In this study, the reinforcement by screws for the wood perpendicular to the grain subjected to a rotational moment has been studied. For the estimation of rotational stiffness and yield moment, the reinforcement effe...In this study, the reinforcement by screws for the wood perpendicular to the grain subjected to a rotational moment has been studied. For the estimation of rotational stiffness and yield moment, the reinforcement effect by the screws which varies depending on their position under the bearing plate was evaluated by taking the internal displacement distribution of the wood into account. The Finite Element Analysis (FEA) was used to investigate the internal displacement distribution of the wood. Then an appropriate function was found out to meet well with various internal displacement distributions under the bearing plate. The equations, which can estimate rotational stiffness and yield moment of the bearing performance of the wood reinforced by screws, were derived from the shear resistance mechanism between the screw and wood by considering their relative displacement distribution. Then rotational tests were carried out with the wood reinforced by the screws, setting screw thread at the various positions. Agreements between prediction and experimental results were very well. It was found that the screw reinforcement was effective, provided screw length should be longer for the wood height.展开更多
Twisted multilayers of two-dimensional materials attract widespread research interest due to their intriguing electronic and optical properties related to their chiral symmetry breaking and moiréeffects.The two-d...Twisted multilayers of two-dimensional materials attract widespread research interest due to their intriguing electronic and optical properties related to their chiral symmetry breaking and moiréeffects.The two-dimensional transition metal dichalcogenide MoSe_(2) is a particularly promising material for twisted multilayers,capable of sustaining moiréexcitons.Here,we report on a rational bottomup synthesis approach for twisted MoSe_(2) flakes by chemical vapor transport(CVT).Screw dislocation-driven growth was forced by surface-fused SiO_(2)nanoparticles on the substrates that serve as potential nucleation points in low supersaturation condition.Thus,crystal growth by in-situ CVT under addition of MoCl_(5) leads to bulk 2H-MoSe_(2) in a temperature gradient from 900 to 820℃ with a dwell time of 96 h.Hexagonally shaped 2H-MoSe_(2) flakes were grown from 710 to 685℃ with a dwell time of 30 min on SiO_(2)@Al_(2)O_(3)(0001)substrates.Electron backscatter diffraction as well as electron microscopy reveals the screw dislocation-driven growth of triangular 3R-MoSe_(2) with individual step heights between 0.9 and 2.9 nm on SiO_(2)@Si(100)under the same conditions.Finally,twisted MoSe_(2) flakes exhibiting a twist angle of 19°with respect to the[010]zone axis could be synthesized.展开更多
BACKGROUND Bioabsorbable interference screws are a widely used option for graft fixation in anterior cruciate ligament(ACL)reconstruction.Their ability to degrade over time and avoid secondary hardware removal makes t...BACKGROUND Bioabsorbable interference screws are a widely used option for graft fixation in anterior cruciate ligament(ACL)reconstruction.Their ability to degrade over time and avoid secondary hardware removal makes them advantageous.However,complications such as breakage and intra-articular migration of screws can cause significant clinical issues,including joint pain,swelling,and cartilage damage.Early diagnosis and management are critical in such cases.CASE SUMMARY A 26-year-old male presented with knee pain and swelling one year after ACL reconstruction using a hamstring graft and bioabsorbable tibial interference screw.The patient had been engaged in rigorous physical activity as part of military training.Clinical examination revealed mild effusion without instability,and imaging showed screw breakage with intra-articular migration.Therapeutic arthroscopy confirmed intact graft tension,and broken screw fragments were removed successfully.The patient resumed normal activity two weeks after surgery.CONCLUSION This case highlights the potential complications associated with bioabsorbable screws,emphasizing the need for meticulous surgical technique,postoperative monitoring,and timely intervention.A comprehensive review of the literature illustrates the mechanisms,risk factors,and preventive strategies associated with screw-related complications.展开更多
BACKGROUND Pedicle screw instrumentation is a critical technique in spinal surgery,offering effective stabilization for various spinal conditions.However,the impact of intraoperative imaging quality—specifically the ...BACKGROUND Pedicle screw instrumentation is a critical technique in spinal surgery,offering effective stabilization for various spinal conditions.However,the impact of intraoperative imaging quality—specifically the use of both anteroposterior(AP)and lateral views—on surgical outcomes remains insufficiently studied.Evaluating whether the adequacy of these imaging modalities affects the risk of unplanned returns to theatre(URTT)within 90 days due to screw malplacement is essential for refining surgical practices and improving patient care.AIM To evaluate how intraoperative imaging adequacy influences unplanned returnto-theatre rates,focusing on AP and lateral fluoroscopic views.METHODS This retrospective cohort study analyzed 1335 patients who underwent thoracolumbar and sacral pedicle screw instrumentation between January 2013 and December 2022.Data on intraoperative imaging adequacy,screw placement,and URTT events were collected and statistically analyzed using IBM SPSS v23.Imaging adequacy was assessed based on the presence of both AP and lateral views,and outcomes were compared between imaging groups.RESULTS A total of 9016 pedicle screws were inserted,with 82 screws identified as malplaced in 52 patients.Of these,46 patients required URTT due to screw malplacement,with 37 returning within 90 days(URTT90).Patients with both AP and lateral imaging saved intraoperatively had significantly lower URTT90 rates compared to those with only lateral imaging saved,demonstrating the critical role of imaging adequacy in improving surgical outcomes.CONCLUSION This study underscores that comprehensive intraoperative imaging with both AP and lateral views reduces unplanned returns,improves outcomes,enhances precision,and offers a cost-effective approach for better spinal surgery results.展开更多
BACKGROUND Retrograde pubic ramus screw placement is an effective technique but requires substantial surgical expertise and specialized equipment.The management of osteoporotic anterior pelvic ring injuries remains ch...BACKGROUND Retrograde pubic ramus screw placement is an effective technique but requires substantial surgical expertise and specialized equipment.The management of osteoporotic anterior pelvic ring injuries remains challenging due to technical difficulties and a high risk of complications.AIM To introduce a novel and simplified surgical approach that utilizes a custom-designed handheld pelvic alignment guide(HPAG)in combination with a 6.0 mm hollow screw,aiming to enhance the accuracy,efficiency,and safety of retrograde pubic ramus screw fixation in osteoporotic pelvic fragility fractures.METHODS The HPAG and 6.0 mm hollow screw were employed during surgical treatment.A 2.0-3.0 cm incision was made to expose the optimal screw entry point.Intraop-erative pelvic inlet and obturator oblique views were used to monitor fracture reduction and guide screw insertion.Clinical outcomes and fracture reduction quality were evaluated using Matta,visual analog scale,and Majeed scores during follow-ups.A representative case is presented to demonstrate the surgical procedure in detail.RESULTS No perioperative complications were observed.The mean operative time was 35.2±6.97 minutes,with a screw insertion time of 7.25±1.86 minutes,an average incision length of 2.8±0.67 cm,and mean blood loss of 43.25±15.64 mL.At one-year follow-up,seven patients achieved excellent Majeed scores and three achieved good scores.CONCLUSION No perioperative complications were observed.The mean operative time was 35.2±6.97 minutes,with a screw insertion time of 7.25±1.86 minutes,an average incision length of 2.8±0.67 cm,and mean blood loss of 43.25±15.64 mL.At one-year follow-up,seven patients achieved excellent Majeed scores and three achieved good scores.展开更多
