Epdemiology and Treatment of Pseudarthrosis of Long Bones in the Servce D Orthopedics-Traumatology of the University Hospital of Donka

Introduction: Pseudarthrosis (PSA) of the diaphysis of long bones still remains a current problem, despite improvements in the treatment of these fractures. Our study aims to study the epidemiological and therapeutic aspects of PSA of the diaphysis of long bones. Method: This retrospective work concerns 30 cases of non-union of the diaphysis of long bones treated in the orthopedic and trauma surgery department at Donka National Hospital, during a period of 18 months from January 1, 2019 to June 30, 2020. Results: We recruited 30 patients, 80% of whom were male, with an average age of 39.9 years. Public road accidents (AVP) represented the main cause of fractures of the diaphysis of long bones 87%, they were open in 25 cases or 83%. The fractures were located in the middle 1/3 of the diaphysis of the long bones in 50% of cases. Treatment of initial fractures was traditional in 21 cases, orthopedic in 2 cases and surgical in 7 cases. It was aseptic nonunion in 28 cases (93%) and septic nonunion in 2 cases. They were hypertrophic in 7 cases, slightly hypertrophic in 5 cases, oligotrophic in 11 cases, atrophic in 6 cases and with bone defect in 1 case. The treatment was based on osteosynthesis including 16 cases of screwed “PV” plate: 7 cases of centromedullary “ECM” nailing, 2 cases of external fixator, 1 case of broaching and 4 cases of Plastering. The results according to ASAMI criteria on an anatomical level were excellent in 19 cases, good in 3 cases and poor in 3 cases, with a union rate of 76%. And 5 patients undergoing consolidation. Conclusion: Based on the literature data and the experience of our department, the true treatment of PSA requires correct management of the initial fracture without forgetting the interest in preventing AVP which appears to be an element essential, making it possible to reduce the incidence of fractures of the diaphysis.

Additive manufactured osseointegrated screws with hierarchical design

Bone screws are devices used to fix implants or bones to bones.However,conventional screws are mechanically fixed with thread and often face long-term failure due to poor osseointegration.To improve osseointegration,screws are evolving from solid and smooth to porous and rough.Additive manufacturing(AM)offers a high degree of manufacturing freedom,enabling the preparation of predesigned screws that are porous and rough.This paper provides an overview of the problems currently faced by bone screws:long-term loosening and screw breakage.Next,advances in osseointegrated screws are summarized hierarchically(sub-micro,micro,and macro).At the sub-microscale level,we describe surface-modification techniques for enhancing osseointegration.At the micro level,we summarize the micro-design parameters that affect the mechanical and biological properties of porous osseointegrated screws,including porosity,pore size,and pore shape.In addition,we highlight three promising pore shapes:triply periodic minimal surface,auxetic structure with negative Poisson ratio,and the Voronoi structure.At the macro level,we outline the strategies of graded design,gradient design,and topology optimization design to improve the mechanical strength of porous osseointegrated screws.Simultaneously,this paper outlines advances in AM technology for enhancing the mechanical properties of porous osseointegrated screws.AM osseointegrated screws with hierarchical design are expected to provide excellent long-term fixation and the required mechanical strength.

Peri-articular elbow fracture fixations with magnesium implants and a review of current literature: A case series

BACKGROUND In recent years,the use of Magnesium alloy implants have gained renewed popularity,especially after the first commercially available ConformitéEuropéenne approved Magnesium implant became available(MAGNEZIX®CS,Syntellix)in 2013.AIM To document our clinical and radiographical outcomes using magnesium implants in treating peri-articular elbow fractures.METHODS Our paper was based on a retrospective case series design.Intra-operatively,a standardized surgical technique was utilized for insertion of the magnesium implants.Post–operatively,clinic visits were standardized and physical exam findings,functional scores,and radiographs were obtained at each visit.All complications were recorded.RESULTS Five patients with 6 fractures were recruited(2 coronoid,3 radial head and 1 capitellum).The mean patient age and length of follow up was 54.6 years and 11 months respectively.All fractures healed,and none exhibited loss of reduction or complications requiring revision surgery.No patient developed synovitis of the elbow joint or suffered electrolytic reactions when titanium implants were used concurrently.CONCLUSION Although there is still a paucity of literature available on the subject and further studies are required,magnesium implants appear to be a feasible tool for fixation of peri-articular elbow fractures with promising results in our series.INTRODUCTION In recent years,the use of Magnesium alloy implants in orthopaedic surgeries have gained renewed popularity.Apart from being bioabsorbable,negating the need for implant removal,magnesium also has good osteoconductive properties[1-4].Biomechanically,it exhibits greater biomechanical strength than any pre-existing polymers,and reduces the stress-shielding effect associated with titanium and steel implants as it has a Young’s modulus closer to bone[4].Currently,the main utility of magnesium implants in the orthopaedic community is within the foot and ankle community where satisfactory results have been reported with its utility in forefoot osteotomies[5-7].However,its utility in the setting of orthopaedic trauma has been steadily increasing[8].Our study aims to document our clinical and radiographical outcomes using magnesium implants to treat peri-articular elbow fractures.To our knowledge,our study is the first study analyzing outcomes in radial head and coronoid fractures in the English literature.

