Feasibility of a novel type of complex anterior cervical fixation by using Mimics software / 中国骨伤

OBJECTIVE@#To investigate the feasibility of mimics software in analyzing a new type of complex anterior cervical fixation -- anterior transpedicular screw fixation+zero notch internal fixation.@*METHODS@#From January 2021 to September 2022, 50 normal pedestrians who underwent cervical spine CT scanning were selected for C1-C7 segment scanning, including 27 males and 23 females, aged from 25 to 65 years old with an average of (46.0 ± 9.0) years old. The dicom format is exported and engraved into the CD, and use the mimics software to perform 3D reconstruction of each segment. A simulated screw is placed on the image according to the critical value of zero notch screw (head and tail angle 44°, internal angle 29°). The position of zero notch screw in each segment is observed to determine the feasibility of anterior transpedicular screw fixation plus zero notch internal fixation.@*RESULTS@#For the upper zero notch screws the three-dimensional images of the cervical spine across all 50 subjects within the C3-C7 segments demonstrated safe position, with no instances of intersection with ATPS. For the lower zero notch screw, in C3-C4 and C4-C5, 4 out of 50 subjects are in the safe position in the three-dimensional images of cervical vertebrae, and 46 cases could achieve secure screw placement when the maximum caudal angle is(32.3±1.9) ° and (36.1±2.2) °, respectively. In C5-C6 and C6-C7 segments, no lower zero notch screws intersected with ATPS, and all screws are in safe positions.@*CONCLUSION@#Lower cervical anterior pedicle screw fixation plus zero notch internal fixation can achieve successful nail placement through the selected entry point and position.

Analysis on clinical efficacy of anterior cervical Hybrid surgery and posterior cervical expansive open-door laminopasty for multilevel cervical spondylotic myelopathy / 吉林大学学报(医学版)

Objective:To analyze the efficacy of anterior cervical Hybrid surgery and posterior cervical expansive open-door laminoplasty(EODL)in the treatment of multilevel cervical spondylotic myelopathy,and to discuss the selection of surgical methods for the patients with multilevel cervical spondylotic myelopathy.Methods:The retrospective analysis was conducted of 70 patients with multilevel cervical spondylotic myelopathy who underwent surgery at Affilated Beijing Traditional Chinese Medicine Hospital of Capital Medical University from July 2017 to July 2020.Based on the different surgical methods,the patients were divided into anterior group(n=35)and posterior group(n=35).The patients in anterior group underwent Hybrid surgery[anterior cervical discectomy and fusion(ACDF)combined with artificial cervical disc replacement(ACDR)],and the patients in posterior group underwent EODL.The hospitalization time,operation time,intraoperative blood loss,and postoperative drainage volume of the patients in two groups were recorded;the efficacy was evaluated by Japanese orthopaedic association(JOA)score,JOA improvement rate,neck disability index(NDI),visual analogue scale(VAS)for pain,and postoperative satisfaction score;the complications of the patients in two groups after surgery were recorded.Results:Compared with posterior group,the intraoperative blood loss,postoperative drainage volume,hospitalization time,and operation time of the patients in anterior group were significantly decreased(P<0.01),and the preoperative score had no significant difference(P>0.05).At the final follow-up after surgery,compared with posterior group,the JOA score and JOA improvement rate of the patients in anterior group were significantly increased(P<0.01),and the NDI score and VAS score were significantly decreased(P<0.01).Compared with before surgery,the JOA scores of the patients in two groups at the final follow-up after surgery were increased(P<0.01),and the NDI and VAS scores were significant decreased(P<0.01).The postoperative satisfaction of the patients in two groups was high based on the postoperative satisfaction score.There was no significant difference in the incidence of postoperative complication of the patients between two groups(P>0.05).Conclusion:Both the anterior cervical Hybrid surgery and EODL achieve the satisfactory results in the treatment of multilevel cervical spondylotic myelopathy.Hybrid surgery has the advantages of less bleeding and shorter surgery time,and the most suitable surgical method should be chosen clinically based on the actual situation of the patients.

Finite element analysis of the correlation between tilt angle of titanium cage and postoperative subsidence of titanium cage after anterior subtotal cervical corpectomy,decompression and fusion / 中国组织工程研究

BACKGROUND:Anterior subtotal corpectomy,decompression and fusion is a conventional method to treat cervical degenerative diseases.A titanium cage is an important implant to maintain the stability of the cervical spine after subtotal corpectomy.In recent years,many patients have complications such as titanium cage sinking,which are highly controversial. OBJECTIVE:To investigate the internal biomechanical relationship between the tilt angle of the titanium cage and postoperative titanium cage subsidence after anterior subtotal cervical corpectomy,decompression and fusion. METHODS:A three-dimensional finite element model of the C4-C6 segment was established by CT images of a normal human cervical spine,in which the anterior subtotal resection,decompression and fusion of the C5 vertebral body were simulated,and titanium cages with different tilt angles(-6° to-1° negative angle,that is,the front edge of titanium cage is shorter than the rear edge of titanium cage;1° to 6° positive angle,that is,the front edge of titanium cage is longer than the rear edge of titanium cage)were placed.After setting the boundary conditions,preloads of 50,100 and 150 N were applied respectively on the C4 vertebral body.The stress value of each contact point between the titanium cage and C4 lower-end plate and C6 lower-end plate(seven stress contact points on the contact surface of titanium mesh)was recorded and statistical analysis was conducted. RESULTS AND CONCLUSION:(1)The tilt angles of the titanium cage of the positive angle group and negative angle group under 50,100 and 150 N stress respectively were found by Mann Whitn test,with P<0.05,which was statistically significant.The dispersion coefficients of the positive angle group were smaller than those of the negative angle group under 50,100 and 150 N stress conditions.(2)Under 50,100 and 150 N stress conditions,the Wilcoxon sign rank test in the positive angle group of titanium cage tilt angle found that when the angle was set to 1° to 5°,the difference was not statistically significant(P>0.05).However,when the tilt angle of the titanium cage was set to 6°,the difference was statistically significant(P<0.05).(3)Under 50,100 and 150 N stress conditions,the Wilcoxon sign rank test in the negative angle group of titanium cage tilt angle found that when the tilt angle was set to-1° to-6°,the difference was not statistically significant(P>0.05).(4)It is concluded that in the sagittal position,the titanium cage with a positive tilt angle is more stable than with a negative tilt angle,which is more suitable for clinical use.The tilt angle of the titanium cage is relatively stable in the range of 1° to 5°.When the tilt angle is 6°,the stability starts to decline,which is easy to cause complications of titanium cage sinking after surgery.It is more suitable to select the titanium cage with a tilt angle of 1° to 5° according to the clinical situation during surgery to improve the efficacy.