Pedicle screw fixation remains the gold standard for stabilizing unstable thoracolumbar fractures.However,ensuring long-term instrumentation stability continues to challenge both surgeons and implant designers.The stu...Pedicle screw fixation remains the gold standard for stabilizing unstable thoracolumbar fractures.However,ensuring long-term instrumentation stability continues to challenge both surgeons and implant designers.The study by Bokov et al contributes significantly to this discussion,identifying predictors of pedicle screw loosening such as low bone radiodensity,longer fixation constructs,and extensive decompression.Adjunctive strategies-auxiliary posterior fusion,anterior column reconstruction,and intermediate screw usage-support an individualized,biomechanically sound surgical plan.In this article,we explore the clinical relevance of these findings within spinal trauma care.We emphasize the role of preoperative bone quality assessment,including computed tomography-based Hounsfield unit analysis and magnetic resonance imaging-derived vertebral bone quality score,as modifiable predictors of long-term outcomes.We also discuss innovations in screw design,surface coatings,and patient-specific planning to reduce failure risk.Furthermore,emerging technologies such as finite element modeling and 3D-printed instrumentation may refine patient-specific strategies.By integrating biomechanical principles with personalized surgical planning,future approaches may enhance fixation durability.Ultimately,aligning mechanical stability with biological sustainability is critical to reducing implant failure in complex thoracolumbar trauma cases.展开更多
In pedicle screw fixation,surgical robot and preoperative planning are enabling technologies to improve the accuracy and safety of pedicle screw placement.In this study,an automatic segmentation method for the pedicle...In pedicle screw fixation,surgical robot and preoperative planning are enabling technologies to improve the accuracy and safety of pedicle screw placement.In this study,an automatic segmentation method for the pedicle and vertebral body is proposed based on the 3D anatomical features of vertebrae.Further,an optimal insertion path is obtained to balance the safety of pedicle screw placement and the vertebral-screw interface strength.The pedicle screw radius is then determined based on the pedicle radius.A classification method is proposed to assess the accuracy of path planning.Finally,the surgical robot’s path can be updated based on the actual positions of the surgical robot and the patient.The CT data of 12 human vertebrae(T6−L5),10 porcine vertebrae(L1−L5)and 5 ovine vertebrae(L1−L5)are used to validate the effectiveness of the proposed method.All pedicle screw placement paths are successfully generated,achieving an excellence or good rate of 98%.Ex vivo pedicle screw placement experiments are conducted on human spine phantom,porcine and ovine spines,and in vivo experiment is conducted on a Bama miniature pig.In the proposed method,both safety and accuracy of pedicle screw placement are improved.According to the widely recognized Gertzbein-Robbins classification,93.18%of the outcomes achieve Grade A,showing promising potential in clinics.展开更多
BACKGROUND Comminuted calcaneal fractures present significant treatment challenges.Open reduction and internal fixation carries risks such as infection and skin necrosis,while minimally invasive techniques may comprom...BACKGROUND Comminuted calcaneal fractures present significant treatment challenges.Open reduction and internal fixation carries risks such as infection and skin necrosis,while minimally invasive techniques may compromise reduction stability.Conservative management is generally limited to minimally displaced fractures.Traditional Chinese manual bone-setting has a long history in fracture treatment and is renowned globally for achieving functional reduction.It offers distinct advantages including lower cost,minimal soft tissue trauma,and the avoidance of expensive reduction equipment or internal fixation materials.CASE SUMMARY A 60-year-old female presented with left foot pain and limited mobility following a fall.Computed tomography scan revealed a Sanders type IV calcaneal fracture with a Böhler angle of 0°.A standardized,stepwise Traditional Chinese manual bone-setting was initially performed,followed by percutaneous screw fixation through several mini-incisions after satisfactory alignment was confirmed under fluoroscopy.The Visual Analog Scale score decreased from 5 on postoperative day 1 to 3 by day 3.The American Orthopaedic Foot and Ankle Society score improved from 73 at 6 weeks to 90 at 3 months,indicating rapid functional recovery and high patient satisfaction.At 7 months postoperatively,the American Orthopaedic Foot and Ankle Society score reached 95,prompting removal of internal fixation.At the 6-year follow-up,reduction remained well maintained,with the Böhler angle preserved at 22°.CONCLUSION The combination of Traditional Chinese manual bone-setting and percutaneous screw fixation achieved satisfactory functional reduction for comminuted calcaneal fractures.展开更多
The aim of this study was to assess the potential of surgical guides as a complementary tool to augmented reality(AR)in enhancing the safety and precision of pedicle screw placement in spinal surgery.Four trainers wer...The aim of this study was to assess the potential of surgical guides as a complementary tool to augmented reality(AR)in enhancing the safety and precision of pedicle screw placement in spinal surgery.Four trainers were divided into the AR navigation group using surgical guides and the free-hand group.Each group consisted of a novice and an experienced spine surgeon.A total of 80 pedicle screws were implanted.First,the AR group reconstructed the 3D model and planned the screw insertion route according to the computed tomography data of L2 lumbar vertebrae.Then,the Microsoft HoloLens™2 was used to identify the vertebral model,and the planned virtual path was superimposed on the real cone model.Next,the screw was placed according to the projected trajectory.Finally,Micron Tracker was used to measure the deviation of screws from the preoperatively planned trajectory,and pedicle screws were evaluated using the Gertzbein-Robbins scale.In the AR group,the linear deviations of the experienced doctor and the novice were(1.59±0.39)mm and(1.73±0.52)mm respectively,and the angle deviations were 2.72°±0.61°and 2.87°±0.63°respectively.In the free-hand group,the linear deviations of the experienced doctor and the novice were(2.88±0.58)mm and(5.25±0.62)mm respectively,and the angle deviations were 4.41°±1.18°and 7.15°±1.45°respectively.Both kinds of deviations between the two groups were significantly different(P<0.05).The screw accuracy rate was 95%in the AR navigation group and 77.5%in the free-hand group.The results of this study indicate that the integration of surgical guides and AR is an innovative technique that can substantially enhance the safety and precision of spinal surgery and assist inexperienced doctors in completing the surgery.展开更多
Objective:To observe and study the actual effects of percutaneous pedicle screw minimally invasive surgery in the treatment of spinal fractures and its impact on spinal function.Methods:This study included 48 patients...Objective:To observe and study the actual effects of percutaneous pedicle screw minimally invasive surgery in the treatment of spinal fractures and its impact on spinal function.Methods:This study included 48 patients with spinal fractures admitted between May 2023 and May 2024.The patients were divided into a control group and an experimental group based on treatment differences,with 24 patients in each group.The control group underwent open internal fixation surgery,while the experimental group received percutaneous pedicle screw minimally invasive surgery.Clinical index improvements,cervical dysfunction index,Japanese Orthopaedic Association scores,and pain level improvements were compared between the two groups.Results:The intraoperative blood loss,incision length,operation time,and hospitalization duration in the experimental group were(88.63±18.85),(6.32±1.05),(73.42±4.05),and(12.58±2.56),respectively,compared to(279.95±17.32),(12.89±1.36),(89.93±4.79),and(22.41±2.87)in the control group.Significant differences were observed between the groups,with the experimental group showing superior improvements across all metrics(P<0.05).Conclusion:Percutaneous pedicle screw minimally invasive surgery shows more significant effects in treating spinal fractures,particularly in improving cervical and lumbar spine function,enhancing treatment efficacy and safety,reducing pain levels,and shortening recovery time.Clinical application and promotion are recommended.展开更多
The 3 D non isothermal flow of non Newtonian viscous polymer melt in a co rotating twin screw extruder is modeled. The distributions of the velocity, temperature, pressure and the viscous dissipation in the fl...The 3 D non isothermal flow of non Newtonian viscous polymer melt in a co rotating twin screw extruder is modeled. The distributions of the velocity, temperature, pressure and the viscous dissipation in the flow domain are presented by using a fluid dynamics analysis package (Polyflow). The numerical results show that the temperatures are high in the intermeshing region and on the screw surface, the maximum pressure and the minimum pressure occur in the intermeshing region, and the flow rate is almost proportional to the screw speed.展开更多
