Aims. Vertebral body tethering (VBT) is a non-fusion technique to correct scoliosis. It allows correction of scoliosis through growth modulation (GM) by tethering the convex side to allow concave unrestricted growth similar to the hemiepiphysiodesis concept. The other modality is anterior scoliosis correction (ASC) where the tether is able to perform most of the correction immediately where limited growth is expected. Methods. We conducted a retrospective analysis of clinical and radiological data of 20 patients aged between 9 and 17 years old, (with a 19 female: 1 male ratio) between January 2014 to December 2016 with a mean five-year follow-up (4 to 7). Results. There were ten patients in each group with a total of 23 curves operated on. VBT-GM mean age was 12.5 years (9 to 14) with a mean Risser classification of 0.63 (0 to 2) and VBT-ASC was 14.9 years (13 to 17) with a mean Risser classification of 3.66 (3 to 5). Mean preoperative VBT-GM Cobb was 47.4° (40° to 58°) with a Fulcrum unbend of 17.4 (1° to 41°), compared to VBT-ASC 56.5° (40° to 79°) with 30.6 (2° to 69°)unbend. Postoperative VBT-GM was 20.3° and VBT-ASC Cobb angle was 11.2°. The early postoperative correction rate was 54.3% versus 81% whereas Fulcrum Bending Correction Index (FBCI) was 93.1% vs 146.6%. The last Cobb angle on radiograph at mean five years’ follow-up was 19.4° (VBT-GM) and 16.5° (VBT-ASC). Patients with open triradiate cartilage (TRC) had three over-corrections. Overall, 5% of patients required fusion. This one patient alone had a over-correction, a second-stage tether release, and final conversion to fusion. Conclusion. We show a high success rate (95%) in helping children avoid fusion at five years post-surgery. VBT is a safe technique for correction of scoliosis in the skeletally immature patient. This is the first report at five years that shows two methods of VBT can be employed depending on the skeletal maturity of the patient: GM and ASC. Cite this article: Bone Jt Open 2022;3(2):123–129

Clinical and radiological assessment of results of vertebral body stenting procedure. Introduction: Use of metallic stents along with cement have shown good restoration of the vertebral body in cadaveric spines. We have presented the early results of vertebral body stenting done at Royal Derby Hospitals. Patients and Methods: All patients had a transpedicular approach to the vertebral body. The vertebral body stent was expanded using a balloon as in balloon kyphoplasty. The balloon was removed leaving the stent in place. The resultant cavity was filled with partially cured polymethyl methacrylate in osteoporotic fractures and calcium phosphate cement in traumatic fractures. Radiological assessment included pre operative measurement of vertebral body angle, correction achieved and maintenance of correction at follow up. All patients were assessed using the visual analogue score and oswestry disability index. The procedure was done in 14 fractures (10 patients). 9 fractures were traumatic while 5 were osteoporotic fractures. The mean age of the traumatic fractures was 54.28 years while the mean age of osteoporotic fractures was 82.34 years. Mean follow up was 10 months. All traumatic fractures were type A 3.1. Mean vertebral body angle correction achieved was 8.3° (4° to 14.2°). None of the patients lost the reduction at follow up. The mean VAS for pain at 6 months was 3.8. The mean oswestry disability index was 22% for traumatic fractures, while it was 44% for osteoporotic fractures. Vertebral body stenting is a safe procedure. It was successful in restoring the anterior column with encouraging radiological and clinical results