Three-dimensional finite element analysis of a new horizontal screw-screw crosslink in posterior atlantoaxial internal fixation / 中国组织工程研究

BACKGROUND:The addition of traditional rod-rod fixation for atlantoaxial joint disease to C1-C2 pedicle screw-rod fixation(C1-C2 PSR)can provide stronger anti-rotation stability for screw/rod fixation,but there is a risk of installation difficulties,impact on bone graft bed,and spinal cord injury.The new horizontal screw-screw crosslink(hS-S CL)designed by the authors can effectively overcome the above shortcomings,but its biomechanical properties are unclear. OBJECTIVE:To analyze biomechanical properties of new horizontal screw-screw crosslink in C1-C2 PSR by three-dimensional finite element analysis. METHODS:CT thin layer scanning data were collected from the occipital base to the axis(C0-2)of one adult healthy male volunteer.The atlantoaxial finite element models were established respectively:the normal group,the unstable group,the non-crosslink group(unstable+C1-C2 PSR),and the crosslink group(C1-C2 PSR+hS-S CL).Range of motion and Von Miss Stresses in flexion and extension,lateral flexion and rotation of the four groups were calculated by applying 1.5 Nm torque to each finite element model,and the stress cloud was extracted. RESULTS AND CONCLUSION:(1)Range of motion of the unstable group was increased by 43.8%-78.7%compared with the normal group,and the range of motion of the internal fixation groups was 90.2%-98.7%lower than that of the unstable group under six conditions.The range of motion of the crosslink group and the non-crosslink group was basically the same in flexion and extension states,but in lateral flexion and rotation states,the range of motion of the crosslink group decreased 34.3%-43.8%and 78.6%-79.1%,respectively,compared with the non-crosslink group,and range of motion decreased most obviously in rotation state.(2)The stress peak of the internal plant model:The maximum stress of the crosslink group was generally smaller than that of the non-crosslink group,and the stress peak value of all the internal fixation groups was the lowest when the extension was carried out.(3)The stress cloud of internal plants showed that there was no obvious stress concentration phenomenon in the internal fixation,and the main stress distribution areas were the screw root and bone joint,and the crosslink ends were the screw tail groove or the joint rod joint.(4)The new horizontal screw-screw crosslink can obviously improve the anti-rotation stability of internal fixation and it can share part of the pressure in the three-dimensional motion direction of the internal fixation system and reduce the maximum stress of the internal plants.However,the stress distribution is obvious at both ends of the crosslink,and this part may be prone to fracture of the crosslink.

Micromorphological characteristics of the pedicle of the lower cervical vertebra / 中国组织工程研究

BACKGROUND:The lower cervical vertebral pedicle is the main stress site of the posterior column of the spine,which is of great significance for the maintenance of the stability of the human center of gravity and the reduction of shock.At present,there are few reports on the characteristics of the internal bone trabeculae,and the characteristics of the joint site of the vertebral pedicle with the articular process and the vertebral body.It is urgent to understand the fine anatomical structure of the vertebral pedicle and the relationship and function of each part. OBJECTIVE:To observe the microanatomical morphology of the vertebral pedicle by Micro-CT scanning of cervical vertebra specimens,and to measure and analyze the microstructure and morphometric parameters of the bone trabecula in the cervical pedicle under normal conditions to evaluate the safety performance of the cervical spine. METHODS:Micro-CT scanning was performed on 31 sets of cervical vertebrae C3-C7.By checking and reconstructing the areas of interest in the bone trabecular within the vertebral pedicle,the morphological characteristics and distribution direction of the bone trabecular within the cervical pedicle were observed,and the bone microstructure parameters were detected,and the differences in the bone microstructure of the C3-C7 vertebral pedicle were analyzed and compared. RESULTS AND CONCLUSION:(1)The Micro-CT images showed that the honeycomb bone trabeculae of the pedicle of the lower cervical spine presented a complex network of microstructures.The trabeculae near the cortical bone were lamellar and relatively compact,extending forward toward the vertebral body and backward toward the articular process lamina.Abatoid bone trabeculae extended into the medullary cavity and transformed into a network structure,and then into rod-shaped bone trabeculae.The rod-shaped bone trabeculae were sparsely distributed in the medullary cavity.(2)Statistical results of morphological parameters of bone trabeculae showed that bone volume fraction values in C4 and C5 were higher than that in C7(P＜0.05).The bone surface/bone volume value in C7 was higher than that in C3,C4 and C6(P＜0.05).The bone surface density of bone trabeculae in C7 was higher than that in C3,C4,C5 and C6(P＜0.05).Trabecular thickness in C7 was higher than that in C3,C4 and C5(P＜0.05).Bone surface/bone volume and bone surface density of the left pedicle bone trabecular were greater than those on the right side(P＜0.05).(3)The microstructural changes of C3-C7 were summarized,in which the load capacity and stress of the C7 pedicle were poor,and the risk of injury was high in this area.

