Abstract:[Objective] To compare the clinical consequence of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with or without robot-assistance. [Methods] From January 2021 to July 2023, 120 patients who were undergoing MIS-TLIF for lumbar degenerative diseases were included in this study and randomly divided into two groups. Of them, 60 patients had MIS-TLIF with robot-assistance, while the other 60 patients had the operation performed with the conventional techniques. The perioperative period, follow-up and imaging documents were compared between the two groups. [Results] The robot group proved significantly superior to the conventional group in terms of operative time [min, (161.3±14.5) vs (173.9±20.7), P＜0.001], incision length [cm, (3.8±1.1) vs (9.7±0.8), P＜0.001], intraoperative blood loss [mL, (260.4±50.1) vs (543.1±74.6), P＜0.001], intraoperative fluoroscopy times [(10.6±3.0) vs (20.9±5.4), P＜0.001], ambulation time [days, (1.5±0.3) vs (2.1±0.4), P＜0.001], and hospital stay [days, (4.7±1.5) vs (8.9±1.4), P＜0.001]. The follow-up period lasted for (15.7±2.4) months in a mean, and the robot group returned to full weight-bearing activities significantly earlier than the conventional group [days, (127.0±20.9) vs (143.3±38.1), P=0.004]. The low back pain VAS, leg pain VAS and ODI scores were significantly decreased in both groups over time (P＜0.05). The robot group was significantly better than the conventional group in terms of low back pain VAS score [points, (2.4±0.5) vs (3.7±1.1), P＜0.001], leg pain VAS score [points, (2.0±0.3) vs (2.7±0.4), P＜0.001] and ODI score [%, (19.5±4.8) vs (22.4±3.6), P＜0.001] 3 months postoperatively. Radiographically, the robot group was also significantly better than the conventional group in terms of lumbar lordosis (LL) [°, (43.2±7.5) vs (40.1±7.0), P=0.021] and sacral slope (SS) [°, (30.4±4.5) vs (28.7±3.3), P=0.019] at the last follow-up, despite of the fact that there was no a significant difference in pelvic tilt (PT) between the two groups (P＞0.05). Moreover, the robot group was significantly superior to the conventional group regarding facet joint violation (FJV) after operation [cases, 0/1/2/3, (55/4/1/0) vs (39/16/3/20), P=0.005], the Brantigan, Steffee, and Fraser (BSF) fusion grades at the last follow-up [cases, 1/2/3, (0/5/55) vs (0/13/47), P= 0.041]. [Conclusion] The robot-assisted MIS-TLIF has the advantages of less surgical trauma, less intraoperative bleeding, faster recovery and more effective improvement of the spinal and pelvic sagittal balance over the conventional counterpart.