The complexity of the kinematics and dynamics of a manipulator makes it necessary to simplify the modeling process.However,the traditional representations cannot achieve this because of the absence of coordinate invar...The complexity of the kinematics and dynamics of a manipulator makes it necessary to simplify the modeling process.However,the traditional representations cannot achieve this because of the absence of coordinate invariance.Therefore,the coordinate invariant method is an important research issue.First,the rigid-body acceleration,the time derivative of the twist,is proved to be a screw,and its physical meaning is explained.Based on the twist and the rigid-body acceleration,the acceleration of the end-effector is expressed as a linear-bilinear form,and the kinematics Hessian matrix of the manipulator（represented by Lie bracket）is deduced.Further,Newton-Euler＇s equation is rewritten as a linear-bilinear form,from which the dynamics Hessian matrix of a rigid body is obtained.The formulae and the dynamics Hessian matrix are proved to be coordinate invariant.Referring to the principle of virtual work,the dynamics Hessian matrix of the parallel manipulator is gotten and the detailed dynamic model is derived.An index of dynamical coupling based on dynamics Hessian matrix is presented.In the end,a foldable parallel manipulator is taken as an example to validate the deduced kinematics and dynamics formulae.The screw theory based method can simplify the kinematics and dynamics of a manipulator,also the corresponding dynamics Hessian matrix can be used to evaluate the dynamical coupling of a manipulator.展开更多
Because the deployable structures are complex multi-loop structures and methods of derivation which lead to simpler kinematic and dynamic equations of motion are the subject of research effort, the kinematics and dyna...Because the deployable structures are complex multi-loop structures and methods of derivation which lead to simpler kinematic and dynamic equations of motion are the subject of research effort, the kinematics and dynamics of deployable structures with scissor-like-elements are presented based on screw theory and the principle of virtual work respectively. According to the geometric characteristic of the deployable structure examined, the basic structural unit is the common scissor-like-element（SLE）. First, a spatial deployable structure, comprised of three SLEs, is defined, and the constraint topology graph is obtained. The equations of motion are then derived based on screw theory and the geometric nature of scissor elements. Second, to develop the dynamics of the whole deployable structure, the local coordinates of the SLEs and the Jacobian matrices of the center of mass of the deployable structure are derived. Then, the equivalent forces are assembled and added in the equations of motion based on the principle of virtual work. Finally, dynamic behavior and unfolded process of the deployable structure are simulated. Its figures of velocity, acceleration and input torque are obtained based on the simulate results. Screw theory not only provides an efficient solution formulation and theory guidance for complex multi-closed loop deployable structures, but also extends the method to solve dynamics of deployable structures. As an efficient mathematical tool, the simper equations of motion are derived based on screw theory.展开更多
Computer-navigated pedicle screw insertion is applied to the thoracic and lumbar spine to attain high insertion accuracy and a low rate of screw-related complications.However,some in vivo and in vitro studies have sho...Computer-navigated pedicle screw insertion is applied to the thoracic and lumbar spine to attain high insertion accuracy and a low rate of screw-related complications.However,some in vivo and in vitro studies have shown that no advantages are gained with the use of navigation techniques compared to conventional techniques.Additionally,inconsistent conclusions have been drawn in various studies due to different population characteristics and methods used to assess the accuracy of screw placement.Moreover,it is not clear whether pedicle screw insertion with navigation techniques decreases the incidence of screw-related complications.Therefore,this study was sought to perform a meta-analysis of all available prospective evidence regarding pedicle screw insertion with or without navigation techniques in human thoracic and lumbar spine.We considered in vivo comparative studies that assessed the results of pedicle screw placement with or without navigation techniques.PubMed,Ovid MEDLINE and EMBASE databases were searched.Three published randomized controlled trials（RCTs） and nine retrospective comparative studies met the inclusion criteria.These studies included a total of 732 patients in whom 4,953 screws were inserted.In conclusion,accuracy of the position of grade I,II,III and IV screws and complication rate related to pedicle screw placement were significantly increased when navigation techniques were used in comparison to conventional techniques.Future research in this area should include RCTs with well-planned methodology to limit bias and report on validated,patient-based outcome measures.展开更多
Pelvic fractures are often caused by high-energy injuries and accompanied by hemodynamic instability.Traditional open surgery has a large amount of bleeding,which is not suitable for patients with acute pelvic fractur...Pelvic fractures are often caused by high-energy injuries and accompanied by hemodynamic instability.Traditional open surgery has a large amount of bleeding,which is not suitable for patients with acute pelvic fracture.Navigationguided,percutaneous puncture-screw implantation has gradually become a preferred procedure due to its advantages,which include less trauma,faster recovery times,and less bleeding.However,due to the complexity of pelvic anatomy,doctors often encounter some problems when using navigation to treat pelvic fractures.This article reviews the indications,contraindications,surgical procedures,and related complications of this procedure for the treatment of sacral fractures,sacroiliac joint injuries,pelvic ring injuries,and acetabular fractures.We also analyze the causes of inaccurate screw placement.Percutaneous screw placement under navigational guidance has the advantages of high accuracy,low incidence of complications and small soft-tissue damage,minimal blood loss,short hospital stays,and quick recovery.There is no difference in the incidence of complications between surgeries performed by new doctors and experienced ones.However,computer navigation technology requires extensive training,and attention should be given to avoid complications such as screw misplacement,intestinal injury,and serious blood vessel and nerve injuries caused by navigational drift.展开更多
Based on the functional theory, catastrophe theory, simultaneity principle and the idea of strength reduction method （SRM）, the bearing capacity functional anti SRM of pile group foundation were established, and the...Based on the functional theory, catastrophe theory, simultaneity principle and the idea of strength reduction method （SRM）, the bearing capacity functional anti SRM of pile group foundation were established, and the criteria of ultimate load and the concept of safety storage coefficient （Css） were advanced. The inclined ultimate loads by the static loading test, load increment method （LIM） and SRM are compared. Theoretically, the ultimate load of piles does not change with the loading levels when it is calculated by SRM. When the one strength reduction parameter is applied in the calculation boundary, there are calculating errors because the bearing capacity action of soils happened in the finite zone. The inclined 10adings are 108, 132 and 144 kN, and SSC are 1.07, 0.94 and 0.79, respectively, so the calculation values of ultimate loads are about 115.56, 124.08 and 113.76 kN, respectively. The error between calculations and observation values is less than 6%. But .the error between calculations of LIM and observations is 20%. Because of the effect of inclined loading, the push-rotation phenomenon of screw pile group appears. Under this testing, the ultimate bearing capacity of piles is mostly determined by the horizontal ultimate bearing capacity, and the effect of the vertical component of inclined load should also be considered.展开更多
