Objective:To investigate spinal cord morphological changes and risk factors in upper cervical spine surgery using C 2 medial "in-out-in" pedicle screws in patients with atlantoaxial dislocation (AAD) and high-riding vertebral artery (HRVA). Methods:A retrospective analysis was conducted on 41 patients with AAD who underwent C 2 medial "in-out-in" pedicle screw implantation at our hospital between January 2019 and December 2023. The cohort included 12 males and 29 females, with a mean age of 47.6±10.3 years (range: 18-68 years). Among them, 30 patients received unilateral C 2 medial "in-out-in" screws, while 11 patients received bilateral screws. All patients underwent posterior reduction and internal fixation. Measurements included C 2 pedicle height, C 2 pedicle width, C 2 horizontal spinal canal width, screw invasion distance into the spinal canal, and spinal canal invasion rate based on CT findings. MRI evaluations included spinal canal-dura mater distance, dura mater-spinal cord distance, spinal canal-spinal cord distance, and spinal cord cross-sectional area. The change rate of spinal cord cross-sectional area was calculated and categorized into >20% decrease group (decreasing group) and ≤20% decrease group (non-decreasing group). Postoperative outcomes were assessed using the Visual Analogue Scale (VAS) and Japanese Orthopedic Association (JOA) scores. Results:The mean operative time was 165.5±30.1 minutes (range: 120-220 minutes). No spinal cord vascular injuries or severe complications were observed. However, five patients experienced cerebrospinal fluid (CSF) leakage, requiring delayed removal of drainage tubes, but their wounds healed successfully. Follow-ups (range: 6-24 months) showed no loosening of internal fixation, fractures, or bone graft nonunion, with a 100% bone fusion rate at 6 months postoperatively. VAS scores improved significantly from a preoperative median of 5.0 (3.5, 6.0) (range: 1-7) to 2.0 (2.0, 3.0) at 3 months and 1.0 (1.0, 1.0) at 6 months ( Z=36.716, P< 0.001). JOA scores improved from 10.0 (9.0, 12.0) (range: 4-14) preoperatively to 13.0 (11.0, 13.5) at 3 months and 14.0 (12.0, 15.0) at 6 months ( Z=67.093, P<0.001). The height of C 2 pedicle was 5.50±1.78 mm, the width of C 2 pedicle was 2.27±1.23 mm, the width of C 2 horizontal spinal canal was 23.76±4.91 mm, the spinal canal-dura mater distance was 3.08±0.85 mm, dura mater-spinal cord distance was 3.23±0.85 mm, the spinal canal-spinal cord distance was 6.31±1.11 mm, the distance of screw invasion into the spinal canal was 2.80±1.54 mm, the rate of spinal canal invasion was 12.1%±6.8%, the preoperative spinal cord cross-sectional area was 69.81±13.27 mm 2, and the postoperative spinal cord cross-sectional area was 68.81±13.94 mm 2. Based on spinal cord cross-sectional area changes, 32 patients were classified into the non-decreasing group, and 9 patients into the decreasing group. The intraclass correlation coefficient (ICC) values ranged from 0.733 to 0.984, indicating high measurement reliability. There were significant differences in the proportion of C 2 bilateral medial "in-out-in" screws (χ 2=6.903, P=0.009), the incidence of CSF leakage (χ 2=15.391, P<0.001), the distance of screw invasion into the spinal canal ( t=4.990, P<0.001) and the rate of spinal canal invasion ( t=4.045, P<0.001) in the decreasing group versus the non-decreasing group. The JOA scores of the non-decreasing group were significantly higher at 3 and 6 months postoperatively compared to the decreasing group ( P<0.05). No other parameters showed significant differences between the groups. Binary logistic regression analysis identified spinal canal invasion rate [ OR=1.963, 95% CI (1.010, 3.817), P=0.047] as an independent risk factor for spinal cord cross-sectional area reduction. The Jordan index was 0.875, with a spinal canal invasion rate threshold of 14.18%, a sensitivity of 1.000, a specificity of 0.875, and an AUC of 0.983, indicating strong predictive value. Conclusion:The C 2 medial "in-out-in" screw technique provides effective posterior fixation and fusion for AAD patients with HRVA. However, to minimize spinal cord morphological changes and associated risks, the spinal canal invasion rate should be kept below 14.18% when using this technique.

