Atlantoaxial dislocation treated by posterior atlantoaxial lateral mass interarticular release,posterior screw reduction and fusion with bone graft / 中国组织工程研究

BACKGROUND:Atlantoaxial dislocation is often facilitated by interlaminar bone grafting.However,there are relatively few reports on the treatment of complex atlantoaxial dislocation with posterior atlantoaxial lateral mass interarticular release and fusion. OBJECTIVE:To explore the safety and effectiveness of atlantoaxial dislocation treated by simple posterior atlantoaxial lateral block interarticular release and fusion. METHODS:We retrospectively analyzed the clinical data of 30 patients with atlantoaxial dislocation who were treated from January 2017 to July 2021,all of whom suffered from reducible atlantoaxial dislocation.Posterior atlantoaxial lateral mass interarticular release and fusion were performed in all patients.During the surgery,patented instruments were used to release the atlantoaxial lateral mass joint,and posterior screw reduction and fixation were used with bone grafting in the lateral mass joint space.The postoperative follow-up period was 6 to 24 months,mean(13.0±5.4)months.During the follow-up period,cervical MRI was reviewed to observe the decompression of the upper cervical spine.X-ray films and CT scans were reviewed to observe the reduction of the upper cervical spine,as well as the internal fixation for looseness and breakage.CT scans were reviewed to assess interlateral block implant fusion.The Japanese Orthopaedic Association score was used to evaluate the improvement of spinal cord function.The neck disability index and the quality of life scale were used to assess the improvement of daily life function.The atlanto-anterior interspace and atlanto-planar spinal effective space were used to evaluate atlantoaxial repositioning and decompression. RESULTS AND CONCLUSION:(1)The surgery of 30 patients went smoothly,and no serious complications such as spinal nerve and vertebral artery injuries occurred during the operation.Postoperative review of cervical MRI showed that the spinal cord compression was lifted.X-ray film and CT showed that the atlanto-anterior gap was significantly reduced;the effective space of atlantoaxial spinal cord was significantly increased,and neurological dysfunctional symptoms were significantly reduced.(2)During the follow-up period,X-ray film and CT showed that the internal fixation was solid;no broken nails or rods occurred,and there was no recurrence of atlantoaxial dislocation.(3)The Japanese Orthopaedic Association scores,neck disability index,and quality of life scores were significantly improved at the last follow-up compared with the preoperative period(P<0.05).The average improvement rate of Japanese Orthopaedic Association scores at the last follow-up was 73.1%.The average neck disability index was 8.80%.All of the patients had a continuous bone-scalp connection between atlantoaxial lateral block joints to achieve osseous fusion.(4)These findings indicate that the use of simple posterior atlantoaxial lateral block interarticular release and fusion for the treatment of atlantoaxial dislocation can significantly increase the fusion rate and shorten the fusion time.

Robot-assisted pedicle screw internal fixation in treatment of atlantoaxial dislocation / 中国组织工程研究

BACKGROUND:Atlantoaxial dislocation,because of its high difficulty and high risk of surgery,has been regarded as the"surgical restricted area"by the international orthopedic community.However,with the rapid development of intelligent digitization in orthopedics,robot-assisted navigation screw placement technology has been widely used in clinical practice,which significantly reduces the difficulty and risk of surgery and improves the safety of surgery.However,there are few reports on the application of this technique in the treatment of atlantoaxial dislocation. OBJECTIVE:To explore the application value of robot-assisted pedicle screw internal fixation in the treatment of atlantoaxial dislocation. METHODS:The medical records of five patients with atlantoaxial dislocation treated with C1-C2 pedicle screw fixation under robot-assisted navigation in Zhuhai Hospital of Guangdong Provincial Hospital of Chinese Medicine from October 2021 to July 2022 were retrospectively analyzed.Operation time,length of neck incision,blood loss,postoperative drainage volume,and length of hospital stay were recorded.Attention should be paid to cerebrospinal fluid leakage,vertebral artery injury,nerve injury,operative area infection and other complications.The visual analog scale score of neck pain,the spinal cord injury grade of the American Spinal Injury Association,the cervical spine score of the Japanese Orthopaedic Association,and the imaging indicators were collected before surgery and at the last follow-up.Screw placement accuracy was assessed. RESULTS AND CONCLUSION:(1)Five patients were successfully completed surgery,without vascular,nerve injury or other complications,and were followed up for 12-20 months.(2)A total of 20 cervical pedicle screws were placed in 5 patients,including 9 type A screws,10 type B screws,and 1 type C screw.The accuracy of screw placement was 95%.(3)At the last follow-up,the visual analog scale score was(0.80±0.71)points,which was significantly lower than that before operation(4.00±2.83)points;the Japanese Orthopaedic Association score was(14.80±0.84)points,which was significantly higher than that before operation(8.00±0.71)points.Anterior atlantodental interval decreased from(7.86±3.25)mm to(2.82±0.93)mm;space available of the spinal cord increased from(6.74±1.99)mm to(12.10±3.51)mm;cervicomedullary angle increased from(133.32±13.55)° to(153.44±9.53)°;clivus-canal angle increased from(128.02±9.92)° to(143.25±12.99)°.The results of the last follow-up indexes were improved compared with those before operation,and the differences were significant(all P<0.05).(4)Postoperative imaging follow-up showed that all patients had bone fusion in the bone graft area,and no internal fixation loosening,fracture or pull-out occurred.(5)This method can avoid relying on the doctor's experience and hand feeling,ensure the accuracy of upper cervical screw placement,reduce the risk of surgery,and obtain satisfactory results in mid-term follow-up.

