| Backgrouds:Scoliosis is a lateral curvature deformity of spine with a curve angle more than 10°.It is common in young children,and has seriously affected the physical and mental health of patients.The idiopathic scoliosis is the maximal proportion of cases of scoliosis,which's pathogenesis is not yet clear.With the improvement of the third internal fixation instrument and the application of the three-dimensional correction, the scoliosis patients could be gain good correction outcomes.However,some cases sufferd decompensation after surgery.Most surgeon considered that a comprehensive and effective classification should be developed to guide the correction surgery.The King,Lenke,PUMC classification could guide the correction surgery effectually in the treatment of idiopathic scoliosis.The three classification have characteristics respectively,and have a correlation among them.How to distinguish the characteristics of the deformity with idiopatic scoliosis classification and select the exact range of fusion,is the criticality of the surgery.The development of pedicle screw instrument improved the spinal surgery significantly and promoted the treatment of serious spinal diseases such scoliosis effectively.Three-dimensional deformity of the spine easily lead to fixation failure, and the wrong screw insertion would lead to serious complications.The Application of Computer Assisted Navigation System increased the efficiency and safety of implanting placement.However,the application could not be extented because of its high price.Therefore we need a precise,simple and practical method of measuring pedicle channel parameters in order to assist surgery.Three-dimensional (3D)reconstruction using computer can be applied to design and mimic the procedure of operation,which combined the visualization technique and the spinal surgery.Objectives:1.A retrospective study was performed to evaluate the outcomes of correction surgery for idiopathic scoliosis.2.To discuss the application of King,Lenke,PUMC classification and compare the significance of guiding correction surgery among three classifications.3.To evaluate the outcome of selective thoracic fusion and fixation in major thoracic(Lenke I type) idiopathic scoliosis,and analyze the influence of distal fusion level(DFL) on postoperative trunk balance.4.To explore the technique of mimicing implanting pedicle screw and the accurately measurement of pedicle channel parameters based on Three-dimensional reconstruction using computer.5.To evaluate it's preliminary clinical application in spinal orthopaedics surgery.Methods:1.Eighty patients with adolescent idiopathic scoliosis were treated with correction surgery from 2001 to 2006.There were 27 males and 53 females with the average age of 15.4 years(range 10 to 18 years).The Cobb angles,apical vertebra translation(AVT) and shift of head(SH) of the major curve,were measured and analyzed in the preoperative,postoperative and the last follow-up X-ray radiographies. 2.All cases were divided into six groups according to whether the surgery technique were strictly in agreement to the guiding principle of the three classifications and trunck balance after surgery,and were compared the rates of postoperative trunk imbalance among groups.3.38 cases of Lenke I type were grouped according to the DFL with reference to the neutroal rotated vertebrae(NV),including NV+(lower than NV) group, NV(exactly NV) group,and NV-(higher than NV) group.The trunk shift and the rates of postoperative trunk imbalance were compared among groups.4.38 cases of Lenke I type were divided into trunck balance group and trunk imbalance group,the correction outcome of thoracic curve,lumber curve,and the NV-DFL were compared between groups.5.Preoperative and postoperative spiral CT scan of deformity levels were performed in 4 spinal deformity patients in our hospital.Scan condition include tube tension 120kv,slice increment 0.625mm,matrix 512×512.All the images were saved as dicom format(515kb) and imported into the personal computer. Mimics10.01 software was used to recombinate data,reconstruct 3D model of spine and mimic implanting the 3D model of pedicle screw.It's calculated the angles,maximal length and diameter of the pedicle channel and screw model.6.Pedicle screws were strictly implanted according to the parameters of preoperative design with the measurement of pedicle channel and model.The success rate of pedicle screw placement were compared between the group(10 screws) of computer-aided mimicing and the group(10 screws) of routine way. TSPA(transverse section pedicle screw angle) were compared between the group of preoperative mimicing implanting and the group of actually implanting. Results:1.The average preoperative coronal Cobb angles was 56.1°,the average postoperative Cobb angles was 22.3°,as the correction was 59%,and the lost of angles at last follow-up was 4.7°.The average preoperative AVT was 5.5cm,the postoperative AVT was 2.4cm,as the correction was 57%,and the lost of distance at the last follow-up was 0.5cm.The average preoperative SH were 2.8cm with 40 cases of trunk imbalance,the postoperative SH was 1.2cm,and the SH at last follow-up was 1.4cm with 23 cases of trunk imbalance.2.All the cases could be classified using the Lenke and PUMC classification;Only 70 cases could be classified using King classification.The patients that were treated strictly in agreement to classification were 48 cases(68.6%)according to King classification,63 cases(81.7%) according to Lenke classification,57(74%) cases according to PUMC classification respectively.The rates of postoperative trunk imbalance from them were 14.5%,14.3%and 7%respectively,there were no statistical significance among the difference of them(P＞0.05).3.There were 8 cases of trunk imbalance in 38 cases Lenke I type.The rate of postoperative trunk imbalance in NV- group(42.9%) was higher than NV+ group(0%) and NV group(13.3%) with statistical significance(P＜0.05);The postoperative trunk shift in NV- group(1.88cm) was higher than NV+ group (0.64cm) and NV group(0.92cm) with statistical significance(P＜0.05).4.The NV-DFL in trunk imbalance group(0.88) was more than in trunk balance group(0) with statistical significance(P＜0.05);The lumber curve Cobb angle in trunk imbalance group(22.5°) was more than in trunk balance group(14.8°) with statistical significance(P＜0.05).5.The parameters and the real axis section from the pedicle of the deformity vertebrae arch can be obtained through 3D reconstruction technique by computer. 6.The group of computer-aided mimicing had no case of failing pedicle screw placement,while the group of routine way had 4 cases.The success rates of them are 100%and 60%respectively,and the difference between them were statistical significance(P＜0.05).The TSPA in preoperative mimicing implanting group and actually implanting group were 17.1°and 17.7°respectively,there were no statistical significance(P＞0.05) and high consistency between them.Conclusions:1.The three-dimensional correction surgery can gain good correction outcomes in the treatment for idiopathic scoliosis.2.The King,Lenke,PUMC classification could guide the correction surgery effectually in the treatment of idiopathic scoliosis.Appropriate correction according to the right selection of fusion area should be based on the characteristic of curve,which is the criticality of the surgery.3.The major thoracic idiopathic scoliosis could gain good correction outcomes by selective thoracic fusion that is based on NV as the DFL.Trunk may be imbalance if the DFL is too high.4.The technique of mimicing implanting pedicle screw with 3D reconstruction can provide the accurate parameters from pedicle channel of the deformity vertebrae arch,which could provide simple and practical new methods for the computer-aided mimesis of spinal surgery.5.The computer-aided technique is more safe and effictive than the rountin way in implanting pedicle screw.
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