Objective:To evaluate the safety and clinical efficacy of the navigation-assisted medial “in-out-in” technique in C 2 pedicle screw fixation. Methods:This study is a retrospective cohort study. The clinical data of 68 patients with high-riding vertebral arteries of the axis who underwent C 2 pedicle screw implantation using the medial “in-out-in” technique in the Department of Spinal Surgery, Henan Provincial People′s Hospital from August 2020 to July 2023 were retrospectively analyzed. There were 32 males and 36 females, with an age of (56.9±10.2) years (range: 35 to 78 years). Among them, 36 patients underwent navigation-assisted medial “in-out-in” technique for C 2 pedicle screw implantation and were included in the navigation group; 32 patients received freehand screw placement and were included in the freehand group. The operative time, intraoperative blood loss, postoperative maximum pedicle-screw distance (PSD max), bone graft fusion time, fusion rate, and occurrence of internal fixation-related complications were recorded and compared between the two groups. The spinal cord cross-sectional area (SSC) was measured before surgery and at 1 week after surgery. The atlanto-dental interval (ADI), clivus-canal angle (CCA), and Japanese Orthopaedic Association (JOA) score were evaluated before surgery, at 1 week, 3 months, 1 year after surgery, and at the final follow-up. Independent sample t-test, repeated measures analysis of variance, paired t-test, χ2 test, or Fisher′s exact test were used for data comparison. Results:Six patients with reduction blocked by atlanto-dental osteophytes first underwent anterior cervical atlanto-dental arthroplasty, followed by posterior surgery in the prone position, while the remaining 62 patients underwent posterior reduction and internal fixation. All 36 patients in the navigation group successfully completed C 2 medial “in-out-in” screw implantation, including 34 cases with unilateral medial ”in-out-in” screw implantation and 2 cases with bilateral implantation. In the freehand group, 28 cases completed medial “in-out-in” screw implantation, with 4 cases (12.5%) of implantation failure; the implantation failure rate in the navigation group was lower than that in the freehand group ( χ 2=5.027, P=0.025). The posterior surgical time in the navigation group was shorter than that in the freehand group ((158.1±25.7) minutes vs. (176.4±27.6) minutes, t=2.829, P=0.006), while there was no statistically significant difference in intraoperative blood loss during posterior surgery between the two groups ((217.5±62.2) ml vs. (212.7±53.2) ml, t=0.340, P=0.735). There was no significant change in SSC before and after surgery in both groups (all P>0.05). The postoperative JOA scores, ADI, and CCA in both the navigation group and the freehand group were significantly improved compared with those before surgery (all P<0.01), and there were no differences between the two groups (all P>0.05). The postoperative PSD max was (4.7±0.9) mm and the bone graft fusion time was (4.9±1.3) months in the navigation group, compared with (4.8±0.5) mm and (4.9±1.7) months in the freehand group, respectively; there were no statistically significant differences between the two groups (all P>0.05). During pedicle preparation, 1 case (2.8%) in the navigation group and 3 cases (9.4%) in the freehand group developed cerebrospinal fluid leakage due to dural puncture by the hand drill. One patient in the freehand group developed symptomatic cerebral infarction postoperatively, presenting with dysarthria, which recovered after medical treatment. There was no significant difference in the incidence of cerebrospinal fluid leakage or vertebral artery injury between the two groups. Conclusion:The navigation-assisted medial “in-out-in” technique enables safe and rapid implantation of three-column fixation screws in patients with high-riding vertebral arteries of the axis, with high accuracy in screw placement and satisfactory clinical outcomes.