Operative strategies for atlanto-axial dislocation revision surgery / 中国脊柱脊髓杂志

Objectives:To explore the operative strategies of revision surgery after atlanto-axial dislocation(AAD)surgery.Methods:12 patients undergone AAD revision surgery in our hospital between January 2016 and August 2019 were analyzed in this retrospective study,including 3 males and 9 females,aged 7-62 years[45.5(34.25,52.50)years].The interval of initial operation and revision operation was 3-360 months[30(5,93)months].Internal fixation and bone graft were removed before revision surgery.The patients were assessed to receive anterior release according to the conditions of 1/6 body weight dose skull traction.According to preoperative imaging and intraoperative exploration,larger diameter and longer screws,new screw track,and extended fixed segments were performed optionally to increase the overall internal fixation strength,and the lateral atlantoaxial joint release and grafting were performed to increase bone graft fusion.The follow-up peri-od ranged 12-50 months[24.0(17.25,34.00)months].The atlanto-dental interval(ADI),clivus-axial angle(CAA),cervico-medullary angle(CMA)and Japanese Orthopaedic Association(JOA)score were assessed at 3 days after surgery and final follow-up,the CT examination was performed at 3 days,3 months,6 months,12months and final follow-up after surgery to evaluate the bone graft fusion.Results:There were 8 patients receiving inter-nal fixation and bone graft removing before revision surgery.Among the patients,4 received anterior releasing combined with posterior reduction and internal fixation and fusion,the other 8 patients underwent posterior reduction and internal fixation and fusion.Of all the patients,occipital screw revision was performed in 4 with new screw track;C1 screw revision was performed in 4,of which 2 patients were fixed with larger di-ameter and longer screws,and 2 patients were fixed with new screw track;C2 screw revision was performed in 8,of which 5 patients were fixed with larger diameter and longer screws,and 3 patients were fixed with new screw track;extended fixed segments were preformed in 3 patients;the lateral atlantoaxial bone grafting was performed in all 12 patients.Anatomical reduction was obtained in all the patients.The postoperative 3d and final follow-up ADI were significantly reduced compared with pre-operative ADI,and the CCA and CMA were significantly increased than those at pre-operation(P＜0.05).The JOA at 3 days after surgery and final follow-up were significantly improved than that at pre-operation.Bony fusion was achieved in all the patients,with a bone fusion rate of 100％,and the bone fusion time ranged 3-7 months[3.5(3.0,6.0)months].Con-clusions:Anterior release is suitable for the patients with un-reduced atlantoaxial dislocation after removal of primary internal fixation under heavy traction.During posterior revision surgery,occipital screws need to change trajectory to maintain firm internal fixation,and larger diameter and longer screw is suitable for C1,and C2 screws,while extended fixed segments are suitable for patients whose C1 or C2 screws cannot be in-serted.The lateral atlantoaxial joint bone grafting is suitable for all AAD revision.

Preliminary application of self-designed posterior reduction forceps for atlantoaxial dislocation in treatment of irreducible atlantoaxial dislocation / 中华创伤骨科杂志

