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28 August 2021, Volume 25 Issue 24 Previous Issue    Next Issue

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A 4-year-old child model of occipito-atlanto-axial joints established by finite element dynamic simulation Li Kun, Li Zhijun, Zhang Shaojie, Gao Shang, Sun Hao, Yang Xi, Wang Xing, Dai Lina 2021, 25 (24):  3773-3778.  doi: 10.12307/2021.078 Abstract ( 370 )   PDF (723KB) ( 88 )   Save BACKGROUND: Children’s occipito-atlanto-axial joints have their own characteristics in morphological development and physiological characteristics, and clinical injuries are more common. The establishment of finite element model can better understand the mechanism of injury, and provide a theoretical basis for the prevention, diagnosis and treatment of craniocervical junction disease, as well as the design and development of internal fixation instruments.  OBJECTIVE: To establish the C0-C2 three-dimensional finite element model for children and to provide experimental application basis for further biomechanical research. METHODS: A 4-year-old normal child was selected as the experimental source of the original data. The original data were obtained by 64-slice spiral CT scanning. The three-dimensional finite element model of C0-C2 joint was simulated by Mimics, Geomagic Studio, Hypermesh, Abaqus and other software, and the motion range and mechanical characteristics of each direction were verified. RESULTS AND CONCLUSION: The 4-year old child C0-C2 three-dimensional model containing ligaments was successfully constructed, including 444 927 grid cells and 657 617 nodes. The range of motion in all directions was good, and the range of motion in all directions of the model was located in the reference range except that C0-C1 had a large degree of motion in forward flexion and left and right rotation. The C0-C2 three-dimensional finite element model has high quasi-truth of local force and activity in all directions, and has good geometric similarity, so the model is real and effective. Figures and Tables | References | Related Articles | Metrics

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A new method for measuring the anteversion angle of the femoral neck by constructing the three-dimensional digital model of the femur  Liu Jianyou, Jia Zhongwei, Niu Jiawei, Cao Xinjie, Zhang Dong, Wei Jie 2021, 25 (24):  3779-3783.  doi: 10.12307/2021.079 Abstract ( 557 )   PDF (674KB) ( 95 )   Save BACKGROUND: The accuracy of prosthesis placement in total hip arthroplasty is very important. The classic femoral neck anteversion should be transformed into the relative position of bone markers, and the relevant bone markers may be missing in total hip arthroplasty or revision. We hope to put forward a new method to measure the anterior inclination of the femoral neck, which can be used conveniently in order to improve the accuracy of prosthesis placement. OBJECTIVE: To propose a new method for measuring the anteversion of the femoral neck through the three-dimensional digital model of the femur, combined with the classical anteversion angle of the femoral neck, to provide anatomical data for the implantation of the femoral stalk prosthesis during complex hip arthroplasty and revision, and to improve the accuracy of prosthesis placement. METHODS: A total of 82 normal femurs from 41 patients who underwent CT with bilateral femurs aged from 50 to 80 years old were selected as subjects. After the three-dimensional digital model of the femur was reconstructed by software, the surface formed by the most prominent points on the medial epicondyle, the lateral epicondyle, the greater trochanter and the axis of the femoral neck was selected, and the angle between them was our new method for measuring the anteversion of the femoral neck. This new angle was called New Anteversion angle. The corresponding points were taken to measure the New Anteversion angle and the classical anteversion angle on the reconstructed femoral model, and the data were collected and statistically analyzed to find out the relationship between them.  RESULTS AND CONCLUSION: (1) The data of 82 cases of femur were independently analyzed by t-test according to sex and orientation groups after point measurement. There was no significant difference in the classical anteversion angle between different genders and different sides (P > 0.05), and there was no significant difference in the New Anteversion angle between different genders and different sides (P > 0.05). (2) The average New Anteversion angle was (7.96±1.11)°; the average classical anteversion angle was (13.21±1.28)°. The linear regression equation was: classical anteversion angle = 10.42 ° + 0.35 × New Anteversion angle. (3) It is concluded that both the New Anteversion angle and the classical anteversion angle of the femoral neck can reflect the anteversion of the femoral neck, and there is a corresponding relationship between them in a certain range, and the combination of the two can show the true anteversion of the femoral neck in many dimensions. Figures and Tables | References | Related Articles | Metrics

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Application of three-dimensional printing technology combined with bone cement in minimally invasive treatment of the collapsed Sanders III type of calcaneal fractures Meng Lingjie, Qian Hui, Sheng Xiaolei, Lu Jianfeng, Huang Jianping, Qi Liangang, Liu Zongbao 2021, 25 (24):  3784-3789.  doi: 10.12307/2021.080 Abstract ( 342 )   PDF (1882KB) ( 61 )   Save BACKGROUND: The treatment of calcaneal fracture is still controversial at present. Traditional complications of open reduction remain high, while minimally invasive treatment has few indications and its application is limited. In recent years, with the development of three-dimensional (3D) printing technology, whether the indications of minimally invasive treatment can be expanded and achieve good results or not is the focus and hot spot of study on the treatment of calcaneal fracture.   OBJECTIVE: To explore the application value of 3D printing technology in the minimally invasive treatment of collapsed Sanders III calcaneal fractures. METHODS:  Eight patients with nine foot Sanders III calcaneal fractures who were admitted to the Department of Hand and Foot Surgery of Zhangjiagang Hospital Affiliated to Soochow University from September 2016 to April 2017. All were males, aged 50-66 years, with an average age of 57.4 years. All patients underwent CT examination and obtained 3D printed personalized posterior foot, followed by bone cement filling surgery assisted by pry reduction after simulating the position and angle of pry needle. The length, width and height of calcaneu and the Gissane angle and Bohler angle before and after surgery of all patients were recorded. The postoperative function was evaluated according to the American Orthopedic Foot Ankle Society Ankle Hindfoot Scale.   RESULTS AND CONCLUSION: (1) All patients were followed up for 26-36 months. All fractures healed. There was no collapse, leakage of bone cement, rejection reaction, skin necrosis or infection. Calcaneal shape recovered satisfactorily, and foot function was good. (2) American Orthopedic Foot Ankle Society Ankle Hindfoot Scale results showed excellent in seven cases, good in one case, and poor in one case, with excellent and good rate of 89%. (3) Bohler angle and Gissane angle of patients respectively improved from (15.73±2.46)° and (145.34±8.6)° before surgery to (25.77±2.65)° and (127.5±8.17)° after surgery. Difference was statistically significant (P < 0.001). There was no significant difference in Bohler angle and Gissane angle between immediately, and 1, 2 years after operation (P > 0.05). (4) It is indicated that 3D printing individualized bone cement filling plays an important clinical role in the treatment of collapsed Sanders III calcaneal fracture and it has the advantages of short time of individualized targeted operation, minor surgical injury, and few complications. Figures and Tables | References | Related Articles | Metrics

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Computer-assisted navigation combined with minimally invasive transforaminal lumbar interbody fusion for lumbar spondylolisthesis Qian Xuankun, Huang Hefei, Wu Chengcong, Liu Keting, Ou Hua, Zhang Jinpeng, Ren Jing, Wan Jianshan 2021, 25 (24):  3790-3795.  doi: 10.12307/2021.081 Abstract ( 502 )   PDF (728KB) ( 50 )   Save BACKGROUND: At present, some studies have reported that navigation assisted spinal surgery has the characteristics of visualization and precision compared with traditional surgery, and this tail will further explore and study it. OBJECTIVE: To compare the clinic effect between minimally invasive transforaminal lumbar interbody fusion with computer navigation and open transforaminal lumbar interbody fusion in the treatment of lumbar spondylolisthesis and provide evidence to choose a batter operative method.  METHODS: A retrospective analysis of 60 patients with lumbar spondylolisthesis who were hospitalized at the Department of Spine Surgery, No.1 People’s Hospital of Qujing from March 2014 to March 2018 undergoing transforaminal lumbar interbody fusion was conducted. Of them, 30 cases were treated with navigation and microendoscopic discectomy (minimally invasive group); other 30 cases underwent open-transforaminal lumbar interbody fusion and pedicle screw fixation (open group). Operation time, blood loss, postoperative drainage volume, postoperative bedridden time, hospitalization time, and complications were collected in both groups. Visual analogue scale scores and Oswestry disability index were followed up. Accuracy of pedicle screw insertion and bone graft fusion rate were assessed using imaging examination between the two groups. Above indexes were statistically analyzed and compared between the two groups.   RESULTS AND CONCLUSION: (1) All patients were followed up from 12 to 40 months. (2) There were no significant differences between two groups in age, sex, preoperative visual analogue scale, Oswestry disability index, and level of spondylolysis (P > 0.05). (3) The operation time was slightly longer in the minimally invasive group than in the open group, but there was no significant difference in operation time between the two groups (P > 0.05). The blood loss, the postoperative drainage volume, bedridden time and hospitalization time of minimally invasive group were significantly less than those of open group (P < 0.05). (4) Oswestry disability index and back pain visual analogue scale scores were significantly decreased after treatment in both groups; moreover, visual analogue scale scores and Oswestry disability index of minimally invasive group were lower than that of open group after operation (P < 0.05). (5) The accuracy of pedicle screw insertion of minimally invasive group was superior to that of open group (P < 0.05). (6) No obvious internal fixation loosening, broken, or abnormal activities were found in all patients during the follow-up. There was no significant difference in the bone graft fusion rate between the two groups at the last follow-up. (7) It is indicated that compared with the open transforaminal lumbar interbody fusion, computer-assisted navigation combined with microendoscopic discectomy channel minimally invasive transforaminal lumbar interbody fusion treatment for lumbar spondylolisthesis has advantages of less blood loss, less trauma, less bedridden time, rapid recovery, higher accuracy of pedicle screw insertion, which is a good selection for lumbar fusion.  Figures and Tables | References | Related Articles | Metrics