Objective:To investigate spinal cord morphological changes and risk factors in upper cervical spine surgery using C 2 medial "in-out-in" pedicle screws in patients with atlantoaxial dislocation (AAD) and high-riding vertebral artery (HRVA). Methods:A retrospective analysis was conducted on 41 patients with AAD who underwent C 2 medial "in-out-in" pedicle screw implantation at our hospital between January 2019 and December 2023. The cohort included 12 males and 29 females, with a mean age of 47.6±10.3 years (range: 18-68 years). Among them, 30 patients received unilateral C 2 medial "in-out-in" screws, while 11 patients received bilateral screws. All patients underwent posterior reduction and internal fixation. Measurements included C 2 pedicle height, C 2 pedicle width, C 2 horizontal spinal canal width, screw invasion distance into the spinal canal, and spinal canal invasion rate based on CT findings. MRI evaluations included spinal canal-dura mater distance, dura mater-spinal cord distance, spinal canal-spinal cord distance, and spinal cord cross-sectional area. The change rate of spinal cord cross-sectional area was calculated and categorized into >20% decrease group (decreasing group) and ≤20% decrease group (non-decreasing group). Postoperative outcomes were assessed using the Visual Analogue Scale (VAS) and Japanese Orthopedic Association (JOA) scores. Results:The mean operative time was 165.5±30.1 minutes (range: 120-220 minutes). No spinal cord vascular injuries or severe complications were observed. However, five patients experienced cerebrospinal fluid (CSF) leakage, requiring delayed removal of drainage tubes, but their wounds healed successfully. Follow-ups (range: 6-24 months) showed no loosening of internal fixation, fractures, or bone graft nonunion, with a 100% bone fusion rate at 6 months postoperatively. VAS scores improved significantly from a preoperative median of 5.0 (3.5, 6.0) (range: 1-7) to 2.0 (2.0, 3.0) at 3 months and 1.0 (1.0, 1.0) at 6 months ( Z=36.716, P< 0.001). JOA scores improved from 10.0 (9.0, 12.0) (range: 4-14) preoperatively to 13.0 (11.0, 13.5) at 3 months and 14.0 (12.0, 15.0) at 6 months ( Z=67.093, P<0.001). The height of C 2 pedicle was 5.50±1.78 mm, the width of C 2 pedicle was 2.27±1.23 mm, the width of C 2 horizontal spinal canal was 23.76±4.91 mm, the spinal canal-dura mater distance was 3.08±0.85 mm, dura mater-spinal cord distance was 3.23±0.85 mm, the spinal canal-spinal cord distance was 6.31±1.11 mm, the distance of screw invasion into the spinal canal was 2.80±1.54 mm, the rate of spinal canal invasion was 12.1%±6.8%, the preoperative spinal cord cross-sectional area was 69.81±13.27 mm 2, and the postoperative spinal cord cross-sectional area was 68.81±13.94 mm 2. Based on spinal cord cross-sectional area changes, 32 patients were classified into the non-decreasing group, and 9 patients into the decreasing group. The intraclass correlation coefficient (ICC) values ranged from 0.733 to 0.984, indicating high measurement reliability. There were significant differences in the proportion of C 2 bilateral medial "in-out-in" screws (χ 2=6.903, P=0.009), the incidence of CSF leakage (χ 2=15.391, P<0.001), the distance of screw invasion into the spinal canal ( t=4.990, P<0.001) and the rate of spinal canal invasion ( t=4.045, P<0.001) in the decreasing group versus the non-decreasing group. The JOA scores of the non-decreasing group were significantly higher at 3 and 6 months postoperatively compared to the decreasing group ( P<0.05). No other parameters showed significant differences between the groups. Binary logistic regression analysis identified spinal canal invasion rate [ OR=1.963, 95% CI (1.010, 3.817), P=0.047] as an independent risk factor for spinal cord cross-sectional area reduction. The Jordan index was 0.875, with a spinal canal invasion rate threshold of 14.18%, a sensitivity of 1.000, a specificity of 0.875, and an AUC of 0.983, indicating strong predictive value. Conclusion:The C 2 medial "in-out-in" screw technique provides effective posterior fixation and fusion for AAD patients with HRVA. However, to minimize spinal cord morphological changes and associated risks, the spinal canal invasion rate should be kept below 14.18% when using this technique.

