Objective:To develop a robotic digestive endoscope system (RDES) and to evaluate its feasibility, safety and control performance by experiments.Methods:The RDES was designed based on the master-slave control system, which consisted of 3 parts: the integrated endoscope, including a knob and button robotic control system integrated with a gastroscope; the robotic mechanical arm system, including the base and arm, as well as the endoscopic advance-retreat control device (force-feedback function was designed) and the endoscopic axial rotation control device; the control console, including a master manipulator and an image monitor. The operator sit far away from the endoscope and controlled the master manipulator to bend the end of the endoscope and to control advance, retract and rotation of the endoscope. The air supply, water supply, suction, figure fixing and motion scaling switching was realized by pressing buttons on the master manipulator. In the endoscopy experiments performed on live pigs, 5 physicians each were in the beginner and advanced groups. Each operator operated RDES and traditional endoscope (2 weeks interval) to perform porcine gastroscopy 6 times, comparing the examination time. In the experiment of endoscopic circle drawing on the inner wall of the simulated stomach model, each operator in the two groups operated RDES 1∶1 motion scaling, 5∶1 motion scaling and ordinary endoscope to complete endoscopic circle drawing 6 times, comparing the completion time, accuracy (i.e. trajectory deviation) and workload.Results:RDES was operated normally with good force feedback function. All porcine in vivo gastroscopies were successful, without mucosal injury, bleeding or perforation. In beginner and advanced groups, the examination time of both RDES and ordinary endoscopy tended to decrease as the number of operations increased, but the decrease in time was greater for operating RDES than for operating ordinary endoscope (beginner group P=0.033; advanced group P=0.023). In the beginner group, the operators operating RDES with 1∶1 motion scaling or 5∶1 motion scaling to complete endoscopic circle drawing had shorter completion time [1.68 (1.40, 2.17) min, 1.73 (1.47, 2.37) min VS 4.13 (2.27, 5.16) min, H=32.506, P<0.001], better trajectory deviation (0.50±0.11 mm, 0.46±0.11 mm VS 0.82±0.26 mm, F=38.999, P<0.001], and less workload [42.00 (30.00, 50.33) points, 43.33 (35.33, 54.00) points VS 52.67 (48.67, 63.33) points, H=20.056, P<0.001] than operating ordinary endoscope. In the advanced group, the operators operating RDES with 1∶1 or 5∶1 motion scaling to complete endoscopic circle drawing had longer completion time than operating ordinary endoscope [1.72 (1.37, 2.53) min, 1.57 (1.25, 2.58) min VS 1.15 (0.86, 1.58) min, H=13.233, P=0.001], but trajectory deviation [0.47 (0.13, 0.57) mm, 0.44 (0.39, 0.58) mm VS 0.52 (0.42, 0.59) mm, H=3.202, P=0.202] and workload (44.62±21.77 points, 41.24±12.57 points VS 44.71±17.92 points, F=0.369, P=0.693) were not different from those of the ordinary endoscope. Conclusion:The RDES enables remote control, greatly reducing the endoscopists' workload. Additionally, it gives full play to the cooperative motion function of the large and small endoscopic knobs, making the control more flexible. Finally, it increases motion scaling switching function to make the control of endoscope more flexible and more accurate. It is also easy for beginners to learn and master, and can shorten the training period. So it can provide the possibility of remote endoscopic control and fully automated robotic endoscope.

