Objective: To explore the current status of hyperopic reserve and its related factors among non-myopia preschool and primary school students aged 5 to 12 years in Guangdong Province, so as to provide a basis for formulating intervention strategies for the pre myopia stage of children. Methods: From October to December 2023, by using stratified cluster random sampling method, a survey on hyperopic reserve among preschool children and primary school students in Guangdong were conducted. And a total of 10 567 children from the senior class of kindergarten to the sixth grade of primary school who completed autorefraction measurements with and without cycloplegia and the questionnaire survey were included in the study. The prevalence characteristics of low hyperopic reserve among non-myopia children were analyzed, and multivariable Logistic regression was used to analyze the related factors. Results: The prevalence rate of low hyperopic reserve among 8 790 non-myopia children was 62.4%. The average spherical equivalent (SE) for children aged 5 to 12 years was 0.88 (0.25, 1.25)D, decreasing from 1.13 ( 0.75 , 1.50)D in senior kindergarten to -1.00 (-2.50, 0.38)D in sixth grade, with the difference was statistically significant ( H=2 475.3, P <0.01). Multivariable Logistic regression analysis, after adjusting for confounders including gender, urban and rural, and grade, revealed that parental myopia was a risk factor for low hyperopic reserve in the preschool stage (one parent with myopia: OR=1.62, 95%CI =1.35-1.93; both parents with myopia: OR=2.05, 95%CI = 1.66 -2.55); in the lower primary school stage, parental myopia (one parent with myopia: OR=1.46, 95%CI =1.27-1.68; both parents with myopia: OR=1.58, 95%CI =1.33-1.89), frequently or always reading or using electronic screens while lying down or on one s stomach ( OR=1.43, 95%CI =1.13-1.81), and never or occasionally maintaining a viewing distance of over 3 meters when watching TV/playing video games ( OR=1.34, 95%CI =1.04-1.72) were risk factors; in the higher primary school stage, failing to take a break every hour during near work ( OR=1.79, 95%CI =1.16-2.75) was a risk factor (all P <0.05). Conclusions The emmetropization of children aged 5-12 years in Guangdong Province is accelerated, and non-myopia children generally exhibit insufficient hyperopic reserve. The contributing factors for insufficient hyperopia reserve in non-myopia children vary across different educational stages, necessitating targeted precision interventions.

Objective:To explore the efficacy of percutaneous vertebroplasty (PVP) using the partition injection technique in the treatment of Kümmell’s disease of stages Ⅰ and Ⅱ.Methods:A retrospective study was conducted of the 30 patients with stage Ⅰ or Ⅱ Kümmell’s disease (the partition group) who had been treated by PVP using the partition injection technique at Department of Spinal Surgery, Zhengzhou Orthopedic Hospital from January 2020 to January 2022. The data of another 30 patients who had been treated at the same department and the same period using conventional PVP for stage Ⅰ or Ⅱ Kümmell's disease were selected as the conventional group. In the partition group, there were 13 males and 17 females, with an age of (72.3±10.1) years and disease duration of (3.1±1.5) months. Seventeen thoracic and 13 lumbar vertebrae were affected. In the conventional group, there were 11 males and 19 females, with an age of (75.5±12.7) years and disease duration of (3.5±1.8) months. Eighteen thoracic and 12 lumbar vertebrae were affected. Surgical time, volume of bone cement injected, bone cement leakage, and bone cement distribution were compared between the 2 groups. The heights of the anterior and middle vertebral bodies, kyphotic Cobb angle, visual analog scale (VAS) pain score, and Oswestry disability index (ODI) were assessed postoperatively at 1 day, 6 months, and the last follow-up and compared between the 2 groups.Results:No significant differences were found in the baseline data between the 2 groups, indicating comparability ( P>0.05). All patients were followed up for (17.3±3.1) months. There were no significant differences in the surgical time or bone cement leakage between the 2 groups ( P>0.05). The volume of bone cement injected in the partition group was significantly higher [(6.3±1.5) mL] than that in the conventional group [(4.9±1.0) mL] ( P<0.05). Bone cement distribution was significantly better in the partition group than that in the conventional group ( P<0.05). At postoperative 1 day, 6 months, and the last follow-up, the partition group was significantly better than the conventional group in anterior vertebral body height, middle vertebral body height, and kyphotic Cobb angle ( P<0.05). At the 6-month and the last follow-ups, the partition group was also significantly better than the conventional group in VAS pain score and ODI ( P<0.05). Conclusion:In the treatment of Kümmell’s disease of stages Ⅰ and Ⅱ, compared with conventional PVP, PVP using the partition injection technique may lead to better long-term outcomes due to its better bone cement distribution, more adequate cement injection, and better restoration of vertebral body heights and correction of local deformity.