Objective:To evaluate the safety and clinical efficacy of the navigation-assisted medial “in-out-in” technique in C 2 pedicle screw fixation. Methods:This study is a retrospective cohort study. The clinical data of 68 patients with high-riding vertebral arteries of the axis who underwent C 2 pedicle screw implantation using the medial “in-out-in” technique in the Department of Spinal Surgery, Henan Provincial People′s Hospital from August 2020 to July 2023 were retrospectively analyzed. There were 32 males and 36 females, with an age of (56.9±10.2) years (range: 35 to 78 years). Among them, 36 patients underwent navigation-assisted medial “in-out-in” technique for C 2 pedicle screw implantation and were included in the navigation group; 32 patients received freehand screw placement and were included in the freehand group. The operative time, intraoperative blood loss, postoperative maximum pedicle-screw distance (PSD max), bone graft fusion time, fusion rate, and occurrence of internal fixation-related complications were recorded and compared between the two groups. The spinal cord cross-sectional area (SSC) was measured before surgery and at 1 week after surgery. The atlanto-dental interval (ADI), clivus-canal angle (CCA), and Japanese Orthopaedic Association (JOA) score were evaluated before surgery, at 1 week, 3 months, 1 year after surgery, and at the final follow-up. Independent sample t-test, repeated measures analysis of variance, paired t-test, χ2 test, or Fisher′s exact test were used for data comparison. Results:Six patients with reduction blocked by atlanto-dental osteophytes first underwent anterior cervical atlanto-dental arthroplasty, followed by posterior surgery in the prone position, while the remaining 62 patients underwent posterior reduction and internal fixation. All 36 patients in the navigation group successfully completed C 2 medial “in-out-in” screw implantation, including 34 cases with unilateral medial ”in-out-in” screw implantation and 2 cases with bilateral implantation. In the freehand group, 28 cases completed medial “in-out-in” screw implantation, with 4 cases (12.5%) of implantation failure; the implantation failure rate in the navigation group was lower than that in the freehand group ( χ 2=5.027, P=0.025). The posterior surgical time in the navigation group was shorter than that in the freehand group ((158.1±25.7) minutes vs. (176.4±27.6) minutes, t=2.829, P=0.006), while there was no statistically significant difference in intraoperative blood loss during posterior surgery between the two groups ((217.5±62.2) ml vs. (212.7±53.2) ml, t=0.340, P=0.735). There was no significant change in SSC before and after surgery in both groups (all P>0.05). The postoperative JOA scores, ADI, and CCA in both the navigation group and the freehand group were significantly improved compared with those before surgery (all P<0.01), and there were no differences between the two groups (all P>0.05). The postoperative PSD max was (4.7±0.9) mm and the bone graft fusion time was (4.9±1.3) months in the navigation group, compared with (4.8±0.5) mm and (4.9±1.7) months in the freehand group, respectively; there were no statistically significant differences between the two groups (all P>0.05). During pedicle preparation, 1 case (2.8%) in the navigation group and 3 cases (9.4%) in the freehand group developed cerebrospinal fluid leakage due to dural puncture by the hand drill. One patient in the freehand group developed symptomatic cerebral infarction postoperatively, presenting with dysarthria, which recovered after medical treatment. There was no significant difference in the incidence of cerebrospinal fluid leakage or vertebral artery injury between the two groups. Conclusion:The navigation-assisted medial “in-out-in” technique enables safe and rapid implantation of three-column fixation screws in patients with high-riding vertebral arteries of the axis, with high accuracy in screw placement and satisfactory clinical outcomes.