Scissor-like element has a number of applications in deployable structures such as planar deployable structure (PDS) and ring deployable structure(RDS). However, the mobility analysis of the multi-loop deployable stru...Scissor-like element has a number of applications in deployable structures such as planar deployable structure (PDS) and ring deployable structure(RDS). However, the mobility analysis of the multi-loop deployable structures is made more difficulty by the traditional mobility formula, because the deployable structure is a very complex structure with multi-loop. Therefore, On the basis of screw theory, the calculation method of mobility of deployable structures of SLE is thoroughly discussed. In order to investigate the mobility, decomposing and composing structures(DCS) are developed, and the basic units are able to be obtained. On the basis of the deployable structures’ geometrical characteristics, there exists a closed-loop quadrilateral structure and some non-closed-loop quadrilateral structures in PDS. Also, a six legs parallel structure is present in RDS. The basic units’ mobility can be solved by both the methods of screw theory and topology constraint graphs. Then, composing the related basic units, the formula of planar deployable structures’ mobility can be built and solves the mobility of ring deployable structure. The analysis method solves the mobility analysis of the multi-loop deployable structures which is difficulty by the traditional method, and plays an important role in further research about the mobility of other complex deployable structures.展开更多
[Abstract] Objective： To discuss the indications, surgical procedures, and curative effect of dynamic hip screw （DHS） in the treatment of femoral neck fracture in the elderly. Methods： A retrospective study was c...[Abstract] Objective： To discuss the indications, surgical procedures, and curative effect of dynamic hip screw （DHS） in the treatment of femoral neck fracture in the elderly. Methods： A retrospective study was conducted to analyse the clinical data of 42 elderly patients who had been treated for femoral neck fracture with DHS in our department between June 2009 and November 2011. There were 21 males and 21 females with a mean age of 68.5 years （range 60-75 years）. According to the Garden Classification, there were 19 cases of type II, 21 cases of type III and 2 cases of type IV fractures. By the Singh In- dex Classification, there were 3 cases of level 2, 19 cases of level 3 and 20 cases of level 4 fractures. The Harris cri- terion, complications and function recovery after operation were analysed. Results： The average hospitalization time in 42 patients was 11.2 days （range 7-21 days）. All patients were followed up for 12-26 months （mean 18 months）. No lung infection, deep venous thrombosis or other complications occurred. Partial backing-out of the screws was found in 2 cases. The internal fixation device was with- drawn after fracture healing. Internal fixation cutting was found in 1 case, and he had a good recovery after total hip arthroplasty. The time for fracture healing ranged from 3-6 months （average 4.5 months）. According to Harris criteri- on, 15 cases were rated as excellent, 24 good, 2 fair and 1 poor. The Harris scale was significantly improved from 30.52＋2.71 preoperatively to 86.61＋2.53 at 6 months post- operatively （P〈0.05）. Conclusion： DHS, being minimal invasive, al- lowing early activity and weight-bearing, is advisable for treatment of elderly patients with femoral neck fracture. In addition, it can avoid complications seen in artificial joint replacement. It is especially suitable for patients with mild osteoporosis.展开更多
To enhance the fusion of graft bone in thoracolumbar vertebrae and minimize the postoperative loss of correction, short-segment pedicle screw fixation was reinforced with posterior moselizee bone grafting in vertebrae...To enhance the fusion of graft bone in thoracolumbar vertebrae and minimize the postoperative loss of correction, short-segment pedicle screw fixation was reinforced with posterior moselizee bone grafting in vertebrae for spinal fusion in patients with thoracrolumbar vertebrate fractures. Seventy patients with thoracrolumbar vertebrate fractures were treated by short-segment pedicle screw fixation and were randomly divided into two groups. Fractures in group A （n=20） were rein-forced with posterior morselized bone grafting in vertebrae for spinal fusion, while patients group B （n=50） did not receive the morselized bone grafting for bone fusion. The two groups were compared in terms of kyphotic deformity, anterior vertebral height, instrument failure and neurological functions after the treatment. Frankel grading system was used for the evaluation of neurological evaluation and Denis scoring scale was employed for pain assessment. The results showed that the kyphosis correction was achieved in both group A and group B （group A： 6.4 degree; group B： 5.4 degree）/At the end of follow-up, kyphosis correction was maintained in group A but lost in group B （P=0.0001）. Postoperatively, greater anterior height was achieved in group A than in group B （P〈0.01）. During follow-up study, anterior vertebral height was maintained only in Group A （P〈0.001）. Both group A and group B showed good Denis pain scores （P1 and P2） but group A outdid group B in terms of control of severe and constant pain （P4 and P5）. By Frankel criteria, the changes in neurological functions in group A was better than those of group B （P〈0.001）. It is concluded that reinforcement of short-segment pedicle fixation with morselized bone grafting for the treatment of patients with thoracolumbar vertebrae fracture could achieve and maintain kyphosis correction, and it may also increase and maintain anterior vertebral height. Morselized bone grafting in vertebrae offers immediate spinal stability in patients with thoracolumbar vertebrate fractures, decreases the instrument failure and provides better postoperative pain control than without the morselized bone grafting.展开更多
This study explored the feasibility of employing computer-aided design(CAD)and 3 dimensional(3D)-printed personalized guide plate for the mini-invasive percutaneous internal screw fixation of fractured scaphoid.The st...This study explored the feasibility of employing computer-aided design(CAD)and 3 dimensional(3D)-printed personalized guide plate for the mini-invasive percutaneous internal screw fixation of fractured scaphoid.The study consisted of two parts:(1)experimentation on upper limbs from corpses and(2)preliminary clinical application.Corpse experiments involved upper limbs of 6 adult corpses.The specimens of upper limbs were subjected to plain CT scan.Then the CT data were input into computer to conduct 3D reconstruction of wrist region.The direction and depth of the guide wire and screw were designed on the basis of the principle that screw should lie at the center of scaphoid and the long axis of the screw should be aligned with that of the scaphoid.The carpal bone model and the guide plate were designed and 3D-printed.By using the guide plates,the guide wire was placed and the cannulated compression screw was inserted.The wrist region was examined by X-ray and CT to observe the location of the screw in the scaphoid.The scaphoid was longitudinally excised to grossly observe the location and evaluate the result of screw insertion.For clinical application,the guide plate was employed in 4 patients with fresh scaphoid fracture using the aforementioned operative technique.Our results showed that,in the 6 corpse limbs,the guide plate well fitted the skin surface and the guide wire and screw were accurately put in place in one session.X-ray examination and gross observation confirmed that the screw was satisfactorily positioned and the result met the requirements of the preoperative design.For 4 patients,the guide wire and screw were all precisely inserted into place in one session.The operation time and X-ray exposure times were apparently reduced.The imaging examination exhibited satisfactory results and the hand functioned well.It was concluded that the operative guide plate used for the miniinvasive percutaneous internal screw fixation of fractured scaphoid not only can assist in accurate placement of screw but also shorten operation time and reduce insertion and X-ray exposure times,thereby reducing the radiation injury and damage to the substance and the blood circulation of carpal bone.Its use can also improve the learning curve of surgeons.展开更多
文摘In this study, the reinforcement by screws for the wood perpendicular to the grain subjected to a rotational moment has been studied. For the estimation of rotational stiffness and yield moment, the reinforcement effect by the screws which varies depending on their position under the bearing plate was evaluated by taking the internal displacement distribution of the wood into account. The Finite Element Analysis (FEA) was used to investigate the internal displacement distribution of the wood. Then an appropriate function was found out to meet well with various internal displacement distributions under the bearing plate. The equations, which can estimate rotational stiffness and yield moment of the bearing performance of the wood reinforced by screws, were derived from the shear resistance mechanism between the screw and wood by considering their relative displacement distribution. Then rotational tests were carried out with the wood reinforced by the screws, setting screw thread at the various positions. Agreements between prediction and experimental results were very well. It was found that the screw reinforcement was effective, provided screw length should be longer for the wood height.