Objective:To compare the efficacy of O-arm navigation-assisted and freehand posterior pedicle screw fixation in the treatment of ankylosing spondylitis (AS) associated with lower cervical fractures in adults.Methods:A retrospective cohort study was conducted to analyze the clinical data of 29 adult AS patients with lower cervical fractures admitted to Zhengzhou Orthopedic Hospital from June 2020 to September 2024, including 22 males and 7 females, aged 35-72 years [(52.3±11.1)years]. Injured segments involved C 5~6 in 6 patients, C 6 in 8, C 6~7 in 8, and C 7 in 7. Accirdubg to AO classification, the fracture was classified as type B3 in 22 patients and type C in 7. All the patients underwent posterior cervical pedicle screw fixation, among whom 15 patients were treated with navigation-assisted screw placement (navigation screw placement group, with 120 screws) and 14 with freehand technique (freehand screw placement group, with 112 screws). The two groups were compared in terms of the operative time, intraoperative blood loss, and postoperative drainage volume. The accuracy of screw placement, penetration rate of the pedicle cortex and fracture healing time were evaluated in the two groups. The Cobb angle before surgery and at 3 days after surgery and American Spinal Injury Association (ASIA) classification before surgery and at the last follow-up were recorded in the two groups. The visual analogue scale (VAS) score, Japanese Orthopedic Association (JOA) score and neck dysfunction index (NDI) before surgery, at 1 week, 3 months after surgery and at the last follow-up were compared between the two groups. The incidence of postoperative complications was also investigated. Results:All the patients were followed up for 6-57 months [(29.3±14.1)months]. The operation duration, intraoperative blood loss, and postoperative drainage volume were (166.0±31.4)minutes, (256.7±70.7)ml, and (91.0±14.4)ml in the navigation screw placement group, which were shorter or less than (219.29±31.7)minutes, (342.1±60.7)ml, and (123.2±20.7)ml in the freehand screw placement group ( P<0.01). The accuracy of screw placement in the navigation screw placement group was 98.3% (118/120) and penetration rate of the pedicle cortex was 5.8% (7/120), which were both superior to 89.3% (100/112) and 18.8% (21/112) in the freehand screw placement group ( P<0.01). No significant difference was detected in fracture healing time between the two groups ( P>0.05). There were no significant differences in the Cobb angle before surgery and at 3 days after surgery, as well as in the ASIA grading before surgery and at the last follow-up between the two groups ( P>0.05). The Cobb angle and ASIA classification at 3 days after surgery and at the last follow-up were improved compared with those before surgery ( P<0.05). Before surgery, at 1 week, 3 months after surgery, and at the last follow-up, the VAS scores were 8.0(7.0, 9.0)points, 4.0(3.0, 4.0)points, 2.0(1.0, 2.0)points, and 0.0(0.0, 1.0)points in the navigation screw placement group, which were not significantly different from 8.0(7.0, 9.0)points, 4.0(3.0, 4.0)points, 1.5(1.0, 2.0)points, and 0.0(0.0, 1.0)points in the freehand screw placement group ( P>0.05); the JOA scores were (7.5±1.4)points, (10.9±1.2)points, (13.2±1.5)points, and (15.7±1.0)points in the navigation screw placement group, which were not significantly different from (7.2±2.8)points, (10.1±3.2)points, (11.8±3.8)points, and (14.1±4.3)points in the freehand screw placement group ( P>0.05); the NDI were 48.0(44.0, 56.0)%, 30.0(30.0, 34.0)%, 18.0(16.0, 22.0)%, 8.0(6.0, 10.0)% in the navigation screw placement group, which were not significantly different from 44.0(40.0, 52.0)%, 30.0(29.0, 34.5)%, 17.0(16.0, 20.0)%, and 8.0(5.5, 10.0)% in the freehand screw placement group ( P>0.05). The VAS scores, JOA scores, and NDI were improved at 1 week, 3 months after surgery, and at the last follow-up in both groups, compared to those before surgery and they were gradually improved with the passage of the follow-up time ( P<0.05). One patient in the navigation screw placement group developed postoperative pulmonary infection and recovered after symptomatic treatment, with an incidence of complications 7% (1/15). Two patients in the freehand screw placement group had postoperative cerebrospinal fluid leakage and dural rupture and recovered after symptomatic treatment, with an incidence of complications 14% (2/14). Throughout the follow-up period, no complications such as screw breakage, implant loosening, or loss of correction were found in either group. Conclusion:Compared with freehand screw placement, the O-arm navigation system-assisted posterior pedicle screw fixation in the treatment of AS associated with lower cervical fractures in adults demonstrates significant advantages, including reduced operative time, decreased intraoperative blood loss and postoperative drainage volume, improved accuracy of screw placement, and reduced penetration rate of the pedicle cortex.

