Objective:To explore the prognostic factors associated with clear cell adenocarcinoma (CCAC) of the uterine cervix based on data in the Surveillance, Epidemiology and End Results (SEER) database.Methods:Clinical data were collected from 431 patients with confirmed CCAC in the SEER database from 1976 to 2017. Survival analysis was performed using the Kaplan-Meier method with log-rank test for comparison between subgroups. Cox proportional hazards model was used to analyze the influencing factors of overall survival (OS).Results:The median age [ M ( Q1, Q3)] of 431 patients was 54 years old (40 years old, 71 years old); there were 333 cases (77.3%) of whit. The median OS time of 431 patients was 93 months (95% CI: 47-148 months), and the 1-, 2-, and 5-year OS rates were 80.1%, 65.8% and 54.2%, respectively. The median OS time was not reached in patients with American Joint Committee on Cancer (AJCC) stage Ⅰ, 83 months (95% CI: 21-144 months) for stage Ⅱ, 32 months (95% CI: 16-47 months) for stage Ⅲ, and 9 months (95% CI: 5-13 months) for stage Ⅳ ( P < 0.001). Median OS time was not reached in patients with SEER stage of localized lesions, 46 months (95% CI: 8-83 months) for regional lesions stage, and 9 months (95% CI: 5-12 months) for distant metastases stage ( P < 0.001). Of the patients with clear AJCC staging and some with unspecified AJCC staging, 118 received surgical treatment alone and 119 received postoperative radiotherapy, the median OS time of the two groups was 443 months (95% CI: 162-723 months) and 102 months (95% CI: 75-129 months), and the difference in OS between the two groups was statistically significant ( P < 0.001). Among the patients with AJCC stage Ⅰ, the 5-year OS rates in surgery-only group and postoperative radiotherapy group were 82.5% and 78.5%, the stage Ⅱ were 80.0% and 52.3%, and the stage Ⅲ were 27.8% and 63.3%, respectively; the differences in OS between different stages were not statistically significant (all P>0.05). Among the patients with SEER localized lesions stage, the 5-year OS rates in surgery-only group and postoperative radiotherapy group were 88.9% and 73.1%, and the difference was statistically significant ( P = 0.012); the regional lesions stage were 45.5% and 60.0%, and the difference was not statistically significant ( P = 0.568). The results of multivariate Cox regression analysis showed that AJCC staging (stage Ⅰ vs. stage Ⅳ, HR = 0.281, 95% CI: 0.178-0.543, P < 0.001; stage Ⅱ vs. stage Ⅳ, HR = 0.347, 95% CI: 0.113-0.439, P < 0.001; stage Ⅲ vs. stage Ⅳ, HR = 0.399, 95% CI: 0.030-0.145, P < 0.001), SEER staging (localized lesions stage vs. distant metastases stage, HR = 0.104, 95% CI: 0.059-0.182, P < 0.001; regional lesions stage vs. distant metastases stage, HR = 0.301, 95% CI: 0.195-0.463, P < 0.001) and whether or not receive surgery (yes vs. no, HR = 0.359, 95% CI: 0.241-0.535, P < 0.001) were independent influencing factors of OS in CCAC patients. Conclusions:AJCC staging, SEER staging and surgery are independent influence factors for OS in patients with CCAC, and postoperative radiotherapy may not provide more survival benefit.