Objective:To investigate the differences in terms of blood cerebrospinal fluid barrier immune surveillance injury by lead acetate and nano-lead sulfide exposure in order to provide basis for the study of their mechanism of nerve injury caused by exposure to lead and nano lead.Methods:In June 2015, forty-five SPF SD male rats were randomly divided into control group, lead acetate group (20 mg/kg) and nano-lead sulfide group (20 mg/kg), with 15 rats in each group. The rats were intragastric five times a week, for nine weeks. The numbers of CD4 + T lymphocytes in blood and cerebrospinal fluid were detected by flow cytometry. The levels of interleukin-4 (IL-4) and interferon-γ (IFN-γ) in serum and cerebrospinal fluid were detected by ELISA. The expressions and distribution of intercellular cell adhesion molecule-1 (ICAM-1) and CD4 + T lymphocytes in choroid plexus were detected by laser confocal fluorescence immunoassay. The mRNA expression levels of IL-4, IFN-γ and ICAM-1 in the choroid plexus were detected by real-time PCR. Results:Compared with the control group, the proportion of CD4 + T lymphocytes in blood of rats in lead acetate group was increased, the proportions of CD4 + T lymphocytes in cerebrospinal fluid of rats in lead acetate group and nano-lead sulfide group were increased, the contents of IL-4 and IFN-γ in serum of rats in lead acetate group and nano-lead sulfide group were increased, the content of IL-4 in cerebrospinal fluid of rats in lead acetate group and the contents of IL-4 and IFN-γ in cerebrospinal fluid of rats in nano-lead sulfide group were increased, the differences were statistically significant ( P<0.05). The fluorescence intensity of ICAM-1 and CD4 + T lymphocytes in choriochoroid plexus of rats in lead acetate group and nano-lead sulfide group were stronger than those in control group, and the fluorescence intensity of CD4 + T lymphocytes of rats in nano-lead sulfide group was weaker than that in lead acetate group. Compared with the control group, the mRNA expression levels of ICAM-1, IL-4 and IFN-γ in choriochoroids plexus of rats in lead acetate group and nano-lead sulfide group were increased, and the mRNA expression levels of ICAM-1 and IL-4 in nano-lead sulfide group were higher than those in lead acetate group, while the mRNA expression level of IFN-γ in nano-lead sulfide group was lower than that in lead acetate group ( P<0.05) . Conclusion:Exposure to lead and nano-lead sulfide can cause the increase of CD4 + T lymphocytes, IL-4, IFN-γ and ICAM-1, which may be related to the damage to the immune surveillance of the blood cerebrospinal fluid barrier. And there is a difference in the injury caused by lead and nano-lead sulfide exposure.

Objective:To investigate the differences in terms of blood cerebrospinal fluid barrier immune surveillance injury by lead acetate and nano-lead sulfide exposure in order to provide basis for the study of their mechanism of nerve injury caused by exposure to lead and nano lead.Methods:In June 2015, forty-five SPF SD male rats were randomly divided into control group, lead acetate group (20 mg/kg) and nano-lead sulfide group (20 mg/kg), with 15 rats in each group. The rats were intragastric five times a week, for nine weeks. The numbers of CD4 + T lymphocytes in blood and cerebrospinal fluid were detected by flow cytometry. The levels of interleukin-4 (IL-4) and interferon-γ (IFN-γ) in serum and cerebrospinal fluid were detected by ELISA. The expressions and distribution of intercellular cell adhesion molecule-1 (ICAM-1) and CD4 + T lymphocytes in choroid plexus were detected by laser confocal fluorescence immunoassay. The mRNA expression levels of IL-4, IFN-γ and ICAM-1 in the choroid plexus were detected by real-time PCR. Results:Compared with the control group, the proportion of CD4 + T lymphocytes in blood of rats in lead acetate group was increased, the proportions of CD4 + T lymphocytes in cerebrospinal fluid of rats in lead acetate group and nano-lead sulfide group were increased, the contents of IL-4 and IFN-γ in serum of rats in lead acetate group and nano-lead sulfide group were increased, the content of IL-4 in cerebrospinal fluid of rats in lead acetate group and the contents of IL-4 and IFN-γ in cerebrospinal fluid of rats in nano-lead sulfide group were increased, the differences were statistically significant ( P<0.05). The fluorescence intensity of ICAM-1 and CD4 + T lymphocytes in choriochoroid plexus of rats in lead acetate group and nano-lead sulfide group were stronger than those in control group, and the fluorescence intensity of CD4 + T lymphocytes of rats in nano-lead sulfide group was weaker than that in lead acetate group. Compared with the control group, the mRNA expression levels of ICAM-1, IL-4 and IFN-γ in choriochoroids plexus of rats in lead acetate group and nano-lead sulfide group were increased, and the mRNA expression levels of ICAM-1 and IL-4 in nano-lead sulfide group were higher than those in lead acetate group, while the mRNA expression level of IFN-γ in nano-lead sulfide group was lower than that in lead acetate group ( P<0.05) . Conclusion:Exposure to lead and nano-lead sulfide can cause the increase of CD4 + T lymphocytes, IL-4, IFN-γ and ICAM-1, which may be related to the damage to the immune surveillance of the blood cerebrospinal fluid barrier. And there is a difference in the injury caused by lead and nano-lead sulfide exposure.