Abstract:[Objective] To compare the clinical efficacy of robot-assisted percutaneous pedicle screw fixation (PPSF) versus conventional freehand PPSF in the treatment of thoracolumbar fractures. [Methods] A retrospective research was conducted on 72 patients who received PPSF combined with vertebral body bone grafting for thoracolumbar fractures in our hospital from January 2022 to November 2023. According to the communication between doctors and patients, 35 patients were treated with robot-assisted PPSF, while other 37 patients were with conventional manual PPSF. The perioperative, follow-up, and imaging data of the two groups were compared. [Results] All patients in both groups had corresponding surgeries performed successfully without severe complications. There were no statistically significant differences in operation time, incision length, and hospital stay between the two groups (P＞0.05), but the robot-assisted group had significantly fewer intraoperative fluoroscopy [times, (13.1±1.0) vs (35.8±4.4), P＜0.001], less intraoperative blood loss [mL, (64.7±37.4) vs (101.1±81.5), P＜0.001], and better incision healing grades [cases, A/B/C, (35/0/0) vs (33/4/0), P＜0.001] than the conventional group. All patients were followed up for more than one year, and the robot-assisted group regained ambulation [d, (1.9±0.8) vs (2.7±0.9), P＜0.001] and full weight-bearing activity [d, (31.4±3.5) vs (44.8±3.0), P＜0.001] significantly earlier than the conventional group. The VAS and ODI scores significantly decreased over time in both groups (P＜0.05), which in the robot-assisted group were significantly better than the conventional group 3 days postoperatively (P＜0.05), and became not statistically different between the two groups 3 months postoperatively and at the last followup (P＞0.05). Regarding imaging, the robot-assisted group proved significantly superior to the conventional group in terms of Badu grade [0/1/2/3, (149/5/2/0) vs (150/12/4/4), P=0.016], GRS grade for screw placement [A/B/C/D/E, (199/9/2/0/0) vs (190/29/ 1/2/0), P=0.002], vertebral vacuum signs [cases, yes/no, (4/31) vs (13/24), P=0.018], and bone graft scale [cases, 0/1/2/3/4, (0/0/5/11/19) vs (0/3/12/14/8), P＜0.001]. In addition, the robot-assisted group was also significantly better than the conventional group in terms of local kyphotic angles [°, (6.1±0.8) vs (7.3±0.9), P＜0.001] and anterior vertebral height [mm, (25.7±1.0) vs (24.6±2.3), P=0.011] at the last followup. [Conclusion] The robot-assisted percutaneous pedicle screw fixation and bone grafting does improve screw placement accuracy, effectively correct local kyphotic deformity, restore vertebral height, and achieve satisfactory clinical outcomes for thoracolumbar fractures.

Abstract: [Objective] To compare clinical efficacy of oblique lateral interbody fusion (OLIF) versus minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) in the treatment of lumbar degenerative diseases. [Methods] A retrospective study was conducted on 64 patients who received lumber fusion for lumbar degenerative diseases from June 2020 to June 2021. According to the doctor-patient communication, 30 patients underwent navigational unidirectional OLIF, while other 34 patients received MI-TLIF. The documents regarding peri-operative period, follow-up and imaging were compared between the two groups. [Results] The OLIF group was significantly superior to the MI-TLIF group in terms of operation time [min, (115.3±12.1) vs (150.6±16.8), P＜0.001], ambulation time [days, (1.9±0.6) vs (3.2±0.7), P＜ 0.001] and postoperative hospital stay [days, (5.6±0.8) vs (6.1±0.9), P=0.022], despite of the fact that the former had significantly longer incision than the latter [cm, (11.4±1.6) vs (7.4±1.2), P＜0.001]. The follow-up time was of (14.8±2.3) months, and the OLIF group resumed full weight bearing activity significantly earlier than the MI-TLIF group [days, (26.4±3.2) vs (46.4±4.1), P＜0.001]. As time went on, the VAS, ODI and JOA scores of patients in both groups were significantly improved (P＜0.05). The OLIF group was significantly better than the MI-TLIF group in low back pain VAS score [points, (3.1±0.9) vs (3.9±0.8), P＜0.001] and JOA score [points, (17.8±1.8) vs (16.5±1.6), P= 0.003] 3 months after surgery. As for imaging, the vertebral canal area, intervertebral height and lumbar lordosis angle were significantly increased in both groups at the last follow-up compared with those preoperatively (P＜0.05). At the last follow-up, the OLIF group had significantly greater intervertebral height [mm, (10.9±1.5) vs (8.9±1.5), P＜0.001] and lumbar lordotic angle [°, (43.2±5.8) vs (39.7±7.4), P=0.038] than the MI-TLIF group, although there were no significant differences in spinal canal area and Bridwell fusion grade between the two groups (P＞0.05). [Conclusion] Both OLIF and MI-TLIF achieve satisfactory clinical consequences in the treatment of lumbar degenerative diseases. OLIF is a more minimally invasive surgical technique with advantages of short operation time, quick postoperative recovery and mild early lumbago over the MI-TLIF