Aims. Spinal fusion remains the gold standard in the treatment of idiopathic scoliosis. However, anterior vertebral body tethering (AVBT) is gaining widespread interest, despite the limited data on its efficacy. The aim of our study was to determine the clinical efficacy of AVBT in skeletally immature patients with idiopathic scoliosis. Methods. All consecutive skeletally immature patients with idiopathic scoliosis treated with AVBT enrolled in a longitudinal, multicentre, prospective database between 2013 and 2016 were analyzed. All patients were treated by one of two surgeons working at two independent centres. Data were collected prospectively in a multicentre database and supplemented retrospectively where necessary. Patients with a minimum follow-up of two years were included in the analysis. Clinical success was set a priori as a major coronal Cobb angle of < 35° at the most recent follow-up. Results. A total of 57 patients were included in the study. Their mean age was 12.7 years (SD 1.5; 8.2 to 16.7), with 95% being female. The mean preoperative Sanders score and Risser grade was 3.3 (SD 1.2), and 0.05 (0 to 3), respectively. The majority were thoracic tethers (96.5%) and the mean follow-up was 40.4 months (SD 9.3). The mean preoperative major curve of 51° (SD 10.9°; 31° to 81°) was significantly improved to a mean of 24.6° (SD 11.8°; 0° to 57°) at the first postoperative visit (45.6% (SD 17.6%; 7% to 107%); p < 0.001)) with further significant correction to a mean of 16.3° (SD 12.8°; -12 to 55; p < 0.001) at one year and a significant correction to a mean of 23° (SD 15.4°; -18° to 57°) at the final follow-up (42.9% (-16% to 147%); p < 0.001). Clinical success was achieved in 44 patients (77%). Most patients reached skeletal maturity, with a mean Risser score of 4.3 (SD 1.02), at final follow-up. The complication rate was 28.1% with a 15.8% rate of unplanned revision procedures. Conclusion. AVBT is associated with satisfactory correction of deformity and an acceptable complication rate when used in skeletally immature patients with idiopathic scoliosis. Improved patient selection and better implant technology may improve the 15.8% rate of revision surgery in these patients. Further scrutiny of the true effectiveness and long-term risks of this technique remains critical. Cite this article: Bone Joint J 2020;102-B(12):1703–1708

To explore a novel machine learning model to evaluate the vertebral fracture risk using Decision Tree model and train the model by Bone Mineral Density (BMD) of different compartments of vertebral body. We collected a Computed Tomography image dataset, including 10 patients with osteoporotic fracture and 10 patients without osteoporotic fracture. 40 non-fracture Vertebral bodies from T11 to L5 were segmented from 10 patients with osteoporotic fracture in the CT database and 53 non-fracture Vertebral bodies from T11 to L5 were segmented from 10 patients without osteoporotic fracture in the CT database. Based on the biomechanical properties, 93 vertebral bodies were further segmented into 11 compartments: eight trabecular bone, cortical shell, top and bottom endplate. BMD of these 11 compartments was calculated based on the HU value in CT images. Decision tree model was used to build fracture prediction model, and Support Vector Machine was built as a compared model. All BMD data was shuffled to a random order. 70% of data was used as training data, and 30% left was used as test data. Then, training prediction accuracy and testing prediction accuracy were calculated separately in the two models. The training accuracy of Decision Tree model is 100% and testing accuracy is 92.14% after trained by BMD data of 11 compartments of the vertebral body. The type I error is 7.14% and type II error is 0%. The training accuracy of Support Vector Machine model is 100% and the testing accuracy is 78.57%. The type I error is 17.86% and type II error is 3.57%. The performance of vertebral body fracture prediction using Decision Tree is significantly higher than using Support Vector Machine. The Decision Tree model is a potential risk assessment method for clinical application. The pilot evidence showed that Decision Tree prediction model overcomes the overfitting drawback of Support Vector Machine Model. However, larger dataset and cohort study should be conducted for further evidence

Introduction: Vertebral body osteophytes are common in elderly spines, but their mechanical function is unclear. Do they act primarily to reduce compressive stress on the vertebral body, or to stabilise the spine in bending? How do they influence estimates of vertebral strength based on bone mineral density (BMD)?. Methods: Spines were obtained from cadavers aged 51–92 yrs (mean 77 yrs) with radiographic evidence of vertebral osteophytes (mostly antero-lateral). Twenty motion segments, from T5-T6 to L3–L4, were dissected and loaded a) in compression to 1.5 kN, and b) in bending to 10–25 Nm. Vertebral movements were tracked at 50 Hz using an optical MacReflex system. Bending tests were performed in random order, in flexion, extension, and lateral bending. Resistance to bending and compression was measured before and after surgical excision of all osteophytes. The bone mineral content (BMC) and density (BMD) of each vertebra was measured in the antero-posterior direction, using DXA. Density measurements were repeated after excision of all osteophytes. ANOVA was used to detect changes after osteophyte excision, and regression was used to examine the influence of osteophyte size and BMC. Results: Removal of osteophytes reduced-vertebral BMD by 9% (SD 13%). Compressive stiffness was affected rather more, being reduced by an average 17% (p< 0.05). Bending stiffness was reduced in flexion and extension by 50% and 39% respectively (p< 0.01), and in left and right lateral bending by 41% and 49% respectively (p< 0.01). Osteophyte removal increased the neutral zone and range of motion in each mode of bending. Most mechanical changes were proportional to osteophyte mass, and to changes in BMC (p< 0.01). Conclusions: Vertebral body osteophytes primarily stabilise the spine in bending, and do not play a major role in resisting compression. Animal models show that osteophytes grow in response to experimentally-induced instability, so their formation can be seen as mechanically-adaptive (restoring stability) rather than degenerative. The influence of typical osteophytes on compressive stiffness is greater than their influence on vertebral BMD (17% vs 9%) so predictions of vertebral compressive strength based on BMD measurements are likely to be under-estimates if osteophytes are present