Objective To explore the predictive value of spectral CT quantitative parameters combined with radiomics for early liver fibrosis using rat models.Methods Prospective animal experiments were conducted,and the intervention models were constructed for liver fibrosis in rats.A total of 112 spectral CT plain samples were collected from 56 rats,and quantitative parameters(40,60 and 100 keV CT values,slope of the spectral curve)were measured in the spectral CT images to assess the value of each parameter in the staging of liver fibrosis.The regions of interest were sketched out in the 60 keV monoenergetic images using 3D Slicer software,and from which the radiomics features were extracted.The t-test,correlation analysis and the least absolute contraction and selection operator algorithms were used for radiomics feature screening,and the Rad-score was calculated.According to the pathological results,they were classified into non-significant liver fibrosis and significant liver fibrosis,and 3 Logistic regression models(spectral CT model,radiomics model and combined model)were established using the selected spectral CT parameters and radiomics features.The predictive value of these models was evaluated using receiver operating characteristic curves,and calibration curves were plotted to evaluate model fit.Results Except for 100 keV CT value,spectral CT parameters and Rad-score differed statistically between non-significant and significant liver fibroses(P<0.05).The spectral CT model,radiomics model and combined model had AUC of 0.850,0.895,0.939 in the training set,and 0.818,0.803,0.883 in the test set.The calibration curves showed that the 3 models were well fitted,without significant deviation.Conclusion The model constructed with spectral CT and radiomics performes well,worthy of further optimization.

Objective To explore the predictive value of spectral CT quantitative parameters combined with radiomics for early liver fibrosis using rat models.Methods Prospective animal experiments were conducted,and the intervention models were constructed for liver fibrosis in rats.A total of 112 spectral CT plain samples were collected from 56 rats,and quantitative parameters(40,60 and 100 keV CT values,slope of the spectral curve)were measured in the spectral CT images to assess the value of each parameter in the staging of liver fibrosis.The regions of interest were sketched out in the 60 keV monoenergetic images using 3D Slicer software,and from which the radiomics features were extracted.The t-test,correlation analysis and the least absolute contraction and selection operator algorithms were used for radiomics feature screening,and the Rad-score was calculated.According to the pathological results,they were classified into non-significant liver fibrosis and significant liver fibrosis,and 3 Logistic regression models(spectral CT model,radiomics model and combined model)were established using the selected spectral CT parameters and radiomics features.The predictive value of these models was evaluated using receiver operating characteristic curves,and calibration curves were plotted to evaluate model fit.Results Except for 100 keV CT value,spectral CT parameters and Rad-score differed statistically between non-significant and significant liver fibroses(P<0.05).The spectral CT model,radiomics model and combined model had AUC of 0.850,0.895,0.939 in the training set,and 0.818,0.803,0.883 in the test set.The calibration curves showed that the 3 models were well fitted,without significant deviation.Conclusion The model constructed with spectral CT and radiomics performes well,worthy of further optimization.

Cyperi Rhizoma is a common Chinese medicine in clinical practice， which has a long history of processing. In order to sort out the process of its processing， starting with the angle of processing excipients， the historical evolution and developmental venation of Cyperi Rhizoma processing were analyzed and summarized by consulting relevant literature of ancient medical records and modern codes. After combing the ancient and modern literature， it was found that there were many processing methods of Cyperi Rhizoma， the processing methods without auxiliary materials included frying， boiling， steaming and so on， and the adding auxiliary materials included vinegar， ginger， salt， multiple excipients， etc. However， with the evolution of history， some characteristic excipients have gradually disappeared， while vinegar-processed products are mainly used in modern times. Meanwhile， processing methods of Cyperi Rhizoma are well documented in various processing standards， the phenomenon of multiple methods adopted in one place and different methods in different places exists， which lacks unified quality standards and leads to uneven quality of Cyperi Rhizoma decoction pieces， which may even affect the safety and effectiveness of its clinical medication. Based on this， the problems existing in the processing research of Cyperi Rhizoma were analyzed in this paper， and made an outlook on the inheritance of the ancient processing methods and the quality standard improvement of the decoction pieces， in order to provide important literature evidence and theoretical support for the study of processing process and mechanism of Cyperi Rhizoma.

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.