Objective:To evaluate the preliminary clinical application of our self-designed posterior reduction forceps for atlantoaxial dislocation in the reduction and fixation of irreducible atlantoaxial dislocation with simple posterior screw-rod system.Methods:Our posterior reduction forceps was self-designed and developed to assist simple posterior screw-rod system in the treatment of irreducible atlantoaxial dislocation based on the posterior atlantoaxial screw-rod system. A retrospective study was conducted to analyze the clinical data of 5 patients with irreducible atlantoaxial dislocation who had been treated from January 2021 to October 2022 at Department of Spine Surgery, General Hospital of Southern Theatre Command of PLA with our self-designed posterior reduction forceps. There were 2 males and 3 females, aged 53, 62, 45, 32 and 48 years, respectively. Diagnosis: 1 case of free odontoid process combined with atlantoaxial dislocation, 2 cases of atlantoaxial dislocation, and 2 cases of old odontoid process fracture combined with atlantoaxial dislocation. Respectively, their preoperative Japanese Orthopaedic Association (JOA) scores were 9, 11, 12, 13 and 10 points and their atlanto-dental intervals (ADI) 9.8, 7.4, 6.6, 6.4 and 8.5 mm. Postoperatively, atlantoaxial reduction and spinal cord compression were evaluated by X-ray, CT, and MRI examinations, and internal fixation, atlanto-axial sequence, and bone graft fusion by X-ray and CT examinations. One week after surgery, the JOA scores were used to evaluate the patients' neurological function and the ADI was measured to evaluate the atlantoaxial reduction.Results:The surgery was successfully performed in the 5 patients, with no intraoperative complications like neurovascular injuries to the spinal cord. The postoperative atlantoaxial reduction was satisfactory, the position of internal fixation was good, the compression to the spinal cord was relieved, and the clinical symptoms were significantly improved. At 1 week after surgery, respectively, the JOA score: 13, 14, 14, 15 and 13; the ADI: 2.6, 2.1, 1.8, 1.5 and 2.2 mm; the follow-up time: 3, 6, 12, 9 and 6 months; the bone fusion time: 3, 3, 6, 6 and 3 months. Follow-ups revealed no loosening or fracture of internal fixation, good atlanto-axial sequence, and no recurrence of dislocation.Conclusion:Our self-designed posterior reduction forceps for atlantoaxial dislocation can assist the simple posterior screw-rod system to treat irreducible atlantoaxial dislocation, leading to good preliminary clinical outcomes.

Biomechanical Study on Atlantoaxial Dislocation Combined with Basilar Invagination by Different Posterior Internal Fixation Methods / 医用生物力学

Objective To investigate biomechanical differences of two posterior occipitocervical internal fixation techniques for treating basilar invagination with atlantoaxial dislocation (BI-AAD). Methods Intra-articular cage + posterior occipital plate+C2 pedicle screw (Cage+C2PS+OP), and intra-articular cage+C1 lateral mass screw+C2PS (Cage+C1LMS+C2PS) models were established based on occipitocervical CT data of the BI-AAD and clinical operation scheme, and the stability of atlantoaxial joint and stress distribution characteristics of C2 endplate and implanted instruments under different motion states were analyzed. Results Compared with the Cage+C1LMS+C2PS model, the atlantoaxial range of motion ( ROM) under flexion, extension, lateral bending and axial rotation in the Cage+C2PS+OP model were reduced by 5. 26% , 33. 33% , 43. 75% , -5. 56% , and stress peak of screw-rod fixation system were reduced by 47. 81% , 60. 90% , 48. 45% , 39. 14% , respectively. Under two internal fixation modes, stresses of C2 endplate and cage were mainly distributed on the compressive side during the motion, and both the screw-bone interface and the caudal side of screw subjected to large loading. Conclusions Two internal fixation methods could provide similar stability. However, the stress concentration of screw-rod system was more obvious and the possibility of screw loosening and fracture was greater under Cage+ C1LMS+C2PS fixation.

Application of medial "in-out-in" axis pedicle screw in upper cervical spine surgery / 中华神经医学杂志

Objective:To investigate the clinical efficacy of medial "in-out-in" axial pedicle screw in the treatment of atlantoaxial dislocation or instability during upper cervical spine surgery.Methods:Thirty-one patients with atlantoaxial dislocation or instability, admitted to our hospital from January 2017 to January 2020, were chosen in our study; 17 patients were with unilateral stenosis at the pedicle of vertebral arch, including 15 with dominant vertebral artery and 2 with unilateral vertebral artery, and medial "in-out-in" axis pedicle screw was placed on this side and conventionally axis pedicle screw was implanted on the other side; 14 patients were with bilateral stenosis at the pedicle of vertebral arch, including 13 with dominant vertebral artery and one with unilateral vertebral artery, and the medial "in-out-in" axial pedicle screw weas placed on the side of the dominant or unilateral vertebral artery and the medial or lateral "in-out-in" axial pedicle screw was inserted on the other side. X-ray, CT, and MRI were performed before, and 5 d and 3, 6, and 12 months after surgery to observe the fusion of bone grafts. Scores of visual analogue scale (VAS) and Japanese Orthopedic Association (JOA) were compared before surgery, and 7 d, and 3 and 6 months after surgery, and during the last follow-up to evaluate the clinical efficacy of these patients.Results:The surgical time was (164.2±28.3) min (136-224 min); the intraoperative blood loss was (283.6±74.5) mL (180-560 mL), and there was no spinal cord vascular injury or other serious complications. Two patients had cerebrospinal fluid leakage after surgery, the drainage tube was pulled out after a delay of 8 d, and the wounds healed at one stage. The distal end of the screw did not enter the vertebral body of one patient during the surgery, and the screw was inserted again after the distal end was tapped to enter the vertebral body. Follow up for 9-25 months was performed in all patients, with an average of 13 months. The imaging examination showed no loosening of internal fixation, fracture, or fusion of bone grafts at 6 months after surgery. Seven d, and 3 and 6 months after surgery and during the last follow-up, the VAS scores were 1.56±0.98, 1.13±1.01, 1.11±0.86 and 1.09±0.91, respectively, which were significantly lower than those before surgery (3.52±1.97, P<0.05); the JOA scores were 11.8±2.1, 12.3±1.9, 12.5±2.2, and 12.6±1.8, respectively, which were significantly improved as compared with those before surgery (8.2±1.7, P<0.05). Conclusion:The use of medial "in-out-in" axial pedicle screw posterior fusion and internal fixation has a positive clinical effect in treatment of atlantoaxial dislocation or instability during upper cervical spine surgery.