【Objective】 To investigate the effects of one-stage additional posterior pedicle screws （PPS） internal fixation on early Cage subsidence after oblique lateral interbody fusion （OLIF）. 【Methods】 We made a retrospective analysis of 118 patients with lumbar degenerative diseases treated with OLIF at the Department of Orthopedics， Sir Run Run Shaw Hospital， School of Medicine， Zhejiang University， from January 2016 to December 2019. We divided the patients into OLIF stand-alone group （58 ones） and OLIF with PPS fixation group （60 ones） according to the surgical procedure. All the patients had preoperative frontal and lateral radiographs of the lumbar spine， and CT and MR scans were performed. The clinical outcomes and reoperation rates of the two groups were compared at immediate postoperative follow-up and at 1， 3， 6 and 12 months. X-ray and CT examinations were performed to assess Cage subsidence in both groups at each postoperative follow-up. 【Results】 There was no statistical difference between the two groups in baseline data and surgical segmentation. Of the 118 patients with 141 discs who underwent OLIF surgery， 58 patients with 68 discs received OLIF stand-alone surgery and 60 ones with 73 discs received OLIF with PPS fixation. There were no significant differences in intraoperative bleeding， complications， or postoperative clinical outcomes between the two groups （P>0.05）， and the Cage subsidence rate was 22.4% in OLIF stand-alone group and 5% in OLIF with PPS fixation group， with significant difference between the two groups （P<0.01）. 【Conclusion】 Both OLIF stand-alone and OLIF additional PPS fixation can achieve good early clinical outcomes， and first-stage additional PPS fixation can significantly reduce the occurrence of Cage subsidence in the early postoperative period after OLIF.

Oblique lumbar interbody fusion （OLIF） is an internationally popular and innovative technique for treating various lumbar diseases. Introduced to China in 2014， it has been widely used to treat lumbar spine diseases. Advances in biomechanical theory and new instruments have broadened the indications for OLIF surgery and reduced its learning curve. The development of standalone OLIF makes OLIF more minimally invasive. The improvement of localized surgical methods based on Chinese anatomical studies makes OLIF more suitable for Chinese patients. The development of L5/S1 OLIF technology has expanded the application range of OLIF. This paper reviews the clinical application and research progress of OLIF.

Objective:To investigate the safety and clinical efficacy of primary anterior lesion removal and bone graft fusion combined with secondary posterior fixation in the treatment of cervical suppurative spondylitis.Methods:Retrospective analysis was performed on the data of twenty cervical suppurative spondylitis patients treated with primary anterior lesion removal and bone graft fusion combinedwith secondary posterior fixation in our hospital from May 2016 to December 2020, including 14 males and 6 females. Aging from 40 to 87 years, with an average of 60.2±12.6 years. The laboratory tests of preoperative blood culture, such as white blood cell count (WBC), erythrocyte sedimentation rate (ESR), and hypersensitive C-reactive protein (CRP) were performed.The selection and duration of antibiotic usewere guided according to bacterial culture and laboratory test results. visual analogue scale (VAS) score, Japanese Orthopeadic Association (JOA) score and Frankle classification of neurological function were evaluated before surgery, 3 months after surgery, and 12 months after surgery, so were the Cobb angle and segmental angle of cervical lordosis. Single factor repeated measure ANOVA was used for statistical analysis of data.Results:Surgeries were performed successfully for all the 20 patients. 9 cases of Staphylococcus aureus, 4 cases of Streptococcus and 2 case of Escherichia coli were detected by pathogen examination. The remaining 5 cases were negative in bacterial culture. All 20 patients were followed up for 18.3±6.7 months. WBC, ESR and CRP at 3 and 12 months after surgery were significantly lower than those before surgery ( F value: 17.90, 30.65, 18.64, P<0.001). The VAS at 3 months after surgery 1.35±0.49 and 12 months after surgery 1.15±0.48 were significantly lower than that before surgery 4.95±1.10 ( F=176.12, P<0.001). The JOA score at 3 months after surgery 15.40±1.93 and 12 months after surgery 16.06±1.36 were significantly better than that before surgery 11.45±2.78 ( F=65.33, P<0.001). The Cobb Angle of C 2-C 7 cervical lordosis after surgery 14.45°±4.36° and 12 months after surgery (13.70°±3.15°) were significantly larger than that before surgery (8.25°±4.36°) ( F=72.54, P<0.001). Cobb angle of the lesion segment after surgery (3.60°±1.90°) and 12 months after surgery (2.90°±1.44°) were significantly better than that before surgery (-3.55°±5.74°) (negative value indicated kyphosis) ( F=42.49, P<0.001). Bone fusion was observed in all graft areas at 12 months of follow-up. Conclusion:The treatment of cervical suppurative spondylitis with primary anterior lesion removal and bone graft fusion combined with secondary posterior fixation can effectively obtain intraspinal decompression, improve pain and nerve function, as well as restore cervical stability and correct kyphosis, with satisfactory clinical efficacy.