Objective:To report the long-term outcomes of Chinese rectal cancer patients after adopting a Watch and Wait (W&W) strategy following neoadjuvant therapy (NAT).Methods:This multicenter, cross-sectional study was based on real-world data. The study cohort comprised rectal cancer patients who had achieved complete or near complete clinical responses (cCRs, near-cCRs) after NAT and were thereafter managed by a W&W approach, as well as a few patients who had achieved good responses after NAT and had then undergone local excision for confirmation of pathological complete response. All participants had been followed up for ≥2 years. Patients with distant metastases at baseline or who opted for observation while living with the tumor were excluded. Data of eligible patients were retrospectively collected from the Chinese Wait-and-Watch Data Collaboration Group database. These included baseline characteristics, type of NAT, pre-treatment imaging results, evaluation of post-NAT efficacy, salvage measures, and treatment outcomes. We herein report the long-term outcomes of Chinese rectal cancer patients after NAT and W&W and the differences between the cCR and near-cCR groups.Results:Clinical data of 318 rectal cancer patients who had undergone W&W for over 2 years and been followed up were collected from eight medical centers (Peking University Cancer Hospital, Fudan University Shanghai Cancer Center, Sun Yat-sen University Cancer Center, Shanghai Changhai Hospital, Peking Union Medical College Hospital, Liaoning Cancer Hospital, the First Hospital of Jilin University, and Yunnan Cancer Hospital.) The participants comprised 221 men (69.4%) and 107 women (30.6%) of median age 60 (26-86) years. The median distance between tumor and anal verge was 3.4 (0-10.4) cm. Of these patients, 291 and 27 had achieved cCR or near-cCR, respectively, after NAT. The median duration of follow-up was 48.4 (10.2-110.3) months. The 5-year cumulative overall survival rate was 92.4% (95%CI: 86.8%-95.7%), 5-year cumulative disease-specific survival (CSS) rate 96.6% (95%CI: 92.2%-98.5%), 5-year cumulative organ-preserving disease-free survival rate 86.6% (95%CI: 81.0%-90.7%), and 5-year organ preservation rate 85.3% (95%CI: 80.3%-89.1%). The overall 5-year local recurrence and distant metastasis rates were 18.5% (95%CI: 14.9%-20.8%) and 8.2% (95%CI: 5.4%-12.5%), respectively. Most local recurrences (82.1%, 46/56) occurred within 2 years, and 91.0% (51/56) occurred within 3 years, the median time to recurrence being 11.7 (2.5-66.6) months. Most (91.1%, 51/56) local recurrences occurred within the intestinal lumen. Distant metastases developed in 23 patients; 60.9% (14/23) occurred within 2 years and 73.9% (17/23) within 3 years, the median time to distant metastasis being 21.9 (2.6-90.3) months. Common sites included lung (15/23, 65.2%), liver (6/23, 26.1%), and bone (7/23, 30.4%) The metastases involved single organs in 17 patients and multiple organs in six. There were no significant differences in overall, cumulative disease-specific, or organ-preserving disease-free survival or rate of metastases between the two groups (all P>0.05). The 5-year local recurrence rate was higher in the near-cCR than in the cCR group (41.6% vs. 16.4%, P<0.01), with a lower organ preservation rate (69.2% vs. 88.0%, P<0.001). The success rates of salvage after local recurrence and distant metastasis were 82.1% (46/56) and 13.0% (3/23), respectively. Conclusion:Rectal cancer patients who achieve cCR or near-cCR after NAT and undergo W&W have favorable oncological outcomes and a high rate of organ preservation. Local recurrence and distant metastasis during W&W follow certain patterns, with a relatively high salvage rate for local recurrence. Our findings highlight the importance of close follow-up and timely intervention during the W&W process.