基金funding from SFB 1415 subproject B04(Deutsche Forschungsgemeinschaft,No.417590517)supported by the Deutsche Forschungsgemeinschaft through the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter-ct.qmat(EXC 2147,No.390858490)the support provided by the DRESDEN-concept alliance of research institutions.
文摘Twisted multilayers of two-dimensional materials attract widespread research interest due to their intriguing electronic and optical properties related to their chiral symmetry breaking and moiréeffects.The two-dimensional transition metal dichalcogenide MoSe_(2) is a particularly promising material for twisted multilayers,capable of sustaining moiréexcitons.Here,we report on a rational bottomup synthesis approach for twisted MoSe_(2) flakes by chemical vapor transport(CVT).Screw dislocation-driven growth was forced by surface-fused SiO_(2)nanoparticles on the substrates that serve as potential nucleation points in low supersaturation condition.Thus,crystal growth by in-situ CVT under addition of MoCl_(5) leads to bulk 2H-MoSe_(2) in a temperature gradient from 900 to 820℃ with a dwell time of 96 h.Hexagonally shaped 2H-MoSe_(2) flakes were grown from 710 to 685℃ with a dwell time of 30 min on SiO_(2)@Al_(2)O_(3)(0001)substrates.Electron backscatter diffraction as well as electron microscopy reveals the screw dislocation-driven growth of triangular 3R-MoSe_(2) with individual step heights between 0.9 and 2.9 nm on SiO_(2)@Si(100)under the same conditions.Finally,twisted MoSe_(2) flakes exhibiting a twist angle of 19°with respect to the[010]zone axis could be synthesized.
文摘BACKGROUND Bioabsorbable interference screws are a widely used option for graft fixation in anterior cruciate ligament(ACL)reconstruction.Their ability to degrade over time and avoid secondary hardware removal makes them advantageous.However,complications such as breakage and intra-articular migration of screws can cause significant clinical issues,including joint pain,swelling,and cartilage damage.Early diagnosis and management are critical in such cases.CASE SUMMARY A 26-year-old male presented with knee pain and swelling one year after ACL reconstruction using a hamstring graft and bioabsorbable tibial interference screw.The patient had been engaged in rigorous physical activity as part of military training.Clinical examination revealed mild effusion without instability,and imaging showed screw breakage with intra-articular migration.Therapeutic arthroscopy confirmed intact graft tension,and broken screw fragments were removed successfully.The patient resumed normal activity two weeks after surgery.CONCLUSION This case highlights the potential complications associated with bioabsorbable screws,emphasizing the need for meticulous surgical technique,postoperative monitoring,and timely intervention.A comprehensive review of the literature illustrates the mechanisms,risk factors,and preventive strategies associated with screw-related complications.
文摘BACKGROUND Pedicle screw instrumentation is a critical technique in spinal surgery,offering effective stabilization for various spinal conditions.However,the impact of intraoperative imaging quality—specifically the use of both anteroposterior(AP)and lateral views—on surgical outcomes remains insufficiently studied.Evaluating whether the adequacy of these imaging modalities affects the risk of unplanned returns to theatre(URTT)within 90 days due to screw malplacement is essential for refining surgical practices and improving patient care.AIM To evaluate how intraoperative imaging adequacy influences unplanned returnto-theatre rates,focusing on AP and lateral fluoroscopic views.METHODS This retrospective cohort study analyzed 1335 patients who underwent thoracolumbar and sacral pedicle screw instrumentation between January 2013 and December 2022.Data on intraoperative imaging adequacy,screw placement,and URTT events were collected and statistically analyzed using IBM SPSS v23.Imaging adequacy was assessed based on the presence of both AP and lateral views,and outcomes were compared between imaging groups.RESULTS A total of 9016 pedicle screws were inserted,with 82 screws identified as malplaced in 52 patients.Of these,46 patients required URTT due to screw malplacement,with 37 returning within 90 days(URTT90).Patients with both AP and lateral imaging saved intraoperatively had significantly lower URTT90 rates compared to those with only lateral imaging saved,demonstrating the critical role of imaging adequacy in improving surgical outcomes.CONCLUSION This study underscores that comprehensive intraoperative imaging with both AP and lateral views reduces unplanned returns,improves outcomes,enhances precision,and offers a cost-effective approach for better spinal surgery results.
基金Supported by Shanghai Tongren Hospital,Shanghai Jiaotong University School of Medicine,No.TRYJ2024 LC16the National Natural Science Foundation of China,No.82102577the Laboratory Open Fund of Key Technology and Materials in Minimally Invasive Spine Surgery,No.2024JZWC-YBA05.