Study of Incidence of Ponticulus Posterior In Dry Human Atlas Vertebra and Its Clinical Significance

Background: Atlas is the first cervical vertebra. The vertebral artery lies in the groove on posterior arch of the atlas. The vertebral artery groove may sometimes get converted into a foramen. This is commonly known as ponticulus posterior (ponticulus posticus) or arcuate foramen of the atlas. These foramina may be complete or incomplete. This can lead to compression of the vertebral artery and produce symptoms like headache, syncope, altered consciousness etc. It can also complicate manipulations of the cervical spine by reducing the blood flow during extreme rotations of head and neck. It is also associated with vertebrobasilar artery stroke So, neurosurgeons or orthopaedic surgeons who operate in this area should have a detailed knowledge of variations of groove for the vertebral artery. Materials and Methods: The present study was conducted on 50 dried and fully ossified adult human atlas of unknown age and sex collected from the department of Anatomy, Government Medical college, Nagpur. Each atlas vertebra was carefully observed for the presence or absence of complete or incomplete ponticuli on superior surface of posterior arch of atlas. Results: Out of the 50 vertebra studied 7(14%) showed the presence of Ponticuli. Ponticuli were incomplete in all 7 atlas vertebras. Complete ring was not observed in any of the atlas vertebra .Out of the 7 ponticuli 6(12%) were found to be unilateral and in only 1 (2%) case it was found to be bilateral. Out of the 6 ponticuli 4(8%) were noticed on the Left side and 2(4%) were present on the right side. Conclusion: Presence of incomplete ponticulus posterior might cause cervical pain and even cerebrovascular disorders due to pressure on third part of vertebral artery present in the vertebral artery groove. This anatomical knowledge is important for neurosurgeons, orthopaedic surgeons, radiologists and clinicians while dealing with this region.

Posterior cervical pedicle screw rod short-segment internal fixation for the treatment of atlantoaxial fracture and dislocation / 中国骨伤

OBJECTIVE@#To investigate the clinical efficacy of posterior cervical pedicle screw short-segment internal fixation for the treatment of atlantoaxial fracture and dislocation.@*METHODS@#The clinical data of 60 patients with atlantoaxial vertebral fracture and dislocation underwent surgery between January 2015 and January 2018 were retrospectively analyzed. The patients were divided into study group and control group according to different surgical methods. There were 30 patients in study group, including 13 males and 17 females, with an average age of (39.32±2.85) years old, were underwent short-segment internal fixation with posterior cervical pedicle screws. There were 30 patients in control group, including 12 males and 18 females, with an average age of (39.57±2.90) years old, were underwent posterior lamina clip internal fixation of the atlas. The operation time, intraoperative blood loss, postoperative ambulation time, hospitalization time and complications between two groups were recorded and compared. The pain visual analogue scale(VAS), Japanese Orthopedic Association(JOA) score of neurological function, and fusion status were evaluated between two groups.@*RESULTS@#All patients were followed up for at least 12 months. The study group was better than control group in operation time, intraoperative blood loss, postoperative off-bed activity time, and hospital stay (P=0.000). One case of respiratory tract injury occurred in study group. In control group, 2 cases occurred incision infection, 3 cases occurred respiratory tract injury, and 3 cases occurred adjacent segmental joint degeneration. The incidence of complications in study group was lower than that in control group (χ2=4.705, P=0.030). At 1, 3, 7 days after operation, VAS of study group was lower than that of control group(P=0.000). At 1, 3 months after operation, JOA score of study group was higher than that of control group(P=0.000). At 12 months after operation, all the patients in the study group achieved bony fusion. In control group, there were 3 cases of poor bony fusion and 3 cases of internal fixation fracture, the incidence rate was 20.00%(6/30). The difference between two groups was statistically significant (χ2=4.629, P=0.031).@*CONCLUSION@#Posterior cervical short-segment pedicle screw fixation for atlantoaxial fracture and dislocation has the advantages of less trauma, shorter operation time, fewer complications, and less pain, and can promote the recovery of nerve function as soon as possible.

Evidence-based guideline for clinical diagnosis and treatment of acute combination fractures of the atlas and axis in adults (version 2023) / 中华创伤杂志

The acute combination fractures of the atlas and axis in adults have a higher rate of neurological injury and early death compared with atlas or axial fractures alone. Currently, the diagnosis and treatment choices of acute combination fractures of the atlas and axis in adults are controversial because of the lack of standards for implementation. Non-operative treatments have a high incidence of bone nonunion and complications, while surgeries may easily lead to the injury of the vertebral artery, spinal cord and nerve root. At present, there are no evidence-based Chinese guidelines for the diagnosis and treatment of acute combination fractures of the atlas and axis in adults. To provide orthopedic surgeons with the most up-to-date and effective information in treating acute combination fractures of the atlas and axis in adults, the Spinal Trauma Group of Orthopedic Branch of Chinese Medical Doctor Association organized experts in the field of spinal trauma to develop the Evidence-based guideline for clinical diagnosis and treatment of acute combination fractures of the atlas and axis in adults ( version 2023) by referring to the "Management of acute combination fractures of the atlas and axis in adults" published by American Association of Neurological Surgeons (AANS)/Congress of Neurological Surgeons (CNS) in 2013 and the relevant Chinese and English literatures. Ten recommendations were made concerning the radiological diagnosis, stability judgment, treatment rules, treatment options and complications based on medical evidence, aiming to provide a reference for the diagnosis and treatment of acute combination fractures of the atlas and axis in adults.