Objective: To investigate the clinical effectiveness of anterior cervical discectomy and fusion (ACDF)plus plating in the treatment of unstable Hangman's fractures. Methods: A retrospective case series study was carried out to analyze 12 patients who received ACDF plus plate internal fixation for unstable Hangman's fracture admitted to Sir Run Run Shaw Hospital affiliated to Zhejiang University School of Medicine from July 2014 to July 2018. There were nine males and three females, aged 24-70 years with an average of 46.2 years. According to Levine-Edwards typing, there were seven patients of type Ⅱ, four patients of type Ⅱ A and one patient of type Ⅲ. There were two patients of grade D and 10 patients of grade E according to the American Spinal Injury Association (ASIA) classification. The operation time, intraoperative blood loss and the operational complications were recorded. At 3 days, 1, 3, 6, 12 and 24 months after operation, the height of intervertebral disc, physiological curvature of cervical spine, fracture healing and bone graft fusion were evaluated. The recovery of neurological function was assessed by ASIA, and the neck pain relief and function improvement was assessed by visual analogue scale (VAS) and the neck disability index (NDI). Results: All patients were followed for 6-48 months(mean, 27.7 months). The operation time ranged from 50-100 minutes, with an average of 72.5 minutes. The intraoperative blood loss was 30-120 ml (mean, 65.8 ml). No serious complications occurred during and after operation. Two patients had dysphagia after operation, and the symptoms were relieved at the follow-up of 3 months. All patients achieved bony fusion of C_2-3 within the 6 month follow-up. No subsidence or migration of cages and significant loss of intervertebral space height were observed. The patient's neck and occipital pain was relieved obviously, and the flexion, extension and rotation of cervical spine were good. The neurologic dysfunction of two patients of ASIA Grade D recovered after surgery, and the final ASIA grade was E. The VAS score was decreased from 5.0 (4.0, 6.0)points preoperatively to 1.0(0, 1.0)points at the last follow-up (P<0.01). The NDI score was improved from (28.5±6.4)points preoperatively to (5.3±2.7)points at the last follow-up (P<0.01). Conclusion ACDF combined with plate internal fixation can provide immediate postoperative stability, high fusion rate, less complications, less pain, and satisfactory function recovery.

Objective To evaluate the influence of age on the surgical risk and prognosis for elderly patients who suffered from lumbar spinal stenosis.Methods A total of 129 patients above 70 years old with lumbar stenosis from January 2015 to August 2018 were divided into 4 groups by age:younger than 69 years,70-74 years,75-79 years and 80 years and above.50 patients below 69 years old were chosen at random as control group.Different parameters such as operation methods,predicted complication rate (POSSUM score),actual complication rate,number of operation levels,operation time,surgical blood loss,occult blood loss,total hospital stay,postoperative hospital stay,hospital cost and the ODI score in 3 months followup were recorded.The surgical risk and prognosis of elderly patients were analyzed by comparing the differences of above parameters between different age groups.Results There was no significant correlation between different age groups and surgical methods (F=15.637,P=0.208).The operation time and surgical blood loss both showed no significant difference between 4 groups.The predicted incidence of complications (POSSUM score) in group older than 80 years old (38.5％+12.34％) and 75-79 years old (41.1％+ 11.82％) were higher than the group younger than 69 years old (28.4％+ 15.44％).There was no significant difference between the two groups over 75 years old,and there was no significant difference between the 70-74 years old group and the other three groups.The actual incidence of complications was 43.75％ in group over 80 years old,42.86％ in group 75-79 years old and 42.03％ in group 70-74 years old.The actual complication rate of the group younger than 69 years was lower than other three groups,and the three other groups showed no significant difference between each other.The totally hospital stay and numbers of operation levels in groups 75-79 and 80 years and above were higher than groups 70-74 and 69 years and below.There was no significant difference in those parameters between groups 75-79 and 80 years and above,and between groups 70-74 years and 69 years and below.The ODI scores between 4 groups also showed no significant difference.Conclusion The risk of surgery for lumbar disc stenosis patients older than 75 years has increased,but the patient's surgical outcome has not decreased.Old age should not be a key factor in determining whether a patient is suitable for surgery.