文摘BACKGROUND Retrograde pubic ramus screw placement is an effective technique but requires substantial surgical expertise and specialized equipment.The management of osteoporotic anterior pelvic ring injuries remains challenging due to technical difficulties and a high risk of complications.AIM To introduce a novel and simplified surgical approach that utilizes a custom-designed handheld pelvic alignment guide(HPAG)in combination with a 6.0 mm hollow screw,aiming to enhance the accuracy,efficiency,and safety of retrograde pubic ramus screw fixation in osteoporotic pelvic fragility fractures.METHODS The HPAG and 6.0 mm hollow screw were employed during surgical treatment.A 2.0-3.0 cm incision was made to expose the optimal screw entry point.Intraop-erative pelvic inlet and obturator oblique views were used to monitor fracture reduction and guide screw insertion.Clinical outcomes and fracture reduction quality were evaluated using Matta,visual analog scale,and Majeed scores during follow-ups.A representative case is presented to demonstrate the surgical procedure in detail.RESULTS No perioperative complications were observed.The mean operative time was 35.2±6.97 minutes,with a screw insertion time of 7.25±1.86 minutes,an average incision length of 2.8±0.67 cm,and mean blood loss of 43.25±15.64 mL.At one-year follow-up,seven patients achieved excellent Majeed scores and three achieved good scores.CONCLUSION No perioperative complications were observed.The mean operative time was 35.2±6.97 minutes,with a screw insertion time of 7.25±1.86 minutes,an average incision length of 2.8±0.67 cm,and mean blood loss of 43.25±15.64 mL.At one-year follow-up,seven patients achieved excellent Majeed scores and three achieved good scores.
文摘Pedicle screw fixation remains the gold standard for stabilizing unstable thoracolumbar fractures.However,ensuring long-term instrumentation stability continues to challenge both surgeons and implant designers.The study by Bokov et al contributes significantly to this discussion,identifying predictors of pedicle screw loosening such as low bone radiodensity,longer fixation constructs,and extensive decompression.Adjunctive strategies-auxiliary posterior fusion,anterior column reconstruction,and intermediate screw usage-support an individualized,biomechanically sound surgical plan.In this article,we explore the clinical relevance of these findings within spinal trauma care.We emphasize the role of preoperative bone quality assessment,including computed tomography-based Hounsfield unit analysis and magnetic resonance imaging-derived vertebral bone quality score,as modifiable predictors of long-term outcomes.We also discuss innovations in screw design,surface coatings,and patient-specific planning to reduce failure risk.Furthermore,emerging technologies such as finite element modeling and 3D-printed instrumentation may refine patient-specific strategies.By integrating biomechanical principles with personalized surgical planning,future approaches may enhance fixation durability.Ultimately,aligning mechanical stability with biological sustainability is critical to reducing implant failure in complex thoracolumbar trauma cases.
基金Supported by Guangdong Basic and Applied Basic Research Foundation(Grant No.2024A1515011897)Shenzhen Science and Technology Program(Grant No.KQTD20210811090143060)+1 种基金Sustainable Development Science and Technology Special Project of Shenzhen(Grant No.KCXFZ20230731100900002)Tianjin Municipal Science and Technology Program(Grant No.22JCYBJC01240).
文摘In pedicle screw fixation,surgical robot and preoperative planning are enabling technologies to improve the accuracy and safety of pedicle screw placement.In this study,an automatic segmentation method for the pedicle and vertebral body is proposed based on the 3D anatomical features of vertebrae.Further,an optimal insertion path is obtained to balance the safety of pedicle screw placement and the vertebral-screw interface strength.The pedicle screw radius is then determined based on the pedicle radius.A classification method is proposed to assess the accuracy of path planning.Finally,the surgical robot’s path can be updated based on the actual positions of the surgical robot and the patient.The CT data of 12 human vertebrae(T6−L5),10 porcine vertebrae(L1−L5)and 5 ovine vertebrae(L1−L5)are used to validate the effectiveness of the proposed method.All pedicle screw placement paths are successfully generated,achieving an excellence or good rate of 98%.Ex vivo pedicle screw placement experiments are conducted on human spine phantom,porcine and ovine spines,and in vivo experiment is conducted on a Bama miniature pig.In the proposed method,both safety and accuracy of pedicle screw placement are improved.According to the widely recognized Gertzbein-Robbins classification,93.18%of the outcomes achieve Grade A,showing promising potential in clinics.
基金Supported by Jin-Wen Liu Academic Experience Heritage Studio Special Fund of National Famous Traditional Chinese Medicine,No.75.
文摘BACKGROUND Comminuted calcaneal fractures present significant treatment challenges.Open reduction and internal fixation carries risks such as infection and skin necrosis,while minimally invasive techniques may compromise reduction stability.Conservative management is generally limited to minimally displaced fractures.Traditional Chinese manual bone-setting has a long history in fracture treatment and is renowned globally for achieving functional reduction.It offers distinct advantages including lower cost,minimal soft tissue trauma,and the avoidance of expensive reduction equipment or internal fixation materials.CASE SUMMARY A 60-year-old female presented with left foot pain and limited mobility following a fall.Computed tomography scan revealed a Sanders type IV calcaneal fracture with a Böhler angle of 0°.A standardized,stepwise Traditional Chinese manual bone-setting was initially performed,followed by percutaneous screw fixation through several mini-incisions after satisfactory alignment was confirmed under fluoroscopy.The Visual Analog Scale score decreased from 5 on postoperative day 1 to 3 by day 3.The American Orthopaedic Foot and Ankle Society score improved from 73 at 6 weeks to 90 at 3 months,indicating rapid functional recovery and high patient satisfaction.At 7 months postoperatively,the American Orthopaedic Foot and Ankle Society score reached 95,prompting removal of internal fixation.At the 6-year follow-up,reduction remained well maintained,with the Böhler angle preserved at 22°.CONCLUSION The combination of Traditional Chinese manual bone-setting and percutaneous screw fixation achieved satisfactory functional reduction for comminuted calcaneal fractures.
基金the National Natural Science Foundation of China(No.11502146)the 1 Batch of 2021 MOE of PRC Industry University Collaborative Education Program(No.202101042008)。
文摘The aim of this study was to assess the potential of surgical guides as a complementary tool to augmented reality(AR)in enhancing the safety and precision of pedicle screw placement in spinal surgery.Four trainers were divided into the AR navigation group using surgical guides and the free-hand group.Each group consisted of a novice and an experienced spine surgeon.A total of 80 pedicle screws were implanted.First,the AR group reconstructed the 3D model and planned the screw insertion route according to the computed tomography data of L2 lumbar vertebrae.Then,the Microsoft HoloLens™2 was used to identify the vertebral model,and the planned virtual path was superimposed on the real cone model.Next,the screw was placed according to the projected trajectory.Finally,Micron Tracker was used to measure the deviation of screws from the preoperatively planned trajectory,and pedicle screws were evaluated using the Gertzbein-Robbins scale.In the AR group,the linear deviations of the experienced doctor and the novice were(1.59±0.39)mm and(1.73±0.52)mm respectively,and the angle deviations were 2.72°±0.61°and 2.87°±0.63°respectively.In the free-hand group,the linear deviations of the experienced doctor and the novice were(2.88±0.58)mm and(5.25±0.62)mm respectively,and the angle deviations were 4.41°±1.18°and 7.15°±1.45°respectively.Both kinds of deviations between the two groups were significantly different(P<0.05).The screw accuracy rate was 95%in the AR navigation group and 77.5%in the free-hand group.The results of this study indicate that the integration of surgical guides and AR is an innovative technique that can substantially enhance the safety and precision of spinal surgery and assist inexperienced doctors in completing the surgery.