A clinical study of a novel manual screw placement based on anatomical study of the 7th cervical vertebra / 中华创伤骨科杂志

Objective:To evaluate the feasibility, accuracy, effectiveness and safety of a novel manual placement of cervical 7 pedicle screws via the posterior approach of cervicothoracic junction.Methods:A retrospective case series study was conducted to analyze the 35 patients with injury to the lower cervical spine or cervicothoracic junction who had been treated by a novel manual placement of cervical 7 pedicle screws at Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University from March 2015 to July 2021. There were 16 males and 19 females, with an age of (52.7±13.2) years. The core of this placement was to determine the entry point of cervical 7 pedicle screws. After the intersection of the upper edge of the cervical 7 lamina and the medial edge of the superior articular process was recorded as point A while the intersection of the lateral edge of the inferior articular process and the lower edge of the transverse process as point B, the intersection of the outer and middle 1/3 of the AB line was taken as the screw entry point, with the screw placement angle perpendicular to the lamina line or slightly inclined from 30° to 40° to the head side and outward. The length, diameter and placement angle of the cervical 7 pedicle screws were recorded and compared postoperatively between the left and right sides to explore the feasibility of this novel manual placement. According to the Rampersaud method, the screw positions were graded 1 week and 6 months after operation to evaluate the accuracy of this manual placement. The visual analogue scale (VAS) and the Japanese Orthopaedic Association (JOA) score were compared between preoperation, 1 week and 6 months after operation to evaluate the effectiveness of this placement. The postoperative complications were counted to evaluate the safety of this method. Loosening, displacement and breakage of the screws were observed by CT scanning at 6 months after operation.Results:This case series was followed up for (9.8±1.7) months. There was no significant difference in the length, diameter or placement angle of the screws between the left and right sides ( P>0.05). A total of 66 cervical 7 pedicle screws were placed. There was no change in the screw position grading at 1 week or 6 months after surgery. Grade A was achieved in 64 screws, Grade B in 2 screws, and Grade C or D in none. The VAS scores before operation, 1 week and 6 months after operation were respectively 4.4±1.7, 3.8±1.0 and 1.1±1.1, and the JOA scores respectively 6.7±2.2, 13.2±1.5 and 15.3±1.2. The VAS and JOA scores at 1 week and 6 months after operation were significantly improved compared with the preoperative values ( P<0.05). The improvement rates in JOA at 1 week and 6 months after operation were 62.7%±13.3 % and 83.9%±11.6%, respectively. There were no complications related to the placement of cervical 7 pedicle screws; there was no wound hematoma or infection. No loosening, displacement or breakage of the screws was observed by the 6-month follow-up. Conclusion:The novel manual placement of cervical 7 pedicle screws via the posterior approach of cervicothoracic junction is feasible, accurate, effective and safe.

Subclassification and clinical treatment options of refractory atlantoaxial dislocation / 中华骨科杂志

Objective:To subdivide clinical classification of refractory atlantoaxial dislocation, and evaluate the reliability of new subdivide clinical classification of refractory atlantoaxial dislocation.Methods:From January 2010 to December 2018, 48 patients with refractory atlantoaxial dislocation were treated, including 19 males and 29 females, aged 16 to 65 years, with an average of 39.2±13.3 years. According to the changes of relative anatomical position of C 1 and C 2 under general anesthesia with heavy traction of 1/6 body weight, subdivide clinical classification of refractory atlantoaxial dislocation were proposed, and refractory atlantoaxial dislocation was divided into traction loosening type (atlantoaxial angle≥5°) and traction stabilization type (atlantoaxial angle<5°). The traction loosening type was directly reduced by posterior atlantoaxial screw-rod fixation and fusion without anterior or posterior soft tissue release. For traction stabilization type, transoral soft tissue release was performed first, and then transoral anterior reduction plate fixation and fusion or posterior atlantoaxial screw-rod fixation and fusion were performed. Atlantodental interval (ADI) and atlantoaxial angle (AAA) were measured and collected before and after surgery to evaluate atlantoaxial reduction. The space available for the spinal cord (SAC) were measured to evaluate spinal cord compression. Visual analogue score (VAS) was used to evaluate the neck pain levels, and Japanese Orthopaedic Association (JOA) scores was used to evaluate the neurological function. American Spinal Cord Injury Association impairment scale (AIS) was used to evaluate the degree of spinal cord injury. One week, 3, 6, 12 months postoperatively and the annual review of the X-ray and CT scan were checked, in order to evaluate the reduction, internal fixation and bone graft fusion. Results:Among all 48 cases, 22 cases were traction loosening type, of which posterior atlantoaxial screw-rod fixation and fusion were performed in 16 cases and occipitocervical fixation and fusion in 6 cases. 26 cases were traction stabilization type, and they all underwent anterior transoral release, and then, anterior TARP fixation and fusion were performed in 24 cases and posterior screw-rod fixation and fusion in the other 2 cases. X-ray, CT and MRI images and of all patients 1 week after surgery showed good atlantoaxial reduction and decompression of spinal cord. In each of the two types, there was one case lost to follow-up. For 46 cases in follow-up, the follow-up time ranged from 6 to 72 months, with an average of 38.0±17.2 months. Among 46 cases, 21 cases of traction loosening type showed that, ADI reduced from preoperative 9.9±2.2 mm to 2.3±0.9 mm at 3 months after surgery and 2.3±1.0 mm at the last follow-up, AAA increased from preoperative 57.9°±12.3° to 91.0°±2.2° at 3 months after surgery and 90.9°±2.2° at the last follow-up, SAC increased from preoperative 9.8±1.3 mm to 15.1±0.7 mm at 3 months after surgery and 14.9±0.7 mm at the last follow-up, VAS score reduced from preoperative 1.5±2.1 to 0.7±1.0 at 3 months after surgery and 0.3±0.6 at the last follow-up, and JOA score increased from preoperative 10.2±1.7 to 13.3±1.3 at 3 months after surgery and 14.9±1.5 at the last follow-up. Twenty-five cases of traction stabilization type presented that, ADI reduced from preoperative 9.7±2.0 mm to 2.1±1.4 mm at 3 months after surgery and 2.1±1.3 mm at the last follow-up, AAA increased from preoperative 55.8°±9.2° to 90.9°±1.4° at 3 months after surgery and 90.9°±1.3° at the last follow-up, SAC increased from preoperative 10.5±1.0 mm to 15.4±0.5 mm at 3 months after surgery and 14.8±2.8 mm at the last follow-up, VAS score reduced from preoperative 1.7±2.1 to 0.7±0.9 at 3 months after surgery and 0.3±0.5 at the last follow-up, and JOA score increased from preoperative 10.1±1.3 to 12.9±1.5 at 3 months after surgery and 14.4±1.3 at the last follow-up. In the traction loosening type, all the 10 grade D patients were improved to grade E at the last follow-up. In the 2 grade C patients of traction stabilization type before surgery, 1 patient was improved to grade E, 1 patient was improved to grade D, and all 11 patients with grade D were improved to grade E at the last follow-up. Bony fusion was obtained in all patients from 3 to 6 months, with an average of 4.4±1.5 months. During follow-up period, no looseness of internal fixation or redislocation happened.Conclusion:Refractory atlantoaxial dislocation can be divided into traction loosening type and traction stabilization type. For traction loosening type, satisfactory reduction can be achieved by using posterior atlantoaxial screw-rod system without soft tissue release. For traction stabilization type, anterior release is preferable, and then anterior TARP or posterior screw-rod can be used to achieve satisfactory reduction.