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Computer aided diagnosis of lumbar disc degeneration based on metabolomics Jiang Lihong, Wu Xiaofeng, Ouyang Lin, Luo Aifang, Huang Li 2021, 25 (24):  3796-3803.  doi: 10.12307/2021.082 Abstract ( 428 )   PDF (1194KB) ( 230 )   Save BACKGROUND: The diagnosis of lumbar disc degeneration is of great significance for the prevention of lumbar disease, and the diagnosis of lumbar disc degeneration mainly relies on the subjective evaluation of the imaging physician, which is likely to misjudge because of insufficient experience.  OBJECTIVE: To propose a computer-aided diagnosis technique for classification on the lumbar disc degeneration, and to provide reference for imaging doctors.  METHODS: Spearman correlation analysis is used to verify the correlation between magnetic resonance imaging metabolic indices of lumbar intervertebral disc and the Pfirrmann grades of lumbar disc degeneration. Several classifiers for the intelligent diagnosis of lumbar disc degeneration are developed by means of machine learning strategies such as the Softmax regression, the neural network and the support vector machine.  RESULTS AND CONCLUSSION: The result of correlation analysis showed that three metabolic indices such as fat fraction (FF) of adjacent upper and lower vertebral bodies of degenerative disc, T2* values were significantly correlated with lumbar disc degeneration. The classification accuracy of the softmax regression, the neural network and the support vector machine respectively was 0.477, 0.515 and 0.523, and kappa’s coefficient of these three diagnostic models was 0.311, 0.300 and 0.330, respectively. The actual analysis indicates that it is feasible to establish a computer-aided intelligent diagnosis of lumbar disc degeneration by using the MRI metabolic indices, showing a promising approach for the diagnosis of lumbar disc degeneration. Figures and Tables | References | Related Articles | Metrics

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Three-dimensional printing assisted screw placement and freehand pedicle screw fixation in the treatment of thoracolumbar fractures: 1-year follow-up Hu Jing, Xiang Yang, Ye Chuan, Han Ziji 2021, 25 (24):  3804-3809.  doi: 10.12307/2021.083 Abstract ( 356 )   PDF (820KB) ( 98 )   Save BACKGROUND: Percutaneous pedicle screw internal fixation was a common surgical method to reconstruct the spine and restore local stability. The accuracy and safety of pedicle screw placement directly affect the postoperative mobility and quality of life of patients. Three-dimensional (3D) printing technology can reconstruct the local structure model of the spine of patients before surgery based on accurate imaging data, simulate screw placement operation, accurately measure the insertion point, direction, and angle, and then provide the data support for intraoperative operation. Theoretically, 3D printing assisted nail placement had a higher accuracy and better prognosis than freehand nail placement, but that needed a large number of clinical data to confirm. OBJECTIVE: To investigate the clinical characteristics and influence on the postoperative stability of thoracolumbar fractures treated with 3D printing-assisted pedicle screw fixation and freehand pedicle screw fixation. METHODS: Patients with thoracolumbar fracture (T10-L3) and treated by the percutaneous pedicle screw internal fixation surgery were selected in the Affiliated Hospital of Guizhou Medical University from October 2016 to July 2018 as the research objects. According to the surgical plan, there were 30 patients with unarmed nailing by perspective guided method, and 30 patients with nailing by 3D printing aided. The operation time, blood loss, intraoperative fluoroscopy times, the number of nailing, and nailing accuracy for the first time were compared. The anterior vertebral height ratio, kyphosis Cobb angle, curvature changes, and functional recovery were compared between the two groups during a 1-year follow-up.  RESULTS AND CONCLUSION: (1) Compared with the freehand group, the amount of intraoperative blood loss and intraoperative fluoroscopy were reduced; the operation time and hospital stay were shortened; and the accuracy and accuracy rate of the first intraoperative nail placement were increased in the 3D printing group, with statistically significant differences (P < 0.05). (2) There was no statistically significant difference between the two groups in visual analogue scale score and postoperative 1 year satisfaction (P > 0.05). (3) Compared with the freehand group, the correction degree of sagittal curvature of the fixed segment increased after surgery in the 3D printing group. (4) The Oswestry disability index of the 3D printing group decreased at 7 days, 3 and 12 months after the operation compared with the freehand group, and the difference was statistically significant (P < 0.05). (5) In terms of vertebral stability, the anterior vertebral height ratios of the two groups showed a downward trend at 7 days, 3 and 12 months after surgery, while the Cobb angle showed an increasing trend. However, there was no significant difference between the two groups (P > 0.05). (6) It is indicated that 3D printing assisted pedicle screw placement relies on advanced reconstruction technology to realize simulated surgery, and the data related to pedicle screw placement formed on this basis can guarantee the accuracy of one-time pedicle placement in real surgery, so as to maximize the short-term recovery and mid-term stability of spinal function. Figures and Tables | References | Related Articles | Metrics

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Three-dimensional finite element analysis of a new three-dimensional printed porous fusion cage for cervical vertebra Shu Qihang, Liao Yijia, Xue Jingbo, Yan Yiguo, Wang Cheng 2021, 25 (24):  3810-3815.  doi: 10.12307/2021.084 Abstract ( 514 )   PDF (660KB) ( 193 )   Save BACKGROUND: Anterior cervical discectomy with fusion has become a common procedure in clinical practice. However, the upper and lower radian of the traditional fusion cage is difficult to be consistent with the upper and lower endplates, which is easy to cause a series of complications such as the settlement of the intervertebral fusion cage. Our research group developed a new three-dimensional (3D) printed porous fusion cage that is consistent with the upper and lower endplates. OBJECTIVE: The mechanical characteristics of the new 3D printed porous fusion cage were evaluated by 3D finite element analysis to provide theoretical basis for clinical application and further improvement.  METHODS: A 3D finite element model of anterior cervical discectomy with fusion was established. Traditional cervical fusion cage and a new cervical 3D printed porous fusion cage were used for reconstruction. In addition, 50 N preload and 1.0 N•m additional bending moment were applied under six working conditions of forward bending and backward stretching, left and right side bending, left and right rotation. The peak values of vertebral displacement and the peak values of Von-Mises stress on titanium plates, titanium nails, fusion cage, and upper and lower end plates were observed. RESULTS AND CONCLUSION: (1) Combined with the 3D finite element analysis, we found that the peak values of vertebral displacement and the peak values of Von-Mises stress on fusion cage, upper and lower end plates were significantly lower in the new cervical 3D printed porous fusion cage group than those of the traditional cage group under the six conditions of forward bending, back stretching, left and right side bending and left and right rotation. (2) As for titanium plates and titanium nails, except under the two working conditions of posterior extension and right rotation, the peak value in the new cervical 3D printed porous fusion cage group was larger than in the traditional cage group. Under the other four working conditions, stress peak values were smaller in the new cervical 3D printed porous fusion cage group than in the traditional cage group. (3) Therefore, compared with the traditional fusion cage, the application of the new 3D printed porous intervertebral fusion cage can avoid the stress concentration of upper and lower endplates, improve the stability of fixed segments, and reduce the sinking risk of internal plants to a certain extent. Figures and Tables | References | Related Articles | Metrics