Effective time, correction speed and termination time of hemiepiphysiodesis in children

In children with asymmetric growth on the medial and lateral side of limbs,if there still remains growth potential,the guided growth technique of hemiepiphysiodesis on one side of the epiphysis is recognized as a safe and effective method.However,when the hemi-epiphysiodesis start to correct the deformities,how many degrees could hemi-epiphysiodesis bring every month and when to remove the hemi-epiphysiodesis implant without rebound phenomenon are still on debate.This article reviews the current studies focus on the effective time,correction speed and termination time of hemi-epiphysiodesis.

C1C2 Wiring and Posttraumatic Atlantoaxial Dislocation: An Effective and Cheap Surgical Procedure in a Developing Country

Objectives: Atlantoaxial dislocation remains a rare and serious condition with a high preoperative and postoperative morbidity and mortality. Its successful surgical management is still challenging and gratifying for neurosurgeons. Several technics have been described such as wiring, trans articular screwing, C1C2 screwing with plate and screw introduced by Goel et al., and modified by insertion of polyaxially screw and rod many years later by Harms. Unavailability and expensiveness of upper cervical spine instrumentation device led us to C1C2 Wiring resulting in a good outcome. Finally, a quadriplegic patient with a more comfortable financial condition had ordered devices from abroad and benefit for Goel and Harms screwing technique and improved dramatically from ASIA A to ASIA E. Material and methods: This is a retrospective study of patients managed in our department by a same neurosurgeon from January 2019 to April 2024. Results: We defined 6 men and 1 woman with an average age of 33 years. Unrestrained driver in a rollover motor vehicle accident was most common. Only one patient was neurologically intact on admission. Neurovegetative disorders were noticed in one patient. Dislocation was associated to a fracture of the dens in two patients. Three patients have been successfully operated with remarkable outcome, mostly from ASIA A to E. Conclusion: C1C2 dislocation is a serious condition and C1C2 Wiring represents an effective and cheaper technic. Therefore, this technic should deserve consideration above all in low incomes countries when screwing devices are not available. Seatbelt should be demanded for motor vehicle drivers and passengers.

Watson-Jones Anatomical Approach for Open Reduction and Internal Fixation of Proximal Femoral Fractures without Image Intensifier in a Low-Resource Setting

Introduction: Standard procedures for surgical fixation of proximal femoral fractures (PFF) require an image intensifier which in developing countries remains a luxury. We hypothesized that, with a well-codified technique, the Watson Jones approach (WJA) without image intensifier nor traction table, can allow open reduction and internal fixation (ORIF) of PFF using Dynamic hip screw (DHS), with satisfactory outcome. Patients and methods: Forty one consecutive patients (mean age 59.5 ± 21.6 years, 61% males) who were followed in a Teaching Hospital for PFF treated by ORIF using the WJA and DHS from January 2016 to December 2020 were reassessed. The outcome measures were the quality of the reduction, the positioning of the implants, the tip-apex distance (TAD), the rate and delay of consolidation, the functional results using Postel Merle d’Aubigné (PMA) score, the rate of surgical site infection (SSI) and the overall mortality. Logistic regression was used to determine factors associated with mechanical failure. Results: The mean follow-up period was 33.8 ± 15.0 months. Fracture reduction was good in 31 (75.6%) cases and acceptable in 8(19.5%) cases. Implant position was fair to good in 37 (90.2%) patients. The mean TAD was 26.1 ± 3.9 mm. Three patients developed SSI. Consolidation was achieved in 38 (92.6%) patients. The functional results were good to excellent in 80.5% of patients. The overall mortality rate was 7.3%. There were an association between mechanical failure and osteoporosis (p = 0.04), fracture reduction (p = 0.003), and TAD (p = 0.025). In multivariate logistic regression, no independent factors were predictive of mechanical failure. Conclusion: This study shows that ORIF using DHS for PFF via the Watson-Jones approach without an image intensifier can give satisfactory anatomical and functional outcomes in low-resource settings. It provides and validates a reliable and reproducible technique that deserves to be diffused to surgeons in austere areas over the world.