Objective:To compare the efficacy of whole-process visualization system-assisted pedicle screw internal fixation and free-hand pedicle screw internal fixation in the treatment of thoracolumbar burst fracture (TLBF) without neurologic symptoms.Methods:A retrospective cohort study was conducted to analyze the clinical data of 64 patients with TLBF without neurologic symptoms admitted to Zhengzhou Orthopedic Hospital from December 2020 to October 2022, including 41 males and 23 females, aged 23-52 years [(42.1±6.6)years]. The injured vertebrae involved T 11 in 26 patients, T 12 in 17, L 1 in 12, and L 2 in 9. The Wiltse approach was used in all the patients, 31 of whom were treated with pedicle screw internal fixation assisted by the whole-process visualization system (visualization system-assisted screw placement group) and 33 of whom were treated with free-hand pedicle screw internal fixation (free-hand screw placement group). The two groups were compared in terms of operation time, single screw placement time, intraoperative blood loss, intraoperative total radiation dose and total length of hospital stay. The accuracy of pedicle screw placement and penetration rate of the pedicle cortex were evaluated in the two groups. The Cobb angle and lumbar visual analogue scale (VAS) before surgery, at 1 week, 3 months after surgery and at the last follow-up were compared between the two groups. The incidence of postoperative complications was also investigated. Results:All the patients were followed up for 10-33 months [(17.5±4.8)months]. The operation time was (106.9±11.8)minutes in the visualization system-assisted screw placement group, shorter than (121.3±11.4)minutes in the free-hand screw placement group ( P<0.01). The single screw placement time was (9.1±1.0)minutes in the visualization system-assisted screw placement group, shorter than (11.7±1.5)minutes in the free-hand screw placement group ( P<0.01). The total radiation dose was (10.4±2.4)mGy in the visualization system-assisted screw placement group, lower than (51.8±7.2)mGy in the screw placement group ( P<0.01). There was no significant difference in intraoperative blood loss or total length of hospital stay between the two groups ( P>0.05). The accuracy of pedicle screw placement was 96.6% (197/204) in the visualization system-assisted screw placement group, significantly higher than 89.3% (191/214) in the free-hand screw placement group ( P<0.01). Both groups showed significant improvements in Cobb angle and VAS scores at 1 week, 3 months after surgery, and at the last follow-up ( P<0.05). There were no significant differences in Cobb angle or VAS scores between the two groups at each time point ( P>0.05). In the visualization system-assisted screw placement group, one patient had incision infection at 4 days after operation, which was cured with antibiotics. One patient in the free-hand screw placement group developed the symptoms of nerve root irritation at 2 days after surgery, which disappeared at 7 days after revision. There was no significant difference in the incidence of complications between the two groups ( P>0.05). During the follow-up, no patients had broken screws, loosening of internal fixation, or loss of correction in either group. Conclusions:Compared with free-hand pedicle screw internal fixation, the whole-process visualization system-assisted pedicle screw internal fixation in the treatment of TLBF without neurologic symptoms can shorten the time of operation and screw placement, reduce the radiation dose, and improve the accuracy of pedicle screw placement, suggesting that it is a safer and more effective auxiliary method for pedicle screw placement.