Anterior vertebral body tethering (AVBT) is a growth modulating procedure used to manage idiopathic scoliosis by applying a flexible tether to the convex surface of the spine in skeletally immature patients. The purpose of this study is to determine the preliminary clinical outcomes for an adolescent patient cohort. 18 patients with scoliosis were selected using a narrow selection criteria to undergo AVBT. Of this cohort, 11 had reached a minimum follow up of 2 years, 4 had reached 18 months, and 3 had reached 6 months. These patients all demonstrated a primary thoracic deformity that was too severe for bracing, were skeletally immature, and were analysed in this preliminary study of coronal plane deformity correction. Using open-source image analysis software (ImageJ, NIH) PA radiographs taken pre-operatively and at regular follow-up visits post-operatively were used to measure the coronal plane deformity of the major and compensatory curves. Pre-operatively, the mean age was 12.0 years (S.D. 10.7 – 13.3), mean Sanders score 2.6 (S.D. 1.8-3.4), all Risser 0 and pre-menarchal, with mean main thoracic Cobb angle of 52° (S.D. 44.2-59.8°). Post-operatively the mean angle decreased to 26.4° (S.D. 18.4-32°) at 1 week, 30.4° (S.D. 21.3-39.6°) at 2 months, 25.7° (S.D. 18.7-32.8°) at 6 months, 27.9° (S.D. 16.2-39.6°) at 12 months, and 36.8° (S.D. 22.6– 51.0°) at 18 months and 38.2° (S.D. 27.6-48.7°) at 2 years. The change in curve at 2 years post-operative was statistically significant (P=0.004). There were 4 tether breakages identified that did not require return to theatre as yet, one patient underwent a posterior spinal instrumented fusion due to curve progression. AVBT is a promising new growth modulation technique for skeletally immature patients with progressive idiopathic scoliosis. This study has demonstrated a reduction in scoliosis severity

Introduction: Vertebral body osteophytes are common in elderly spines, but their mechanical function is unclear. Do they act primarily to reduce compressive stress on the vertebral body, or to stabilise the spine in bending?. Methods: Spines were obtained from cadavers aged 51–92yrs (mean 77yrs) with radiographic evidence of vertebral osteophytes (mostly antero-lateral). Twenty motion segments, from T5-T6 to L3-L4, were dissected and loaded a) in compression to 1.5kN, and b) in bending to 10–25Nm. Vertebral movements were tracked at 50Hz using an optical MacReflex system. Bending tests were performed in random order, in flexion, extension, and lateral bending. Resistance to bending and compression was measured before and after surgical excision of all osteophytes. Bone mineral content (BMC) of osteophytes was measured using DXA. ANOVA was used to detect changes after osteophyte excision, and regression was used to examine the influence of osteophyte size. Results: Compressive stiffness was reduced by an average 17% following osteophyte removal (p< 0.05). In flexion and extension, bending stiffness was reduced by 60% and 79% respectively (p< 0.01). In left and right lateral bending, stiffness was reduced by 42% and 49% respectively. Osteophyte removal increased the neutral zone and range of motion in each mode of bending, and changes were proportional to osteophyte mass and BMC (p< 0.01). Conclusion: Vertebral body osteophytes primarily stabilise the spine in bending, and do little to resist compression, despite their considerable BMC. Predictions of vertebral compressive strength based on BMC measurements are likely to be over-estimates if large osteophytes are present