Abstract:[Objective] To compare the clinical efficacy of unilateral biportal endoscopy (UBE) decompression versus posterior lumbar interbody fusion (PLIF) in the treatment of double-segment lumbar spinal stenosis (LSS). [Methods] A retrospective research was conducted on 60 patients who underwent surgical treatment for double-segment LSS from January 2017 to January 2022. According to the preoperative doctor-patient communication, 30 patients received UBE decompression, while other 30 patients underwent PLIF. The perioperative, follow-up and imaging data of the two groups were compared. [Results] The UBE group proved significantly superior to the PLIF group in terms of operating time [min, (102.7±7.8) vs (121.3±14.7), P＜0.001], incision length [cm, (5.0±0.1) vs (8.5±0.8), P＜0.001], intraoperative blood loss [mL, (79.7±9.8) vs (695.3±61.9), P＜0.001], intraoperative fluoroscopy times [(4.6±0.7) vs (6.2±0.8), P＜0.001], drainage volume within 24 hours after operation [mL, (66.9±6.1) vs (145.9±24.2), P＜0.001], postoperative ambulation time [days, (1.9±1.3) vs (3.6±0.9), P＜ 0.001] and hospital stay [days, (7.8±1.8) vs (10.0±2.1), P＜0.001]. As time elapsed during follow-up period lasted for (12.6±0.7) months in a mean, the VAS scores for low back and leg pain, as well as ODI score in both groups decreased significantly (P＜0.05). The UBE group was significantly better than the PLIF group in the VAS score for low back pain 7 days after surgery [points, (3.4±0.7) vs (4.2±1.0), P＜0.001] and the ODI 1 month postoperatively [%, (28.8±4.0) vs (33.1±4.8), P＜0.001], despite of no statistically significant differences in the above indicator between the two groups at 3 months after surgery and the last follow-up (P＞0.05). As for imaging, the UBE group was significantly smaller than the PLIF group regarding the dural sac area of the responsible segment [mm² , (114.2±8.7) vs (123.7±6.8), P＜0.001] and the intervertebral space height [mm, (10.8±0.8) vs (11.6±0.7), P＜0.001] at the last follow-up. However, the former proved significantly superior to the latter in lumbar extension-flexion mobility [°, (27.6±6.3) vs (15.2±4.0), P＜0.001]. [Conclusion] The UBE decompression does achieve good clinical outcome for double-segment LSS with good stability, takes advantages of less trauma, lower risk, less early low back pain, faster functional recovery, and less impact on the lumbar mobility over PLIF.

Abstract:Far lateral lumbar disc herniation (FLLDH), a distinct subtype of lumbar disc herniation, involves nerve root compression at a segment one level higher than the typical herniation, which is crucial for diagnosis and differential identification. Various minimally invasive techniques exhibit specific characteristics accordingly. For example, the microendoscopic discectomy and minimally invasive transfo-raminal lumbar interbody fusion demonstrate reliable efficacy, but need facet resection or internal fixation, which result in greater surgical trauma. The percutaneous endoscopic transforaminal discectomy balances minimal invasiveness with effectiveness, while faces challenges including a steep learning curve, inefficient canal decompression and disc removal, with relatively high recurrence rates. The emerging techniques like unilateral biportal endoscopy and split-endoscope systems maintain surgical efficacy while offering advantages of minimal trauma, low recurrence rates, and a gentler learning curve. This review systematically synthesizes the anatomical classification and minimally invasive treatment options for FLLDH to inform clinical decision-making.

Abstract:Adult spinal deformity (ASD) primarily manifests as abnormalities in spinal alignment and curvature, often resulting in low back pain, with or without lower extremity neurological symptoms, severely impacting patients' quality of life. Although spinal corrective surgery can alleviate pain and improve function, the procedure is complex and associated with a high incidence of complications. Among these, proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are severe complications following long-segment spinal corrective surgery, frequently necessitating subsequent revision surgery. However, there is no clear consensus currently on which patients with PJK/ PJF should undergo revision surgery, without a widely recognized and accepted classification system. Therefore, further familiarization with and comparison of relevant clinical classification systems, and the identification of a clinical classification that considers both clinical symptoms and treatment strategies, are of great significance for standardizing the clinical diagnosis and treatment of PJK/PJF and enhancing treatment outcomes.