The clinical characteristics and treatment of "sandwich" atlantoaxial dislocation / 中华骨科杂志

Objective:To evaluate the specialty of the clinical features, treatment procedure, clinical outcome, and prognosis in the patients with "sandwich" atlantoaxial dislocation (AAD).Methods:From 2008 to 2018, 160 cases with "sandwich" AAD were retrospectively selected from the case series of AAD in Peking University Third Hospital. The case series had 80 males and 80 females. The mean age at the initial visit was 35.5±14.6 years (range, 5-77). The clinical courses, treatment methodology and prognosis were reviewed. And the surgical approach, posterior fixation segment and the recovery of neurological function were mainly summarized. The atlantodental interval (ADI), the distance by which the odontoid exceeded the Chamberlain line and the cervical-medullary angle were analyzed.Results:The most common symptoms included weakness or numbness of the limbs (67.5%, 108/160), unstable gait (30%, 48/160) and vertigo (20%, 32/160). Among all, 130 cases (81.3%, 130/160) had myelopathy, with the Japanese Orthopaedic Association (JOA) scores from 4 to 16 (mean JOA scores 13.5±2.5). Cranial neuropathy was involved in 20 cases (12.5%). Radiological findings showed brainstem and/or cervical-medullar in 130 cases (81.3%), syringomyelia in 37 cases (23.1%) and Chiari malformation in 30 cases (18.8%). Computed tomography angiography (CTA) was performed in 90 cases, which showed vertebral artery anomalies in 55 cases (61.0%) and excessive medialized internal carotid artery in 5 cases (5.6%). All cases had no spinal cord or vertebral artery injury. The surgery included posterior occipito-cervical fusion (reducible dislocation, 145 cases), and transoral release followed by posterior fusion (irreducible dislocation, 15 cases). Fifty-seven cases were treated using alternative fixation technique. The average follow-up time was 50.5±22.4 months (range, 24 to 120 months). All of 152 cases (95.0%) achieved solid atlantoaxial fusion; there was no obvious osseous fusion formation on postoperative images in 6 cases (3.8%), but no atlantoaxial instability was found on dynamic radiographs; screw loosening happened in 2 patients (1.2%). Nine patients (5.6%) suffered complications, including 4 cases with recurrent dislocation, 2 screw loosening, 2 cases with bulbar paralysis and 1 wound infection. The mean postoperative JOA was 15.1±1.8 (range, 5-17), and the mean neurological improvement rate was 42.9%±33.3% in the patients with myelopathy.Conclusion:"Sandwich" AAD, a subgroup of AAD, has unique clinical features: earlier onset age and more severe myelopathy. The incidence of bone and vascular malformation is higher. So alternative surgical plan and hybrid fixation should be prepared for this subgroup of AAD.

