Both posterior and anterior surgery have potential for complete scoliosis correction. Significant difference in judging the procedures still persists. Aim. To establish objective advantages and risks of the procedures, basing upon long term results. Method. From 1982–2007, 859 anterior(A) and 388 posterior(P) instrumentations were performed by the same surgeon. Single level thoracotomy used even in double curves. Spinal canal was never opened, rib heads left intact, ribs were fractured at the top of rib hump. Zielke rod was used for correction, and another rod added for aditional correction and stabilisation. Various posterior instrumentations were used. Results. CORRECTION (A)frontal 67-45-16(76%), sagital +6, (P)frontal 66-44-29(56%), sag+3; OP. TIME (A)140(50–300), (P)155(110–350); BLOOD REPL. (A)18%, (P)92%; HOSP STAY (A)10, (P)13; VC (A)-10%, (P)0%; SPORT ACT. (A)3mths, (P)12mths; MAJOR COMPLICATIONS: no deaths, (A)1 aorta rupture, 1 bronchus penetration, 0,7% haematothorax, 0,6% reinstrumentation, 0,7% infections demanding op, (P)2 paraplegia (0,5%), 3.9% infections, 4.9% reinstrumentation. Discussion. (A)required no neuromonitoring, no intensive care unit. Blood replacement was occasionally used only for double curves (11 segm), and in preop. anemia. Most of the complications were preventable. Hospitalisation was longer in (P) group due to wound problems. Pulmonary decrease was found only in curves greater than 100 °. Halo traction improved VC, but both instr. had no influence on further improv. In (A)VC recovered in 6 months. Conclusions. (A) can be performed in less radical and agressive way. Anterior release significantly mobilizes the spine and decreases necessary corrective forces. Infection was more frequent in (P) but consequences were more dramatic in (A). All major complications in (A) were preventable. There is temporary decrease in pulmonary function after (A). We could not find objectives for (A) to have more morbidity than (P). Due to superior results we still prefer (A) in surgery of AIS. Our indications for (P) is VC<40%, age, poor bone quality, surgery in upper thoracic spine

Introduction. Short-segment posterior instrumentation for spine fractures is threatened by unacceptable failure rates. Two important design objectives of pedicle screws, bending and pullout strength, may conflict with each other. Hypothesis. Multiobjective optimization study with artificial neural network (ANN) algorithm and genetic algorithm (GA). Materials & Methods. Three-dimensional finite element (FE) methods were applied to investigate the optimal designs of pedicle screws with an outer diameter of 7 mm using a multiobjective approach for these two objectives. Based on the FE results on an L25 orthogonal array, two objective functions were developed by an ANN algorithm. Then, the trade-off solutions known as Pareto optima were explored by a GA. The optimal design was validated by mechanical tests. Results. The knee solutions of the Pareto fronts had simultaneous high bending and pullout strength ranging from 92 to 94 percent of their maxima. The corresponding range of the design parameters was 3.8 to 4.06 mm for inner diameter and 3.21 to 3.3 mm for pitch; 0 mm for beginning position of conical angle, 0.4 mm for proximal root radius, 5 degrees for proximal half angle, and 0.1 mm for thread width. The optimal design was well validated by mechanical tests, comparing with commercially available pedicle screws. Discussion & Conclusions. The optimal design of pedicle screws obtained could achieve an ideal with high mechanical performance in both bending and pullout tests

Study Design. Retrospective review. Objective. To report the technique and results of vertebral column decancellation (VCD) for the management of sharp angular spinal deformity. Summary of Background Data. The goal of management of sharp angular spinal deformity is to realign the spinal deformity and safely decompress the neurological elements. However, some shortcomings related to current osteotomy treatment for these deformities are still evident. Methods. From January 2004 to March 2007, 45 patients (27 males/18 females) with severe sharp angular spinal deformities at our institution underwent VCD. The diagnoses included 29 congenital kyphoscoliosis and 16 Pott's deformity. The operative technique included multilevel VCD, disc removal, osteoclasis of the concave cortex, compression of the convex cortex accompanied by posterior instrumentation with pedicle screws. Preoperative and postoperative radiographic evaluation was performed. Intraoperative, postoperative and general complications were noted. Results. For a kyphosis type deformity, an average of 2.2 vertebrae was decancellated (range, 2to 4 vertebrae). The mean preoperative kyphosis was +98.6° (range, 82° to 138°), and the meankyphosis in the immediate postoperative period was +16.4° (range, 4° to 30°) with an averagepostoperative correction of +82.2° (range, 61° to 124°). For a kyphoscoliosis type deformity, thecorrection rate was 64% in the coronal plane (from 83.4° to 30.0°) postoperatively and 32.5°(61% correction) at 2 years follow-up. In the sagittal plane, the average preoperative curve of88.5° corrected to 28.6° immediately after surgery and to 31.0° at 2 years follow-up. All patientshad solid fusion at latest follow-up. Complications were encountered in 8 patients (17.8%) andincluded transient neurological deficit and complete paralysis (n = 1). Conclusion. Single stage posterior vertebral column decancellation (VCD) is an effective option to manage severe sharp angular spinal deformities