Objective:To analyze the clinical efficacy of asymmetric T 1 transpedicular wedge resection Smith-Petersen osteotomy (T 1 SPO) in the treatment of stiff cervical thoracic lateral kyphosis deformity. Methods:This is a retrospective case series study. The clinical data of nine patients with stiff cervical thoracic kyphosis who underwent asymmetric T 1 SPO corrective treatment from June 2012 to October 2022 were collected. There were 7 males and 2 females, aged 45 to 68 years. The surgery time, intraoperative blood loss, and complications were recorded. The chin brow vertical angle (CBVA), cervical thoracic kyphosis Cobb angle, cervical thoracic scoliosis Cobb angle, and cervical thoracic sagittal axis (C 2-T 1 sagittal vertical axis, SVA) before surgery, after surgery, and at the last follow-up were measured and the correction rates were calculate. Results:All 9 patients successfully completed the surgery. The operation time ranged from 245 to 320 minutes, and the intraoperative blood loss was 1 400 to 2 200 ml. All patients were followed up for 24 to 48 months. The preoperative CBVA was 93.7° to 112.0°, which improved to 25.2° to 31.7° at the last follow-up, with an correction rate of 73.4%. The preoperative cervicothoracic kyphosis Cobb angle was -57.0° to -16.6°, which improved to 10.3° to 18.5° at the last follow-up, with an correction rate of 166.7%. The preoperative scoliosis Cobb angle was 13.0° to 16.5°, which improved to 2.2° to 3.8° at the last follow-up, with an correction rate of 84.9%. The preoperative SVA was 7.8 to 12.5 cm, which improved to 4.5 to 6.8 cm at the last follow-up, with an correction rate of 42.3%. One patient experienced numbness and weakness in the left hand after surgery, which recovered after 3 months. One patient had poor healing of the surgical incision, which healed after symptomatic treatment. During the follow-up, the coronal and sagittal balance of all patients was maintained, and no other neurological complications occurred. There were no cases of screw loosening, broken screws, or broken rods, or other internal fixation failures.Conclusion:The application of asymmetric T 1 SPO technique in the treatment of stiff cervical thoracic lateral kyphosis deformity can achieve relatively satisfactory correction effects.

Objective To explore the interaction mechanisms among different dimensions of online learning competence in undergraduates,providing scientific evidence for optimizing software design and online education strategies.Methods A cross-sectional study was conducted with 347 undergraduates from Kunming Medical University via an online questionnaire in October 2024.Reliability testing and exploratory factor analysis were performed using SPSS 26.0,while structural equation modeling was constructed with Amos 24.0.Results Driving force directly and positively influenced regulatory force(β=0.778,P<0.001)and reciprocal force(β=0.302,P=0.003),but had no significant direct effect on adaptive force(β=0.131,P=0.182).Regulatory force and reciprocal force both exerted direct positive effects on adaptive force(β=0.262,P=0.022;β=0.410,P<0.001).The indirect effect of driving force on adaptive force accounted for 78.1%of the total effect(P=0.007),with regulatory force showing a significant mediating role(β=0.178,P=0.023),while reciprocal force alone did not(β=0.108,P=0.060).A chain mediating effect(driving force→regulatory force→reciprocal force→adaptive force)was confirmed(β=0.124,P=0.004).Conclusion Driving force serves as the core of online learning competence,and adaptive capacity is enhanced through regulatory and reciprocal forces.To promote knowledge internalization and adaptability,it is required to optimize feedback mechanisms and deepen interactive designs in online learning platforms.