Introduction: Several recently published case series report the development of vertebral body osteolysis following the insertion of bone morphogenetic proteins (BMP) in the interbody space. The aim of this case report was to highlight the development of severe vertebral body osteolysis following posterior lumbar interbody fusion with recombinant human bone morphogenetic protein (rhBMP-2). Methods: A 62 year old male who developed adjacent segment disease 13 years after an L4/5 and L5/S1 posterolateral fusion underwent what appeared to be a successful instrumented L3/4 posterior lumbar interbody fusion using morselised posterior elements and scavenged drilled particulate interbody autograft together with a single large sized sponge of rhBMP-2. Results: He continued to experience intermittent episodes of severe low back pain following that procedure, and a CT scan performed three months post-operatively revealed severe osteolysis of the L3 and L4 vertebral bodies. Although he was a type 2 diabetic, extensive investigations did not reveal any evidence of infection. Discussion: Vertebral body osteolysis has previously been reported following the use of BMP in the interbody space. The mechanism for this is unclear, but may be due to osteoclast activation. The prevalence of this complication following the use of BMP is not known. It is recommended that a process of independent post-marketing surveillance be established to further investigate this possible complication of the use of BMP in posterior interbody fusion

Introduction: Osteoporotic fractures affect certain bones more than others, suggesting that systemic bone loss is not the only underlying cause. We have shown that age-related intervertebral disc degeneration causes the anterior vertebral body (VB) to be stress-shielded in erect postures, and yet severely loaded when the spine is flexed (1). We hypothesise that this unequal loading causes exaggerated bone loss from the anterior vertebral body, making it vulnerable to fracture when the spine is heavily loaded in a forward stooping (flexed) posture. Materials and Methods: Regional volumetric bone mineral density (BMD) was measured in 35 thoracolumbar motion segments (aged 64–92 yrs) using dual-energy x-ray absorptiometry. The distribution of compressive stress was measured along the mid-sagittal diameter of each intervertebral disc using a miniature pressure transducer. Stresses were integrated over area to give the compressive force acting on the anterior and posterior halves of the VB (1). Motion segment compressive strength was measured in moderate flexion. Results: BMD of the anterior half of the VB was 26% (STD 13%) lower than that of the posterior half (p< 0.0001), was correlated with % load on the anterior VB in erect posture (r. 2. =0.48, p< 0.0001), and was a better predictor of motion segment compressive strength (in flexion) than was BMD of the whole vertebral body (r. 2. = 0.79 compared to r. 2. = 0.59). Conclusion: These results clearly support our hypothesis. It appears that intervertebral disc degeneration leads to exaggerated bone loss from the anterior VB, leaving it more vulnerable to fracture when the spine is flexed. Future work aims to confirm this important result on a larger number of specimens, and to compare the relative importance of disc degeneration and overall bone loss on vertebral compressive strength. Pollintine P et al (2001). SBPR Annual Meeting, Bristol. Backcare Research Award 2002

Since 1985 an original cementless, stainless prosthesis for C3-C7 cervical vertebral body substitution has been in use, fixed to contiguous vertebral bodies with screws. The prosthesis was employed in 151 patients, who were mostly affected by cervical metastases involving intractable pain with signs of nerve-root and/or myelon compression, using a permanent collar. The use of this kind of prosthesis allowed a easy and quick surgery with early post-surgical mobilisation of the patient without any external support. Cervical pain resolution was very evident in all patients. Cervical substitution did not affect the prognosis of tumour but allowed a better nursing and quality of life of these patients. At a follow-up of 2.5 years we have not observed any prosthesis mobilisation. In the last year some modifications were added to the prosthesis. Overall the prothesis was made of titanium, produced in two fashions, closed and open, and different lengths. The closed prosthesis is employed according to the indications of the previous prosthesis (in cases of corporectomy in neoplasms). The second one, open and empty, is filled with bone chips (autologous or etherologous) to achieve fusion with sorrounding vertebral bodies. Indications for the last type was corporectomy for discoarthrosis at two contiguous levels in patients in whom the intermediate vertebra were removed to assure a complete and safe cord decompression. The open prosthesis could also be used in burst fractures, avoiding other systems that require an anterior plate. The implantation technique presents no difficulties and can be easily incorporated into the group of standard surgical procedures for anterior interbody fusion. We have used the prosthesis in 11 cases. The new titanium prothesis was easy to handle and provided immediate stability in all cases. Clinical and radiological follow-up examinations were performed at the time of discharge from hospital, and 3 and 6 months postoperatively. The clinical outcome was good or excellent in all the cases performed. On X-rays there was no implant migration or dislocation at the last follow-up and, to date, in CT reconstruction no insufficient fusion or pseudarthrosis has been observed. We cannot report any local complication. Results were promising and encouraging at a short-term control. Follow-up will be continued