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Application of three-dimensional visualization technology for digital orthopedics in the reduction and fixation of intertrochanteric fracture  Wang Yihan, Li Yang, Zhang Ling, Zhang Rui, Xu Ruida, Han Xiaofeng, Cheng Guangqi, Wang Weil 2021, 25 (24):  3816-3820.  doi: 10.12307/2021.085 Abstract ( 664 )   PDF (778KB) ( 89 )   Save BACKGROUND: For complex intertrochanteric fractures, there is lack of effective preoperative planning, which lead to prolonged operation time and increased difficulty. At the same time, the application of digital orthopedics three-dimensional (3D) visualization technology in the operation of intertrochanteric fracture lacks clinical application verification. OBJECTIVE: 3D visualization technology for digital orthopedics can be used to clarify the displacement of complex intertrochanteric fractures and realize preoperative simulated reduction and fixation, thus providing ideas and methods for intraoperative reduction and fixation of complex intertrochanteric fractures. METHODS: Patients with complex intertrochanteric fractures (AO typing: A2 and A3) admitted to Renji Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from January 2019 to January 2020 were selected and randomly divided into Mimics 3D reconstruction simulation reduction group and control group according to the order of admission. According to medical procedures, all the patients were implemented with plain X-ray examination of the affected hip and CT scanning of the affected hip. Patients in the Mimics 3D reconstruction simulation reduction group achieved 3D reconstruction through Mimics 17.0 software, and then the shattered fracture blocks were simulated reduction and fixation. Patients in the control group were treated with internal fixation only according to preoperative imaging examination. Data were collected to compare the differences between the two groups in terms of operation time, intraoperative blood loss, hip reduction quality score, and hip function during follow-up.  RESULTS AND CONCLUSION: (1) The operation time was significantly shorter in the Mimics 3D reconstruction simulation reduction group than that in the control group, and intraoperative blood loss was significantly reduced in the Mimics 3D reconstruction simulation reduction group compared with the control group, and the difference between the two groups was statistically significant (P < 0.05). (2) The excellent and good rate of hip reduction quality score was significantly higher in the Mimics 3D reconstruction simulation reduction group (96%) than that in the control group (82%) (P < 0.05). (3) The hip function score was significantly higher in the Mimics 3D reconstruction simulation reduction group (95.7±5.8) points than that in the control group (82.9±10.2) points 6 months after surgery (P < 0.05). (4) The results confirmed that for complex femoral intertrochanteric fractures, preoperative 3D reconstruction simulations by Mimics software reset can help to get a comprehensive understanding of fracture displacement, detailed guide the choice of intraoperative fracture reduction and internal fixation, help to shorten the operation time, lessen intraoperative blood loss, and improve the curative effect of intertrochanteric fracture. Figures and Tables | References | Related Articles | Metrics

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Development and biomechanical analysis of a new anterior cervical pedicle screw fixation system Sun Maji, Wang Qiuan, Zhang Xingchen, Guo Chong, Yuan Feng, Guo Kaijin 2021, 25 (24):  3821-3825.  doi: 10.12307/2021.086 Abstract ( 347 )   PDF (1306KB) ( 119 )   Save BACKGROUND: In clinical practice, to solve the problems of cervical spine revision/osteoporosis/long-segment fixation, anterior and posterior internal fixation is generally chosen to obtain satisfactory postoperative stability, which will inevitably aggravate the surgical trauma of the patients and increase probability of postoperative complications and hospitalization costs. The anterior cervical reverse pedicle internal fixation can obtain the stability of the anterior and posterior combined internal fixation through a single anterior operation, but there is no clinically applicable anterior cervical pedicle fixation system. OBJECTIVE: A new anterior cervical pedicle screw fixation system was developed based on the relevant anatomical structure of the cervical spine, and its biomechanical properties were evaluated on fresh cadaver cervical spine specimens to provide a basis for preliminary clinical application.  METHODS: The three-dimensional numerical value of the new nail plate system was obtained from the anatomical data of cervical spine specimens, and the system was produced by three-dimensional printing technology. Fresh adult cadaver cervical spine specimens were used to measure biomechanical stability in intact state (group A: complete group), and then to make a C5-7 instability model, followed by traditional cervical anterior nail plate system fixation (group B), anterior cervical spine displacement, strength, stiffness, torsion torque, under the fixed state of four screws fixed by the pedicle screw system (group C) and six screws (group D) of the anterior cervical pedicle screw system (group D) test.   RESULTS AND CONCLUSION: (1) In terms of load-displacement relationship: the average displacement difference between group D and group C after the test was 25%, group D and group B were 30%, and group C and B were 18%, and the differences were statistically significant (P < 0.05). (2) In terms of the axial stiffness of the cervical spine: group D was 20% higher than group C and 40% higher than group B; group C was 20% higher than group B when fixed; group D and C were both better than group A; the differences were statistically significant (P < 0.05). (3) In terms of torsion mechanical properties of the cervical spine: the group D was higher than group C by 21%, higher than group B by 40%; group C was higher than group B by 30%; the difference was statistically significant (P < 0.05). (4) Biomechanical tests showed that in terms of load-displacement, axial stiffness and torsional mechanical properties, the anterior cervical pedicle locking and guiding internal fixation system group was better than the traditional group. The six-screw fixation group (group D) was better than the four-screw fixation group (group C). It is concluded that the new anterior cervical pedicle screw fixation system conforms to Chinese anatomy and has better mechanical stability than traditional fixation methods. It is a new reliable anterior cervical pedicle internal fixation system for clinical practice. Figures and Tables | References | Related Articles | Metrics

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Adopting expanded lateral approach to enhance the mechanical stability and knee function for treating posterolateral column fracture of tibial plateau  Lin Wang, Wang Yingying, Guo Weizhong, Yuan Cuihua, Xu Shenggui, Zhang Shenshen, Lin Chengshou 2021, 25 (24):  3826-3827.  doi: 10.12307/2021.087 Abstract ( 362 )   PDF (1707KB) ( 50 )   Save BACKGROUND: The posterolateral column fracture on tibial plateau is the difficult point of traumatic orthopedics. The choice of operative approach is one of critical steps of treatment. However, nowadays there is not an acknowledged standard of choosing approach to be accepted by most scholars. OBJECTIVE: To investigate the characteristics and the incidence rate of posterolateral column fracture on tibial plateau, discuss the application prospect on adopting expanded lateral approach to treat the posterolateral column fracture. METHODS: The data of the patients with tibial plateau fractures were screened by International Classification of Disease Code from an electronic medical records database of the patients hospitalized in Mindong Hospital Affiliated to Fujian Medical University between July 2009 and March 2019. The Picture and Archiving Communication System was used to review the radiographic record on all patients’ tibial plateau fractures. Schatzker classification and three-column classification was respectively used to classify the fracture types. The posterior column was divided into posterolateral and posteromedial column. The “independent posterolateral column fracture” was defined as a fracture whose main fragment disconnected with lateral and posteromedial columns’ main body. The fracture characteristics of the posterolateral column were researched. The expanded lateral approach was adopted to treat 21 cases with displaced independent posterolateral column fractures. RESULTS AND CONCLUSION: (1) Totally 426 patients were enrolled, including 427 tibial plateau fractures. The posterolateral column fractures were involved in 267 cases and the “independent posterolateral column fractures” were involved in 126 cases. Totally 73 cases had lateral column fracture + displaced independent  posterolateral column fracture within 4 cm under the articular surface on tibial plateau. (2) Twenty-one cases adopted expanded lateral approach obtained bony union. (3) It is concluded that expanded lateral approach suits lateral column + displaced independent  posterolateral column fracture within 4 cm under the articular surface on tibial plateau. It will be singly adopted to treat Schatzker type II fracture or combined medial approach to treat Schatzker type V and VI fractures. The percentage of cases having the indication to adopt expanded lateral approach is about 17% in all tibial plateau fractures. The expanded lateral approach has a good application prospect.  Figures and Tables | References | Related Articles | Metrics