Objective:To develop an artificial intelligence (AI)-based automatic scoring model for magnetic resonance imaging-detected extramural vascular invasion (AI-mrEMVI) and evaluate its performance and prognostic value in patients with rectal cancer.Methods:In this multicenter retrospective cohort study, a total of 2 501 rectal cancer patients from seven centers between November 2012 and December 2020 were included and divided into completely independent training ( n=1 830) and validation ( n=671) cohorts. A nnUNet-based AI-mrEMVI scoring model was constructed. Manual mrEMVI scores assigned by two radiologists served as the reference standard for accessing the accuracy of the AI-mrEMVI scoring. Kaplan-Meier survival analysis and Cox regression were used to evaluate the prognostic stratification ability of the AI-mrEMVI scores. The concordance index (C-index) was calculated to evaluate prognostic performance. Results:In the validation cohort, the manual mrEMVI scores were 0-2 in 425 patients (63.3%), 3 in 89 (13.4%), and 4 in 157 (23.4%). The AI-mrEMVI model identified 0-2 in 375 patients (55.9%), 3 in 95 (14.2%), and 4 in 201 (30.0%), with an overall accuracy of 81.1% (544/671, 95% CI 77.9%-84.0%). The 3-year disease-free survival (DFS) rates for patients with AI-mrEMVI scores of 0-2, 3, and 4 were 85.2%, 70.0%, and 58.2%, respectively, and the 5-year overall survival (OS) rates were 87.2%, 81.6%, and 62.6%, respectively (DFS: χ2=48.74, P<0.001; OS: χ2=30.04, P<0.001). Multivariable Cox regression showed that for DFS, AI-mrEMVI scores of 3 and 4 were associated with hazard ratios ( HR) of 1.75 (95% CI 1.11-2.77, P=0.016) and 2.65 (95% CI 1.86-3.78, P<0.001), respectively. For OS, an AI-mrEMVI score of 4 was associated with an HR of 2.56 (95% CI 1.62-4.03, P<0.001). The C-index values of the AI-mrEMVI scoring model for predicting DFS and OS were 0.647 (95% CI 0.608-0.686) and 0.650 (95% CI 0.598-0.702), respectively. Conclusion:The proposed AI-mrEMVI automatic scoring model demonstrated high diagnostic accuracy and performed favorably in predicting DFS and OS prognostic risk in patients with rectal cancer.

OBJECTIVE: To explore the safety and effectiveness of the "talus home technique (THT) " in the surgery of pronation open ankle fractures (POAF). METHODS: A retrospective analysis was conducted on 14 patients with POAF admitted between January 2023 and December 2023 who met the selection criteria. There were 7 males and 7 females; age ranged from 26 to 58 years, with a median age of 53 years. Injury causes included 9 cases of traffic accident injury, 3 cases of fall from hight injury, and 2 cases of crush injury. There were 5 cases of type Ⅱ, 6 cases of type ⅢA, and 3 cases of type ⅢB according to Gustilo classification; and 6 cases of pronation-abduction grade Ⅲ and 8 cases of pronation-external rotation grade Ⅳ according to Lauge-Hansen classification. Emergency first-stage debridement of the ankle joint was performed, followed by second-stage open reduction and internal fixation surgery. The THT was used through a limited incision on the lateral malleolus to restore the height of the lateral malleolus, rotational alignment, and anatomical relationship of the distal tibiofibular syndesmosis (DTFS). Wound healing was observed postoperatively. At 4 months postoperatively, weight-bearing anteroposterior, lateral, and mortise view X-ray films and CT scans of both ankles were reviewed to measure the medial clear space (MCS), tibiofibular clear space (TFCS), distal fibular tip to lateral process of talus (DFTL), and anterior/posterior syndesmosis distances of DTFS, and the quality of reduction of ankle fractures was evaluated. Ankle joint function was assessed using the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, and active dorsiflexion/plantar flexion range of motion were recorded at last follow-up. RESULTS: After second-stage internal fixation, 8 patients achieved wound healing by first intention, 1 case had skin edge necrosis, 2 cases had local skin necrosis, 1 case had extensive medial soft tissue defect, and 2 cases developed medial wound infection with sinus formation. All 14 patients were followed up 13-24 months (mean, 16.8 months). Postoperative X-ray films showed 1 case of delayed union of the lateral malleolus, which healed after bone grafting at 12 months; the remaining 13 cases achieved clinical union at 12-32 weeks (mean, 21.5 weeks). At 4 months postoperatively, X-ray films and CT examination showed no significant differences in MCS, TFCS, DFTL, and anterior/posterior syndesmosis distances of DTFS between the healthy and affected sides ( P>0.05), with no poor DTFS reduction. AOFAS ankle-hindfoot score ranged from 80 to 95, with an average of 87.7; ankle range of motion ranged from 10° to 25° (mean, 19.6°) in dorsiflexion and from 32° to 50° (mean, 41.2°) in plantar flexion. CONCLUSION THT is safe and effective in POAF surgery. It can restore lateral malleolar height and rotational alignment, enhance DTFS reduction quality, and obtain satisfactory short-term functional recovery of the ankle.
Humans ; Male ; Female ; Middle Aged ; Ankle Fractures/surgery* ; Adult ; Retrospective Studies ; Fracture Fixation, Internal/methods* ; Pronation ; Fractures, Open/surgery* ; Talus/surgery* ; Treatment Outcome ; Debridement/methods* ; Ankle Joint/surgery* ; Open Fracture Reduction/methods*

OBJECTIVE: To evaluate the safety and effectiveness of reducing posterior malleolar fractures via the modified Rammelt transfibular approach. METHODS: A retrospective analysis was conducted on 26 patients with ankle fractures who met the selection criteria and were admitted between September 2023 and May 2024. There were 13 males and 13 females, aged from 14 to 59 years (median, 43.5 years). Causes of injury included traffic accident (1 case), falls (7 cases), and sprains (18 cases). Time from injury to operation ranged from 1 to 13 days (mean, 3.9 days). According to the Lauge-Hansen classification, there were 5 supination-external rotation type Ⅲ fractures and 21 supination-external rotation type Ⅳ fractures. According to the Bartoníček classification for posterior malleolar fractures, there were 12 type Ⅱ fractures, 10 type Ⅲ fractures, and 4 type Ⅳ fractures. During operation, the fracture was exposed via the modified Rammelt transfibular approach; then, the fracture reduction was achieved under direct vision using techniques such as towel clip traction, posterolateral compression, and lifting with a posterior transverse periosteal elevator; finally, the fracture was fixed using anteroposterior cannulated screws or Kirschner wires. The incision healing was observed after operation. At 4 months after operation, X-ray film and CT were reviewed to evaluate the quality of fracture reduction. The medial clear space, tibiofibular clear space, and the anterior/posterior tibiofibular syndesmotic distances were measured. At last follow-up, the ankle function was assessed using the American Orthopaedic Foot & Ankle Society (AOFAS) score and the range of motion. RESULTS: The marginal necrosis occurred in 2 lateral malleolar incisions, and superficial infection occurred in 1 lateral malleolar incision; the remaining incisions healed by first intention. All 26 patients were followed up 13-21 months (mean, 15.6 months). X-ray films showed that fractures in 25 patients achieved clinical union within 3-8 months (mean, 5.4 months); 1 case had delayed union of the lateral malleolus. At 4 months after operation, no significant difference was found between the injured and healthy sides in the medial clear space, tibiofibular clear space, or the anterior/posterior tibiofibular syndesmotic distances ( P>0.05). No malreduction of the posterior malleolus or the tibiofibular syndesmosis occurred. At last follow-up, the AOFAS score ranged from 80 to 100 (mean, 91.9). The range of motion ranged from 17° to 22° (mean, 21.0°) in active ankle dorsiflexion and from 40° to 49° (mean, 44.6°) in plantar flexion. Internal fixator was removed in 12 patients at 1 year after operation, with no ankle instability occurring. Ankle joint degeneration was observed in 1 patient at last follow-up. CONCLUSION The modified Rammelt transfibular approach is a safe and reliable technique. It enables precise reduction under direct vision, improves the quality of reduction for the distal tibial articular surface and the tibiofibular syndesmosis, and provides satisfactory ankle functional recovery in short-term follow-up.
Humans ; Male ; Female ; Adult ; Ankle Fractures/diagnostic imaging* ; Middle Aged ; Retrospective Studies ; Fracture Fixation, Internal/instrumentation* ; Adolescent ; Treatment Outcome ; Young Adult ; Bone Screws ; Ankle Joint/surgery* ; Fibula/surgery* ; Range of Motion, Articular

Objective:To compare the efficacy of O-arm navigation-assisted and freehand posterior pedicle screw fixation in the treatment of ankylosing spondylitis (AS) associated with lower cervical fractures in adults.Methods:A retrospective cohort study was conducted to analyze the clinical data of 29 adult AS patients with lower cervical fractures admitted to Zhengzhou Orthopedic Hospital from June 2020 to September 2024, including 22 males and 7 females, aged 35-72 years [(52.3±11.1)years]. Injured segments involved C 5~6 in 6 patients, C 6 in 8, C 6~7 in 8, and C 7 in 7. Accirdubg to AO classification, the fracture was classified as type B3 in 22 patients and type C in 7. All the patients underwent posterior cervical pedicle screw fixation, among whom 15 patients were treated with navigation-assisted screw placement (navigation screw placement group, with 120 screws) and 14 with freehand technique (freehand screw placement group, with 112 screws). The two groups were compared in terms of the operative time, intraoperative blood loss, and postoperative drainage volume. The accuracy of screw placement, penetration rate of the pedicle cortex and fracture healing time were evaluated in the two groups. The Cobb angle before surgery and at 3 days after surgery and American Spinal Injury Association (ASIA) classification before surgery and at the last follow-up were recorded in the two groups. The visual analogue scale (VAS) score, Japanese Orthopedic Association (JOA) score and neck dysfunction index (NDI) before surgery, at 1 week, 3 months after surgery and at the last follow-up were compared between the two groups. The incidence of postoperative complications was also investigated. Results:All the patients were followed up for 6-57 months [(29.3±14.1)months]. The operation duration, intraoperative blood loss, and postoperative drainage volume were (166.0±31.4)minutes, (256.7±70.7)ml, and (91.0±14.4)ml in the navigation screw placement group, which were shorter or less than (219.29±31.7)minutes, (342.1±60.7)ml, and (123.2±20.7)ml in the freehand screw placement group ( P<0.01). The accuracy of screw placement in the navigation screw placement group was 98.3% (118/120) and penetration rate of the pedicle cortex was 5.8% (7/120), which were both superior to 89.3% (100/112) and 18.8% (21/112) in the freehand screw placement group ( P<0.01). No significant difference was detected in fracture healing time between the two groups ( P>0.05). There were no significant differences in the Cobb angle before surgery and at 3 days after surgery, as well as in the ASIA grading before surgery and at the last follow-up between the two groups ( P>0.05). The Cobb angle and ASIA classification at 3 days after surgery and at the last follow-up were improved compared with those before surgery ( P<0.05). Before surgery, at 1 week, 3 months after surgery, and at the last follow-up, the VAS scores were 8.0(7.0, 9.0)points, 4.0(3.0, 4.0)points, 2.0(1.0, 2.0)points, and 0.0(0.0, 1.0)points in the navigation screw placement group, which were not significantly different from 8.0(7.0, 9.0)points, 4.0(3.0, 4.0)points, 1.5(1.0, 2.0)points, and 0.0(0.0, 1.0)points in the freehand screw placement group ( P>0.05); the JOA scores were (7.5±1.4)points, (10.9±1.2)points, (13.2±1.5)points, and (15.7±1.0)points in the navigation screw placement group, which were not significantly different from (7.2±2.8)points, (10.1±3.2)points, (11.8±3.8)points, and (14.1±4.3)points in the freehand screw placement group ( P>0.05); the NDI were 48.0(44.0, 56.0)%, 30.0(30.0, 34.0)%, 18.0(16.0, 22.0)%, 8.0(6.0, 10.0)% in the navigation screw placement group, which were not significantly different from 44.0(40.0, 52.0)%, 30.0(29.0, 34.5)%, 17.0(16.0, 20.0)%, and 8.0(5.5, 10.0)% in the freehand screw placement group ( P>0.05). The VAS scores, JOA scores, and NDI were improved at 1 week, 3 months after surgery, and at the last follow-up in both groups, compared to those before surgery and they were gradually improved with the passage of the follow-up time ( P<0.05). One patient in the navigation screw placement group developed postoperative pulmonary infection and recovered after symptomatic treatment, with an incidence of complications 7% (1/15). Two patients in the freehand screw placement group had postoperative cerebrospinal fluid leakage and dural rupture and recovered after symptomatic treatment, with an incidence of complications 14% (2/14). Throughout the follow-up period, no complications such as screw breakage, implant loosening, or loss of correction were found in either group. Conclusion:Compared with freehand screw placement, the O-arm navigation system-assisted posterior pedicle screw fixation in the treatment of AS associated with lower cervical fractures in adults demonstrates significant advantages, including reduced operative time, decreased intraoperative blood loss and postoperative drainage volume, improved accuracy of screw placement, and reduced penetration rate of the pedicle cortex.