Abstract:At present, there is no a consensus on the treatment of collapsed osteoporotic vertebral compression fracture complicated with neurological dysfunction, and how to formulate a reasonable treatment strategy remains a direction of clinical research. This review provides a comprehensive description of the causes, risk factors, classification and corresponding treatment strategies for the collapsed osteoporotic vertebral compression fracture complicated with neurological dysfunction. It also states that the incidence of the vertebral body collapse associated with neurological dysfunction is high, with main cause of local instability. As the surgical purpose to maintain spinal stability, proper decompression and correction of kyphotic deformity, the traditional posterior and anterior-posterior procedures have risk in some extent, while simple fixation and improved osteotomy procedures also achieve satisfactory outcome.

Abstract:Andersson lesion (AL) is a serious complication in the later stages of ankylosing spondylitis (AS), characterized by pain, limited movement, and even kyphosis and nerve compression. This disease is rarely reported in China, with unclear cause and uniform diagnostic standard and undefined treatment strategy. We report a case of mid-thoracic (T7) AL with a history of AS. The patient developed this lesion without timely treatment after low energy fracture, and was treated with open surgery after conservative treatment failed. Based on the analysis of this case, the authors conclude that the overall incidence of AL is low, especially in the middle thoracic spine. In view of the diagnosis, classification and treatment of the disease, we reviewed the literature at home and abroad in order to provide some reference for the clinician.

Abstract:Bone tissue repair is a hot issue in orthopaedic surgery. How to select bone repair materials has always been the focus in orthopaedic field. As an emerging additive manufacturing technology, 3D printing has attracted wide attention in the field of orthopedics because of its advantages in personalized customization. This paper reviewed the relevant literature of 3D printed biomaterials, summarized various 3D printed biomaterials applied to spinal fusion in recent years, and analyzed the advantages and disadvantages of bioceramics, metals, polymers and other materials. In view of the limitations of single materials, composite materials have become the focus of current research. 3D printing technology can more effectively compound a variety of biological materials, and the combination of this emerging technology and new materials open up a new direction for the development of bone repair materials in the future.

Abstract:[Objective] To compare the accuracy and efficiency of two registration methods, including 2D planning (2D group) and 3D planning (3D group), in robotic assisted thoracic pedicle screw placement in cadavers. [Methods] Orthbot robotic assisted thoracic pedicle screw placement was conducted on 7 fresh frozen cadavers in T7~12 by abovesaid two registration methods. The general data and deviation distance (DD) and deviation angle (DA) were compared between the two groups. [Results] All specimens had guide pin placement conducted successfully. The 2D group consumed significantly longer planning time for single pin than the 3D group [min, (2.3±2.0) vs (1.6±1.2), P= 0.043], whereas the former had significantly shorter placement time of the single pin than the latter [min, (2.3±1.6) vs (4.6±3.2), P＜0.001]. There were 42 pins in each group, all of them were marked grade A, without penetrating the cortex. The 2D group proved significantly inferior to the 3D group in terms of pin placement DD [mm, (1.5±0.3) vs (0.7±0.1), P＜0.001], entering point DD [mm, (1.4±0.3) vs (0.7±0.3), P＜ 0.001] and exiting point DD [mm, (1.6±0.3) vs (0.7±0.1), P＜0.001]. In addition, the former was also inferior to the latter in terms of coronal pin DA [°, (10.4±9.5) vs (5.7±6.4), P=0.009] sagittal pin DA [°, (5.4±2.9) vs (2.4±3.1), P=0.007]. [Conclusion] Both 2D and 3D registration methods can accurately guide the thoracic pedicle screw placement. The 3D technique has shorter planning time, while the 2D consumes shorter operation timer. However, imaging measurement shows that the 3D method had better accuracy of pin placement than the 2D counterpart.