Objective:To report the long-term outcomes of Chinese rectal cancer patients after adopting a Watch and Wait (W&W) strategy following neoadjuvant therapy (NAT).Methods:This multicenter, cross-sectional study was based on real-world data. The study cohort comprised rectal cancer patients who had achieved complete or near complete clinical responses (cCRs, near-cCRs) after NAT and were thereafter managed by a W&W approach, as well as a few patients who had achieved good responses after NAT and had then undergone local excision for confirmation of pathological complete response. All participants had been followed up for ≥2 years. Patients with distant metastases at baseline or who opted for observation while living with the tumor were excluded. Data of eligible patients were retrospectively collected from the Chinese Wait-and-Watch Data Collaboration Group database. These included baseline characteristics, type of NAT, pre-treatment imaging results, evaluation of post-NAT efficacy, salvage measures, and treatment outcomes. We herein report the long-term outcomes of Chinese rectal cancer patients after NAT and W&W and the differences between the cCR and near-cCR groups.Results:Clinical data of 318 rectal cancer patients who had undergone W&W for over 2 years and been followed up were collected from eight medical centers (Peking University Cancer Hospital, Fudan University Shanghai Cancer Center, Sun Yat-sen University Cancer Center, Shanghai Changhai Hospital, Peking Union Medical College Hospital, Liaoning Cancer Hospital, the First Hospital of Jilin University, and Yunnan Cancer Hospital.) The participants comprised 221 men (69.4%) and 107 women (30.6%) of median age 60 (26-86) years. The median distance between tumor and anal verge was 3.4 (0-10.4) cm. Of these patients, 291 and 27 had achieved cCR or near-cCR, respectively, after NAT. The median duration of follow-up was 48.4 (10.2-110.3) months. The 5-year cumulative overall survival rate was 92.4% (95%CI: 86.8%-95.7%), 5-year cumulative disease-specific survival (CSS) rate 96.6% (95%CI: 92.2%-98.5%), 5-year cumulative organ-preserving disease-free survival rate 86.6% (95%CI: 81.0%-90.7%), and 5-year organ preservation rate 85.3% (95%CI: 80.3%-89.1%). The overall 5-year local recurrence and distant metastasis rates were 18.5% (95%CI: 14.9%-20.8%) and 8.2% (95%CI: 5.4%-12.5%), respectively. Most local recurrences (82.1%, 46/56) occurred within 2 years, and 91.0% (51/56) occurred within 3 years, the median time to recurrence being 11.7 (2.5-66.6) months. Most (91.1%, 51/56) local recurrences occurred within the intestinal lumen. Distant metastases developed in 23 patients; 60.9% (14/23) occurred within 2 years and 73.9% (17/23) within 3 years, the median time to distant metastasis being 21.9 (2.6-90.3) months. Common sites included lung (15/23, 65.2%), liver (6/23, 26.1%), and bone (7/23, 30.4%) The metastases involved single organs in 17 patients and multiple organs in six. There were no significant differences in overall, cumulative disease-specific, or organ-preserving disease-free survival or rate of metastases between the two groups (all P>0.05). The 5-year local recurrence rate was higher in the near-cCR than in the cCR group (41.6% vs. 16.4%, P<0.01), with a lower organ preservation rate (69.2% vs. 88.0%, P<0.001). The success rates of salvage after local recurrence and distant metastasis were 82.1% (46/56) and 13.0% (3/23), respectively. Conclusion:Rectal cancer patients who achieve cCR or near-cCR after NAT and undergo W&W have favorable oncological outcomes and a high rate of organ preservation. Local recurrence and distant metastasis during W&W follow certain patterns, with a relatively high salvage rate for local recurrence. Our findings highlight the importance of close follow-up and timely intervention during the W&W process.

Objective:To investigate the clinical significance of a new classification system for atlas fractures based on pre- and post-treatment CT features, with a focus on diagnosis and treatment.Methods:A retrospective analysis was conducted on 75 cases of cervical vertebra fractures treated at the Sixth Hospital of Ningbo City between January 2015 and December 2020. The study included 44 males and 31 females, with an average age of 53.3±13.0 years (range: 27-81 years). The fractures were classified according to the Landells classification, resulting in 12 cases of type I, 13 cases of type II, 33 cases of type III, 9 cases that were difficult to classify due to fracture lines located at anatomical junctions, and 8 cases that could not be classified using the Landells classification due to diverse injury mechanisms. To establish a new preliminary classification for cervical vertebra fractures, the researchers considered whether the fracture line in the CT images involved the facet joint surface of the atlas, the impact on bilateral half-rings, and the displacement distance of the fracture ends. Five spinal surgeons were