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.

Prevalence and radiographic morphology of atlantoaxial dislocation in Kashin-Beck disease / 西安交通大学学报(医学版)

【Objective】 Until now, most clinical and basic studies on Kashin-Beck disease (KBD) have focused on the visible deformed extremities, and there is a lack of reports concerning their spinal features, especially for the atlantoaxial joint. The purpose of this study was to determine the prevalence and radiographic features of atlantoaxial dislocation (AAD) in KBD in adult patients. 【Methods】 The prevalence and radiographic features of AAD were determined by the basic information collected, clinical symptoms, and lateral and dynamic plain radiography in 111 KBD patient and 120 non-KBD participants. In the KBD group, AAD and non-AAD patients were compared in age, gender, height, weight, BMI, smoking history, chronic history, disease duration and grade of disease so as to identify the related factors of the occurrence of AAD. 【Results】 Symptoms at the neck or neurological manifestations were present in 17.5% (21/120) in the non-KBD population and 39.6% (44/111) patients with KBD. AAD case was not detected in the non-KBD population, while in 16.2% (18/111) of KBD patients in the endemic area. The prevalence was higher in the KBD patients than in the non-KBD population, and there was a significant difference in the detection rate of AAD between the two groups (χ2=21.10, P<0.001). Plain radiography demonstrated that there were 10 (55.6%) cases with separation of the odontoid process and the other 8 (44.4%) cases with hypoplasia of odontoid process. Anterior AAD was noted in 12 (66.7%) patients and posterior AAD in 6 (33.3%) cases based on the displacement direction, while 16 (88.9%) cases were reducible and 2 (11.1%) cases were irreducible on the basis of the reducibility. Comparing the 93 patients with non-AAD KBD patients and 18 patients with AAD patients, there was no significant difference in age, sex, BMI, history of medical disease or smoking (all P>0.05). There were significant differences in height, weight, disease duration and grade of disease between AAD and non-AAD patients (all P<0.05). 【Conclusion】 KBD can cause the occurrence of atlantoaxial dislocation by inducing separation or hypoplasia of the odontoid process. This research may provide clinical evidence for screening, earlier prevention and treatment of atlantoaxial dislocation in adult KBD patients.

Biomechanical Simulation on Absorbable Magnesium Alloy Fixation System for Atlantoaxial Dislocation / 医用生物力学

Objective To investigate the feasibility of absorbable magnesium alloy screws in atlantoaxial dislocation fixation. Methods Four kinds of screws with triangular, rectangular, trapezoidal and zigzag thread were designed with WE43 magnesium alloy. The finite element simulation analyses were performed on the screw- polyurethane model and atlantoaxial fixation system model. The stress and displacement distributions on the models were obtained. Results The pull-out force simulations were carried out on four kinds of magnesium alloy screws according to ASTM F543 standard specification. The stresses of screws with triangular, rectangular, trapezoidal and zigzag thread were 146.20, 185.22,194.98, 264.55 MPa, respectively. The pull-out strength of the screw with triangular thread was the largest, and the peak stress was the smallest. The magnesium alloy screw with triangular thread used for atlantoaxial fixation could meet the strength requirements of flexion/extension, rotation and bending of the neck. The peak stress of the screw was reduced by 17.16 MPa after adding hydroxyapatite (HA) coating on the surface, and the stress on the screw was within the range of bonding strength between coating and magnesium alloy substrate. Conclusions Under the same loading condition, the screw with triangular thread has good stability and the best pull-out force performance. After heat treatment, the strength of magnesium alloy screw with triangular thread meets the load-bearing requirements for atlantoaxial dislocation fixation. HA coating on screw surface can optimize mechanical properties of the screw, and there exits good bonding strength between the coating and the screw.

