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 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.

Objective:To evaluate the axial instrument strategy for atlantoaxial dislocation with complex vertebral artery variation.Methods:A total of 55 patients with atlantoaxial dislocation who underwent surgical treatment from January 2019 to December 2021 were retrospectively analyzed, including 14 males and 41 females, aged 54.0±12.8 years (range, 22-78 years). Among these patients, 10 patients with unilateral vertebral artery high ride with contralateral vertebral artery occlusion, 30 patients with bilateral vertebral artery high ride with single dominant vertebral artery, 15 patients with bilateral vertebral artery high ride. All patients underwent posterior reduction and internal fixation. Visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) score were used to evaluate the postoperative efficacy.Results:All patients completed the surgery successfully with a follow-up time of 14.6±5.5 months (range, 6-24 months). C 2 pedicle screw fixation was performed on the non-dominant side of unilateral vertebral artery high ride and the non-dominant side of bilateral vertebral artery high ride with one dominant vertebral artery (40 vertebraes). The dominant side of unilateral high vertebral artery and bilateral high vertebral artery with one dominant vertebral artery was fixed with C 2 medial "in-out-in" screw (10 vertebraes), C 2 isthmus screw (21 vertebraes), C 2 without screw (9 vertebraes) only extended the fixed segment. For bilateral vertebral artery high ride patients, one side was used C 2 "in-out-in" pedicle screws (right 10 vertebraes, left 5 vertebraes), and the other side was fixed with C 2 medial "in-out-in" screw (8 vertebraes), C 2 isthmus screw (5 vertebraes), C 2 without screw only extended the fixed segment (2 vertebraes). The JOA scores were 8.5±1.8, 13.9±1.3, and 14.4±1.1 preoperatively, 6 months postoperatively, and at the final follow-up, respectively, with statistically significant differences ( F=279.40, P<0.001). JOA at 6 months postoperatively and at the final follow-up was greater than preoperatively, and the differences were statistically significant ( P<0.05), whereas the differences in JOA scores at 6 months postoperatively and at the final follow-up was not statistically significant ( P>0.05). Preoperative, 6 months postoperatively and final follow-up cervical VAS scores were 3.7±1.9, 2.1±0.9 and 1.6±1.0, respectively, with statistically significant differences ( F=39.53, P<0.001). The cervical VAS at 6 months postoperatively and at the last follow-up was less than that before surgery, and the differences were statistically significant ( P<0.05). Cervical VAS scores at 6 months postoperatively were greater than at the last follow-up, with a statistically significant difference ( P<0.05). Conclusion:For patients with atlantoaxial dislocation with complex vertebral artery variation, C 2 lateral "in-out-in" screw, C 2 medial "in-out-in" screw, isthmus screw fixation or C 2 without screw only extended the fixed segment can obtain good clinical efficacy.

Objective:To compare the efficacy of posterior atlas uniaxial and polyaxial screw instrumentation and fusion with bone graft for Gehweiler type IIIb atlas fracture.Methods:A retrospective cohort study was performed to analyze the clinical data of 36 patients with Gehweiler type IIIb atlas fracture admitted to Henan Provincial People′s Hospital from January 2015 to October 2020. There were 29 males and 7 females, with age range of 23-82 years [(48.8±15.5)years]. All patients were treated with posterior atlas screw-rod internal fixation and fusion with bone graft, of which 14 received atlas uniaxial screw internal fixation (uniaxial screw group) and 22 received atlas polyaxial screw internal fixation (polyaxial screw group). The operation time and intraoperative blood loss were compared between the two groups. The atlas fracture union rate and atlantoaxial posterior arch bone fusion rate were compared between the two groups at 3 months and 6 months after operation. The anterior atlantodental interval (ADI), basion-dens interval (BDI) and lateral mass displacement (LMD) were compared between the two groups to evaluate the reduction of fracture fragments before operation, at 1, 3, 6 months after operation and at the last follow-up. At the same time, the visual analogue scale (VAS) and neck dysfunction index (NDI) were compared between the two groups to evaluate neck pain and functional recovery. The postoperative complications were observed.Results:All patients were followed up for 12-44 months [(27.2±9.9)months]. There was no significant difference in operation time or intraoperative blood loss between the two groups (all P>0.05). The atlas fracture union rate and atlantoaxial posterior arch bone fusion rate were 85.7% (12/14) and 78.6% (11/14) in uniaxial screw group at 3 months after operation, insignificantly different from those in polyaxial screw group [72.7% (16/22) and 77.3% (17/22)] (all P>0.05). All patients in the two groups achieved bone union and fusion at 6 months after operation. There was no significant difference in ADI between the two groups before and after operation (all P>0.05). The BDI in the two groups did not differ significantly before operation ( P>0.05), but a significantly higher value was found in uniaxial screw group at 1, 3, and 6 months after operation and at the last follow-up [(5.9±1.3)mm, (5.8±1.3)mm, (5.9±1.2)mm and (5.8±1.2)mm] than in polyaxial screw group [(3.1±0.6)mm, (3.1±0.6)mm, (3.1±0.6)mm and (3.1±0.6)mm] (all P<0.01). The two groups did not differ significantly before operation ( P>0.05), but LMD at 1, 3, and 6 months after operation and at the last follow-up was (1.6±0.8)mm, (1.5±0.8)mm, (1.5±0.7)mm and (1.5±0.9)mm in uniaxial screw group, significantly lower than that in polyaxial screw group [(4.8±1.6)mm, (4.6±1.6)mm, (4.9±1.6)mm and (4.9±1.6)mm] (all P<0.01). There was no significant difference in VAS between the two groups before operation ( P>0.05). The VAS at 1, 3, and 6 months after operation and at the last follow-up was 3.0(3.0, 4.0)points, 2.0(1.0, 2.0)points, 1.0(0.8, 2.0)points and 1.0(0.0, 1.3)points in uniaxial screw group and was 3.5(3.0, 4.0)points, 2.0(2.0, 3.0)points, 2.0(1.0, 2.0)points and 2.0(1.0, 3.0)points in polyaxial screw group. In comparison, the VAS scored much lower in uniaxial screw group than in polyaxial screw group at 6 months after operation and at the last follow-up (all P<0.01). There was no significant difference in NDI between the two groups before operation ( P>0.05). The NDI at 1, 3, and 6 months after operation and at the last follow-up was 34.9±6.3, 23.4±6.2, 13.9±2.7 and 9.4±2.8 in uniaxial screw group and was 33.2±6.1, 24.4±6.3, 18.1±4.1 and 12.7±3.2 in polyaxial screw group, showing a significantly lower NDI in uniaxial screw group than in polyaxial screw group at 6 months after operation and at the last follow-up (all P<0.01). The complication rate was 21.4% (3/14) in uniaxial screw group when compared to 22.7% (5/22) in polyaxial screw group ( P>0.05). Conclusion:For Gehweiler type IIIb atlas fracture, both techniques can attain atlas fracture union and atlantoaxial posterior arch bone fusion, but the posterior atlas uniaxial screw instrumentation and fusion is superior in reduction of atlas fracture displacement and lateral mass separation, neck pain relief and functional improvement.