文摘Objective:To observe and study the actual effects of percutaneous pedicle screw minimally invasive surgery in the treatment of spinal fractures and its impact on spinal function.Methods:This study included 48 patients with spinal fractures admitted between May 2023 and May 2024.The patients were divided into a control group and an experimental group based on treatment differences,with 24 patients in each group.The control group underwent open internal fixation surgery,while the experimental group received percutaneous pedicle screw minimally invasive surgery.Clinical index improvements,cervical dysfunction index,Japanese Orthopaedic Association scores,and pain level improvements were compared between the two groups.Results:The intraoperative blood loss,incision length,operation time,and hospitalization duration in the experimental group were(88.63±18.85),(6.32±1.05),(73.42±4.05),and(12.58±2.56),respectively,compared to(279.95±17.32),(12.89±1.36),(89.93±4.79),and(22.41±2.87)in the control group.Significant differences were observed between the groups,with the experimental group showing superior improvements across all metrics(P<0.05).Conclusion:Percutaneous pedicle screw minimally invasive surgery shows more significant effects in treating spinal fractures,particularly in improving cervical and lumbar spine function,enhancing treatment efficacy and safety,reducing pain levels,and shortening recovery time.Clinical application and promotion are recommended.
文摘The 3 D non isothermal flow of non Newtonian viscous polymer melt in a co rotating twin screw extruder is modeled. The distributions of the velocity, temperature, pressure and the viscous dissipation in the flow domain are presented by using a fluid dynamics analysis package (Polyflow). The numerical results show that the temperatures are high in the intermeshing region and on the screw surface, the maximum pressure and the minimum pressure occur in the intermeshing region, and the flow rate is almost proportional to the screw speed.
基金Supported by National Natural Science Foundation of China(Grant Nos.51375420,51105322)
文摘The complexity of the kinematics and dynamics of a manipulator makes it necessary to simplify the modeling process.However,the traditional representations cannot achieve this because of the absence of coordinate invariance.Therefore,the coordinate invariant method is an important research issue.First,the rigid-body acceleration,the time derivative of the twist,is proved to be a screw,and its physical meaning is explained.Based on the twist and the rigid-body acceleration,the acceleration of the end-effector is expressed as a linear-bilinear form,and the kinematics Hessian matrix of the manipulator（represented by Lie bracket）is deduced.Further,Newton-Euler＇s equation is rewritten as a linear-bilinear form,from which the dynamics Hessian matrix of a rigid body is obtained.The formulae and the dynamics Hessian matrix are proved to be coordinate invariant.Referring to the principle of virtual work,the dynamics Hessian matrix of the parallel manipulator is gotten and the detailed dynamic model is derived.An index of dynamical coupling based on dynamics Hessian matrix is presented.In the end,a foldable parallel manipulator is taken as an example to validate the deduced kinematics and dynamics formulae.The screw theory based method can simplify the kinematics and dynamics of a manipulator,also the corresponding dynamics Hessian matrix can be used to evaluate the dynamical coupling of a manipulator.
基金Supported by National Natural Science Foundation of China(Grant No.51175422)
文摘Because the deployable structures are complex multi-loop structures and methods of derivation which lead to simpler kinematic and dynamic equations of motion are the subject of research effort, the kinematics and dynamics of deployable structures with scissor-like-elements are presented based on screw theory and the principle of virtual work respectively. According to the geometric characteristic of the deployable structure examined, the basic structural unit is the common scissor-like-element（SLE）. First, a spatial deployable structure, comprised of three SLEs, is defined, and the constraint topology graph is obtained. The equations of motion are then derived based on screw theory and the geometric nature of scissor elements. Second, to develop the dynamics of the whole deployable structure, the local coordinates of the SLEs and the Jacobian matrices of the center of mass of the deployable structure are derived. Then, the equivalent forces are assembled and added in the equations of motion based on the principle of virtual work. Finally, dynamic behavior and unfolded process of the deployable structure are simulated. Its figures of velocity, acceleration and input torque are obtained based on the simulate results. Screw theory not only provides an efficient solution formulation and theory guidance for complex multi-closed loop deployable structures, but also extends the method to solve dynamics of deployable structures. As an efficient mathematical tool, the simper equations of motion are derived based on screw theory.
文摘Computer-navigated pedicle screw insertion is applied to the thoracic and lumbar spine to attain high insertion accuracy and a low rate of screw-related complications.However,some in vivo and in vitro studies have shown that no advantages are gained with the use of navigation techniques compared to conventional techniques.Additionally,inconsistent conclusions have been drawn in various studies due to different population characteristics and methods used to assess the accuracy of screw placement.Moreover,it is not clear whether pedicle screw insertion with navigation techniques decreases the incidence of screw-related complications.Therefore,this study was sought to perform a meta-analysis of all available prospective evidence regarding pedicle screw insertion with or without navigation techniques in human thoracic and lumbar spine.We considered in vivo comparative studies that assessed the results of pedicle screw placement with or without navigation techniques.PubMed,Ovid MEDLINE and EMBASE databases were searched.Three published randomized controlled trials（RCTs） and nine retrospective comparative studies met the inclusion criteria.These studies included a total of 732 patients in whom 4,953 screws were inserted.In conclusion,accuracy of the position of grade I,II,III and IV screws and complication rate related to pedicle screw placement were significantly increased when navigation techniques were used in comparison to conventional techniques.Future research in this area should include RCTs with well-planned methodology to limit bias and report on validated,patient-based outcome measures.
文摘Pelvic fractures are often caused by high-energy injuries and accompanied by hemodynamic instability.Traditional open surgery has a large amount of bleeding,which is not suitable for patients with acute pelvic fracture.Navigationguided,percutaneous puncture-screw implantation has gradually become a preferred procedure due to its advantages,which include less trauma,faster recovery times,and less bleeding.However,due to the complexity of pelvic anatomy,doctors often encounter some problems when using navigation to treat pelvic fractures.This article reviews the indications,contraindications,surgical procedures,and related complications of this procedure for the treatment of sacral fractures,sacroiliac joint injuries,pelvic ring injuries,and acetabular fractures.We also analyze the causes of inaccurate screw placement.Percutaneous screw placement under navigational guidance has the advantages of high accuracy,low incidence of complications and small soft-tissue damage,minimal blood loss,short hospital stays,and quick recovery.There is no difference in the incidence of complications between surgeries performed by new doctors and experienced ones.However,computer navigation technology requires extensive training,and attention should be given to avoid complications such as screw misplacement,intestinal injury,and serious blood vessel and nerve injuries caused by navigational drift.