Design and application of fulcrum screws for atlantoaxial dislocation / 中国组织工程研究

BACKGROUND: Atlantoaxial dislocation often needs surgery for reduction, and posterior screw-rod fixation fusion is the most commonly used surgery. However, the current screw-rod fixation system often increases the reduction effect by increasing the degree of curvature of connecting rod, causing great difficulty of placing rod, which increases the probability of spinal cord injury. OBJECTIVE: To evaluate the preliminary results of fulcrum screws for atlantoaxial dislocation. METHODS: From January 2017 to December 2018,11 patients with atlantoaxial dislocation were selected from General Hospital of Southern Theater Command of PLA, including 4 males and 7 females, at the age of 8-51 years. All patients were treated with posterior screw-rod fixation fusion: Conventional posterior cervical screws were implanted on both sides of the atlas and pivot screws were implanted on both sides of the axis. Atlantodental interval and Japanese Orthopaedic Association scores were recorded before and after operation. Patients were followed up and underwent X-ray and CT to estimate reduction, fixation and bone graft fusion. This study was approved by the Ethics Committee of General Hospital of Southern Theater Command of PLA. RESULTS AND CONCLUSION: (1) Eleven patients underwent operations successfully without vertebral artery or spinal nerve injury. (2) All patients were followed up for 3-12 months, with an average of 6 months. The symptoms of neck pain and neurological dysfunction were improved in varying degrees. All patients obtained atlantoaxial bone fusion, with an average fusion time of 6 months. (3) At postoperative 1 week, X-ray and CT images showed that atlantoaxial reduction was satisfactory and internal fixation was in good position. (4) Atlantodental interval reduced from preoperatively (6.8±1.5) mm to postoperatively (2.4±0.9) mm (f=17.854, P=0.000). Japanese Orthopaedic Association score increased from preoperatively (14.1±1.3) to postoperatively (15.9±0.9) (f=-10, P=0.000). (5) No complication occurred during follow-up, without recurrence or dislocation. (6) These results showed that using fulcrum screw in posterior screw-rod fixation fusion has an effective reduction for treating atlantoaxial dislocation and its preliminary clinical effects are satisfactory.

Relationship between transoral atlantoaxial reduction screw-rod system fixation and oropharyngeal airway stenosis / 中国组织工程研究

BACKGROUND: In patients undergoing transoral atlantoaxial reduction and internal fixation, anterior atlantoaxial plate placement, soft tissue swelling and other factors may affect oropharyngeal space. Up to now no anatomical factors regarding dysphagia or dyspnea after anterior approach for atlantoaxial dislocation have been reported. OBJECTIVE: To observe the spatial changes of oropharyngeal airway after atlantoaxial dislocation and internal fixation with transoral atlantoaxial reduction screw-rod system and analyze the related influencing factors. METHODS: Sixty-six patients with atlantoaxial dislocation undergoing transoral atlantoaxial reduction screw-rod system surgery were retrospectively included from January 2012 to December 2016 in the General Hospital of Southern Theater Command. There were 38 males and 28 females aged from 11 to 71 years. All patients signed the informed consent. This study was approved by the Hospital Ethics Committee. The narrowest oropharyngeal airway space, thickness of soft tissue before C2 vertebra, anterior atlantodental interval, O-C2 angle, and C2-C6 angle were measured in the neutral position before and after surgery. Changes of postoperative data and their effects on the narrowest airway distance in oropharynx were analyzed. RESULTS AND CONCLUSION: (1) The narrowest airway distance in oropharynx, anterior atlantodental interval and C2-C6 angle were significantly decreased after surgery compared with that before surgery (P <0.001). Thickness of soft tissue before C2 vertebra and O-C2 angle increased significantly after surgery compared with that before surgery (P < 0.001). (2) In the multiple regression analysis, the change in the anterior atlantodental interval (0=7.070) and thickness of soft tissue before C2 vertebra 03=0.387) were significant variables related to the change in the narrowest airway distance in oropharynx. On the contrary, there was no significant correlation with the O-C2 angle. (3) It is indicated that reduction of atlantoaxial dislocation and the thickness of soft tissue before C2 vertebrae have negative effect on the oropharyngeal airway space. Therefore, reduction of atlantoaxial dislocation during transoral reduction screw-rod surgery may cause postoperative dysphagia despite maintenance of the O-C2 angle.