Introduction. Vertebral body tethering (VBT) is a non-fusion technique to correct scoliosis. It allows correction of scoliosis through Growth Modulation (GM) by tethering the convex side to allow concave unrestricted growth similar to the hemi-epiphysiodesis concept. The other modality is Anterior Scoliosis Correction (ASC) where the tether is able to perform most of the correction immediately where limited growth is expected. Methods. Retrospective analysis of clinical and radiographic data of 20 patients between 2014 to 2016 with a mean 5 year follow (range 4–6). Results. There were 10 patients in each group with a total of 23 curves operated on. VBT-GM mean age was 12.5y with mean Risser 0.63 and VBT-ASC was14.9y with a Risser of 3.66. Mean preop VBT-GM Cobb was 46° with a Fulcrum unbend of 13.6° compared to VBT-ASC 56.9° with 32.2° unbend. Postop VBT-GM was 21° and VBT-ASC Cobb was 10.8°. The early postop Correction Rate was 54.3% vs 81% whereas FBCI was 77.1% vs 186.6%. The last XR at mean 5y was 22.2° (VBT-GM) and 16.9° (VBT-ASC) 95% avoided fusion. Open TRC group had 3 over corrections. 1 patient alone had overcorrection, unplanned second stage and conversion to fusion. Discussion and Conclusion. We show a high success rate (95%) in helping children avoid fusion. Vertebral body tethering is a safe technique for correction of scoliosis in the skeletally immature patient. This is the first report at 5 years that shows two modalities of VBT can be employed depending on the skeletal maturity of the patient: Growth Modulation and Anterior Scoliosis Correction

Although previous studies have shown poor correlation between clinical symptoms due to lumbar stenois and radiologic stenosis, no study has corrected for congenital variation in vertebral body size among individuals. This purpose of this study is to determine the relationship between the degree of radiographic lumbar spinal stenosis, adjusted with an internal control for vertebral body size, and disability from lumbar stenosis. One hundred and twenty-three consecutive patients with clinical and radiologic confirmation of neural impingement secondary to lumbar stenosis were enrolled prospectively. Thecal sac AP diameter (TSD) and cross sectional area (CSA), and vertebral body AP dimension (VBD) were determined. These parameters were then correlated with patients’ symptoms using the modified Roland-Morris Questionnaire (RMQ) disability score. This study found no statistically significant inverse correlation between TSD and RMQ score (p=0.433) or CSA and RMQ Score (p=0.124). In addition, there was no significant inverse correlation between CSA/VBD ratio and RMQ score (p=0.036) or TSD/VBD ratio and RMQ score (p=0.109). There was a significant difference in mean RMQ scores when the patients were divided into those with CSA greater than or equal to 70 mm2 and those less than 70 mm2, with T=−2.104 and p=0.038. The degree of radiographic lumbar spinal stenosis, even with the use of an internal control of vertebral body size and standardized disability questionnaires, does not correlate with clinical symptoms. However, patients with more severe stenosis below a cross-sectional area critical threshold of 70mm2, have significantly greater functional disability