Anterior cervical release and posterior fixation for the treatment of irreducible atlantoaxial dislocation with retropharyngeal internal carotid artery / 中华骨科杂志

Objective:To investigate the clinical effect of anterior cervical release and posterior fixation in the treatment of irreducible atlantoaxial dislocation with retropharyngeal internal carotid artery.Methods:Thirteen patients with irreducible atlantoaxial dislocation of retropharyngeal internal carotid artery from January 2015 to July 2019 were treated with anterior cervical release and posterior fixation. There were 8 males and 5 females, aged from 34 to 65 years with an average of 46.1±12.6 years. Positive, lateral and dynamic X-ray films, MR and CTA were performed before operation. There were 4 cases with bilateral retropharyngeal internal carotid artery and 9 cases with unilateral retropharyngeal internal pharyngeal artery. The time of operation, the amount of bleeding and intraoperative and postoperative complications were recorded. The main observations were Japanese Orthopaedic Association (JOA) score, atlantodental interval (ADI), Chamberlain line (CL), and changes in the morphology of the retropharyngeal internal carotid artery and implant fusion.Results:All the operations completed successfully. The operation time was 210-260 min, the average was 245±21 min; the blood loss was 350-600 ml, the average blood loss was 490±107 ml. There was no injury of internal carotid artery, vertebral artery, spinal cord or nerve root during the operation. All patients were followed up for 9 to 24 months, with an average of 15.1±6.2 months. Preoperative JOA score was 6.9±2.3 points, 1 month after operation was 13.5±2.5 points, and the last follow-up was 14.3±2.1 points. The difference was statistically significant ( F=30.91, P<0.001). The difference between 1 month after operation and before operation was statistically significant ( P<0.001), and the improvement rate of JOA score was 75.6%±15.2%. There was no significant difference between the last follow-up and 1 month after operation ( P>0.05). The preoperative ADI was 8.9±2.2 mm, 1 month after operation was 1.1±0.8 mm, and the last follow-up was 1.2±0.9 mm. The difference was statistically significant ( F=114.69, P<0.001). The difference between 1 month after operation and before operation was statistically significant ( P<0.001), and ADI had returned to normal level. There was no significant difference between the last follow-up and 1 month after operation ( P>0.05). The preoperative CL was 11.7±4.8 mm, 1 month after operation was 1.6±2.1 mm, and the last follow-up was 1.8±2.3 mm. The difference was statistically significant ( F=34.19, P<0.001). The difference between 1 month after operation and before operation was statistically significant ( P<0.001), and the position of odontoid process returned to normal level. There was no significant difference between the last follow-up and 1 month after operation ( P>0.05). Bone graft fusion was received at 6 to 12 months after operation, with an average of 10.2 months. Conclusion:CTA examination should be performed before anterior release of atlantoaxial dislocation to understand the position and shape of internal carotid artery. Anterior cervical release combined with posterior bone graft fusion is an effective method for the treatment of irreducible atlantoaxial dislocation with retropharyngeal internal carotid artery without increasing the risk of internal carotid artery injury.

Diagnosis and treatment of atlantoaxial dislocation / 中华骨科杂志

Atlantoaxial dislocation is a pathological anatomical condition caused by the loss of stability between the atlantoaxial joints, which is a serious disabling disease in spine surgery, and may even endanger the patient's life. The causes of atlantoaxial dislocation include traumatic, congenital, inflammatory, degenerative, tumor, and other factors. Since the symptoms and signs are not specific in clinic, imaging examination is particularly important. Atlantoaxial dislocation is mainly classified according to the etiology, the relative position of atlas and axis, and the difficulty of reduction. Accurate classification is of great significance for the selection of treatment options. There is no popular guideline for surgical indications of atlantoaxial dislocation. Patients presenting with related symptoms or spinal cord dysfunction are generally recognized surgical indications in clinical practice. With the continuous improvement and optimization of atlantoaxial screw placement, reduction and fusion technology, supplemented by new equipment in spine surgery, the surgery-related risks and complications have been greatly reduced, and the surgical treatment of atlantoaxial dislocation can obtain good reduction and fusion results. This tutorial summariz the etiology, diagnosis, classification, treatment, complications, and prognosis of atlantoaxial dislocation, in order to provide a more complete and refined reference for clinical diagnosis and treatment.

Effect of cervical Luschka joint degenerative change on expression of VEGF and its receptor / 局解手术学杂志

Objective To observe the effect of cervical degenerative change on the expression of vascular endothelial growth factor(VEGF)and vascular endothelial growth factor receptor-2(VEGFR-2).Methods The C3 to C7 segments of bilateral healthy cervical vertebrae of adult cadavers were taken as the control group,and the C3 to C7 segments of bilateral degenerative cervical vertebrae of adult cadavers were taken as the experimental group.The expression changes of VEGF and VEGFR-2 of the two groups were observed and analyzed by immunohistochemistry,immunofluorescence staining and real-time quantitative PCR.Results The protein and mRNA expressions of VEGF and VEGFR-2 in the experimental group were higher than those in the control group,with statistically significant differences(P<0.05).Conclusion Cervical Luschka joint degenerative change significantly up-regulates the expression of VEGF and VEGFR-2,which is closely related to the microenvironmental changes around the Luschka joint caused by degeneration of joint-like structure.

Biomechanical evaluation of four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs

Purpose: This study compared, through biomechanical evaluation under ventral flexion load, four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs. Methods: In total, 28 identical atlantoaxial joint models were created by digital printing from computed tomography images of a dog, and the specimens were divided into four groups of seven. In each group, a different technique for ventral stabilization of the atlantoaxial joint was performed: transarticular lag screws, polyaxial screws, multiple screws and bone cement (polymethylmethacrylate­PMMA), and atlantoaxial plate. After the stabilization technique, biomechanical evaluation was performed under ventral flexion load, both with a predefined constant load and with a gradually increasing load until stabilization failure. Results: All specimens, regardless of stabilization technique, were able to support the predefined load without failing. However, the PMMA method provided significant more rigidity (p ≤ 0.05) and also best resisted the gradual increase in load, supporting a significantly higher maximum force (p ≤ 0.05). There was no statistical difference in flexural strength between the transarticular lag screws and plate groups. The polyaxial screws method was significantly less resistant to loading (p ≤ 0.05) than the other groups. Conclusions: The PMMA technique had biomechanical advantages in ventral atlantoaxial stabilization over the other evaluated methods.