Roller Screw and Threaded Chain Speed Reducer: An Experimental Evaluation

We are developing a speed reducer that can be considered a transformation of a worm gear reducer: the worm is replaced by an inverted roller screw, and the gear is replaced by a threaded chain drive. This configuration lessens wear, increases load capacity, and improves efficiency. The threaded chain consists of nut-shaped links. This paper presents the results of tests carried out on a prototype with a reduction ratio of 46.

Distal clavicle fractures treated by anteroinferior plating with a single screw: Two case reports

BACKGROUND For the treatment of distal clavicle fractures,each treatment method has its own advantages and disadvantages,and there is no optimal surgical solution.CASE SUMMARY Based on this,we report 2 cases of distal clavicle fractures treated utilizing an anterior inferior plate with a single screw placed in the distal,in anticipation of providing a better surgical approach to distal clavicle fracture treatment.Two patients were admitted to the hospital after trauma with a diagnosis of distal clavicle fracture,and were admitted to the hospital for internal fixation of clavicle fracture by incision and reduction,with good postoperative functional recovery.CONCLUSION With solid postoperative fixation and satisfactory prognostic functional recovery,this technique has been shown to be simple,easy to perform and effective.

Numerical investigation on the spewing mechanism of earth pressure balance shield in a high-pressure water-rich sand stratum

The spewing of a screw conveyor easily occurs from the earth pressure balance(called EPB)shield in a water-rich sand stratum.This may lead to the collapse of the tunnel face and even serious subsidence of the ground surface.To understand the spewing mechanism of the shield screw conveyor and explore the critical hydraulic condition of soil spewing in a shield–soil chamber,a simplified theoretical model for the spewing of the screw conveyor was developed based on the equation of groundwater flow in the screw conveyor under turbulent state.Thus,coupling Darcy's law with Brinkman's equation,this model was implemented within the COMSOL Multiphysics framework.The underground water flow in the shield screw conveyor was simulated so as to obtain its velocity and flow rate.Numerical simulations show that the water pressure distribution is concentrated in the lower part of the soil chamber after the groundwater enters the soil chamber.When the groundwater enters the screw conveyor,its pressure gradually decreases along the direction of the screw conveyor.When the water flow reaches the stratum–shield interface,the flow velocity changes markedly:first increases and concentrates at the entrance of the lower soil chamber,plummets and stabilizes gradually,and increases again at the exit.The soil chamber and screw conveyor are significantly depressurized.It is also found that the soil permeability coefficient can be reduced to k<2.6×10^(−4)cm/s through appropriate soil improvement,which can effectively prevent the occurrence of spewing disasters.

Gravity-Based Kinetostatic Modeling of Parallel Manipulators Using Screw Theory

The pose accuracy of parallel manipulators(PMs)is a key index to measure their performance.Establishing the grav-ity-based kinetostatic model of a parallel robot provides an important basis for its error composition and accuracy improvement.In this paper,a kinetostatic modeling approach that takes real gravity distribution into consideration is proposed to analyze the influence of gravity on the infinitesimal twist and actuator forces of PMs.First,the duality of the twist screw and constraint wrenches are used to derive the gravity-attached constraint wrenches independent of the external load and the limb stiffness matrix corresponding to the kinematics-based constraint wrenches.Sec-ond,the gravity model of the mechanism is established based on the screw theory and the principle of virtual work.Finally,the analytical formulas of the infinitesimal twist and the actuator force of PMs are obtained,and the influences of the external load,platform gravity,and rod gravity on the stiffness of the mechanism are decoupled.The non-overconstrained 3RPS and overconstrained 2PRU-UPR PMs are taken as examples to verify the proposed method.This research proposes a methodology to analyze the infinitesimal deformation of the mechanism under the influence of gravity.