Introduction: Large anterior column defects of the thoracolumbar spine, after fracture decompression, tumour or other pathological resection, or spinal osteotomy present significant difficulties in respect to autograft procurement, donor site morbidity, graft instability and residual spinal instability. Titanium Mesh Cages for reconstruction thoracolumbar vertebral body defects (after corpectomy) offer an alternative to structural iliac crest autograft or allograft. The use of TMCs for inter-body reconstruction has been addressed yet the use of larger cages for corpectomy reconstruction has not. This study examines implant stability and deformity correction of TMCs following corpectomy reconstruction in the thoracolumbar spine. Methods: Independent radiological review before, after and at follow-up (one year) was performed for 27 patients having implantation of TMCs. Measurement of thoracolumbar kyphosis was performed before surgery, immediately post operatively, and at one year follow-up. Correction of kyphosis was expressed both as angular improvement and percentage improvement. Cage settling into adjacent vertebral bodies, translational deformities and any evidence of implant failure was sought. Results: Indications for reconstruction with TMC included burst fracture (13), post traumatic kyphosis (8), primary tumour resection (3), debridement of infection (1), and stabilisation of severe kyphotic deformity in achodroplasia with associated spinal stenosis requiring decompression (2). Desired resection and decompression was achieved as indicated. Correction of kyphosis was a mean of 12 deg / 61% (range 0 – 38 deg, 0–85%). No cage moved. One patient had kyphosis recurrence of > 5 deg (12 deg). Five patients demonstrated some settling of the cage within adjacent vertebral bodies (1–8%, mean 3.4% of height loss over construct length – the vertebral body above to the body below). Translational malposition of three cages occurred. One of these cases demonstrated the maximum settling and another was associated with the only case of instrumentation failure. Clinically significant spinal canal intrusion did not occur. One cage demonstrated buckling of the wall without evidence of other problem and the clinical result was excellent. Discussion: Use of TMCs is safe when managing vertebral body reconstruction. Significant kyphosis or translational deformity has not occurred, however minor cage settling within adjacent vertebra may occur. Fusion rate is unknown as the cage mesh obscures graft maturation. Construct failure has only occurred after pre operative translational malalignment could not be corrected. This demanding procedure offers a reconstructive option with superior structural stability and reduced bone grafting morbidity

Aims: The purpose of this study was to evaluate the clinical and radiological results of expandable titanium cages for vertebral body replacement in a prospective clinical trial. Methods: Since 04/1999 81 patients with thoracolumbar burst fractures underwent posterior stabilisation followed by vertebral body replacement using expandable titanium cages (VBR, Ulrich, Germany) þlled with cancellous bone graft. Postoperatively at 3, 6, 12 and 24 months clinical and radiological evaluation was performed including ßexion/extension views and quantitative CT-scans to assess stability and fusion. Results: Until 09/2002 40 patients had a one year, 12 a two year follow-up. Pain decreased from 62 to 25 on VAS, ROM increased and preoperative neurologic deþcit improved in 25% of patients. Average postoperative loss of lordosis was 5.5 degrees, subsidence of the cages was 4.5 mm. CT scans showed solid bony fusion in 25%, incomplete fusion in 35% and non-fusion in 40% after one year. One patient suffered of left side paralysis of diaphragm, 9 patients of post-thoracotomy-syndrome. Conclusion: With expandable cages a very exact adaptation to the height of the defect and a gradual press þt of the cage and endplates can be achieved. The clinical outcome after one and two years is similar to operative techniques using tricortical iliac crest bone graft or non-expandable cages. However, fusion could not be achieved in 40% of patients after one year

Introduction: Titanium mesh cages (TMC) for the reconstruction of thoracolumbar vertebral body defects offer an alternative to structural iliac crest autograft or allograft. The stability and safety of these cages has not been addressed. Aim: To assess the stability and safety of titanium mesh cages in the reconstruction of thoracolumbar vertebral body defects. Method: Independent radiological review before and after surgery, and at follow-up was performed for 27 patients having implantation of TMCs. Measurements of thoracolumbar kyphosis, cage settling, translational deformities and any evidence of implant failure were recorded. Results: Indications for reconstruction with TMC included burst fracture (13), post-traumatic kyphosis (8), primary tumour resection (3), debridement of infection (1) and stabilisation of severe kyphotic deformity in achondroplasia with spinal stenosis (2). Kyphoses were corrected by a mean of 12 degrees (61%, range: zero degrees to 38 degrees, 0% to 85%). No cage moved. One patient had a recurrence of the kyphosis of more than five degrees (12 degrees). Five patients demonstrated some settling of the cage within adjacent vertebral bodies (1% to 8%, mean = 3.4% of height loss over length). Translational malposition of three cages occurred. One of these cases demonstrated the maximum settling and another was associated with the only case of instrumentation failure. Spinal canal intrusion did not occur. Conclusions: We found that the use of TMCs was safe when managing vertebral body reconstruction. Significant kyphosis or translational deformity did not occur, however minor cage settling within adjacent vertebra did. The fusion rate is unknown as the mesh cage obscured graft maturation. Construct failure only occurred after pre-operative translational malalignment could not be corrected. This demanding procedure offers a reconstructive option with superior structural stability and reduced bone grafting morbidity