randomly selected to classify the CT images of the 75 patients using the new classification method. After one month, the imaging data of the 75 cases of cervical vertebra fractures were randomized and reclassified to assess the reliability and repeatability of the classification.Results:The new cervical vertebra fracture classification method comprised three types based on whether the fracture line involved the facet joint surface of the atlas: type A (no involvement of the facet joint surface of the atlas), type B (involvement of one side of the facet joint surface with intact contralateral half-ring), and type C (involvement of one side of the facet joint surface with fractured contralateral half-ring). Additionally, based on the maximum displacement distance between the fracture ends (>4 mm), six subtypes were identified: subtype 1 (≤4 mm displacement) and subtype 2 (>4 mm displacement). Consequently, the subtypes were classified as A1, A2, B1, B2, C1, and C2. According to the new classification method, the 75 patients included 17 cases of A1, 12 cases of A2, 7 cases of B1, 13 cases of B2, 12 cases of C1, and 14 cases of C2. The classification demonstrated excellent consistency, as assessed by the five doctors, with Kappa values of 0.85 and 0.91 for reliability and repeatability, respectively. At the final follow-up, all conservatively treated patients achieved bone healing, while four surgically treated patients experienced non-union of the fracture ends but exhibited good fusion between the atlas and axis. The remaining surgically treated patients achieved bony union without complications such as loosening or fracture of internal fixation.Conclusion:The new cervical vertebra fracture classification method, based on CT imaging features, comprehensively covers common clinical cases of cervical vertebra fractures and demonstrates excellent consistency. It provides valuable clinical guidance for the diagnosis and treatment of cervical vertebra fractures.

Objective:To investigate the safety and efficacy of short-segment fixation covering the fractured vertebrae via posterior intermuscular approach plus percutaneous kyphoplasty (PKP) through the outer upper edge of the base of the fractured vertebral pedicle in the treatment of osteoporotic thoracolumbar burst fracture.Methods:A retrospective case series study was used to analyze the clinical data of 56 patients with osteoporotic thoracolumbar burst fracture admitted to Ningbo No.6 Hospital from January 2018 to February 2021, including 24 males and 32 females; aged 56-72 years [(63.5±4.6)years]. All patients underwent short-segment fixation covering the fractured vertebrae via posterior intermuscular approach combined with PKP through the outer upper edge of the base of the fractured vertebral pedicle. The operation time, intraoperative blood loss, hospitalization day and surgery-related complications were recorded. The visual analogue score (VAS) of back pain, ratios of the anterior, middle and posterior height of the fractured vertebrae and kyphotic Cobb angle were compared before operation, at postoperative 2 days and at the final follow-up.Results:All patients were followed up for 12-28 months [(14.5±2.2)months]. The operation time was 55-85 minutes [(62.0±12.1)minutes], intraoperative blood loss was 80-150 ml [(94.0±18.5)ml], and hospitalization day was 5-9 days [(7.4±1.1)days]. Based on CT examination at postoperative 2 days, there were 2 patients with paravertebral cement leakage, 2 with intervertebral space leakage and 1 with intracanal leakage, but none reported associated clinical symptoms. No implant failure or fractures of adjacent segments was detected during the follow-up period. The VAS was significantly decreased from preoperative (7.5±1.2)points to (3.2±0.8)points at postoperative 2 days ( P<0.01), and the score was further lowered to (2.2±0.8)points at the final follow-up when compared with that at postoperative 2 days ( P<0.01). The ratios of the anterior, middle and posterior height of the fractured vertebrae and kyphotic Cobb angle were significantly improved at postoperative 2 days [(89.5±13.2)%, (85.8±7.9)%, (89.5±9.0)% and (5.6±3.2)°] when compared with those before operation [(48.9±11.8)%, (61.9±11.9)%, (79.9±9.8)% and (26.3±5.6)°] (all P<0.01). Slight losses were observed in the ratios of the anterior, middle and posterior height of the fractured vertebrae and kyphotic Cobb angle at the final follow-up [(87.0±12.7)%, (82.1±7.8)%, (88.6±10.0)% and (5.4±3.2)°], but not significantly different from those at postoperative 2 days (all P>0.05). Conclusion:Short-segment fixation covering the fractured vertebrae via posterior intermuscular approach plus PKP through the outer upper edge of the base of the fractured vertebral pedicle can safely and effectively treat osteoporotic thoracolumbar burst fracture, for it can significantly improve back pain, restore the height of the fractured vertebrae and correct the kyphotic deformity.