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Finite element analysis for treatment of osteoporotic femoral fracture with far cortical locking screw Zhu Yun, Chen Yu, Qiu Hao, Liu Dun, Jin Guorong, Chen Shimou, Weng Zheng 2021, 25 (24):  3832-3837.  doi: 10.12307/2021.088 Abstract ( 487 )   PDF (998KB) ( 85 )   Save BACKGROUND: To overcome the shortcomings of high stress at the near side of the plate and high stiffness of standard locking screw, a new far cortical locking screw has been developed. The biomechanical character of osteoporotic femoral fracture with far cortical locking screw is still unclear. OBJECTIVE: To investigate the biomechanical difference of osteoporotic femoral fracture with standard locking screw and far cortical locking screw by finite element analysis so as to provide reference for the clinical application of far cortical locking screw. METHODS: One male old volunteer with osteoporosis was selected, and the two-dimensional CT data of osteoporotic femur were obtained. The finite element model of osteoporotic femoral fracture was established using the software of Mimics, Geomagic, and the finite element models of internal fixators were established using the software of UG. With three-dimensional finite element analysis, biomechanical characteristics of established model under axial compression, torsion and four point bending loading were analyzed using Abaqus software.  RESULTS AND CONCLUSION: (1) The stress of femur in far cortical locking group was smaller than those of in locking screw group, which decreased the risk of refracture. (2) The plate stress of far cortical locking group was less than that of locking screw group, and dispersed. The stress distribution on the screw in far cortical locking group was evenly distributed on all the far cortical locking screws, and the stress of the locking screws was evenly distributed throughout the screw, to avoid the breakage of internal fixation due to large local stress of plate and screw. (3) Far cortical locking group provided nearly parallel interfragmentary motion, and this motion promoted secondary fracture healing by callus formation. (4) The results imply that treatment of osteoporotic femoral fracture with far cortical locking screw can decrease the stress of femur and distribution of the stress on the internal fixation, and reduce the risk of reoperation due to refracture or internal fixation fracture. Far cortical locking screw can provide nearly parallel interfragmentary motion to promote callus formation.   Figures and Tables | References | Related Articles | Metrics

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Stability of load-bearing cross barrier of different arch structures Wang Xinting, Xu Dandi, Zhang Junxia, Su Hailong Wang Qi 2021, 25 (24):  3838-3843.  doi: 10.12307/2021.089 Abstract ( 519 )   PDF (929KB) ( 162 )   Save BACKGROUND: Walking across obstacles with weight is more common in daily life. Changes in the structure of the arch of the foot can easily cause foot diseases, thereby affecting the gait characteristics of walking. OBJECTIVE: To study the changes of spatial and temporal gait parameters and kinetic parameters during normal foot, high arch, flat foot and load-bearing stride, and to explore the influence of arch structure on gait stability.  METHODS: Thirty healthy male college students at school were divided into three groups according to the shape of the foot arches (n=10 per group). The 10 cases in the normal foot group were at the age of (25.2±0.87) years old and height of (175.73±5.54) cm. The 10 cases in the flat foot group were at the age of (25.57±1.29) years old and height of (175.29±5.55) cm. The 10 cases in the high foot arch group were at the age of (25.1±0.94) years old and height of (174.7±5.61) cm. The VICON three-dimensional motion capture system and Pedar-X insole plantar pressure measurement system were used to collect spatial and temporal gait parameters, and dynamic parameters. The changes of parameters such as the gait cycle and the center of pressure trajectory under different weights were analyzed. RESULTS AND CONCLUSION: (1) Differences in center of pressure displacements of different arch structures during weight-bearing cross-obstacle. The displacements of plantar pressure center in X and Y axes of the high arch and flat foot were larger than those of the normal foot. Compared with the normal foot and the high arch, the flat foot had a longer proportion of the gait cycle in the dual support phase, and the single support phase had a shorter proportion in the gait cycle. (2) To conclude, the arch structure has a significant effect on the stability during weight-bearing trans-obstacle. Compared with normal feet, the gait stability of the high arch and the flat foot is lower; the high arch requires more medial support; and the flat foot requires more lateral support to improve gait stability. The conclusion of this study provides a certain reference for the design of orthopedic rehabilitation insoles with flat feet and high arches. Figures and Tables | References | Related Articles | Metrics

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Construction of a Nomogram prediction model for postoperative delirium after hip fracture in the elderly based on medical records from a hospital Su Baotong, Wang Hanyu, Xu Yilang, Xie Yajuan, Cheng Zhian 2021, 25 (24):  3844-3849.  doi: 10.12307/2021.090 Abstract ( 457 )   PDF (779KB) ( 86 )   Save BACKGROUND: With the development of the aging population, the number of elderly patients with hip fracture is getting larger and larger, and the number of delirium after surgical treatment of hip fracture is also increasing. It has become a hot spot to study the risk factors of postoperative delirium in elderly patients with hip fracture and build a prediction model. OBJECTIVE: To explore the clinical risk factors of postoperative delirium in elderly patients with hip fracture and to establish a Nomogram prediction model of postoperative delirium in elderly patients with hip fracture.  METHODS: The elderly patients with hip fracture aged ≥ 65 years old who were treated in the Second Department of Orthopedics, Guangdong Province Traditional Chinese Medical Hospital from January 2015 to June 2019 were found and screened, and the medical records were analyzed retrospectively. Lasso regression and multivariate Logistic regression analysis were used to screen the independent risk factors of postoperative delirium in hip fracture. R software was used to construct risk prediction nomogram and evaluate the model.  RESULTS AND CONCLUSION: (1) Postoperative delirium occurred in 243 cases (28.1%) of 864 elderly patients with hip fracture, including 166 females and 77 males, with an average age of 83.36 years. Postoperative delirium was not observed in 621 patients, including 453 females and 168 males, with an average age of 81.71 years. (2) Lasso regression and multivariate Logistic regression analysis showed that age, preoperative waiting time, preoperative anemia, intraoperative blood loss, preoperative low albumin, diabetes, cerebrovascular disease and hypoxemia were independent risk factors for postoperative delirium in elderly patients with hip fracture. (3) Nomogram model evaluation showed that the area under the receiver operating characteristic curve was 0.773 (95%CI:0.698-0.931). The calibration curve was a straight line with a slope close to 1, indicating that the model was accurate in predicting the risk of postoperative delirium in elderly patients with hip fracture. (4) The analysis of clinical decision curve showed that the model was clinically practical. (5) It is concluded that the Nomogram prediction model of postoperative delirium in elderly patients with hip fracture can individually predict the occurrence of postoperative delirium in elderly patients with hip fracture, and provide reference for clinical early identification and intervention of postoperative delirium in elderly patients with hip fracture. Figures and Tables | References | Related Articles | Metrics

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Finite element biomechanical study of full endoscopic fenestration decompression for cervical spondylotic myelopathy Liu Jinyu, Ding Yiwei, Lu Zhengcao, Gao Tianjun, Cui Hongpeng, Li Wen, Du Wei, Ding Yu 2021, 25 (24):  3850-3854.  doi: 10.12307/2021.091 Abstract ( 457 )   PDF (807KB) ( 58 )   Save BACKGROUND: Improper treatment of the lamina and facet joints during the cervical spine fenestration decompression can easily lead to cervical structure transformation, which causes segmental biomechanical change, and in turn results in cervical vertebra degeneration acceleration and instability in the long run. Clinically, we need to understand how the endoscopic cervical spine fenestration decompression affects the segmental biomechanics and the related anatomic relevance. OBJECTIVE: The finite element reverse engineering technology is used to accurately simulate the three-dimensional finite element model for the treatment of cervical spondylotic myelopathy with endoscopic cervical spine fenestration decompression, in order to study the biomechanics of cervical spine under physiological conditions. METHODS: A volunteer’s cervical vertebrae CT data were obtained and imported into MIMICS 20.0 software to establish C4-7 finite element model M. The model M was imported into 3-matic software to simulate unilateral C4-5 fenestration model M1 and bilateral C4-5 fenestration model M2. ANSY Sworkbench 18.0 software was used to apply same physiological conditions’ pressures and torques for the above three models, and the biomechanical changes under six different working conditions, i.e., left/right bending, forward bending, backward extension and left/right rotation, were analyzed. RESULTS AND CONCLUSION: (1) Compared with the intervertebral disc stress in model M, the stress value increased by 10% to 16% at intervertebral disc region B and D in model M1 at right bending, while increased by 10% to 15% in model M2 at right bending and increased by 10% to 14% at intervertebral disc region A and C at left bending. Compared with the intervertebral disc displacement in model M, the displacement of the intervertebral disc in model M1 increased by 10%-17% at left bending, and in model M2, the displacement of intervertebral disc increased by 10%-18% at left/right bending. The stress and displacement values of the C4-5 intervertebral discs in the three models showed no significant difference under other working conditions. (2) The results showed that the treatment of cervical spondylotic myelopathy with endoscopic cervical spine fenestration decompression could achieve accurate control, and there have little impact on the biomechanical stability of the surgical segment in both unilateral or bilateral decompressiom when removing partial lamina and facet joint within 1/2, and thus no auxiliary internal fixation is required to reconstruct segmental stability.   Figures and Tables | References | Related Articles | Metrics