Demographics changes and the increasing incidence of metastatic bone disease are driving the significant issues of vertebral body (VB) fractures as an important consideration in the quality of life of the elderly. Whilst osteoporotic vertebral fractures have been widely studies both clinically and biomechanically, those fractures arising from metastatic infiltration in the spine are relatively poorly understood. Biomechanical in-vitro assessment of these structurally weaker specimens is an important methodology for gaining an understanding of the mechanics of such fractures in which a key aspect is the development of methodologies for predicting the failure load. Here we report on a method to predict the vertebral strength by combining computed tomography assessment with an engineering beam theory as an alternative to more complex finite element analyses and its verification within a laboratory scenario. Ninety-two human vertebral bodies with 3 different pathologies: osteoporosis, multiple myeloma (MM) and specimens containing cancer metastases were loaded using a define protocol and the failure loads recorded. Analysis of the resulting data demonstrated that the mean difference between predicted and experimental failure loads was 0.25kN, 0.41kN and 0.79 kN, with adjunct correlation coefficients of 0.93, 0.64 and 0.79 for osteoporotic, metastatic and MM VBs, respectively. Issues in predicting vertebral fracture arise from extra-vertebral bony formations which add to vertebral strength in osteoporotic VB but are structurally incompetent in metastatic disease. The methodology is currently used in providing better experimental design/benchmarking within in-vitro investigations together with further exploration of its utility in the clinical arena

Introduction. : Measurements of overall vertebral bone mineral density (BMD. v. ) do not adequately explain the observed patterns of osteoporotic vertebral fracture. Perhaps bone loss from specific regions of the vertebra has a more important effect on vertebral strength, and risk of fracture, than overall bone loss? We hypothesise that ‘stress shielding’ of the anterior vertebral body by the neural arch in erect standing postures can reduce BMD. v. in the anterior vertebral body and thereby reduce vertebral compressive strength. Materials and Methods: A compressive force of 1.5kN was applied to lumbar ‘motion segments’. positioned to simulate erect standing posture. Compressive stresses within the intervertebral disc were measured by pulling a miniature pressure transducer through it. ‘Stress profiles’ were integrated over area to calculate the total compressive force on the disc. 1. This was subtracted from the 1.5kN to calculate the force resisted by the neural arch. Motion segments were then compressed to failure in moderate flexion (to simulate heavy lifting) and their compressive strength obtained. After disarticulation, the BMD. v. , of the whole and the anterior half of each vertebral body was measured by dual energy x-ray absorptiometry (DXA). We report preliminary results from 9 specimens, aged 72–92 yrs. Results: Vertebral strength (in flexion) was inversely related to load-bearing by the neural arch in erect posture (r. 2. =0.42, p=0.05). Strength was directly related to the BMD. v. of the whole (r. 2. =0.65, p=0.06) and the anterior (r. 2. =0.8, p=0.005) vertebral body. Conclusions: These results suggest that habitual load-bearing by the neural arch in erect postures can lead to stress shielding of the anterior vertebral body so that the latter losesBMD. v. , and the vertebra is weakened in the anterior vertebral body appears to be a BMD. v. better predictor of vertebral strength than BMD. v,. of the whole vertebra