Abstract:[Objective] Mendelian randomization (MR) was used to explore the causal relationship between common skeletal diseases and osteonecrosis to provide theoretical support for clinical prevention and treatment. [Methods] Using publicly available data from the genome-wide association study (GWAS), we extracted instrumental variables (IVs) associated with nine common skeletal diseases, including rheumatoid arthritis, ankylosing spondylitis, desiccation syndrome, psoriasis, osteoporosis, gout, knee osteoarthritis, hip osteoarthritis, and systemic lupus erythematosus as the exposure factor, whereas osteonecrosis as the endpoint factor. Inverse-variance weighted (IVW), MREgger and Weighted median (WME) methods were used to assess the association between common skeletal diseases and osteonecrosis, and to supplement the validation results. The experimental results were also subjected to heterogeneity test, sensitivity analysis and multiple validity analysis. [Results] In the positive MR analysis, the results of the inverse variance weighting method showed the risk of osteonecrosis in ankylosing spondylitis (OR=1.054, 95%CI: 1.006~1.104, P=0.027), rheumatoid arthritis (OR=1.304, 95%CI: 1.143~1.489, P＜0.001) with positive causal relationship, while no causal relationship was found between the other seven skeletal diseases (P＞0.05) and osteonecrosis. Inverse MR analysis showed that there were no significant causal effects of osteonecrosis on common skeletal diseases (P＞0.05). MR-Egger analysis showed that there was no pleiotropy in this study (P＞0.05), Cochran's Q test (P＞0.05) indicated that the results of the study were not heterogeneous, in addition, as leave-one-out method to sequentially exclude each single nucleotide polymorphisms (SNPs) participating in MR analysis, the individual SNPs had no significant effect on the overall effect, which proved that the results of the present study were stable and reliable. [Conclusion] There is a causal relationship of osteonecrosis with ankylosing spondylitis and rheumatoid arthritis in this study.

Abstract:[Objective] To introduce the surgical technique and preliminary clinical results of endoscopic decompression of extraspinal L₅ erve entrapment at isthmus through large channel in water medium. [Methods] A patient received abovementioned endoscopic surgery for extraspinal L₅ nerve entrapment at the isthmus. At the L₅S₁ intervertebral space, a fine needle was punctured through a 1.5 cm skin incision outside the outer edge of the pedicle. As fluoroscopy confirmed the needle located at the left L₅ isthmus, the needle was replaced with the channel. Under endoscope, the osteophyte parts of the outer edge of the superior facet, the transverse process and the S₁ sacral wing were removed with bur, and then, the ventral side of the superior facet and the outer edge of the isthmus were resected, finally, the outer edge of the ventral ligamentum flavum was exposed and resected until the L₅ nerve root was fully decompressed. The decompression was performed gradually inward along the nerve root to remove the hyperplastic facet, the thickened ligamentum flavum, and the ventral intervertebral disc nucleus pulposus tissue. [Results] After the operation, the patient had pains in the left buttocks and left lower extremity significantly relieved compared with those before. The rechecked lumbar spine MRI showed the protruding nucleus pulposus completely removed, while CT showed sufficient decompression of bony stenosis, such as the superior facet and transverse process. The patients got symptoms of pain in the buttocks and legs disappeared 1 and 3 months after the operation, with VAS score of 0. [Conclusion] This endoscopic decompression of ex- traspinal L₅ nerve entrapment at isthmus through large channel in water medium is safe and effective technique, does relieve various factors leading L₅ nerve entrapment outside the spinal canal.