Safety depth of acupuncture at Yamen (GV 15) in patients with atlantoaxial dislocation / 中国针灸

OBJECTIVE@#To explore and compare the safety depths of perpendicular and oblique acupuncture at Yamen (GV 15) in patients with atlantoaxial dislocation (AAD) and healthy volunteers.@*METHODS@#One bundred and seventy-seven patients with atlantoaxial dislocation were selected as an AAD group, and 207 patients without atlantoaxial dislocation and with normal anatomical structure were selected as a normal group. All participants were moderately sized. The MRI scanning of the cervical vertebra was performed, and the safety depth of perpendicular and oblique acupuncture at Yamen (GV 15) was calculated on the sagittal image.@*RESULTS@#In the AAD group, the safety depth of men was (45.33±5.17) mm for perpendicular acupuncture and (48.58±4.41) mm for oblique acupuncture; the safety depth of women was (44.17±7.80) mm for perpendicular acupuncture and (47.49±7.32) mm for oblique acupuncture. In the normal group, the safety depth of men was (47.72±5.06) mm for perpendicular acupuncture and (42.69±5.53) mm for oblique acupuncture; the safety depth of women was (44.63±5.85) mm for perpendicular acupuncture and (39.88±6.18) mm for oblique acupuncture. The safety depth of men and women for oblique acupuncture was longer than that for perpendicular acupuncture in the AAD group (0.05); the safety depth of perpendicular and oblique acupuncture for men was longer than that for women in the normal group (0.05), while the safety depth of oblique acupuncture in the AAD group was longer than that in the normal group (<0.01).@*CONCLUSION@#The safe depth of acupuncture at Yamen (GV 15) has significantly changed under AAD, so during the clinical acupuncture the needle insertion should be less than its safe depth.

Short-term effectiveness of axis laminar screws for reducible atlantoaxial dislocation / 中国修复重建外科杂志

Objective: To investigate reliability and short-term effectiveness of axis laminar screws for reducible atlantoaxial dislocation (RAAD). Methods: A clinical data of 41 patients with RAAD who were admitted between February 2013 and February 2018 and met the inclusion criteria was retrospectively analyzed. The atlases in all patients were fixated by lateral mass screws, and the axes were fixed by laminar screws in 13 cases (LS group) and by pedicle screws in 28 cases (PS group). There was no significant difference in gender, age, and preoperative Japanese Orthopedic Association (JOA) score between the two groups ( P>0.05). The effectiveness was estimated by post-operative JOA score; and the accuracy of the axis screw, atlantoaxial bone graft fusion, and the fixation stability were examined by X-ray film and CT. Results: All incisions healed by first intention. All patients were followed up 12-17 months (mean, 13.8 months) in LS group and 12-20 months (mean 14.1 months) in PS group, and the difference in follow-up time was not significant ( Z=-0.704, P=0.482). At last follow-up, JOA scores were 13.9±1.6 in LS group and 14.3±1.8 in PS group, which significantly improved when compared with the pre-operative scores in the two groups ( t=-9.033, P=0.000; t=-15.835, P=0.000); while no significant difference was found between the two groups ( t=-0.630, P=0.532). Twenty-five screws of 26 screws in LS group and 54 screws of 56 screws in PS group were implanted accurately, with no significant difference in the accuracy of the axis screw between the two groups ( Z=-0.061, P=0.951). All patients obtained atlantoaxial bone graft fusion, except 1 case in PS group. There was no significant difference in the atlantoaxial bone graft fusion between the two groups ( Z=-0.681, P=0.496). Conclusion: For RAAD, Axis laminar screws can maintain the atlantoaxial primary stability and had a good short-term effectiveness. So, it could be an alternative and reliable technique for axis screw.

Modified posterior occipital fusion for treatment of atlantooccipital and atlantoaxial dislocation in children and adolescents / 中华神经医学杂志

Objective To study the clinical efficacy of modified posterior occipital fusion in atlantooccipital and atlantoaxial dislocation in children and adolescents. Methods The clinical data of 11 children or adolescents with atlantooccipital and atlantoaxial dislocation, admitted to and accepted modified posterior occipital fusion in our hospital from November 2013 to March 2018, were retrospectively analyzed. Before and after the surgery, Japanese orthopedic association (JOA) scale was used to evaluate the cervical vertebral function of the patients, the atlanto-dens interval (ADI) was measured by CT images to evaluate the dislocation and reduction of joints, and the medulla bulbar cervical medulla angle (CMA) of the patients was measured by MR imaging to evaluate the degrees of spinal cord compression. Results The clinical symptoms of 11 patients improved in different degrees. No postoperative complications occurred. JOA scale scores after operation were significantly higher than those before operation (15.0±1.0 vs. 12.2±1.6). Significantly decreased of ADI and significantly increased CMA after operation were noted as compared with those before operation (P<0.05). Conclusion Modified posterior occipital fusion is safe and effective for treatment of atlantooccipital and atlantoaxial dislocation in children and adolescents.

