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A novel scoliosis instrumentation using special superelastic nickel-titanium shape memory rods: a biomechanical analysis using a calibrated computer model and data from a clinical trial.
Wang, X, Yeung, K, Cheung, JPY, Lau, JY, Qi, W, Cheung, KM, Aubin, CE
Spine deformity. 2020;(3):369-379
Abstract
STUDY DESIGN Biomechanical analysis of scoliosis instrumentation using superelastic Nickel-titanium shape memory (SNT) rods. OBJECTIVE To compare SNT with conventional Titanium (Ti) and Cobalt-chrome (Co-Cr) rods. A clinical trial has documented comparable efficacy between two adolescent idiopathic scoliosis (AIS) cohorts instrumented using SNT versus conventional Ti rods. The shape memory and superelasticity of the SNT rod are thought to allow easy rod insertion, progressive curve correction, and correction from spinal tissue relaxation, but study is yet to be done to assess the effects of the shape memory and superelasticity. METHODS Instrumentations of AIS patients from the clinical trial were computationally simulated using SNT, Ti and Co-Cr rods (5.5 or 6 mm; 30°, 50° or 60° sagittal contouring angles; 0°, 25° or 50° coronal over-contouring angles). Curve correction, its improvement from stress relaxation in the spine, and loads in the instrumentation constructs were computed and compared. RESULTS The simulated main thoracic Cobb angles (MT) and thoracic kyphosis with the SNT rods were 4°-7° higher and 1°-2° lower than the Ti and Co-Cr rods, respectively. Bone-implant forces with Ti and Co-Cr rods were higher than the SNT rods by 84% and 130% at 18 °C and 35% and 65% at 37 °C, respectively (p < 0.001). Further corrections of the MT from the simulated stress relaxation in the spine were 4°-8° with the SNT rods versus 2°-5° with the Ti and Co-Cr rods (p < 0.001). CONCLUSION This study concurs with clinical observation that the SNT rods are easier to insert and can result in similar correction to the conventional rods. The SNT rods allow significantly lower bone-implant forces and have the ability to take advantage of post-instrumentation correction as the tissues relax.
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Surgical Outcomes of Anterior Versus Posterior Fusion in Lenke Type 1 Adolescent Idiopathic Scoliosis.
Vavruch, L, Brink, RC, Malmqvist, M, Schlösser, TPC, van Stralen, M, Abul-Kasim, K, Ohlin, A, Castelein, RM, Tropp, H
Spine. 2019;(14):E823-E832
Abstract
STUDY DESIGN Retrospective study. OBJECTIVE To describe surgical results in two and three dimensions and patient-reported outcomes of scoliosis treatment for Lenke type 1 idiopathic curves with an open anterior or posterior approach. SUMMARY OF BACKGROUND DATA Different surgical techniques have been described to prevent curve progression and to restore spinal alignment in idiopathic scoliosis. The spine can be accessed via an anterior or a posterior approach. However, the surgical outcomes, especially in three dimensions, for different surgical approaches remain unclear. METHODS Cohorts of Lenke curve type 1 idiopathic scoliosis patients, after anterior or posterior spinal fusion were recruited, to measure curve characteristics on conventional radiographs, before and after surgery and after 2 years follow-up, whereas the vertebral axial rotation, true mid-sagittal anterior-posterior height ratio of individual structures, and spinal height differences were measured on 3D reconstructions of the pre- and postoperative supine low-dose computed tomography (CT) scans. Additionally, the intraoperative parameters were described and the patients completed the Scoliosis Research Society outcomes and the 3-level version of EuroQol Group questionnaires postoperatively. RESULTS Fifty-three patients with Lenke curve type 1 idiopathic scoliosis (26 in the anterior cohort and 27 in the posterior cohort) were analyzed. Fewer vertebrae were instrumented in the anterior cohort compared with the posterior cohort (P < 0.001), with less surgery time and lower intraoperative blood loss (P < 0.001). The Cobb angle correction of the primary thoracic curve directly after surgery was 57 ± 12% in the anterior cohort and 73 ± 12% in the posterior cohort (P < 0.001) and 55 ± 13% and 66 ± 12% (P = 0.001) at 2 years follow-up. Postoperative 3D alignment restoration and questionnaires showed no significant differences between the cohorts. CONCLUSION This study suggests that Lenke type 1 curves can be effectively managed surgically with either an open anterior or posterior approach. Each approach, however, has specific advantages and challenges, as described in this study, which must be considered before treating each patient. LEVEL OF EVIDENCE 3.