Multitrack and multianchor point screw technique combined with the Wiltse approach for lesion debridement for lumbar tuberculosis

BACKGROUND The incidence of lumbar tuberculosis is high worldwide,and effective treatment is a continuing problem.AIM To study the safety and efficacy of the multitrack and multianchor point screw technique combined with the contralateral Wiltse approach for lesion debridement to treat lumbar tuberculosis.METHODS The C-reactive protein(CRP)level,erythrocyte sedimentation rate(ESR),visual analogue scale(VAS)score,oswestry disability index(ODI)and American Spinal Injury Association(ASIA)grade were recorded and analysed pre-and postoperatively.RESULTS The CRP level and ESR returned to normal,and the VAS score and ODI were decreased at 3 mo postoperatively,with significant differences compared with the preoperative values(P<0.01).Neurological dysfunction was relieved,and the ASIA grade increased,with no adverse events.CONCLUSION The multitrack,multianchor point screw fixation technique combined with the contralateral Wiltse approach for debridement is an effective and safe method for the treatment of lumbar tuberculosis.

Type Synthesis of Fully Decoupled Three Translational Parallel Mechanism with Closed-Loop Units and High Stifness

In order to solve the problem of weak stifness of the existing fully decoupled parallel mechanism, a new synthesis method of fully decoupled three translational (3T) parallel mechanisms (PMs) with closed-loop units and high stifness is proposed based on screw theory. Firstly, a new criterion for the full decoupled of PMs is presented that the reciprocal product of the transmission wrench screw matrix and the output twist screw matrix of PMs is a diagonal matrix, and all elements on the main diagonal are nonzero constants. The forms of the transmission wrench screws are determined by the criterion. Secondly, the forms of the actuated and unactuated screws can be obtained according to their relationships with the transmission wrench screws. The basic decoupled limbs are generated by combination of the above actuated and unactuated screws. Finally, a closed-loop units construction method is investigated to apply the decoupled mechanisms in a better way on the high stifness occasion. The closed-loop units are constructed in the basic decoupled limbs to generate a high-stifness fully decoupled 3T PM. Kinematic and stifness analyses show that the Jacobian matrix is a diagonal matrix, and the stifness is obviously higher than that of the coupling mechanisms, which verifes the correctness of the proposed synthesis method. The mechanism synthesized by this method has a good application prospect in vehicle durability test platform.

Task-Oriented Topology System Synthesis of Reconfigurable Legged Mobile Lander Integrating Active and Passive Metamorphoses

To explore hostile extraterrestrial landforms and construct an engineering prototype,this paper presents the task-oriented topology system synthesis of reconfigurable legged mobile lander(ReLML)with three operation modes from adjusting,landing,to roving.Compared with our preceding works,the adjusting mode with three rotations(3R)provides a totally novel exploration approach to geometrically matching and securely arriving at complex terrains dangerous to visit currently;the landing mode is redefined by two rotations one translation(2R1T),identical with the tried-and-tested Apollo and Chang'E landers to enhance survivability via reasonable touchdown buffering motion;roving mode also utilizes 2R1T motion for good motion and force properties.The reconfigurable mechanism theory is first brought into synthesizing legged mobile lander integrating active and passive metamorphoses,composed of two types of metamorphic joints and metamorphic execution and transmission mechanisms.To reveal metamorphic principles with multiple finite motions,the finite screw theory is developed to present the procedure from unified mathematical representation,modes and source phase derivations,metamorphic joint and limb design,to final structure assembly.To identify the prototype topology,the 3D optimal selection matrix method is proposed considering three operation modes,five evaluation criteria,and two topological subsystems.Finally,simulation verifies the whole task implementation process to ensure the reasonability of design.