Objective:To investigate the effects of different surgical time points on the treatment efficacy of acute traumatic central cord syndrome (ATCCS).Methods:Retrospectively analyzed were the 84 ATCCS patients who had been treated at Department of Spinal Surgery, Henan Provincial People's Hospital from January 2013 to February 2021. According to the surgical timing, the patients were divided into 3 groups. In group A (surgery < 48 hours) of 16 cases, there were 11 males and 5 females, aged from 43 to 76 years; in group B (surgery within 3 to 7 days) of 41 cases, there were 31 males and 10 females, aged from 41 to 78 years; in group C (surgery within 8 to 14 days) of 27 cases, there were 15 males and 12 females, aged from 46 to 83 years. Anterior, posterior or combined anterior and posterior approaches were used according to their specific condition. The American Spinal Injury Association (ASIA) motor scores and Japanese Orthopaedic Association (JOA) scores at admission, 7 days and 12 months after operation, postoperative ICU duration, and complications were compared among the 3 groups.Results:There were no significant differences in the preoperative general information or surgical approaches among the 3 groups, showing they were comparable ( P> 0.05). In all patients, the ASIA motor scores and JOA scores at 7 days and 12 months after operation were significantly better than those at admission, and the ASIA motor scores and JOA scores at 12 months after operation were significantly better than those at 7 days after operation ( P<0.01). There was no significant difference in the ASIA motor score or JOA score between the 3 groups at 7 days or 12 months after operation ( P>0.05). The postoperative ICU duration in group A was 42 (26, 61) h, significantly longer than 23 (16, 35) h in group B and 24 (14, 38) h in group C ( P<0.05). There were no deaths in the 84 patients; there was no significant difference in the overall incidence of serious complications or in that of general complications among the 3 groups ( P>0.05). Conclusions:Surgery is safe and effective for ATCCS. However, decompression surgery within 2 weeks may achieve better outcomes.

Objective:To observe the effect of insertion of in-out-in axis pedicle screws on the vertebral artery in the posterior occipitocervical surgery for atlantoaxial subluxation or instability.Methods:The data of 52 patients with atlantoaxial dislocation or instability were analyzed who had been treated by internal fixation with in-out-in pedicle screws in the posterior occipitocervical surgery from January 2015 to February 2021 at Department of Spine and Spinal Cord Surgery, Henan Provincial People's Hospital. There were 30 males and 22 females, aged from 17 to 65 years (mean, 41.2 years). There were 26 cases of unilateral vertebral artery high-riding, 3 cases of bilateral high-riding, 19 cases of unilateral narrow pedicle due to C2 and C3 fusion, and 4 cases of bilateral narrow pedicles. X-ray, CTA and MRI were performed before and 3 days after surgery. The patients' clinical symptoms were recorded. CTA was used to measure the diameter of the vertebral artery at the transverse foramina of C 2 and C 3 and to observe the effect of in-out-in screws on the morphology of the vertebral artery. X-ray and CT examinations were performed at 6 months after surgery to observe the bone fusion. Results:The surgery went on uneventfully in all the patients. In the 9 cases undergoing anterior and posterior surgery, the operation time averaged 271.2 min (from 213 to 352 min) and the bleeding volume 471.5 mL (from 230 to 830 mL). In the 43 cases undergoing posterior surgery, the operation time averaged 171.6 min (from 131 to 226 min) and the bleeding volume 395.9 mL (from 170 to 660 mL). There was no such complication as spinal or vascular injury. The CTA reexamination 3 days after surgery showed that the diameter of the vertebral artery was (2.92±0.55) mm and (3.04±0.54) mm, respectively at the cervical 2 and 3 transverse foramina, showing no significant change compared with the preoperative values [(2.91±0.68) mm and (3.11±0.50) mm] ( P>0.05) and that the vertebral artery was displaced externally and inferiorly in 21 cases. Follow-ups for all patients ranged from 7 to 24 months (mean, 11 months). At 6 months after surgery, bone fusion was observed by imaging and no breakage or displacement of the internal fixation was observed. Conclusion:The in-out-in pedicle screws in the posterior occipitocervical surgery may have little impact on the vertebral artery, leading to reliable clinical outcomes.

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.