基金Project(51178457) supported by the National Natural Science Foundation of ChinaProject(cstc2012jjys0001) supported by the Natural Science Foundation of Chongqing,ChinaProject(L2011231) supported by the Liaoning Education Department,China
文摘Based on the functional theory, catastrophe theory, simultaneity principle and the idea of strength reduction method （SRM）, the bearing capacity functional anti SRM of pile group foundation were established, and the criteria of ultimate load and the concept of safety storage coefficient （Css） were advanced. The inclined ultimate loads by the static loading test, load increment method （LIM） and SRM are compared. Theoretically, the ultimate load of piles does not change with the loading levels when it is calculated by SRM. When the one strength reduction parameter is applied in the calculation boundary, there are calculating errors because the bearing capacity action of soils happened in the finite zone. The inclined 10adings are 108, 132 and 144 kN, and SSC are 1.07, 0.94 and 0.79, respectively, so the calculation values of ultimate loads are about 115.56, 124.08 and 113.76 kN, respectively. The error between calculations and observation values is less than 6%. But .the error between calculations of LIM and observations is 20%. Because of the effect of inclined loading, the push-rotation phenomenon of screw pile group appears. Under this testing, the ultimate bearing capacity of piles is mostly determined by the horizontal ultimate bearing capacity, and the effect of the vertical component of inclined load should also be considered.
基金supported by National Natural Science Foundation of China(Grant No. 50875210)
文摘Scissor-like element has a number of applications in deployable structures such as planar deployable structure (PDS) and ring deployable structure(RDS). However, the mobility analysis of the multi-loop deployable structures is made more difficulty by the traditional mobility formula, because the deployable structure is a very complex structure with multi-loop. Therefore, On the basis of screw theory, the calculation method of mobility of deployable structures of SLE is thoroughly discussed. In order to investigate the mobility, decomposing and composing structures(DCS) are developed, and the basic units are able to be obtained. On the basis of the deployable structures’ geometrical characteristics, there exists a closed-loop quadrilateral structure and some non-closed-loop quadrilateral structures in PDS. Also, a six legs parallel structure is present in RDS. The basic units’ mobility can be solved by both the methods of screw theory and topology constraint graphs. Then, composing the related basic units, the formula of planar deployable structures’ mobility can be built and solves the mobility of ring deployable structure. The analysis method solves the mobility analysis of the multi-loop deployable structures which is difficulty by the traditional method, and plays an important role in further research about the mobility of other complex deployable structures.
文摘[Abstract] Objective： To discuss the indications, surgical procedures, and curative effect of dynamic hip screw （DHS） in the treatment of femoral neck fracture in the elderly. Methods： A retrospective study was conducted to analyse the clinical data of 42 elderly patients who had been treated for femoral neck fracture with DHS in our department between June 2009 and November 2011. There were 21 males and 21 females with a mean age of 68.5 years （range 60-75 years）. According to the Garden Classification, there were 19 cases of type II, 21 cases of type III and 2 cases of type IV fractures. By the Singh In- dex Classification, there were 3 cases of level 2, 19 cases of level 3 and 20 cases of level 4 fractures. The Harris cri- terion, complications and function recovery after operation were analysed. Results： The average hospitalization time in 42 patients was 11.2 days （range 7-21 days）. All patients were followed up for 12-26 months （mean 18 months）. No lung infection, deep venous thrombosis or other complications occurred. Partial backing-out of the screws was found in 2 cases. The internal fixation device was with- drawn after fracture healing. Internal fixation cutting was found in 1 case, and he had a good recovery after total hip arthroplasty. The time for fracture healing ranged from 3-6 months （average 4.5 months）. According to Harris criteri- on, 15 cases were rated as excellent, 24 good, 2 fair and 1 poor. The Harris scale was significantly improved from 30.52＋2.71 preoperatively to 86.61＋2.53 at 6 months post- operatively （P〈0.05）. Conclusion： DHS, being minimal invasive, al- lowing early activity and weight-bearing, is advisable for treatment of elderly patients with femoral neck fracture. In addition, it can avoid complications seen in artificial joint replacement. It is especially suitable for patients with mild osteoporosis.
文摘To enhance the fusion of graft bone in thoracolumbar vertebrae and minimize the postoperative loss of correction, short-segment pedicle screw fixation was reinforced with posterior moselizee bone grafting in vertebrae for spinal fusion in patients with thoracrolumbar vertebrate fractures. Seventy patients with thoracrolumbar vertebrate fractures were treated by short-segment pedicle screw fixation and were randomly divided into two groups. Fractures in group A （n=20） were rein-forced with posterior morselized bone grafting in vertebrae for spinal fusion, while patients group B （n=50） did not receive the morselized bone grafting for bone fusion. The two groups were compared in terms of kyphotic deformity, anterior vertebral height, instrument failure and neurological functions after the treatment. Frankel grading system was used for the evaluation of neurological evaluation and Denis scoring scale was employed for pain assessment. The results showed that the kyphosis correction was achieved in both group A and group B （group A： 6.4 degree; group B： 5.4 degree）/At the end of follow-up, kyphosis correction was maintained in group A but lost in group B （P=0.0001）. Postoperatively, greater anterior height was achieved in group A than in group B （P〈0.01）. During follow-up study, anterior vertebral height was maintained only in Group A （P〈0.001）. Both group A and group B showed good Denis pain scores （P1 and P2） but group A outdid group B in terms of control of severe and constant pain （P4 and P5）. By Frankel criteria, the changes in neurological functions in group A was better than those of group B （P〈0.001）. It is concluded that reinforcement of short-segment pedicle fixation with morselized bone grafting for the treatment of patients with thoracolumbar vertebrae fracture could achieve and maintain kyphosis correction, and it may also increase and maintain anterior vertebral height. Morselized bone grafting in vertebrae offers immediate spinal stability in patients with thoracolumbar vertebrate fractures, decreases the instrument failure and provides better postoperative pain control than without the morselized bone grafting.
文摘This study explored the feasibility of employing computer-aided design(CAD)and 3 dimensional(3D)-printed personalized guide plate for the mini-invasive percutaneous internal screw fixation of fractured scaphoid.The study consisted of two parts:(1)experimentation on upper limbs from corpses and(2)preliminary clinical application.Corpse experiments involved upper limbs of 6 adult corpses.The specimens of upper limbs were subjected to plain CT scan.Then the CT data were input into computer to conduct 3D reconstruction of wrist region.The direction and depth of the guide wire and screw were designed on the basis of the principle that screw should lie at the center of scaphoid and the long axis of the screw should be aligned with that of the scaphoid.The carpal bone model and the guide plate were designed and 3D-printed.By using the guide plates,the guide wire was placed and the cannulated compression screw was inserted.The wrist region was examined by X-ray and CT to observe the location of the screw in the scaphoid.The scaphoid was longitudinally excised to grossly observe the location and evaluate the result of screw insertion.For clinical application,the guide plate was employed in 4 patients with fresh scaphoid fracture using the aforementioned operative technique.Our results showed that,in the 6 corpse limbs,the guide plate well fitted the skin surface and the guide wire and screw were accurately put in place in one session.X-ray examination and gross observation confirmed that the screw was satisfactorily positioned and the result met the requirements of the preoperative design.For 4 patients,the guide wire and screw were all precisely inserted into place in one session.The operation time and X-ray exposure times were apparently reduced.The imaging examination exhibited satisfactory results and the hand functioned well.It was concluded that the operative guide plate used for the miniinvasive percutaneous internal screw fixation of fractured scaphoid not only can assist in accurate placement of screw but also shorten operation time and reduce insertion and X-ray exposure times,thereby reducing the radiation injury and damage to the substance and the blood circulation of carpal bone.Its use can also improve the learning curve of surgeons.