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Finite element analysis of absorbable screws and ethibond sutures for the treatment of humerus shaft fractures caused by grenade throwing Qin Wan’an, Cai Zhouyu, Wei Gejin, Lin Zhoudan 2021, 25 (24):  3855-3859.  doi: 10.12307/2021.092 Abstract ( 318 )   PDF (794KB) ( 36 )   Save BACKGROUND: There are many effective treatments for humerus shaft fractures caused by grenade throwing, such as non-operative treatment using hanging cast, operative treatment using locking plate, screw and intramedullary nail. However, it is reported by our team for the first time that using absorbable screw and ethibond suture for the treatment.   OBJECTIVE: To evaluate the stabilization of fractures which are long-spiral humeral shaft fractures caused by grenade throwing fixed with absorbable screws and ethibond sutures in the method of finite element analysis, and provide evidence for clinical application. METHODS: CT data of humerus of a volunteer in Department of Orthopedics, 923 Hospital of Chinese People’s Liberation Army Joint Logistic Support Force were collected. Finite element models of the same fracture with different fixities which were limited contact dynamic compression plate (plate group), absorbable screws (screw group), and absorbable screws with ethibond sutures (combination group) were established. Three working conditions were set up: (1) humeral head was fixed and distal humerus was applied compressive force of 300 N. (2) Humeral head and distal humerus were fixed and the middle part was applied bending load of 350 N. (3) The humeral head was fixed and distal humerus was applied torsion load of 15 N•m. The maximum displacement of fracture surface, the average equivalent stress of fracture surface and the maximum equivalent stress of absorbable screw were assessed in three working conditions.  RESULTS AND CONCLUSION: (1) Under compression, bending or torsion loading, the maximum deformations of fracture surface of the model in the screw group were 0.52, 0.27, and 0.544 mm, respectively, and 0.51, 0.25, and 0.396 mm in the model of the combination group. The maximum deformations of fracture surface of the model of the plate group were 0.495, 0.234, and 0.393 mm. (2) The mean values of von-Mises stress distribution of fracture surface of the model of the screw group were 5.964, 4.512, and 24.176 MPa, respectively. They were 5.651, 4.601, and 21.465 MPa in the model of the combination group, and 1.210, 4.048, and 13.537 MPa in the model of the plate group. (3) The total deformation in the plate group was the smallest, and that in the combination group was close to that in the plate group; the average effective stress of the fracture surface in the combination and screw groups was higher than that in the plate group. (4) The results verify that according to the results of the experiment in the method of finite element analysis, the fracture stability is satisfactory if using absorbable screws and ethibond sutures to fixate long-spiral humeral shaft fracture. Moreover, the stress-shielding effect is lower than that of dynamic compression plate, and advantageous for fracture union and preventing partial osteoporosis. Figures and Tables | References | Related Articles | Metrics

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Short-term follow-up of elastic intramedullary nail and plate in the treatment of displaced middle clavicle type B fracture Zhang Degang, Liu Dong, Li Peng, Wang Zhaolin, Zhang Kai, Zhang Xinjun 2021, 25 (24):  3860-3864.  doi: 10.12307/2021.093 Abstract ( 446 )   PDF (1230KB) ( 61 )   Save BACKGROUND: It has been reported that elastic intramedullary nail has definite clinical effect in the treatment of simple fracture of clavicle shaft type A, with advantages of small trauma and postoperative beauty. However, the application effect of elastic intramedullary nail in type B fracture with wedge-shaped bone block in the middle of clavicle is not clear. OBJECTIVE: To compare the efficacy of elastic intramedullary nail and plate fixation in the treatment of displaced middle clavicle type B fracture (AO classification: 15.2B). METHODS: From November 2017 to October 2019, 28 patients with type B fracture of the middle clavicle in the Affiliated Hospital of Binzhou Medical College, including 18 males and 10 females, aged 19-65 years, were divided into two groups according to different surgical methods. Totally 15 cases in the control group received plate internal fixation, while 13 cases in the observation group received closed reduction (five cases were assisted by small incision) elastic intramedullary nail internal fixation. Intraoperative blood loss, operation time and incision length were recorded in both groups. Fracture healing time, shoulder Constant score, Disabilities of the Arm Shoulder and Hand and complications were recorded in both groups. The trial was approved by the Ethics Committee of Affiliated Hospital of Binzhou Medical University.   RESULTS AND CONCLUSION: (1) The two groups were followed up for 8-24 months. In the control group, one case suffered from superficial infection; four cases received plate removal 8-12 months after operation due to skin irritation; and five cases in the observation group received elastic intramedullary nail removal 6-10 months after operation due to skin irritation. (2) Intraoperative blood loss, operation time and incision length in the observation group were less than those in the control group (P < 0.05). There was no significant difference in fracture healing time between the two groups (P > 0.05). (3) There was no significant difference in shoulder Constant score and Disabilities of the Arm Shoulder and Hand score between the two groups at the last follow-up (P > 0.05). (4) The results showed that plate and elastic intramedullary nail placement in the treatment of displaced middle clavicle type B fracture had exact curative effect, good shoulder joint function recovery, but elastic intramedullary nail internal fixation had the advantages of small trauma and beautiful incision. Figures and Tables | References | Related Articles | Metrics

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Minimally invasive percutaneous pedicle screw technique for thoracolumbar fractures: biomechanical changes of the spine during 6-month follow-up Zou Shouping, Lu Daoyun, Ye Li 2021, 25 (24):  3865-3869.  doi: 10.12307/2021.094 Abstract ( 385 )   PDF (703KB) ( 62 )   Save BACKGROUND: The rapid development of spine minimally invasive surgery, the treatment of spinal fractures, especially thoracolumbar fractures, has been rapidly updated in recent years in equipment and concepts, reducing surgical trauma, shortening recovery time, and improving treatment satisfaction.  OBJECTIVE: To analyze the therapeutic effect of percutaneous pedicle screw placement and open wound placement in the treatment of thoracolumbar fractures without nerve injury.   METHODS: A retrospective analysis of 52 patients with thoracolumbar fractures without nerve injury who were admitted to Naval Hospital of Eastern Theater Command from January 2015 to December 2018. According to nail placement technology, the patients were divided into two groups. The 24 patients in the observation group received percutaneous pedicle screw placement combined with injured vertebrae nail placement technology. The 28 patients in the control group received open injured vertebrae nail placement. Perioperative indicators (operation time, intraoperative blood loss, intraoperative fluoroscopy, postoperative hospital stay, and incision healing rate) were compared between the two groups. Postoperative low back pain visual analogous scale score, anterior vertebral height percentage, and sagittal kyphotic Cobb angle were analyzed during follow-up.   RESULTS AND CONCLUSION: (1) The operation time and the number of intraoperative fluoroscopy were more in the observation group than those of the control group (P < 0.05), but the blood loss, postoperative hospital stay and incision healing rate were better in the observation group than those of the control group (P < 0.05). (2) All patients completed a follow-up for more than 12 months. The visual analogous scale scores of low back pain at 3 days, 1, 3, 6, and 12 months after surgery in the observation group were better than those in the control group (P < 0.05). There was no significant difference in the anterior body height percentage and the sagittal kyphosis Cobb angle between the two groups (P > 0.05). (3) The results suggest that the minimally invasive percutaneous vertebral nail placement technique reduces surgical trauma, although there are differences in fluoroscopy and operation time. However, the clinical effect is affirmative. Figures and Tables | References | Related Articles | Metrics

