterior column (vertebral body) and posterior column (posterior arch) within the same vertebra (L5). Cefuroxime (1.5 g) was administered intravenously over 10 min. Microdialysates and plasma samples were continuously obtained over 8 hours. Cefuroxime concentrations were quantified by Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry. Microdialysis is a catheter-based pharmacokinetic tool, that allows dynamic sampling of unbound and pharmacologic active fraction of drugs e.g., cefuroxime. The primary endpoint was the time with cefuroxime above the clinical breakpoint minimal inhibitory concentration (T>MIC) for Staphylococcus aureus of 4 µg/mL as this has been suggested as the best predictor of efficacy for cefuroxime. The secondary endpoint was tissue penetration (AUC. tissue. /AUC. plasma. ). Results. Mean T>MIC 4 µg/mL (95% confidence interval) was 123 min (105–141) in plasma, 97 min (79–115) in the anterior column and 93 min (75–111) in the posterior column. Tissue penetration (95% confidence interval) was incomplete for both the anterior column 0.48 (0.40–0.56) and posterior column 0.40 (0.33–0.48). Conclusions. Open lumbar spine surgery often involves extensive soft tissue dissection, stripping and retraction of the paraspinal muscles which may impair the local blood flow exposing the lumbar vertebra to postoperative infections. A single intravenous administration of 1.5 g cefuroxime resulted in comparable T>MIC between the anterior and posterior column of the lumbar spine. Mean cefuroxime concentrations decreased below the clinical breakpoint MIC for S. aureus of 4 µg/mL after 123 min (plasma), 97 min (anterior column) and 93 min (posterior column). This is shorter than the duration of most lumbar spine surgeries, and therefore alternative dosing regimens should be considered in posterior open lumbar spine surgeries lasting more than 1.5 hours

Intra-Discal Vacuum Phenomenon (IDVP) represents an intradiscal nitrogen gas accumulation where a cavity opens in a supine position, lowering intra-discal pressure and generating a bubble. IDVP has been observed in up to 20% of elderly patients and reported in almost 50% of chronic LBP patients. With a highly accurate detection on CT, its significance lacks clarity and consideration within normative data. IDVP occurs with patterns of lumbar and/or lumbopelvic morphology and associated diagnoses. Over-60s population based sample of 2020 unrelated CT abdomen scans without acute spinal presentations, with sagittal reconstructions, inclusive of T12 to femoral heads, were analyzed for IDVP and pelvic incidence (PI). Subjects with diagnostic morphological associations of the lumbar spine, including previous fracture, autofusion, transitional vertebra and listhesis, were selected out and analyzed separately. Subjects were then equally grouped into low, medium and high PI. Prevalence of lumbar spine IDVP is 41.3%. 125 cases were excluded. 1603 subjects yielded 663 IDVP. This was increased in severity towards the lumbosacral junction (L1L2 9.4%, L2L3 10.9%, L3L4 13.7%, L4L5 19.9%, L5S1 28.5%) and those with low PI, while distribution was more even with high PI. 292 had positive diagnostic associations, which were more likely to occur at the level of isthmic spondylolisthesis, adjacent to a previous fracture or suprajacent to lumbosacral transitional vertebra (p<0.05). This study has identified normative values for prevalence and severity of IDVP in a normal aging population. Morphological patterns that influence the pattern of IVDP such as pelvic incidence and diagnostic associations provide novel insights to the function of the aging spine