Objective To compare the long-term effect between minimally invasive (MIS) and open approaches in one-level posterior lumbar interbody fusion (O-PLIF) after more than 10 years follow up. Methods All 131 patients (lumbar spine le-sions) in our hospital were randomized into MIS-PLIF group and O-PLIF group from March 2006 to March 2008. In MIS-PLIF group, there are 66 patients, 34 males and 32 females, with the average of 52.3 ± 6.7 years old (range from 40 to 63). In O-PLIF group, there are 65 patients, 29 males and 36 females, with the average of 51.1 ± 6.9 years old (range from 46 to 63). Regarding March 2018 as last follow-up, differences in intervertebral disc height and segmental lordosis restoration of the operation segment , lumbar lordosis restoration, multifidus cross section area (CSA), multifidus atrophy rate, fusion rate, visual analogue scale (VAS) for back and leg pain, Oswestry Disability Index(ODI), Japanese Orthopaedic Association cores (JOA) and postoperative long-term compli-cations were evaluated between the two groups. The related risk factors of postoperative long-term complications were evaluated in further analysis. Results Complete follow-up data were available on 37 patients in MIS-PLIF group and 35 patients in O-PLIF group, with the follow-up rate of 56.1％and 53.8％respectively,and with the mean follow-up time of 134.5 ±8.4 and 137.1±5.8 months respectively. At three time nodes of one year after operation, five years after operation and last follow-up after operation, there were significant differences in lumbar lordosis restoration (one year after operation and last follow-up after operation)( 5.0°± 2.3° vs. 3.9°±1.4°;4.7°±2.4° vs. 3.7°±1.5°), multifidus CSA (965.4±164.9 mm2 vs. 884.9±168.2 mm2;891.1±155.9 mm2 vs. 783.2± 163.0 mm2; 764.8 ± 148.3 mm2 vs. 643.5 ± 150.0 mm2), multifidus atrophy rate (8.5％± 2.5％ vs. 16.6％± 5.8％; 15.6％± 3.5％ vs. 26.2％±7.4％;27.6％±6.5％vs. 39.3％±9.3％), postoperative VAS for back pain (2.2±1.0 vs. 2.9±1.2;1.7±0.9 vs. 2.2±1.0;1.4±1.0 vs. 2.2±1.2), JOA score (22.3±3.8 vs. 19.9±4.2;23.1±4.3 vs. 19.3±3.9;22.4±4.2 vs. 19.6±4.0) and ODI (11.6％±4.8％vs. 22.0％± 7.7％;9.4％±3.9％vs. 12.3％±4.9％;8.6％±4.0％vs. 11.0％±4.6％) between the two groups (P<0.05). However, there were no sig-nificant differences in segmental lordosis, intervertebral height restoration, lumbar lordosis restoration (one year after operation), fusion rate or postoperative VAS for leg pain between MIS-PLIF and O-PLIF(P>0.05). Intractable back pain and adjacent segment disease were the major postoperative long-term complications for MIS-PLIF group (3 cases and 2 cases) and O-PLIF group (10 cas-es and 7 cases), and the difference was statistically significant in the intractable back pain incidence rate ( 8.5％vs. 28.6％,χ2=5.090, P=0.024), but not in the adjacent segment disease(5.4％vs. 20％,χ2=0.002, P=0.061). What's more, patients with intracta-ble back pain suffered more obviously multifidus atrophy than patients without intractable back pain at three time nodes of one year after operation (19.4±4.4％vs. 10.9±5.1％, P<0.05), five years after operation (30.2±5.4％vs. 18.7±6.7％, P<0.05) and last fol-low-up after operation (44.5±5.7％vs. 30.8±8.9％, P<0.05) . Conclusion In the long-term follow up, compared with O-PLIF, MIS-PLIF had advantages in better maintenance of lumbar lordosis, protection of the multifidus muscle, reduced lower back pain, JOA score, ODI score and intractable back pain incidence rate. Multifidus atrophy may be a related risk factor of intractable back pain.