Atlantoaxial reduction and fixation guided by the intraoperative CT / 北京大学学报(医学版)

Objective: To evaluate the clinical result of atlantoaxial reduction and fixation guided by the intraoperative CT.Methods: Sixteen cases were retrospectively studied, including seven males and nine females, with the mean age of 49.9 years.Twelve cases were diagnosed as chronic atlantoaxial instability or dislocation, while four cases as acute odontoid fracture and dislocation.Among the sixteen cases, fourteen underwent atlantoaxial fusion, while two underwent temporary atlantoaxial fixation without fusion.The intraoperative CT was used in the setting of: 1.Evaluating the atlantoaxial reduction before the screw insertion;2.Guiding the C1 and C2 pedicle drilling (two cases using additional three-dimensional printing drilling template);3.Evaluating the position of the screws and reduction after the atlantoaxial fixation.In addition, three-dimensional drilling template combined with intraoperative CT was used in two cases.CT scanning frequency was calculated.To evaluate the accuracy rate of screw fixation under the intraoperative CT, 19 cases without the intraoperative CT were studied as the control group.Results: Averaged CT scanning frequency was 1.4 times (Once in eleven cases, twice in four and three times in one).Among the sixteen cases, mal-positioned C1 screws were found and revised in two cases.No spinal cord injury or vertebral artery injury occurred.The follow-up ranged from three to ten months, with the mean of 6.7 months.Fourteen cases achieved solid osseous fusion, and two with temporary fixation had odontoid fracture union.Anatomic reduction was achieved in all the cases.Eleven cases with preoperative myelopathy had postoperative improvement and their mean JOA scores improved from 12.1 to 14.4.To the last follow-up, no hardware complications were found including screw broken, rod broken or fixation loosening.All the screws of intraoperative CT group had good positions.For 19 cases of the control group, there were two cases of mal-positioned screws (10.5%).Conclusion: Advantages of atlantoaxial reduction and fixation guided by the intraoperative CT included: improving the accuracy of the atlantoaxial screws, exactly evaluating the reduction of the atlantoaxial joint, immediately discovering the mal-positioned screws and avoiding the revision surgery.A good clinical result was found in the preliminary study.

Anterior Compression Index for Evaluating Atlantoaxial Dislocation and Restoration / 中国神经精神疾病杂志

Objective The study was to investigate the value of deduction and application of anterior compression index in evaluation of atlantoaxial dislocation and restoration. Method Twenty-eight cases of the control group and 28 cases of atlantoaxial dislocation treated with posterior restoration and screw-rod internal fixation technique before and af?ter surgery were recruited in this study and their data was retrospectively analyzed. All of the people underwent sagittal computerized tomography scan films. The anterior compression index was measured in all cases. Results The mean value of anterior compression index of the control group was 87.86±24.98. The mean value of anterior compression index of the preoperative patients was 230.44 ± 97.60 and the mean value of the postoperative patients was 106.27 ± 73.53. There was significant difference in those two parameters between the preoperative patients and the controls(t=-7.50,P<0.0001). There was no significant difference between the postoperative patients and the control group (t=-1.26, P=0.2171). Anteri?or compression index were significantly lower after surgical operation (t=10.35, compared with before, P<0.0001). Con?clusion Anterior compression index can be an excellent measurement tool for the assessment of relationship of atlas and axis in atlantoaxial dislocation patients before and after posterior restoration operation.

Irreducible Atlanto-Axial Dislocation in Neglected Odontoid Fracture Treated with Single Stage Anterior Release and Posterior Instrumented Fusion

It is a well-know fact that type 2 odontoid fractures frequently go into nonunion. If left untreated, patients may develop irreducible atlantoaxial dislocation (AAD). We describe the surgical management of two patients with neglected odontoid fractures and irreducible AAD treated with single stage anterior release followed by posterior instrumented fusion. Both patients presented with history of neglected trauma and progressive myelopathy. Traction under anesthesia failed to achieve reduction of AAD. Anterior release was done by trans-oral approach in one patient and retrophayngeal approach in the other. Posterior fixation was performed with transarticular screws in both the patients. Both patients had full neurological recovery and demonstrated fusion at follow-up. Anterior release followed by posterior instrumented correction may be an effective alternative to the traditional means of treating irreducible dislocations associated with neglected odontoid fractures.

Surgical treatment with cable dragged reduction and cantilever beam internal fixation by posterior approach for odontoid fracture associated with atlantoaxial dislocation / 中国骨伤