Design and dynamic analysis of a scissors hoop-rib truss deployable antenna mechanism

As the support mechanism of space-borne antennas,space deployable antenna mechanism belongs to complex multi-closed-loop coupling mechanism,configuration design and dynamic analysis are more difficult than general parallel mechanism.In this paper,an unequal-length scissors mechanism(ULSM)is proposed by changing the position of the internal rotational joint through a basic scissors mechanism.A scissors hoop-rib truss deployable antenna mechanism(SHRTDAM)is constructed by replacing the parabolic rib with the ULSM.Kinematic analysis of SHRTDAM is conducted,and the degree of freedom(DOF)of the whole antenna mechanism is analyzed based on screw theory,the result showed that it has only one DOF.Velocity and acceleration characteristics of SHRTDAM are obtained by the screw derivative and rotation transformation.Based on Lagrange equation,dynamic model of this mechanism is established,the torque required to drive the mechanism is simulated and verified by Adams and MATLAB software.In addition,a ground experiment prototype of 1.5-m diameter was fabricated and a deployment test is conducted,which demonstrated the mobility and deployment performance of the whole mechanism.The mechanism proposed in this paper can provide a good reference for the design and analysis of large aperture space deployable antennas.

Experimental Investigation on the Strength and Ductility Performance of Steel-Timber-Steel Joints with Screw and Steel-Tube Fasteners

This article presents experimental results of steel-timber-steel(STS)joints loaded parallel to grain.Eight groups of specimens were designed,and tensile tests were performed.The fastener types and fastener numbers were considered to evaluate the tensile strengths and ductility performances of the STS joints.The screws with 6 mm diameter and the innovative steel-tubes with 18 mm diameter were adopted as connecting fasteners.The experimental results were discussed in terms of yielding and ultimate strengths,slip stiffness,and ductility factors.The ductility classification and failure mechanisms of each group of specimens were analyzed.It was demonstrated that the STS joint with large diameter steel-tubes showed acceptable ductility,which was close to the ductility of the STS joint with small diameter screws,thanks to the hollow structure of the steel-tube.The theoretical strengths of various failure modes for the joints with small diameter screws or large diameter steel-tubes were calculated and compared with the experimental results.The ductile performance of the STS joint was discussed by comparing the theoretical strengths of various failure modes.The effective number of the STS joint with multifasteners was also analyzed by considering the failure mechanisms in aspects of tensile strength and slip stiffness.

Nail Holding Performance of Self-Tapping Screws on Masson Pine and Chinese Fir Dimension Lumbers

Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.

Research and experimental analysis of precision degradation method based on the ball screw mechanism

As a key transmission component in computer numerical control(CNC) machine tools,the ball screw mechanism(BSM) is usually investigated under working load conditions. Its accuracy degradation process is relatively long,which is not conducive to the design and development of new products. In this paper,the normal wear depth of the BSM nut raceway is calculated under the variable speed operation condition using the fractal wear analysis method and the BSM’s accelerated degradation proportional wear model. Parameters of the acceleration degradation model of the double-nut preloaded ball screw pair are calculated based on the physical simulation results. The accelerated degradation test platform of the BSM is designed and manufactured to calculate the raceway wear model when the lubrication condition is broken under the variable-speed inertial load and the boundary lubrication condition under the uniform speed state. Three load forces and two samples are selected for the accelerated degradation test of the BSM. The measured friction torque of the BSM is employed as the evaluation index of the accuracy degradation test. In addition,the life cycle of the accuracy retention is accurately calculated by employing the parameters of the physical simulation model of the BSM. The calculations mentioned above can be used to estimate BSM’s accuracy performance degradation law under normal operating conditions. The application of the proposed model provides a new research method for researching the precision retention of the BSM.

Research progress on the safety of nail placement in adolescent idiopathic scoliosis surgery

Adolescent idiopathic scoliosis is a spinal deformity with unknown etiology and high incidence,especially in adolescent females.If scoliosis patients do not get effective treatment in the early stage,the degree of scoliosis will continue to worsen with the growth of age or the rapid development of scoliosis in a short time,and the appearance deformities such as high and low shoulders and razor back will gradually appear,which can affect the cardiopulmonary function and even shorten life expectancy.It has a great impact on the physical and mental health of the patients.Mild scoliosis is often well controlled by bracing,and moderate to severe scoliosis deformity often requires scoliosis corrective surgery.In adolescent idiopathic scoliosis correction,pedicle screws offer better stability and firmness,stronger orthopedic force,and lower incidence of related complications caused by instruments than traditional hook and conical internal fixation instruments.At the same time,scoliosis patients have uneven development of the left and right sides of the vertebral body,narrow diameter of concave pedicle and varying degrees of rotation of parietal vertebra,resulting in changes in the position of important anatomical structures such as spinal cord and thoracic aorta in the spinal canal.It makes it difficult to place pedicle screws,resulting in a high misplacement rate.How to improve the safety of screw placement,reduce the misplacement rate and the risk of spinal cord,nerve root,blood vessels,viscera and so on,has always been the focus of spinal surgeons.This paper summarizes the related literature on the effects of new techniques such as pedicle anatomy,complications of nail placement and computer navigation,and 3D guided template on the accuracy of screw placement in adolescent idiopathic scoliosis patients,and the safety of nail placement.In order to provide reference for clinical practice.