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Effects of anterior corpectomy and fusion versus posterior single open-door laminoplasty on cervical range of motion of patients with multilevel cervical spondylotic myelopathy Zhang Qifu, Ma Yonghong, Wang Tao, Hu Yibo, Zhang Heling, Zong Qunchuan 2021, 25 (24):  3870-3874.  doi: 10.12307/2021.095 Abstract ( 448 )   PDF (709KB) ( 71 )   Save BACKGROUND: Anterior approach and posterior approach are used in the treatment of multilevel cervical spondylotic myelopathy, but it is still controversial about the choice of surgical approach.  OBECTIVE: To investigate the effects of anterior corpectomy and fusion versus posterior single open-door laminoplasty on cervical range of motion of patients with multilevel cervical spondylotic myelopathy.  METHODS: Medical records of patients with multilevel cervical spondylotic myelopathy admitted in Affiliated Hospital of Qinghai University from January 2016 to January 2018 were retrospectively analyzed. According to surgical approaches, they were divided into anterior and posterior groups. Patients in the anterior group (n=33) were treated with anterior corpectomy and fusion, while patients in the posterior group (n=32) were treated with posterior single open-door laminoplasty. The Japanese Orthopaedic Association score was used to evaluate the neurological function before and after surgery in both groups. Cervical range of motion before and after operation was measured in both groups. RESULTS AND CONCLUSION: (1) A total of 65 patients with multilevel cervical spondylotic myelopathy were followed up. The follow-up time ranged from 12 to 25 months. (2) There were no significant differences in age, gender composition, follow-up time, and Japanese Orthopaedic Association score between the two groups before surgery and at the time of the last follow-up (P > 0.05). (3) Cervical range of motion of the two groups after surgery was reduced compared with those before surgery (P < 0.05). The ranges of motion of cervical spine in the posterior group were better than those in the anterior group in flexion, extension, left flexion, right flexion, left rotation and right rotation at the last follow-up. (4) It is indicated that the range of motion of cervical spine was reduced after both anterior corpectomy and fusion and laminoplasty in patients with multilevel cervical spondylotic myelopathy, and the former has more influence on the cervical range of motion than the latter.  Figures and Tables | References | Related Articles | Metrics

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Application and comparison of four commonly used methods for patellar height measurement Jie Ke, Deng Peng, Zeng Yirong 2021, 25 (24):  3875-3881.  doi: 10.12307/2021.096 Abstract ( 707 )   PDF (898KB) ( 94 )   Save BACKGROUND: High tibial osteotomy is one of the more popular knee-preserving operations for the treatment of osteoarthritis of the medial compartment of the knee in recent years. However, the previous literature reported that this operation has different effects on the height of the patella. The main reason is that it uses different measurement methods of patellar height. OBJECTIVE: To assess the consistency and reproducibility of Caton-Deschamps, Blackburne-Peel, Insall-Salvati and modified Insall-Salvati indices before and after high tibial osteotomy.  METHODS: Complete imaging data of 31 patients (34 knees) with medial knee osteoarthritis, who were treated with open-wedge biplane high tibial osteotomy in the Department of Joint Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine from February 2014 to December 2017, were retrospectively analyzed. The lateral films of the knee with 30° knee flexion were selected before and after treatment. Patellar height was independently measured using Caton-Deschamps, Blackburne-Peel, Insall-Salvati and modified Insall-Salvati indices before and after treatment by two researchers. This trial was approved by the Ethics Committee of The First Affiliated Hospital of Guangzhou University of Chinese Medicine on November 6, 2019 (approval No. K2019122).   RESULTS AND CONCLUSION: (1) Caton-Deschamps and Blackburne-Peel indices significantly decreased after treatment compared with preoperative indices. Insall-Salvati and modified Insall-Salvati indices were not significantly different before and after treatment. (2) Quantitative results of consistency showed that the consistency was good between Blackburne-Peel and Caton-Deschamps indices, modified Insall-Salvati and Caton-Deschamps indices, and modified Insall-Salvati and Blackburne-Peel indices before treatment. However, only Blackburne-Peel and Caton-Deschamps indices had good consistency after treatment. (3) Qualitative results of consistency displayed good consistency between Blackburne-Peel and Caton-Deschamps indices before and after treatment. (4) Interobserver consistency displayed highest consistency of Blackburne-Peel index, followed by Insall-Salvati index before treatment; and highest consistency between Blackburne-Peel and Caton-Deschamps indices after treatment. (5) It is indicated that regarding the choice of measurement methods of patellar height, Blackburne-Peel index is recommended as the best evaluation index of patellar height in the treatment of high tibial valgus osteotomy. Figures and Tables | References | Related Articles | Metrics

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Consistency and repeatability of CT and MRI in measurement of spinal canal area in patients with lumbar spinal stenosis Tian Yang, Tang Chao, Liao Yehui, Tang Qiang, Ma Fei, Zhong Dejun 2021, 25 (24):  3882-3887.  doi: 10.12307/2021.097 Abstract ( 440 )   PDF (702KB) ( 87 )   Save BACKGROUND: The domestic and overseas scholars have conducted a large number of studies on the measurement of spinal canal area in patients with lumbar spinal stenosis by CT and MRI. However, due to differences of individuals, spinal canal morphologys, measurement methods and measurement planes, there is no recognized measurement standard and value for the measurement of lumbar spinal canal area at present. There are few reports to evaluate the consistency and repeatability of CT and MRI in measuring lumbar spinal canal area. OBJECTIVE: To analyze the consistency and repeatability of three-dimensional reconstruction CT and MRI in measuring the cross-sectional area of lumbar spinal stenosis, and to explore the best imaging measurement method for the cross-sectional area of lumbar spinal stenosis.  METHODS: The preoperative imaging data of 102 patients with lumbar spinal stenosis who underwent surgical treatment in Department of Spinal surgery, the Affiliated Hospital of Southwest Medical University from January 2013 to January 2018 with three-dimensional reconstruction CT and lumbar MRI were collected. The corresponding spinal canal area of each narrow intervertebral disc on three-dimensional reconstruction CT and lumbar MRI images was measured by two spinal surgeons at three different time points. The spinal canal area corresponding to the midline plane of the narrow intervertebral disc parallel to the lower endplate of the upper vertebral body was selected for measurement. Paired t-test was used to analyze the difference in spinal canal area between the results of the two methods. Pearson correlation analysis was used to evaluate the correlation between the results of spinal canal area between the two methods. Intraclass correlation coefficient and Bland-Altman plot were used to analyze the consistency and repeatability of the two methods in measuring the area of narrow lumbar spinal canal. Z-test was used to compare the ICC values of interobserver and intraobserver in measurement of narrow lumbar spinal canal area by the two methods. The protocols were approved by the Affiliated Hospital of Southwest Medical University Ethics Committee (approval No. KY2020176).  RESULTS AND CONCLUSION: (1) The values of narrow lumbar spinal canal measured by three-dimensional reconstruction CT and MRI were (136.28±2.38) mm2 and (139.98±2.30) mm2; there were significant differences between them (t=-3.96, P < 0.001). Pearson correlation analysis showed that there was a positive correlation between three-dimensional reconstruction CT and MRI measurement of narrow lumbar spinal canal area (r=0.950, P < 0.001). (2) The values of interobserver ICC and intraobserver ICC were 0.908-0.937 and 0.942-0.971. The values of interobserver ICC and intraobserver ICC measured by lumbar MRI were higher than those measured by three-dimensional reconstruction CT (P < 0.05). (3) Bland-Altman plot showed that the 95% distribution range of the difference of spinal canal area between the two methods was -8.0-5.5 mm2. Six points were outside the range, accounting for 3.66%. (4) The results showed that there was a significant difference in spinal canal area between three-dimensional reconstruction CT and MRI, but there was a strong positive correlation. The consistency and reproducibility of measurement of narrow lumber spinal canal area by two imaging examinations were good, but the consistency and repeatability of lumbar MRI in measuring narrow lumber spinal canal area were better than that of three-dimensional reconstruction CT. Figures and Tables | References | Related Articles | Metrics

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MRI findings of anatomical variations of the talus Yi Meizhi, Luo Guanghua, Xiao Yawen, Hu Rong, Chen Xiaolong, Zhao Heng 2021, 25 (24):  3888-3893.  doi: 10.12307/2021.098 Abstract ( 721 )   PDF (1311KB) ( 244 )   Save BACKGROUND: In previous studies, only X-ray or CT imaging was used to describe the anatomical variations of the talus, but MRI has not provided a unified and specific description. OBJECTIVE: To describe the MRI characteristics of anatomical variations of the talus and observe the MRI characteristics of the ankle impingement syndrome caused by the variations of the talus. METHODS: The MRI findings of the First Affiliated Hospital, University of South China in the past three years were retrospectively analyzed. One of the objectives was to describe edema or structural changes associated with anatomical variations in talus. Patients with tumors of talus or infections of talus were excluded in this study. RESULTS AND CONCLUSION: (1) Totally 500 patients were finally included in the study, among which 24 patients showed anatomic variations, the incidence of anatomic variations was 4.8%. The variations of talus on MRI were talar beak (2 cases), talocalcaneal bridge (6 cases), bone island (1 case), and os trigonum (15 cases). (2) Talar beak, talocalcaneal bridge and os trigonum had a certain relationship between ankle joint impingement syndrome. (3) The posterior process of talus varied from person to person. They could be categorized as long tail, middle tail, short tail, and tailless. (4) The incidence rate of posterior ankle discomfort was the highest in the os trigonum group, and the lowest in the tailless type of talus. There was no significant difference in incidence rate between the os trigonum group and the long tail type of talus. Figures and Tables | References | Related Articles | Metrics