Objective:To evaluate the effect of preventive application of PEG-rhG-CSF on the prevention of neutropenia during concurrent chemoradiotherapy in patients with lung cancer.Methods:A total of 149 patients with lung cancer who received concurrent chemoradiotherapy at Peking University Cancer Hospital from April 2020 to April 2021 were retrospectively analyzed. There were 79 cases in the prevention group, including 48 cases of primary prevention group (preventive application of PEG-rhG-CSF in all concurrent chemoradiotherapy cycles) and 31 cases of secondary prevention group (preventive application of PEG-rhG-CSF in the concurrent chemoradiotherapy cycles after neutropenia occurred). There were 70 cases in non-prevention group. The incidence of grade 3-4 neutropenia, the completion rate of concurrent chemoradiotherapy, the rate of chemoradiotherapy dose reduction and treatment delay, and the rate of hematological toxicities related hospitalization were compared between the prevention group and the non-prevention group.Results:The incidence of grade 3-4 neutropenia in the whole group was 32.2% (48/149), including 6.3% (3/48) in the primary prevention group, 9.7% (3/31) in the secondary prevention group, and 35.7% (25/70) in the non-prevention group. The difference was statistically significant ( χ2=17.81, P<0.001) in the incidence of grade 3-4 neutropenia. The incidence of febrile neutropenia was 3.4% (5/149) in the whole group, but none of them occurred in the primary prevention group. The full completion rate of concurrent chemotherapy was 96.2% (76/79) in the prevention group, which was significantly higher than 82.9% (58/70) in the non-prevention group ( χ2=7.30, P=0.007). The incidence of treatment delayed and dose reduction of chemoradiotherapy was 19.0% (15/79) in the prevention group and 40.0% (28/70) in the non-prevention group, and the difference was statistically significant ( χ2=7.98, P=0.005). Conclusions:The preventive application of PEG-rhG-CSF can effectively reduce the incidence of neutropenia and better ensure the concurrent chemoradiotherapy in lung cancer patients on schedule.

Objective:To investigate the anatomical safety and feasibility ofposterior occipitocervical fixation with atlan-tooccipital-clivus screw.Methods:Data of 60 patients who treated in the spinal department of our hospital with upper cervical computed tomographic scans from February 2017 to November 2019 were retrospectively collected. Occipitocervical infection, injury, tumor and deformity were excluded. The Mimics software was used to reconstruct the occiput, atlas and measure the anatomical parameters, including the height and width of the anterior edge of the clivus, the height and width of the middle part of the clivus, the thinnest distance of the soft tissue in front of the clivus, the anteroposterior diameter, transverse diameter, the angle of inside tilting in coronary plane of the occipital condyle, the distance from the hypoglossal canal to the atlantooccipital articular surface, the anteroposterior diameter and transverse diameter of the superior joint of atlas, the height of the lateral mass, and the height and transverse diameter of the inferior articular process of the superior atlas joint. The three-dimensional digital modeling was performed and the screw diameter of 3.5mm was simulated. 3-Matic software were used to measure the screw placement parameters, including the inside tilting angle in coronary plane of screw, and the angle of upper tilting in sagittal plane and length of screw. The atlanto-occipital junction was exposed at the rear of 8 cadavers. According to the above parameters, the titanium alloy screws with a diameter of 3.5 mm were transferred from the inferior articular process and posterior arch of the atlas to the clivus through the atlantooccipital. Finally, the screw path was cut along the nail path with a pendulum saw, and the track of the screw was observed to confirm the safety and effectiveness of the screw.Results:The leading edge height and width of male clivus was 16.8±2.5 mm and 20.1±3.1 mm. The middle part of the clivus