Imaging anatomical study and clinical application of transoral axis slide and rotation osteotomy technique / 中华骨科杂志

Objective:To introduce a novel technique note about anterior decompression through transoral axis slide and rotation osteotomy (ASRO) and identify its imaging parameters related to osteotomy, and to explore its clinical application value.Methods:CT data of cervical spine of 90 subjects were collected, including 54 males and 36 females. The age ranged from 26 to 72 years, with an average age of 48.7 years. The Mimics software was used to reconstruct the atlantoaxial three-dimensional model. We plan to perform osteotomy on both sides of the axis of the vertebral body in the anteroposterior direction and the ASRO related anatomical parameters were measured, including the minimum osteotomy angle, the maximum osteotomy angle, the minimum and maximumdistance between the osteotomy trajectory and the inner side of the articular surface, the length of the upper articular surface of the axis side mass, the depth of osteotomy at the highest point and lowest point of the axial osteotomy surface and the minimum osteotomy depth. A 56-year-old female patient was admitted to the hospital due to atlantoaxial dislocation with failure of occipital-cervical fusion, difficulty walking, weakness and hypoaesthesia in four limbs. Imaging revealed that narrow space between the transversal walking wire and upper-posterior of the odontoid process, compressing the spinal cord from the front and the back respectively. The ASRO technique was performed on the patient under neuro-electrophysiological monitoring, and the osteotomy angle, osteotomy depth, narrowest width of the upper cervical spinal canal, the medullary, spinal cord angle were measured and Japanese Orthopaedic Association Scores (JOA) cervical myelopathy evaluation were performed after the operation to evaluate the surgical treatment effect.Results:The minimum osteotomy angle and the maximum osteotomy angle was 14.7°± 4.36° and 33.0°± 8.67°. The minimum and maximumdistance between the osteotomy trajectory and the inner side of the articular surface, and the length of the upper articular surface of the axis side mass was 6.0±1.80 mm, 12.2±3.17 mm, and 17.2±1.90 mm, the ratio of the former two to the latter was 34%±8.7% and 70%± 15.0%. The depth of osteotomy at the upper edge, lower edge and narrowest place of the axial osteotomy surface were 6.0±1.80 mm, 12.2±3.17 mm and 17.2±1.90 mm. The postoperative imaging of the patient showed that the osteotomy angle was 17.1° on left side and 16.5° on right side, and the depth of osteotomy at the upper edge, lower edge and narrowest place of the axial osteotomy surface were 17.1 mm, 13.2 mm, and 9.1 mm on left side, and 17.4 mm, 11.8 mm, 8.46 mm on right side. All measured values met the ranges which were shown in the imaging anatomical study. The narrowest width of the upper cervical spinal canal increased from 6.58 mm to 15.28 mm, the medullary spinal cord angle increased from 131.7° to 153.8°postoperatively, and the cervical spine JOA score recovered from 6 points to 14 points, suggesting that the postoperative spinal canal space is obvious increased, the compression on the front of the spinal cord was significantly reduced. The patient's symptoms improved significantly.Conclusion:ASRO technique is a good choice for salvage of failed posterior occipitocervical fusion and some irreducible atlantoaxial dislocation because of the anterior bony fusion. It could direct decompress the spinal cord anteriorly, avoid the odontoid resection, which is a safe and feasible new technique.

Research progress of causes and strategies in revision surgery for atlantoaxial dislocation / 中国骨伤

Atlantoaxial dislocation (AAD) is a kind of life-threatening atlantoaxial structural instability and a series of neurological dysfunction caused by common multidisciplinary diseases. The operation risk is extremely high because it is adjacent to the medulla oblongata and the location is deep. With the increase of the number of operations in the upper cervical region, postoperative complications such as failure of internal fixation, non fusion of bone graft and poor prognosis gradually increase.Incomplete primary operation, non fusion of bone graft, infection and congenital malformation are the potential causes. In addition, considering the objective factors such as previous graft, scar formation and anatomical marks changes, revision surgery is further difficult. However, there is currently no standard or single effective revision surgery method. Simple anterior surgery is an ideal choice in theory, but it has high risk and high empirical requirements for the operator;simple posterior surgery has some defects, such as insufficient reduction and decompression;anterior decompression combined with posterior fixation fusion is a more reasonable surgical procedure, but many problems such as posterior structural integrity and multilevel fusion need to be considered.This article reviews the causes and strategies of AAD revision surgery.

Dynamic Response Simulation and Damage Prediction of Pilot Cervical Vertebra During Maneuver Flight / 医用生物力学

Objective To simulate dynamic response of cervical spine of the pilot during typical maneuver flight movements using finite element method, as well as make analysis and prediction on damage failure of the pilot neck during flight by impact injury and fatigue injury model of biological tissues.Methods A geometrically accurate finite element model of the neck was constructed, and validity of the model was verified by relevant examples. Then, the acceleration curves of centrifugal trainer under different modes were loaded for numerical simulation, and impact injury and fatigue injury of tissues were predicted by using the universal cervical injury criterion and the fatigue damage model of biological tissues.Results The maximum stress of the vertebrae and intervertebral disc caused by overload impact was 66.53 MPa and 58.63 MPa respectively during typical maneuver flight. According to the Nij injury criteria, the maximum Nij was 0.096, which was lower than the injury tolerance threshold of 1, and would not cause direct acute injury to cervical tissues. Based on fatigue damage model of biological tissues, it was found that cancellous bone suffered fatigue failure under the condition of uninterrupted repeated loading for more than 40 000 times. Considering the limited flight career of the pilot, the vertebral tissues would not be fractured due to the accumulation of fatigue damage.Conclusions To a certain extent, the results can contribute to formulating pilot training and flight plans, and also provide data support for the development of its protective equipment.