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Effect of Wnt/beta-catenin signaling pathway on osteoblasts under the action of wear particles Wang Qiufei, Gu Ye, Peng Yuqin, Xue Feng, Ju Rong, Zhu Feng, Wang Yijun, Geng Dechun, Xu Yaozeng 2021, 25 (24):  3894-3901.  doi: 10.12307/2021.099 Abstract ( 451 )   PDF (638KB) ( 133 )   Save BACKGROUND: With the progress of the mid-term and long-term follow-up study, it is found that the periprosthesis loosening is an important factor that limits the service life of artificial prosthesis and restricts the development of artificial joint replacement. OBJECTIVE: To further understand the Wnt/β-catenin signaling pathway and provide new targets for drug therapy by analyzing the research results of main signal factors of Wnt/β-catenin signaling pathway on osteoblasts and the cell function of osteoblast origin. METHODS: The first author searched the literature published from 2005 to 2020 by computer with the Chinese key words of “wear debris, peri-prosthetic osteolysis, aseptic loosening, pathogenesis, osteoblast, signaling pathway, bone remodeling, Wnt/β-catenin” in the databases of CNKI, Wanfang and VIP, and with the English key words of “wear debris, wear particles, peri-prosthetic osteolysis, PPO, aseptic loosening, AL, pathogenesis, osteoblast, OB, signal path, bone remodeling, Wnt/β-catenin” in PubMed and Web of Science. The articles regarding the effect and mechanism of Wnt/β-catenin pathway on osteoblasts under the influence of wear particles were collected. Finally, 53 articles were included according to the inclusion and exclusion criteria. RESULTS AND CONCLUSION: (1) During the pathological process of wear particle induced osteolysis around implant and aseptic loosening, Wnt/β-catenin signaling pathways activated by inhibiting bone-forming formation and increasing bone resorption, in turn, affects bone reconstruction, and has played a key role in the pathology of wear particle induced osteolysis around implant and aseptic loosening. (2) In vitro experiments, Wnt/β-catenin signaling pathways were activated by GSK-3β inhibitor LiCl, growth hormone release polypeptide, and protein phosphatase 2A inhibition to promote osteoblast differentiation and osteogenic activity. However, ICG-001 inhibitor blocked the β-catenin signaling pathway, thus weakening the protective effect of LiCl on osteoblastic differentiation, suggesting that GSK-3/β-catenin signaling pathway may be an important mechanism mediating Ti wear particles to induce osteolysis around the prosthesis. (3) In vivo experiments, the application of SOST antibody, protein phosphatase 2A inhibition, LiCl, AR28 and other ways through activation of Wnt/β-catenin and other signal pathways can promote bone formation, inhibit osteoclast absorption, increase local bone mass and bone volume, and resist the effect of osteolysis around the prosthesis induced by Ti and other wear particles. (4) At the gene level, the activity and mineralization of MC3T3-E1 cells were also significantly enhanced under SOST silencing condition, even when treated with titanium particles. On the contrary, the decreased expression level of SOST increased the expression level of β-catenin. The results suggested that the decrease of SOST gene expression could activate the Wnt/β-catenin signaling pathway to promote bone formation and improve the bone loss caused by Ti particles. Figures and Tables | References | Related Articles | Metrics

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Short-segment fixation of thoracolumbar burst fractures: method modification and strategies to reduce failure Wang Ziao, Song Wenhui, Liu Changwen 2021, 25 (24):  3902-3907.  doi: 10.12307/2021.100 Abstract ( 345 )   PDF (607KB) ( 60 )   Save BACKGROUND: Short-segment fixation has been increasingly used in the treatment of thoracolumbar burst fractures. The procedure has been proven to have good clinical, functional and radiologic results. However, Kyphosis may recur after short-segment fixation and has been paid more and more attention by surgeons.   OBJECTIVE: To summarize the classification of thoracolumbar fractures, indication of short-segment fixation, failure of short-segment fixation and the improved method of operation, so as to provide help for clinical treatment.  METHODS: By searching CNKI, Wanfang, PubMed, Web of Science and other Chinese and English databases for articles published from 1983 to 2020, the Chinese search terms were “thoracolumbar fractures, short segment fixation, kyphosis” and the English search terms were “thoracolumbar fractures, short segment fixation, kyphosis”. Through the inclusion and exclusion criteria, 63 articles were finally included for induction and summary.  RESULTS AND CONCLUSION: (1) For almost all type A and type B fractures of the non-ankylosing ridge column, posterior short-segment fixation can achieve good clinical results. Short-segment fixation is associated with a risk of recurrent kyphosis due to collapse of adjacent discs, and the clinical significance of recurrent kyphosis is not clear. (2) The posterior short-segment distraction reduction can effectively reduce the fractured vertebral body and promote the absorption and recovery of the bone mass in the vertebral canal through indirect traction, but it is not effective for the “inverted bone mass”. (3) The use of posterolateral fusion in conjunction with short-segment instrumentation is questionable. It has nothing to do with improving the clinical outcome, nor does it prevent recurrence of kyphosis or failure of internal fixation. (4) The use of load-sharing classification to quantify vertebral comminution and predict posterior fixation failure remains controversial. (5) The strategies for short-term fixation failure mainly focus on strengthening or enhancing the biomechanical strength of the rear structure in front. Transpedicular fixation in the strategy of increasing biomechanical strength of the posterior structure improved the effectiveness of the short-segment instrumentation and significantly reduced the implant failure rate, which is the current mainstream surgery in treatment of thoracolumbar fractures. (6) The surgical results of posterior short-segment fixation combined with transpedicular bone grafting or vertebroplasty for the reduction of fractured vertebrae need more clinical validation. (7) Minimally invasive percutaneous short-segment pedicle screw internal fixation is gradually applied in the treatment of the fracture of the ridge column, which can make the fracture well reduced and fixed in the early postoperative period, and is helpful for the recovery of the patient, and is the direction of development of short-segment fixation. Figures and Tables | References | Related Articles | Metrics

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Etiology and treatment of femoral trochlear dysplasia: congenital genetic determination or stress stimulation of patella Zhou Yuanbo, Wang Jindong 2021, 25 (24):  3908-3913.  doi: 10.12307/2021.101 Abstract ( 923 )   PDF (741KB) ( 138 )   Save BACKGROUND: Patellofemoral instability is the common problem in orthopedics, and the etiology can be multifactorial, such as trochlear dysplasia, patella alta, increased torsion of femur and tibia, elevated tibial tuberosity-trochlea groove distance, and the injury of media patellofemoral ligament. Among them, trochlear dysplasia is regarded as the most important risk factor. OBJECTIVE: To review the etiology, image evaluation, clinical problem of trochlear dysplasia and trochleoplasty. METHODS: The “trochlear dysplasia, trochleoplasty” were used as Chinese and English search terms. The first author searched English database such as PubMed and Chinese databases such as CNKI and Wanfang, and the retrieval deadline was July 2020. Repetitive and irrelevant articles were excluded, and final 56 articles were included for review.  RESULTS AND CONCLUSION: (1) There are two main theories about the etiology of trochlear dysplasia; that is, congenital genetic determination and the stress stimulation of patella. A series of studies from animal experiment to human studies have shown that the stress stimulation is essential to trochlear development. (2) Imagine evaluation of trochlear dysplasia includes the pure lateral radiographs of knee joint and axial CT/MRI which can achieve quantitative evaluation. The classification of trochlear dysplasia has evolved from the classical Dejour classification to the more reliable OBC classification. (3) A series of studies from biomechanics to clinic have supported that trochlear dysplasia is the most important risk factor for patellofemoral instability, and trochlear dysplasia is also associated with cartilage wear and anterior cruciate injury. (4) Trochleoplasty is the most direct way to change the abnormal shape of trochlea. Under the premise of grasping the indications and contraindications, trochleoplasty can achieve satisfactory clinical results. Figures and Tables | References | Related Articles | Metrics