was 9.7±2.3 mm and 22.4±3.7 mm. The thinnest soft tissue in front of the clivus was 5.8±1.48 mm. The anteroposterior diameter of the occipital condyle was 19.1±1.9 mm, the transverse diameter was 12.6±2.0 mm, the inside tilting angle was 33.7°±4.5°, and the vertical distance from the lowest point of the neural tube to the articular surface of the occipital condyle was 9.6±1.1 mm. The height of the lateral mass of atlas was 12.9±2.4 mm, the anteroposterior diameter of the upper joint of atlas was 21.7±1.9 mm, and the transverse diameter was 11.7±1.4 mm. The width of the inferior facet was 14.9±1.4 mm and the height of the inferior facet was 5.7±0.85 mm. The distance from the screw entry point to the vertical line of the lateral mass migration midpoint was 2.5±0.6 mm; The distance from the screw entry point to the horizontal line of the midpoint was 2.3±0.7 mm.The inside titling angle of screw was 18.4°±1.6°, the upper tilting angle was 55.6°±3.1°, the length of the screw track was 53.0±2.8 mm, the adjustment range of upper tilting angle was 15.0±2.8 mm, the adjustment range of inside tilting angle was 10.4±2.4 mm. The anatomical parameters of females were slightly smaller than those of males, and the difference was statistically significant, but there was no significant difference between left and right parameters. The screws of 8 specimens could be inserted safely and effectively.Conclusion:Atlan-tooccipital-clivus screw can be implanted without damaging the nerve and vascular structure, and it can be used as a choice for occipitocervical fixation.

Objective:To analyze the incidence and epidemiological characteristics of traumatic spinal cord injury in China in 2018.Methods:Multi-stage stratified cluster sampling was used to randomly select hospitals capable of treating patients with spinal cord injury from 3 regions，9 provinces and 27 cities in China to retrospectively investigate eligible patients with traumatic spinal cord injury admitted in 2018. National and regional incidence rates were calculated. The data of cause of injury，injury level，severity of injury，segment and type of fracture，complications，death and other data were collected by medical record questionnaire，and analyzed according to geographical region，age and gender.Results:Medical records of 4，134 patients were included in this study，with a male-to-female ratio of 2.99∶1. The incidence of traumatic spinal cord injury in China in 2018 was 50.484 / 1 million （95% CI 50.122-50.846）. The highest incidence in the Eastern region was 53.791 / 1 million （95% CI 53.217-54.365）. In the whole country，the main causes of injury were high falls （29.58%），as well as in the Western region （40.68%），while the main causes of injury in the Eastern and Central regions were traffic injuries （31.22%，30.10%）. The main injury level was cervical spinal cord in the whole country （64.49%），and the proportion of cervical spinal cord injury in the Central region was the highest （74.68%），and the proportion of lumbosacral spinal cord injury in the Western region was the highest （32.30%）. The highest proportion of degree of injury was incomplete quadriplegia （55.20%），and the distribution pattern was the same in each region. A total of 65.87% of the patients were complicated with fracture or dislocation，77.95% in the Western region and only 54.77% in the Central region. In the whole country，the head was the main combined injury （37.87%），as well as in the Eastern and Central regions，while the proportion of chest combined injury in the Western region was the highest （38.57%）. A total of 32.90% of the patients were complicated with respiratory complications. There were 23 patients （0.56%） died in hospital，of which 17（73.91%） died of respiratory dysfunction. Conclusions:The Eastern region of China has a high incidence of traumatic spinal cord injury. Other epidemiological features include high fall as the main cause of injury cervical spinal cord injury as the main injury level，incomplete quadriplegia as the main degree of injury，head as the main combined injury，and respiratory complications as the main complication.