Subluxación rotatoria atloaxoidea o síndrome de Grisel. A propósito de un caso / Rotatory subluxation of the atlantoaxial joint or Grisel's syndrome. Case report

La tortícolis es una contractura involuntaria unilateral del esternocleidomastoideo y de la musculatura posterior del cuello que causa la inclinación de la cabeza hacia un lado. Se han descrito múltiples causas de torticolis siendo una de ellas la subluxación atloaxoidea atraumática asociada a un proceso de carácter inflamatorio en la región de cabeza y cuello, llamada síndrome de Grisel. Aunque la mayoría de los pacientes suelen recuperarse sin secuelas tras tratamiento médico existe la posibilidad de complicaciones graves con déficits funcionales, de ahí la importancia de la realización de un diagnóstico y tratamiento precoz.

Torticollis is an unilateral involuntary contracture of the sternocleidomastoid and posterior neck musculature that causes the head tilts to the one side. Multiple causes of torticolis have been described, one of them being the non-traumatic rotatory subluxation of the atlantoaxial joint associated with an inflammatory process in the head and neck region, called Grisel's syndrome. Although most patients usually recover without sequels after medical treatment, there is the possibility of serious complications with functional deficits, that is why the importance of an early diagnosis and treatment of this potology.

Traumatic atlantoaxial rotatory dislocation in the pediatric population / Luxação rotacional traumática de c1-c2 na população pediátrica / Luxación rotatoria traumática de c1-c2 en población pediátrica

ABSTRACT Objective: The treatment of C1-C2 rotatory dislocation remains controversial and surgery is rare. Surgical treatment is indicated when the injury satisfies the instability criteria or when it cannot be reduced. The objective of this study is to analyze the principles and the adaptations necessary for treating these injuries in the pediatric population. Methods: A retrospective case series study. Three cases of patients diagnosed with traumatic C1-C2 rotatory dislocation and treated surgically in our hospital were studied. Through critical analysis of the available literature, a practical guide was proposed to establish the principles and competencies for the treatment of these injuries. Results: The operated cases were female patients between 8 and 16 years of age, with a diagnosis of traumatic atlantoaxial dislocation. Two patients required preoperative skeletal traction with halo. All patients underwent posterior instrumented arthrodesis, two with a transarticular screw technique and one with mass and C2 isthmic (Göel-Harms) screws. Conclusion:. It is essential to determine if the injury is stable and reducible. We recommend treating this type of injury keeping the criteria and competencies related to the stability, alignment, biology and function of the spine in mind. Level of evidence IV; Case series.

RESUMO Objetivo: O tratamento da luxação rotacional de C1-C2 permanece controverso, e a cirurgia é rara. O tratamento cirúrgico é indicado quando a lesão satisfaz os critérios de instabilidade ou quando não pode ser reduzida. O objetivo deste estudo é analisar os princípios e a adequação necessários para tratar essas lesões na população pediátrica. Métodos: Estudo retrospectivo de série de casos. Foram estudados três casos em pacientes tratados cirurgicamente em nosso hospital com diagnóstico de luxação rotacional traumática de C1-C2. Por meio de análise crítica da literatura disponível, foi proposto um guia prático para estabelecer os princípios e a adequação do tratamento dessas lesões. Resultados: Os casos submetidos à cirurgia foram pacientes do sexo feminino, entre 8 e 16 anos de idade, com diagnóstico de luxação atlantoaxial traumática. Duas pacientes precisaram de tração esquelética pré-operatória com halo. Todas as pacientes foram submetidas à artrodese instrumentada por via posterior, duas com técnica de parafuso transarticular e uma com parafusos de massa e pedículo e lâmina em C2 (técnica de Göel-Harms). Conclusões: É essencial determinar se a lesão é estável e se pode ser reduzida. Recomenda-se tratar esse tipo de lesão tendo em mente os critérios e a adequação relacionados com estabilidade, alinhamento, biologia e função da coluna vertebral. Nível de evidência IV; Série de casos.

RESUMEN Objetivo: El tratamiento de la luxación rotatoria de C1-C2 permanece controversial y la cirugía es rara. Se indica tratamiento quirúrgico cuándo la lesión cumple criterios de inestabilidad o cuándo es considerada irreductible. El objetivo de este estudio es revisar los principios y competencias necesarios para tratar esas lesiones en la población pediátrica. Métodos: Estudio retrospectivo de serie de casos. Se estudian tres casos en pacientes tratados quirúrgicamente en nuestro hospital con diagnóstico de luxación rotatoria de C1-C2 traumática. A través del análisis crítico de la literatura disponible se elabora un esquema práctico para establecer los principios y competencias para el abordaje de estas lesiones. Resultados: Los casos intervenidos fueron pacientes de sexo femenino entre 8 y 16 años, con diagnóstico de luxación atlantoaxoidea traumática. Dos pacientes requirieron tracción esquelética preoperatoria con halo. A todas las pacientes se les practicó artrodesis instrumentada por vía posterior, dos con técnica de tornillos transarticulares y una con tornillos de masa e ístmicos de C2 (Göel-Harms). Conclusiones: Resulta imprescindible determinar si la lesión es estable y reductible. Siempre abordar este tipo de lesiones teniendo presentes los criterios y competencias relacionados con la estabilidad, alineación, biología y función de la columna vertebral. Nivel de Evidencia IV; Serie de casos.