<p><b>OBJECTIVE</b>To explore the clinical effects of surgical treatment with cable dragged reduction and cantilever beam internal fixation by posterior approach for odontoid fracture associated with atlantoaxial dislocation.</p><p><b>METHODS</b>The clinical data of 12 patients with odontoid fracture associated with atlantoaxial dislocation from January 2008 to December 2013 were retrospectively analyzed. There were 8 males and 4 females, ranging in age from 21 to 53 years with an average of 37.2 years. Eleven cases were fresh fracture and 1 case was old fracture, all patients complicated with atlantoaxial anterior dislocation. According to Anderson-D' Alonzo typing method modified by Grauer, 3 cases were type IIA, 5 cases were type IIB, 3 cases were type IIC, and 1 case was type IIIA. All patients underwent surgical treatment with cable dragged reduction and cantilever beam internal fixation by posterior approach. JOA score and ADI method were respectively used to evaluate the nerve function and reductive condition of atlantoaxial dislocation.</p><p><b>RESULTS</b>All patients were followed up from 6 months to 2 years with an average of 1 year and 3 months. At 1 week, 6 months after operation, and final follow up, JOA scores were 13.2±1.3, 13.5±1.4, 14.3±1.5, respectively, and these data were obviously better than that of preoperative 8.3±1.4(<0.05). Postoperative X rays and CT showed satisfactory reduction of atlantoaxial dislocation. At 1 week, 6 months after operation, and final follow up, ADI were (2.2±0.4), (2.4±0.6), (2.3±0.5) mm, respectively, and these data were obviously better than that of preoperative.(5.8±1.2) mm(<0.05). All screws and cables had good location without looseness and breakage, and bone graft got fusion.</p><p><b>CONCLUSIONS</b>Surgical treatment with cable dragged reduction and cantilever beam internal fixation by posterior approach for odontoid fracture associated with atlantoaxial dislocation is a good method, with advantage of firm fixation and high safety. It could obtain good clinical effects.</p>

Clinical observation on the treatment of atlantoaxial dislocation based on the classification / 中国骨伤

<p><b>OBJECTIVE</b>To retrospectively analyze the surgical methods and its clinical effects and explore a clinical classification and treatment strategy for atlantoaxial dislocation(AAD).</p><p><b>METHODS</b>The clinical data of 89 patients with atlantoaxial dislocation were analyzed from September 2005 to September 2013. There were 49 males and 40 females, aged from 13 to 67 years with an average of 48.1 years. According to the reductive effects with preoperative cervical dynamic radiograph and high weight skeletal traction under general anesthesia, the dislocations were classified into three types:easy reduction type, hard reduction type and irreducible type. The patients with easy reduction type were treated with posterior screw rod internal fixation after manual reduction, while the patients with hard reduction type were treated with posterior screw rod fixation after high weight skeletal traction reduction under general anesthesia. The patients with irreducible type were treated with transoral atlantoaxial joint release or depression and posterior internal fixation and fusion. According to JOA scores to evaluate the neurological status and treatment outcome.</p><p><b>RESULTS</b>Thirty patients were classified as easy reduction type, 55 patients as hard reduction type, and 4 patients as irreducible type. The preoperative JOA score was 8.2±3.1 on average, while the postoperative score was 14.2±2.4. The improvement rate was 40.1% to 82.5% with an average of 62.5%. Eighty nine patients were followed up from 6 to 37 months with a mean of 17.3 months. Eighty two cases obtained anatomical reduction and 85 cases obtained bony fusion. One case complicated with hyponatremia after operation and 1 case combined with Guillain-Barre syndrome, 4 cases complicated with delayed union wounds, 1 case died of for respiratory failure 2 years after operation. No wound infections were found in the patients approach for transoral operation.</p><p><b>CONCLUSIONS</b>According to the cervical dynamic radiograph and high weight skeletal traction under general anesthesia to classify for atlantoaxial dislocation, and adopting well strategies to treat the patients, can achieve satisfactory effects.</p>

C2-3 Fusion, C3-4 Cord Compression and C1-2 Posterior Facetal Instability: An Evaluation of Treatment Strategy Based on Four Surgically Treated Cases

STUDY DESIGN: Four patients had C2-3 vertebral fusion and radiologically demonstrated cord compression at C3-4 level related to disc bulge with or without association of osteophytes and C1-2 posterior facetal dislocation. The outcome of treatment by atlantoaxial and subaxial facetal fixation is discussed. PURPOSE: The article evaluates the significance of atlantoaxial facetal instability in cases having C2-3 vertebral fusion and cord compression at the level of C3-4 disc. OVERVIEW OF LITERATURE: C2-3 vertebral fusions are frequently encountered in association with basilar invagination and chornic atlantoaxial dislocations. Even when basilar invagination and atlantoaxial dislocation are not identified by conventional parameters, atlantoaxial instability can be the nodal point of pathogenesis in cases with C2-3 vertebral fusion. METHODS: Between June 2013 and November 2014 four patients having C2-3 fusion presented with progressive symptoms of myelopathy that were related to cord compression at the level opposite the C3-4 disc space. Further investigations revealed C1-2 posterior facetal dislocation. RESULTS: All patients were males. Ages ranged from 18 to 50 years (average, 36 years). All patients were treated by atlantoaxial facetal plate and screw, and subaxial single or multi-segmental transarticular screw fixation. Follow-up (average, 15 months) using a recently described clinical grading system and the Japanese Orthopaedic Association scoring system confirmed marked improvement of symptoms. CONCLUSIONS: Identification and treatment of atlantoaxial facetal instability may be crucial for a successful outcome in cases having C2-3 fusion and high cervical (C3-4) disc related cord compression.