Objective To evaluate and discuss the clinical outcomes and advantages of midline lumbar fusion (MIDLF) with cortical bone trajectory (CBT) screw in the reoperation of lumbar disease. Methods From June 2014 to August 2015, a total of 12 patients, 5 male and 7 female with an average age of 68.5±5.6 years old (ranged from 56-76 years). The indications of reoper-ation including:5 cases of adjacent segment disease, 2 cases of discogenic back pain after lumbar dynamic stabilization, 5 cases of recurrent disc herniation. The interval time from primary surgery to second surgery was 3-9.5 years (average 6.0±2.0 years). Dis-ease level:L2/31 case, L3/42 cases, L4/57 cases, L5/S12 cases. All cases were got the X-ray, CT scan and MRI examination before surgery. The operative duration, blood loss, complications were all evaluated. Back and leg pain were recorded by visual analogue scale (VAS) scores. Functional recovery was evaluated by Oswestry disability index (ODI). Results Operative time was 110-210 min, and mean duration was (158.3±36.4) min. Blood loss was 150-310 ml, and mean loss was (231.7±51.0) ml. There was 1 case of cerebrospinal fluid leakage which treated with pillow supine for 1 week after surgery, and strengthened the prevention of antibi-otics, incision healing, with no headache and other low intracranial pressure of dizziness, the remaining patients had no intraopera-tive and postoperative complications. The time of follow-up was 12-25 months, with an average of (17.9 ± 4.6) months. The back pain of VAS score of preoperative was 3.9±1.4, and the last follow-up was 1.9±0.5, the difference was statistically significant (t=4.506, P=0.001). The VAS score of preoperative leg pain (4.9±1.4) was significant higher than the last follow-up (1.2±0.6, t=9.134, P=0.000). The preoperative ODI was 32.9±3.4, and last follow-up was 13.3±3.2, and the difference was statistically significant (t=15.002, P=0.000). Conclusion MIDLF was applicable with good clinical outcome and technical advantages in current cases, and it might be a choice of reoperation for lumbar disease.

Objective To investigate the radiographic characteristics of posterosuperior fracture fragment of the injured vertebral body and its effects on the results of surgical treatment in thoracolumbar burst fractures.Methods A total of 45 patients with acute thoracolumbar burst treated by either anterior or posterior surgery from January 2014 to December 2015 were analyzed by retrospective casecontrol study.There were 24 males and 21 females with a mean age of 33.6 years (range,23-52 years).Fractured segments included T12 in six cases,L1 in 15,L2 in 14,L3 in 5,and L4 in 5.Based on AO classification,there were ten cases of A3 fractures and 35 cases of Ag fractures,among which four cases of A4 were combined with B2 injuries.Eleven patients underwent anterior surgery and 34 patients posterior surgery.The operation time and intraoperative blood loss were recorded.The following parameters were also measured pre-and post-operatively,namely the displacement and inversion angle of posterosuperior fracture fragment,Cobb angle,anteroposterior diameter (APD) of spinal canal,and American spinal injury association (ASIA) neurological scale.Results All patients were followed up for 11-24 months (mean,17 months).There were no complications except for one case of implant loosening at three months after anterior surgery.The average operation time was 138.3 minutes and intraoperative blood loss was 293.7 ml in anterior surgery while the average operation time was 77.5 minutes and intraoperative blood loss was 54.7 ml in posterior surgery (P ＜ 0.05).Compared with postoperative situation,the canal APD was increased by 55.5％ in anterior surgery and the corresponding increase was 14.9％ in posterior surgery (P ＜ 0.01).There was no significant difference between two groups in Cobb angle correction.Compared with situation before surgery,the postoperative ASIA grading was improved in 73％ of the patients in anterior surgery and while it was enhanced in 24％ of the patients in posterior surgery (P ＜ 0.05).On the aspect of spinal canal decompression,anterior surgery had obvious decompression effects.The canal APD of anterior surgery was 94.4％,which was larger than 88.5％ in posterior surgery,although the difference was not significant.Notably,when the fragment displacement was ≤ 8 mm,posterior surgery could achieve 97.4％ APD which was comparable with that of anterior surgery.In contrast,when the fragment displacement was ＞ 8 mm,the APD was much smaller in posterior surgery with only 78.5％ (P ＜ 0.05).Similarly,when the fragment inversion was ≤25° or ＞ 25°,the APD was significantly different in anterior surgery and posterior surgery (95.4％ vs.80.8％) (P ＜ 0.05).Conclusions Although posterior surgery for thoracolumbar burst fractures is easy to perform and has short operation time and little intraoperative blood loss,it cannot always guarantee adequate decompression of spinal canal.When the posterosuperior fragment displacement is ＞ 8 mm or when its inversion is ＞ 25°,stand-alone posterior indirect reduction technique is likely to lead to inadequacy of canal restoration.In this case,anterior surgery should be considered in order to achieve more complete canal decompression.Therefore,this radiographic characteristic of the posterosuperior fragment could serve as an approach reference for thoracolumbar burst fractures.