Objective:To explore the difference in properties of anterior occipital condyle plate screws compared with common anterior occipitalcervical fusion internal fixation.Methods:A 28-year-old healthy adult male volunteer's CT data of the occiput and neck was selected to establish finite element models：including the normal model，simple artificial vertebral fixation model（special-shaped titanium cage+clival screws），anterior occipital condyle plate and screw fixation model，and clival plate and screw fixation model，then a 50 N gravity and a torque of 1.5 N m were exerted upon the upper surface of the occipital bone to make the model produce flexion and extension，lateral bending and rotation. The motion range，internal fixation stress distribution and occipital bone stress distribution of each model under varying conditions were compared.Results:Under the conditions of flexion，extension，lateral bending and rotation，the range of motion of the normal model was 18.65°，15.35°，9.82° and 34.68°，respectively；that of the simple artificial vertebral fixation model was 3.20°，3.63°，2.94° and 3.92°，respectively；that of the clival plate and screw fixation model was 0.40°，0.50°，0.35° and 0.89°，respectively；that of the anterior occipital condylar plate and screw fixation model was 0.27°，0.33°，0.13° and 0.30°，respectively. Compared with the simple artificial vertebral fixation model，the range of motion of the clival plate and screw fixation model decreased by 87.5%，86.2%，88.1% and 77.3% in flexion，extension，lateral bending and rotation. The range of motion of the anterior occipital condylar plate and screw fixation model decreased by 91.5%，90.1%，95.6% and 92.3%，respectively. Under the conditions of flexion and extension，lateral bending and rotation，the stress peak of the simple artificial vertebral fixation model was 52.3 MPa，51.9 MPa，52.6 MPa，respectively；that of the clival plate and screw fixation was 100.1 MPa，158.1 MPa，170.6 MPa，respectively；that of the anterior occipital condylar plate and screw fixation was 114.2 MPa，62.9 MPa，132.9 MPa，respectively. Under the condition of flexion and extension，lateral bending and rotation，the stress peak of the occipital bone in the simple artificial vertebral body internal fixation model was 52.9 MPa，50.9 MPa and 62.3 MPa，respectively；that of the clival plate and screw fixation model was 19.7 MPa，55.9 MPa and 38.3 MPa，respectively；that of the anterior occipital condylar plate and screw fixation model was 37.8 MPa，15.0 MPa and 16.3 MPa，respectively. The stress in bone near the hypoglossal canal was close to 0 MPa，much smaller than the stress peak in occipital bone.Conclusion:Anterior occipital condylar plate and screw fixation in front of the special-shaped titanium cage can improve the stability of occipitocervical fusion with little effect on the occipital bone and hypoglossal canal or without obvious stress concentration，and hence is a safe and reliable anterior fixation method for upper cervical spine instability.

Objective:To provide a theoretical basis for the clinical application of the posterior route through atlas occipital articular slope screw internal fixation system through the biomechanical study.Methods:Eight cadavers of healthy adults aged 35-60 years and 155-180 cm in height were selected. The specimens with complete anatomical structure and without surgical operation were established as normal models. The model of occipito-atlantoaxial complex was established by breaking the articular capsule, ligament and other connecting structures and cutting the dentate process. The device was established as an internal fixation model through the specimen of atlantooccipital joint slope screw internal fixation system. Given normal model and internal fixation of 1.5 N·m in the moment of flexion, lateral bending and axial rotation and to measure the specimen C 0-C 1 and C 0-C 2 segment of the range (range of motion, ROM), comparative analysis of pillow neck area within the normal model and fixed model changes the range of movement, after the evaluation through the slope between atlas and the occipital screw internal fixation system of mechanical properties. Results:In the normal model, the flexion, flexion and extension, lateral bend and axial rotation ranges of C 0-C 1 segments were 23.85°±2.43°, 4.74°±0.55°, 5.77°±0.75°, respectively; the corresponding activity ranges of C 0-C 2 segments were 30.66°±3.05°, 9.09°±1.37°, 70.97°±9.48°, respectively; in the internal fixation model, the flexion and extension, lateral bend and axial rotation ranges of C 0-C 1 segments were 0.71°±0.24°, 0.24°±0.06°, 0.34°±0.09°, respectively. The corresponding activity range of C 0-C 2 segment was 3.09°±0.82°, 0.74°±0.07°, 1.22°±0.10°, respectively. Compared with the normal model, the range of activity of the internal fixation model in all directions was significantly reduced (<3°), and the reduction ratio of activity was more than 90%. Conclusion:The posterior route through pillow slope screw internal fixation system can effectively reduce the range of motion of the occipital neck in flexion, extension, lateral bending and rotation, and has safe and reliable biomechanical stability.