Abstract: [Objective] To evaluate the clinical efficacy of unilateral biportal endoscopy (UBE) spinal canal decompression in the treatment of continuous two-segment lumbar spinal canal stenosis (LSS). [Methods] From January 2022 to January 2024, 54 patients received UBE spinal canal decompression for continuous two-segment LSS. The perioperative, follow-up and imaging data were assessed. [Results] All patients had the UBS surgery completed smoothly with operation time of (122.4±7.7) min, intraoperative blood loss of (81.7±8.7) mL, incision length of (3.0±0.2) cm, the postoperative ambulation time of (49.0±6.5) hours, and the hospital stay of (7.9±1.1) days. With time elapsed before the operation, 3 days after the operation and the last follow-up, the VAS score for low back pain [points, (5.1±1.1), (3.4±0.8), (0.8± 0.5), P＜0.001], VAS score for leg pain [points, (7.7±0.9), (3.2±0.8), (0.4±0.2), P＜0.001] and ODI score [%, (42.7±2.4), (21.4±3.1), (6.1±1.9), P＜0.001] were significantly declined. As for imaging, compared with those preoperatively, the spinal canal area [mm² , (126.4±6.3), (172.4± 8.1), P＜0.001] and the dural sac area [mm2 , (104.0±7.9), (137.4±5.7), P＜0.001] increased significantly at the last follow-up. [Conclusion] The UBE technique is feasible for spinal canal decompression in the treatment of continuous two-segment LSS, with advantages of minimally invasive surgery and higher safety, achieves definite outcome of spinal canal decompression.

Abstract:[Objective] To explore the clinical efficacy of 3D printing assisted atlantoaxial fusion in the treatment of Anderson type Ⅱ odontoid fractures. [Methods] A retrospective research was conducted on 18 patients who had type Ⅱ odontoid fractures treated by 3D printing assisted atlantoaxial fusion from June 2019 to March 2023. Before the operation, a 3D model of the atlantoaxial vertebrae was made to simulate the pedicle screw placement channel, and the real posterior atlantoaxial vertebrae fixation and fusion were performed based on the preoperative simulation. The clinical and imaging data were evaluated. [Results] All patients had operation performed successfully without complications such as nerve and vascular injuries, and were followed up for a mean of (14.3±2.9) months. Compared with those before the operation, VAS score [points, (7.3±1.6), (4.8±1.4), (2.0±0.5), P＜0.001], NDI score [%, (39.3±3.8), (17.4±2.4), (14.8±1.6), P＜0.001] and JOA score [points, (7.0±2.3), (12.9±1.8), (15.3±1.0), P＜0.001] were significantly improved 3 months postoperatively and at the last follow-up. In term of imaging, compared with that before operation, the odontoid alignment [cases, excellent/good/fair/poor, (0/0/0/18), (15/3/0/0), (14/4/0/ 0), P＜0.001] was significantly improved 3 months after operation and at the last follow-up, despite of the fact that the cervical lordosis angle remained unchanged significantly (P＞0.05). All patients had odontoid fracture healed well at the last follow-up. [Conclusion] The simulation of the pedicle screw placement using 3D printed models does significantly improve the accuracy of screw placement in the atlantoaxial region for odontoid fractures.

Abstract:[Objective] To explore the clinical efficacy of modified unilateral biportal endoscopic discectomy (UBED) in the treatment of lumbar disc herniation (LDH). [Methods] A retrospective analysis was conducted on 108 patients who had LDH treated with the modified UBED in our department from January 2021 to December 2022. The modification of UBE involved maintain the operating field during the operation with a self-made tubular channel. The clinical and imaging data were evaluated. [Results] All the 108 patients had the modified UBED performed smoothly with the average operation time of (63.0±11.7) min and the average postoperative bed rest time of (10.3±1.9) hours, except intraoperative or postoperative complications happened in 6 cases, including 2 cases of dural injury, 1 case of epidural hematoma, 2 cases of transient sensory impairment and 1 case of recurrence of lumbar intervertebral disc protrusion. All patients were followed up for more than one year. With time elapsed preoperatively, 3 and 12 months after operation, the back pain VAS score [points, (4.4 ±0.9), (1.7± 0.6), (1.5±0.6), P＜0.001], lower limb pain VAS [points, (4.4±0.9), (1.7±0.6), (1.5±0.6), P＜0.001], leg pain VAS score [points, (7.4±1.3), (1.7± 0.6), (1.2±0.7), P＜0.001], ODI score [%, (46.2±7.6), (16.9±5.1), (14.8±3.9), P＜0.001] and JOA score [points, (14.9±2.8), (23.1±3.2), (26.1± 3.1), P＜0.001] were improved significantly. In regard of imaging, the spinal canal occupied ratio was decreased significantly after the operation compared with that before the operation (P＜0.05), whereas the intervertebral space height and the lumbar lordosis angle remained unchanged significantly (P＞0.05). [Conclusion] The modified UBED is safe and effective surgical technique for LDH.