Objective To evaluate the clinical outcomes of oblique lateral interbody fusion (OLIF) in the treatment of adult degenerative scoliosis (ADS).Methods From January 2015 to May 2016,17 ADS patients,4 males and 13 females were enrolled with ages from 46 to 80 (average 69.5±9.2 years).The Cobb angle of all was greater than 10°.According to Lenke-Silva classification systems:Ⅰ level,2 cases,decompression alone;Ⅱ level,2 cases,decompression and limited instrumented spinal fusion;Ⅲ levels,4 cases,decompression and lumbar curve instrumented fusion;Ⅳ levels,5 cases,decompression with anterior and posterior spinal instrumented fusion;Ⅴ level,4 cases,thoracic instrumentation and fusion extension.The operation time,blood loss,blood transfusion,and preoperative and postoperative complications were recorded.Clinical and radiological outcomes were evaluated using visual analogue scale (VAS),Oswestry disability questionnaire (ODI) scores,sagittal vertical axis (SVA) and coronal Cobb.All cases were followed up in 3,6,12 and 24 months.Results All of 17 cases underwent OLIF,one level 4 cases,two levels 2 cases,three levels 7 cases and four levels 4 cases.Alone OLIF was 5 cases (2 case of Ⅰ level,1 case of Ⅱ level,1 case of Ⅲ level and 1 case of Ⅳ level).OLIF combined with posterior approach was 12 cases and the interval time were 1-2 weeks,the mean were 1.7±0.5 weeks.Among these 12 cases,posterior fixation was 6 cases,posterior fixation and decompression was 2 cases,and L5/S1 interbody fusion was 4 cases.The operation lasted for 50-460 min,with a mean duration of 230.6± 132.0 min.Blood loss during the operation was 30-640 ml,with a mean of 306.5±213.8 ml.No patient had blood transfusion.The follow-up was 12-28 months and the mean was 17.9±4.5 months.The preoperative Cobb angles were 16.2°-37.7°,the mean was 29.1°±6.4°.The postoperative Cobb angle were 1.5°-10.2°,and the mean were 5.6°±2.4°.The Cobb of all cases improved significantly.The SVA was returned to the normal level in 4 cases of Lenke-Silva V level.The VAS and ODI score decreased from 7.1 ±0.7 preoperatively to 2.4±0.9 at last follow-up,and from 37.9±2.5 to 10.9±3.0,respectively,and both of them were improved significantly.2 cases of OLIF had cage malposition.Left hip flexor weakness occurred in 5 cases and recovered completely within 2 weeks.Left anterior thigh pain occurred in 1 case and disappeared within 2 weeks.Left sympathetic chain injury happened in 1 case and recovered at last follow-up.Conclusion OLIF as a management of ADS showed excellent short-term outcomes.Clinical and radiological results,such as VAS,ODI and Cobb angle,were improved in all cases.OLIF will be a good choice for the treatment of ADS.