Surgery for fibrous dysplasia associated with aneurysmal-bone-cystlike changes in right proximal femur:A case report

BACKGROUND Fibrous dysplasia associated with aneurysmal bone cyst(ABC)-like changes in the right proximal femur has a low incidence.It is considered more difficult to make early diagnosis than for single fibrous dysplasia.CASE SUMMARY A 14-year-old woman was admitted because of persistent pain in the right hip and abnormal gait over the previous 2 mo.She had no history of present or past illness.Preoperative photography,enhanced computed tomography,and magnetic resonance imaging showed ground-glass appearance with cortical scalloping and expansion of the right proximal femur and femoral neck.Pathological examination by preoperative puncture biopsy revealed fibrous dysplasia of the right proximal femur.The patient was diagnosed with fibrous dysplasia based on medical history,physical examination,and results of laboratory,imaging and pathological examinations.According to final pathological examination,the patient was diagnosed with fibrous dysplasia of the right proximal femur associated with ABC.Curettage and allograft along with fixation of compression screws was performed for fibrous dysplasia associated with ABClike changes.No obvious allograft absorption,loosening of fixation,or secondary fracture were observed during 6-months’follow-up with re-examination by plain radiography and computed tomography.Fibrous dysplasia associated with ABClike changes in the right proximal femur has a low incidence and early diagnosis is considered more difficult than for single fibrous dysplasia.CONCLUSION We report a cases of fibrous dysplasia associated with ABC-like changes in the right proximal femur treated with curettage and allograft along with hip compression screws.

Accuracy of screw placement in the apical region of Lenke 1 adolescent idiopathic scoliosis surgery using a calibration technique for the intraoperative navigation error

Objective:To study the position and the grade of screw perforation in the apical region of adolescent idiopathic scoliosis(AIS)surgery using a calibration technique for the intraoperative navigation error,and to analyze the related factors of navigation deviation and the clinical significance of the calibration technique.Methods:From 2017 to 2020,a total of 60 Lenke 1 AIS surgical cases were enrolled in this research.The 30 cases received surgery using the intraoperative navigation system(Navigation group)and another 30 cases were assisted with intraoperative navigation system with calibration technique(Calibration group)for the intraoperative navigation error.The basic information and radiological data of the both groups were all recorded.According to the Fu Chang-feng’s pedicle channel classification system,the pedicle on the apical region of the two groups was classified.And then the accuracy of screw placement of the two groups was evaluated according to the Rao’s classification.Results:A total of 600 screws were placed in the two groups.The 297 and 303 pedicle screws were implanted in the navigation group and the calibration group,respectively.In the apical region of the calibration group,the rates of the grade 0 screw placement in type A,B and C pedicle were 95.7%,86.7%and 68.9%respectively.It was a statistically significant difference from the 73.9%,66.9%and 30.0%in the navigation group respectively(P<0.05).In the calibration group,the rates of the medial cortical perforation in the type A,B,C and D pedicle were 0%,1.6%,1.6%and 0%,respectively.The corresponding rates were 16.3%,16.9%,30.0%and 47.6%in the navigation group,respectively.Moreover,in the concave side of the apical region of the calibration group,the rates of the medial cortical perforation in the type A,B,C and D pedicle were 0%,3.6%,2.6%and 0%,respectively.Compared with the calibration group,the corresponding rates were higher in the navigation group(34.4%,25.9%,37.2%and 60.0%,respectively).No serious complications such as spinal cord or neurovascular injury occurred for the two groups.Conclusion:Compared with the intraoperative navigation system,the calibration technique for the intraoperative navigation error could provide the higher accuracy of pedicle screw placement in the apical region of the major curve,the lower medial cortical perforation rate,the less screws misplacement rate on the concave side and the less complication rate of the severe Lenke 1 AIS patients.