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Association between calcium-phosphorus balance and adolescent idiopathic scoliosis: A meta-analysis.
Zhu, Q, Chen, J, Chen, C, Wang, H, Yang, S
Acta orthopaedica et traumatologica turcica. 2019;(6):468-473
Abstract
STUDY DESIGN A systematic review and meta-analysis. OBJECTIVE The objective of this meta-analysis was to evaluate the association between calcium-phosphorus balance and adolescent idiopathic scoliosis (AIS). METHODS Databases, including PubMed, OVID database, Web of Science, CBM database and CNKI database were searched for the relevant case control studies and cross-sectional studies. Two authors selected studies and extracted data independently. Data analysis was performed by Review Manager Software 5.0. Subgroup analysis was performed on the serum level of vitamin D according to gender and menstruation. RESULTS Five studies were included, with a total of 646 cases of AIS and 791 controls. AIS group had a lower serum level of vitamin D compared to control group [MD = -6.74, 95% CI (-9.47, -4.00)]. Gender and menstruation condition were thought to have no effect on the primary outcome of vitamin D level by subgroup analysis [MD = -5.97, 95% CI (7.61, -4.34)]. The AIS group had a lower calcium level [SMD= -0.77, 95% CI (-1.51, -0.02)] and calcitonin level compared to control group. There was no statistical difference in phosphorus level [SMD=0.5, 95% CI (-0.46, 0.57)] and parathyroid hormone level [SMD = -0.11, 95% CI (-0.54, -0.31)]. Meanwhile, the observational indexes, including serum levels of calcium, phosphorus, parathyroid hormone and calcitonin were within normal limits. CONCLUSION Vitamin D deficiency may be involved in the pathogenesis of AIS by influencing the regulation of calcium-phosphors metabolism on human bone. Therefore, we suggest to screen vitamin D level in AIS patients. LEVEL OF EVIDENCE Level III, Therapeutic Study.
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Is pharmacological anticoagulant prophylaxis necessary for adolescent idiopathic scoliosis surgery?
Kochai, A, Cicekli, O, Bayam, L, Türker, M, Sariyilmaz, K, Erkorkmaz, Ü
Medicine. 2019;(29):e16552
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Abstract
We report the outcomes of mechanical prophylaxis and chemoprophylaxis in patients who underwent elective surgery for idiopathic adolescent scoliosis (AIS).We retrospectively studied the patients who underwent posterior spinal instrumentation for AIS. The patients were divided into three groups: Group A low-molecular-weight heparin (LMWH) started at 8 hours after surgery; Group B LMWH started at 24 hr after surgery; Group C did not receive chemoprophylaxis. The data about wound oozing, need for transfusion, preoperative and postoperative hemoglobin level, length of stay in hospital, interval from the surgery to removal of closed suction drainage tube, postoperative blood loss from closed suction drain, deep venous thrombosis (DVT), and pulmonary embolism (PE) were investigated.The mean age and Lenke classification for all the groups were similar. No DVT or PE was detected in any group. The mean blood loss from the drain was higher in Group A (400 mL) and Group B (450 mL) when compared to Group C (150 mL) (P = .001). There were more wound oozing in Groups A (5) and B (6) than in Group C (3) (P = .585). Three patients in Group B, 3 patients in Group A, and no patient in Group C had superficial infections. However, there was no statistical difference between the groups (P = .182). Postoperative hospital stay was significantly longer in Groups A (6 days) and B (6 days) then in Group C (5 days) (P = .001).Our current study claims that chemoprophylaxis is not necessary for the patients without risk factors after AIS surgery. Early mobilization and mechanoprophylaxis represents adequate prophylaxis in addition to pain management and well hydration in patients' routine treatment. The complications of chemoprophylaxis are not correlated to the initiation time of prophylaxis.