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Role and mechanism of Nel-like molecule-1 in promoting bone fusion after spinal fusion Tang Xiaokai, Li Weiming 2021, 25 (24):  3914-3920.  doi: 10.12307/2021.102 Abstract ( 384 )   PDF (659KB) ( 77 )   Save BACKGROUND: Adequate bone grafting is very necessary during spinal fusion. However, due to the limited number of osteoblasts and the function of the bone microenvironment in elderly patients, as well as the in vivo application of bone morphogenetic protein 2 will cause adverse effects such as ectopic bone. The current method can cause nonunion and other complications. In this case, Nel-like molecule-1 (Nell-1) has entered the field of vision of researchers. Nell-1 is not only equivalent to BMP-2 in osteogenic activity, but also has anti-fat, anti-inflammatory, and pro-vascular properties. These laid the foundation for clinical trial approval of Nell-1 in promoting spinal fusion. OBJECTIVE: To review the effect and mechanism of Nell-1 on bone fusion after spinal fusion. METHODS: Relevant documents were retrieved in Baidu Academic, PubMed, Web of Science, Wanfang, and CNKI. The Chinese and the English search terms were “Nell-1, spinal fusion, bone fusion, pre-osteoblast differentiation, neovascularization, progenitor cell migration”. Finally, 68 articles were included for review. RESULTS AND CONCLUSION: Autologous bone grafting has complications and supply problems related to bone grafting. Bone graft replacement therapy represented by bone morphogenetic protein 2 will produce many non-target effects. Therefore, neither can meet the increasing demand for spinal fusion. In this context, the emergence of Nell-1 provides the possibility to solve this dilemma. Although the role of Nell-1 in promoting bone fusion after spinal fusion is still in the preliminary stage of research, there are still deficiencies in the lack of an optimal route of administration; the molecular mechanism is not fully understood; and whether there are adverse reactions related to the application. Nevertheless, it has the triple effect of promoting progenitor cell migration, pre-osteoblast differentiation, and vascularization, so it has great potential for promoting bone fusion after spinal fusion. Future research should further reveal the detailed underlying mechanism, optimize the dosage and schedule, explore the combined effect with other osteogenic growth factors and stem cells, and translate the potential of Nell-1 for promoting spinal fusion into clinical practice. Figures and Tables | References | Related Articles | Metrics

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Diagnostic value and accuracy of D-dimer in periprosthetic joint infection: a systematic review and meta-analysis Cheng Chongjie, Yan Yan, Zhang Qidong, Guo Wanshou 2021, 25 (24):  3921-3928.  doi: 10.12307/2021.103 Abstract ( 328 )   PDF (1171KB) ( 172 )   Save OBJECTIVE: There is still no single indicator or even a combination of indicators that can definitely confirm or exclude periprosthetic joint infection. D-dimer has recently emerged as a novel index for the diagnosis of periprosthetic joint infection, but its reliability is uncertain. We determined the practical application value and the accuracy of D-dimer in the diagnosis of periprosthetic joint infection by using meta-analysis. METHODS: We conducted a systematic search and screening to identify relevant articles from register databases such as PubMed, Embase, Web of Science, and the Cochrane Library. QUADAS-2 was used to assess the quality of each included study. The bivariate mixed-effects regression model was used to combine sensitivity, specificity, likelihood ratio, diagnostic odds ratio, summary receiver operating characteristic curve, and area under summary receiver operating characteristic curve to evaluate the diagnostic value of overall D-dimer for periprosthetic joint infection. Univariate meta-regression and subgroup analysis were performed to explore the sources of heterogeneity. RESULTS: (1) A total of 11 studies were included in our study, including 1 645 patients. The quality of the included studies was regarded as the upper-middle level. (2) The pooled sensitivity, specificity, pooled positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and area under the curve were 0.80(95%CI:0.72-0.87), 0.74(95%CI:0.62-0.83), 3.04(95%CI:2.01-4.61), 0.27(95%CI:0.18-0.40), 11.40(95%CI:5.50-23.63), and 0.84(95%CI:0.81-0.87). (3) Univariate meta regression showed that sample source and threshold had influence on the heterogeneity of pooled sensitivity results. Subgroup outcomes showed that serum D-dimer had a higher diagnostic accuracy than plasma D-dimer for periprosthetic joint infection (pooled sensitivity: 0.88 vs. 0.67; pooled specificity: 0.78 vs. 0.67; pooled area under the curve: 0.91 vs. 0.68). (4) The Spearman correlation analysis showed that there was no obvious threshold effect among the studies. The heterogeneity might be unrelated to the threshold effects. CONCLUSION: (1) Serum D-dimer had a promising performance for the diagnosis of periprosthetic joint infection, which was shown to have a better diagnostic value than plasma D-dimer. (2) There are no sufficient data existing for subgroup analysis of different periods or joints of periprosthetic joint infection, so we could not assess the differences of D-dimer in diagnosing acute periprosthetic joint infection versus chronic periprosthetic joint infection, or hip joint infection versus knee joint infection. Thus, more large, multicenter prospective studies are needed for verification.  Figures and Tables | References | Related Articles | Metrics

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Efficacy and safety of staged versus simultaneous unicompartmental knee arthroplasty: a meta-analysis#br# Wang Dasai, Zhang Yang, Cheng Yin, Wang Qiang 2021, 25 (24):  3929-3936.  doi: 10.12307/2021.104 Abstract ( 313 )   PDF (880KB) ( 96 )   Save OBJECTIVE: Patients with bilateral knee osteoarthritis who meet the indications for bilateral unicompartmental knee arthroplasty can have treatment options that can be divided into two methods: staged versus simultaneous unicompartmental knee arthroplasty. Thus, meta-analysis was used to compare the efficacy and safety of simultaneous and staged unicompartmental knee arthroplasty.  METHODS: Cochrane Library, PubMed, Web of Science, CNKI, and Wanfang were searched for studies. Retrieval words included “one staged, simultaneous bilateral, two staged, staged bilateral, unicompartmental knee arthroplasty, unicompartmental knee replacement and UKA” in English and Chinese. Literature was case control study, cohort study or randomized controlled trial that included simultaneous and staged unicompartmental knee arthroplasty. RevMan 5.3 software was used for meta-analysis.  RESULTS: (1) Totally 24 studies were included, among which 7 were prospective cohort studies and 17 were historical cohort studies. Nine items of study quality assessment were of high quality, 13 were of medium quality and 2 were of low quality. (2) The meta-analysis showed that the clinical outcomes of staged bilateral unicompartmental knee arthroplasty in blood transfusion rate (odds ratio (OR)=2.93, 95% confidence interval (CI):2.55-3.37, P < 0.000 01), deep vein thrombosis (OR=1.35, 95%CI:1.25-1.46, P < 0.000 01), pulmonary complications (OR=1.49, 95%CI:1.33-1.67, P < 0.000 01), cardiac complications (OR=1.09, 95%CI:1.04-1.15, P=0.000 9), gastrointestinal complications (OR=1.52, 95%CI:1.44-1.60, P < 0.000 01), urinary complications (OR=1.18, 95%CI:1.11-1.25, P < 0.000 01), readmission (OR=1.25, 95%CI:1.06-1.47, P=0.008) and death (OR=1.63, 95%CI:1.42-1.87, P < 0.000 01) were significantly lower than those of simultaneous bilateral unicompartmental knee arthroplasty. (3) Simultaneous bilateral unicompartmental knee arthroplasty went down in ASA class (weighted mean difference (WMD)=-0.08, 95%CI:-0.10 to -0.06, P < 0.000 01), hematoma (OR=0.53, 95%CI:0.49-0.57, P < 0.000 01), infection (OR=0.73, 95%CI:0.66-0.80, P < 0.000 01), craniocerebral complications (OR=0.87, 95%CI:0.77-1.00, P=0.05) and hospital cost (standard mean difference (SMD)=-5.43, 95%CI:-7.13 to -3.73, P < 0.000 01).   CONCLUSION: Staged bilateral unicompartmental knee arthroplasty can more effectively reduce the perioperative risk, and have a lower blood transfusion rate and mortality rate, while simultaneous bilateral unicompartmental knee arthroplasty can effectively reduce hematoma and infection risk. To further compare and evaluate the safety and efficacy of staged and simultaneous bilateral unicompartmental knee arthroplasty, larger sample, and high-quality randomized controlled trials need to be included to provide evidence for verification. Figures and Tables | References | Related Articles | Metrics