Abstract:[Objective] To compare the clinical efficacy of 3D printing-assisted pedicle screw fixation versus freehand counterpart for atlantoaxial dislocation. [Methods] A retrospective study was conducted on 35 patients who had atlantoaxial dislocation treated by pedicle screw fixation and fusion from January 2020 to January 2023. According to the preoperative doctor-patient communication, 15 patients underwent pedicle screw placement based on the preoperative 3D printing simulation design (3D group), while other 20 patients underwent pedicle screw placement by the conventional freehand technique (FH group). The clinical and imaging data of the two groups were compared. [Results] All patients in both groups were operated on successfully. The 3D group proved significantly superior to the FH group in terms of operation time [min, (164.8±14.2) vs (216.7±23.5), P＜0.001] and single screw placement time [min, (5.7±1.5) vs (12.4±2.8), P＜0.001], intraoperative blood loss [mL, (153.3±36.0) vs (303.5±68.3), P＜0.001], one-time screw placement success rate (92.0% vs 72.1%, P=0.007), ambulation time [days, (4.3±0.7) vs (6.3±1.3), P＜0.001] and hospital stay [days, (11.7±2.2) vs (15.4±2.5), P＜0.001]. The VAS and NDI scores in both groups were significantly decreased (P＜0.05), while the JOA score was significantly increased at the latest follow-up lasted for more than 12 months compared with those before the operation (P＜0.05), whereas which were not statistically significant between the two groups at any time points accordingly (P＞0.05). As for imaging, the 3D group was significantly better than the FH group regarding accuracy of screw placement based Reinhold's criteria (P＜0.05). However, there was no statistically significant difference in the Lenke's intervertebral fusion grade between the two groups at the last follow-up (P＞0.05). [Conclusion] The 3D printing-assisted atlantoaxial pedicle screw fixation and fusion does significantly improve surgical efficiency and enhance the accuracy of pedicle screw placement.

Abstract:[Objective] To evaluate the clinical consequence of Delta large-channel endoscopy for double-segment cervical spondylotic radiculopathy. [Methods] A retrospective research was conducted on 15 patients who had double-level cervical spondylotic radiculopathy treated by full endoscopic technique with Delta large-channel endoscope in our hospital from September 2017 to October 2020. The clinical and imaging documents were evaluated. [Results] All the 15 patients were successfully operated with operation time of (93.2±16.6) min, intraoperative blood loss of (34.1±7.4) mL, and the postoperative hospitalization of (2.8±1.3) days. The neck pain VAS score [points, (6.8±1.5), (2.9±0.7), (0.0±0.2), P＜0.001], arm pain VAS score [points, (7.2±1.6), (2.7±2.1), (0.1±0.5), P＜0.001], NDI score [%, (53.0±16.2), (25.2± 13.2), (0.4 ± 1.5), P＜0.001] and JOA score [points, (12.6 ± 1.1), (14.6 ± 1.1), (16.9 ± 0.2), P＜0.001] were significantly improved with time elapsed preoperatively, 3 days after surgery and at the last follow-up. According to the modified MacNab's criteria, the clinical excellent and good rate was of 93.3% at the last interview. As for imaging, the sagittal foramen diameter, intervertebral space height and cervical lordosis angle remained unchanged significantly 3 days postoperatively and at the last follow-up compared with those preoperatively (P＞0.05). [Conclusion] The Delta large-channel endoscopic decompression and discectomy does achieve satisfactory clinincal outcome for double- seg- ment cervical spondylotic radiculopathy.

Abstract: