Objective To evaluate the efficacy of proximal percutaneous pedicle screw fixation combined with distal open osteotomy for sagittal plane imbalance of adult spinal deformity.Methods From January 2011 to June 2015,23 patients with diagnosis of adult spinal deformity were treated with proximal percutaneous pedicle screw fixation combined with distal open osteotomy,there were 8 males and 15 females,aged from 52 to 67 years old (average,62.1 years old).The operation time,blood loss,drainage and perioperative complications were recorded;standing anteroposterior and lateral radiographs of the whole spine were taken and the following parameters were measured:sagittal vertical axis (SVA),lumbar lordosis(LL),pelvic tilt (PT),sacral slope (SS),pelvic incidence/lumbar lordosis mismatch (PI-LL),the above parameters were compared between preoperation and postoperation.Oswestry disability index (ODI) was used to evaluate the clinical efficacy.Results The mean operation time was 253.9±52.1 min,the mean blood loss and drainage was 1 258.5±272.2 ml and 725.1 ± 135.2 ml.No patient got infected,died or had deep vein thrombosis.All patients were followed up for an average of 21.2 months (range,13-52 m).The SVA was restored from 12.6±1.4 cm to 3.5±0.7 cm.In addition,LL,SS,PT,and PL-LL were improved from 13.5°±2.3°,13.9°±2.3°,29.7°±9.6°,29.5°±13.7° to 38.8°±9.6°,25.5°±5.8°,18.9°±8.2°,7.1°±3.6°.The ODI score decreased from 40.3％±12.5％ to 13.6％±2.57％ at the time of the last follow-up compared with preoperation.Conclusion Proximal percutaneous pedicle screw fixation combined with distal open osteotomy for sagittal plane imbalance of adult spinal deformity could restore the sagittal balance and improve the quality of life.

Objective To evaluate the clinical effect of postural reduction combined with miniincision screw-rod system and percutaneous kyphoplasty (PKP) in treating osteoporotic thoracolumbar burst fractures.Methods A retrospective case series study was performed for data of 35 patients with osteoporotic thoracolumbar burst fractures without neurological deficits undergone mini-incision screw-rod system fixation and PKP between January 2012 and January 2014.There were 14 males and 21 females,with a mean age of 63.2 years (range,50-72 years).Operation time,intraoperative blood loss,complications,visual analogue score (VAS),height of fractured vertebrae and kyphosis Cobb angle were recorded.Results Operation time was (49.6 ± 6.8) min,and intraoperative blood loss was (45.6 ±7.8)ml.All patients were followed up for 9-18 months (mean,13.5 months).No intraoperative or postoperative serious complications occurred,including intracanal cement leakage,breakage or loosening of the screws.VAS of back pain was decreased from (8.4 ± 1.1)points preoperatively to (3.5 ± 0.6)points postoperatively (P ＜ 0.05).Height of the fractured vertebrae was improved from (49.62％ ± 5.68)％ preoperatively to (86.64 ± 6.63) ％ postoperatively (P ＜ 0.05).Kyphosis Cobb angle was improved from (28.12 ± 1.06) °preoperatively to (5.15 ± 1.08) °postoperatively (P ＜0.05).At the final follow-up,VAS was further decrease and vertebral height and Cobb’ s showed a slight loss of correction.Conclusion Postural reduction combined with mini-incision screw-rod system and PKP can relieve back pain,restore the height of injured vertebrae,correct kyphotic deformity and reduce operation time and blood loss,indicating a minimally invasive,safe and effective procedure for treatment of osteoporotic thoracolumbar burst fractures.

Objective To investigate the safety of the occipital condylar screw with vertical position and evaluate the selection strategy of the posterior approach of the posterior occipital condylar screw in Chinese people.Methods The clinical imaging data of 60 outpatients from September 2013 to September 2015 were retrospectively analyzed,36 male and 24 female,the average age was 41.6±9.2 (range from 25-58),Excluded occipitocervical injury,tumor and deformity patients.We built a three-dimensional digital model and simulated placing screw by utilizing CT data on Mimics software,after that we took the occipital condyle posterior medial and lateral midpoint as the entry point,then made 2 points equidistantly to the midpoint in vertical direction.We put 3.5 mm diameter virtual screws in 4 different conditions:largest cranial angle,smallest cranial angle,longest screw path and shortest screw path.Then we assessed the anatomical relationship between the screw and the hypoglossal canal or the atlanto-occipital joint by a three-dimensional window and measured the cranial angle,medial angle and length of screw path,then calculated the safety angle of the cranial angle,the successful rate of setting screw,and compared the safety of different screw points by 3-Matic software.Results 120 occipital condyles were obtained from the CT data of 60 patients by Mimics software.There was no significant difference in the data of the cranial angle,medial angle,safety range and length between both left and right sides.The obtained safe cranial angle of each point respectively was 20.9°±6.0° (lowest point),17.0°±6.2° (middle point),and 11.6°±7.1°(top point),obviously the largest angle was in the lower point and the smallest was in the top point.The difference was statistically significant.We then acquired the successful rates of different cranial angle of each point,the highest successful rate was 99.17％,96.67％,74.17％ in lowest,middle and top point when cranial angle were 3°or 4°,3°and 0°respectively.The successful rates of lower point and niddle point were significantly higher than the top point,and the difference was statistically significant.The medial angle parameters obtained were 34.41°±2.59°on left and 34.06°±2.44°on right,and there was no significant difference.The length parameters of the longest screw path acquired were 23.09± 1.47 mm,22.84± 1.40 mm and 23.15± 1.45 mm at top,middle and lowest entry point.The average value of shortest screw path of each point was 21 mm,and there was no significant difference among every entry point.Conclusion Among the occipital condyle posterior screw entering points,selecting the lower point can improve the success rate and safety;the change of nail enter point in the vertical direction has little effect on the length of the nail.We can increase the safety and reduce the risk of occipital condylar screw placement as far as possible through the three-dimensional digital technology.

Objective To investigate the optimal trajectory of posterior occipital condyle screw fixation via radiological and anatomical study.Methods Twelve adult craniocervical junction complete specimens were selected.The length,width and height of occipital condyle and the inclination angle of the longest axis were measured by CT scanning and reconstruction.Subsequently,occipital condyle screws were inserted with reference to CT measurements.After screw fixation,accuracy and safety of the placement of occipital condyle screw were verified by gross observation and CT scanning.Results Preoperative measurements of height and width of the occipital condyles indicated the placement of 4.0 mm bicortical screws was secure.Left vertebral artery horizontal sections of 2 specimens were slightly pressed without damage.CT scanning identified no damage to the inner or outer wall of the occipital condyle and the hypoglossal canal.Trajectory parameters between the right and left sides were slightly different,but no significant difference was observed (P ＞ 0.05).Average screw channel length and inclination angle were (20.8 ±2.6)mm and (37.1 ± 4.7)°respectively.Angle between screw and skull base tangent was observed as (8.5 ± 1.7) °.Distance between screw axis and hypoglossal canal was observed as (3.1 ± 1.1) mm.And the distance averaged (4.6 ± 1.4) mm between occipital condyle screw entry point and skull base and (6.1 ± 1.5) mm between entry point and inside edge of the occipital condyle.Conclusion Occipital condyle can be used as a new alternative fixed point in occipitocervical fusion.

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 explore the biomechanical properties of posterior occipital condyle screws compared with common occipitocervical fusion internal fixation and it's impacts upon stress of hypoglossal canals.Methods Finite element models based on the occipitocervical CT data of one 28-year-old male healthy volunteer were built,including normal model,instability model,internal fixation model by occipital condyle screws,internal fixation model by occipital plate screws,and internal fixation model by transarticular screws.Fifty N gravity and 1.5 N · m torque were exerted upon the surface of occipital bone so that the models could perform lateral bending,flexion,extension,and rotational motions.The motion range and stress distribution of internal fixation were compared under varying conditions among different occipitocervical fusion models.In addition,the impact of occipital condyle screw upon hypoglossal canals was examined.Results Compared with instability model,the motion range in the internal fixation model by occipital condyle screws declined by 96.8％,95.6％,95.0％ and 98.5％ respectively in lateral bending,flexion,extension and rotation.In the internal fixation by occipital plate screws,the motion range decreased by 96.3％,95.7％,98.4％ and 99.6％ respectively.In the internal fixation by transarticular screws,the motion range exhibited a decline of 95.7％,94.0％,94.3％ and 98.9％,respectively.The stress peaks in the occipital condyle screw were 192.4 MPa,201.6 MPa and 187.6 MPa under lateral bending,flexion,and rotation conditions,respectively.The stress peaks in the occipital plate screw were 279.6 MPa,213.7 MPa,and 154.1 MPa,respectively.The stress peaks in the transarticular screw were 232.4 MPa,220.9 MPa,and 224.5 MPa,respectively.The stress impact peak of occipital condyle screw on the hypoglossal canals wall was 12.96 MPa,and the content deformationunder the hypoglossal canal was 0.64％.Conclusions The occipital condyle screw internal fixation has similar stability with common occipitocervical fusion fixations.The occipital condyle screw has more uniform stress distribution and less effect on the hypoglossal canals,and hence is safe and reliable as anchor point on the cranial side in occipitocervical fusion.

Objective To assess the effects of axial spinous process-muscle-vascellum complex transplantation for posterior atlantoarial fusion.Methods Data of 27 cases with altantoarial disease who were treated by posterior atlantoarial fusion using axial spinous process-muscle-vascellum complex transplantation from June 2015 to June 2016 were retrospectively analyzed.There were 19 males and 8 females aged from 9 to 68 years old (mean,41.0±15.4 years old).Two cases were diagnosed with atlanto-axial instability.Fourteen cases were diagnosed with atlas fracture and eleven cases were diagnosed atlanto-axial fracture.All the 27 patients suffered from neck pain or limitations of cervical motion.All patients were assessed clinically by atlantoaxial reduction and bone graft fusion.The pre-operative and post-operative atlanto-dens interval (ADI),visual analogue scale (VAS),Japanese Orthopaedic Association scores (JOA),improvement rate of JOA score and axial symptoms were measured and statistically analyzed.Complications were recorded.Clinical outcome of latest follow-up was evaluated by X-ray and CT scan.Results The time of operation was 2.0-2.5 h and blood loss was 150-300 ml.All the patients were followed-up for 9 to 18 months (mean,11.5±2.1 months).The VAS of neck pain improved from 3.6±2.7 (range,2.0-5.0) pre-operatively to 1.4±0.2 (range,0-2.0) 12 months postoperatively (P=0.000).The JOA score improved from 11.7± 1.9 (range,10.0-15.0) pre-operatively to 15.3±0.6 (range,14.0-17.0)12 months post-operatively (P=0.000).The improvement rate of JOA score at the latest follow-up was 54.1％± 12.4％,including 23 cases (85.19％) excellent,and 4 cases (14.81％) good.The results of axial symptoms were no-symptom in 22 cases (81.48％) and mild symptoms in 5 cases (18.52％).Postoperative cervical spine X-ray and CT showed that the sagittal cervical spine alignment was restored.There was statistically significant difference between ADI of 4.3±1.1 mm (range,3.9-4.5 mm) pre-operatively to 2.5± 0.4 mm (range,2.1-2.6 mm) 12 months post-operatively,which was improved significantly (P=0.000).There were no complications found during the follow-up.Conclusion The application of axial spinous process-muscle-vascellum complex transplantation for posterior atlantoaxial fixation can preserve the dynamic function of muscles and reduce the postoperative pain,as well as avoid donor site morbidity.

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 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 of posterior atlantoaxial transarticular screw combined with atlas pedicle screw fixation in Chinese.Methods:CT data of upper cervical spine in 48 patients were collected from Ningbo No.6 Hospital, including 26 males and 22 females aged 26-58 years [(37.3±13.5)years]. All CT data was transformed into 3D dimensional model and inserted with virtual screws by Mimics 19.0. Firstly, the vertical plane P 1 and the horizontal plane P 2 of the atlas were built in those atlantoaxial models, secondly the atlantoaxial transarticular screw S 0 was inserted by Margel method, and it's insertion point was located at 3 mm lateral and 2 mm cephalad in the C 2 inferior articular process. Finally, four atlas pedicle screws were inserted at the midline of atlas lateral mass. The four screws are inserted as follows. S 1: the screw was tangent to the lateral side of the S 0 or the medial of the atlas pedicle. S 2: the screw was tangent to the lateral wall of the atlas pedicle. S 3: the screw was tangent to the upper wall of the atlas pedicle. S 4: the screw was tangent to the inferior wall of the atlas pedicle. The angles between S 1, S 2 and P 1 as the camber angle, and the angle between S 3, S 4 and P 2 as the gantry angle were measured. Then the safety range of camber angle and gantry angle were calculated, and the screw length of S 1, S 2, S 3 and S 4 was measured. In all models, the camber angle and gantry angle of the screws were adjusted an interval of 2°, the number of successful cases was calculated and the success rate of insertion was calculated. Results:All 3D models were inserted successfully. The minimum value, maximum value and safety range of the camber angle of atlas pedicle screws were (-6.7±5.2)°, (10.4± 4.3)°, (17.1±3.7)°, respectively; and of the gantry angle were (-0.5±3.5)°, (11.0±5.8)°, (11.5±4.9)°, respectively. The length of screw placement was S 1: (31.1±2.4)mm, S 2: (28.3±2.5)mm, S 3: (29.2±3.8)mm, S 4: (29.6±3.0)mm, respectively ( P<0.05). When the camber angle was from -1°to 5°, the success rate of screw placement was 87.5%; when inserting with 2° camber angle, the success rate was 100%; when the gantry angle was 5°, the success rate was 93.8%. Conclusion:The posterior atlantoaxial transarticular screw combined with atlas pedicle screw can achieve satisfy insertion length and success rate.