Abstract. Aims. Vertebral body tethering (VBT) is a non-fusion technique to correct scoliosis allowing correction of scoliosis through growth modulation (GM) by tethering the convex side to allow concave unrestricted growth similar to the hemiepiphysiodesis concept. The other modality is anterior scoliosis correction (ASC) where the tether is able to perform most of the correction immediately where limited growth is expected. Methods. A retrospective analysis of 20 patients (M:F=19:1 – 9–17 years) between January 2014 to December 2016 with a mean five-year follow-up (4 to 7). Results. There were ten patients in each group with a total of 23 curves operated upon. VBT-GM mean age −12.5 years (9 to 14), mean Risser of 0.63 (0 to 2) and VBT-ASC was 14.9 years (13 to 17) and mean Risser of 3.66 (3 to 5). Mean preoperative VBT-GM Cobb was 47.4° (40°–58°) compared to VBT-ASC 56.5° (40°–79°). Postoperative VBT-GM Cobb was 20.3° and VBT-ASC was 11.2°. The early postoperative correction rate was 54.3% versus 81% whereas Fulcrum Bending Correction Index (FBCI) was 93.1% vs 146.6%. Latest Cobb angle at mean five years' follow-up was 19.4° (VBT-GM) and 16.5° (VBT-ASC). Overall, 5% of patients required fusion. Conclusion. We show a high success rate (95%) in helping children avoid fusion at five years post-surgery. VBT is a safe technique for scoliosis correction in the skeletally immature patient. This is the first report at five years showing two possible options of VBT depending on the skeletal maturity of the patient: GM and ASC

Aims: To determine the relationship between the percentage of polymethylmethacrylate cement þll of osteoporotic vertebral bodies during percutaneous vertebroplasty and the percentage restoration of strength and stiffness. Methods: The volume of 120 vertebral bodies (T6-L5) harvested from 10 osteoporotic spines female cadavers was determined by Archimedes displacement. Compression fractures were experimentally created to determine the initial strength and stiffness. The vertebral bodies were stabilized using bipedicular injections of between 2-8mL of cement and then recompressed and post treatment strength and stiffness was measured. Linear regression was used to check for the relationship between percent volume þll and percent restored stiffness and strength. Results: The correlation between percentage þll and restored strength and stiffness was weak, r2 = 0.21 and r2 = 0.27 respectively. The correlation showed that on average, a 16.2% cement þll of the VB volume was needed to restore strength and 29.8% þll was needed to restore stiffness). Conclusions: Strength and stiffness are weakly correlated with the percentage þll volume of cement injected during vertebroplasty

The new distractable titanium implant (Synex) is designated for replacement of the vertebral body following fracture, posttraumatic kyphosis or tumor. Synex was compared with the “Harms” cage (MOSS, 22x28 mm, stabilising ring) in two test series. Test A: Measurement of the compressive strength of the vertebral body end-plate in uniaxial loading via both implants; Test B: Analysis of the bisegmental stability after corpectomy, replacement of L1 and stabilisation. Materials and methods: In testseries A human vertebral specimens (L1) were matched according to bone mineral density (BMD). They were axially loaded (v=5mm/min) to failure via Synex (n=6) or MOSS (n=6) in an electrohydraulic testing device with load-displacement recording. In test series B the bisegmental motion (T12-L2) of 12 spinal specimens were tested in a 3D loading simulator with moments of 0–7.5 Nm for the six directions. After testing the intact spine, we replaced L1 and stabilised with Fixateur interne (USS) or Ventrofix (VFix). Analysis of the range of motion (ROM), elastic zone (EZ) and neutral zone (NZ) for five conditions: 1) Intact specimen, 2) USS+Synex, 3) USS+MOSS, 4) VFix+Synex, 5) VFix+MOSS (randomized order). Results: With Synex, significantly higher compression forces were recorded at 1–2 mm deformation. Ultimate compression force (Fmax) was higher (3396 N vs. 2719 N) and the distance until point of failure (Dmax) was significantly less using Synex. A significant correlation (R=0.89) between Fmax and BMD was found. Significantly higher stability was noted with USS+Synex for extension, lateral bending, and axial rotation. No differences between Synex and MOSS were observed in combination with VFix. The combined instrumentation (USS) was superior to the anterior one (VFix). The possibility of secondary dislocation, loss of correction, or posttraumatic kyphosis can be decreased using Synex for replacement of the vertebral body, compared with MOSS. A combined anterior-posterior stabilisation provides higher biomechanical stability compared with an anterior construct