The AP2/ERF transcription factor MdDREB2A regulates nitrogen utilisation and sucrose transport under drought stress.

Drought stress is one of the main environmental factors limiting plant growth and development. Plants adapt to changing soil moisture by modifying root architecture, inducing stomatal closure, and inhibiting shoot growth. The AP2/ERF transcription factor DREB2A plays a key role in maintaining plant growth in response to drought stress, but the molecular mechanism underlying this process remains to be elucidated. Here, it was found that overexpression of MdDREB2A positively regulated nitrogen utilisation by interacting with DRE cis-elements of the MdNIR1 promoter. Meanwhile, MdDREB2A could also directly bind to the promoter of MdSWEET12, which may enhance root development and nitrogen assimilation, ultimately promoting plant growth. Overall, this regulatory mechanism provides an idea for plants in coordinating with drought tolerance and nitrogen assimilation to maintain optimal plant growth and development under drought stress.

Comparison of transfacet and pedicle screws in oblique lateral interbody fusion for single-level degenerative lumbar spine diseases: a retrospective propensity score-matched analysis.

BACKGROUND: To perform a comparative assessment of percutaneous transfacet screws (TFS) and percutaneous bilateral pedicle screws (BPS) in oblique lateral interbody fusion (OLIF) for the treatment of single-level degenerative lumbar spine diseases in terms of radiological examinations and clinical outcomes. METHODS: Sixty-six patients who received single-level OLIF with percutaneous supplementary fixation assisted by the robot for the treatment of degenerative lumbar spine diseases were selected. There were 16 cases of OLIF with TFS and 50 cases of OLIF with BPS. The propensity score matching method selected 11 patients in each group with matched characteristics to perform a clinical comparison. RESULTS: The estimated blood loss was 68.2 ± 25.2 ml in the OLIF with TFS group compared to 113.6 ± 39.3 ml in the OLIF with BPS group (P < 0.05). The intervertebral disc height raised from 8.6 to 12.9 mm in the TFS group and from 8.9 to 13.9 mm in the BPS group in the immediate postoperative period, and dropped to 10.8 and 12.9 mm at the twelfth month, respectively (P < 0.05). The fusion rates were 91% and 100% for TFS and BPS groups (P > 0.05). Quantitative assessments of back/leg pain of the two groups reached a healthy level in the late period of the follow-up. CONCLUSION: Both TFS and BPS techniques for the OLIF surgery relieve back pain caused by degenerative lumbar spine diseases. The TFS technique exhibits less blood loss compared with the BPS. A moderate cage subsidence is present in TFS but no complication is reported.

Posterior atlantoaxial internal fixation using Harms technique assisted by 3D-based navigation robot for treatment of atlantoaxial instability.

BACKGROUND: To evaluate the accuracy of screw placement using the TiRobot surgical robot in the Harms procedure and to assess the clinical outcomes of this technique. METHODS: This retrospective study included 21 patients with atlantoaxial instability treated by posterior atlantoaxial internal fixation (Harms procedure) using the TiRobot surgical robot between March 2016 and June 2021. The precision of screw placement, perioperative parameters and clinical outcomes were recorded. Screw placement was assessed based on intraoperative guiding pin accuracy measurements on intraoperative C-arm cone-beam computed tomography (CT) images using overlay technology and the incidence of screw encroachment identified on CT images. RESULTS: Among the 21 patients, the mean age was 44.8 years, and the causes of atlantoaxial instability were os odontoideum (n = 11), rheumatoid arthritis (n = 2), unknown pathogenesis (n = 3), and type II odontoid fracture (n = 5). A total of 82 screws were inserted with robotic assistance. From intraoperative guiding pin accuracy measurements, the average translational and angular deviations were 1.52 ± 0.35 mm (range 1.14-2.25 mm) and 2.25° ± 0.45° (range 1.73°-3.20º), respectively. Screw placement was graded as A for 80.5% of screws, B for 15.9%, and C for 3.7%. No complications related to screw misplacement were observed. After the 1-year follow-up, all patients with a neurological deficit experienced neurological improvement based on Nurick Myelopathy Scale scores, and all patients with preoperative neck pain reported improvement based on Visual Analog Scale scores. CONCLUSIONS: Posterior atlantoaxial internal fixation using the Harms technique assisted by a 3D-based navigation robot is safe, accurate, and effective for treating atlantoaxial instability.

Reoperation of decompression alone or decompression plus fusion surgeries for degenerative lumbar diseases: a systematic review.

PURPOSE: The objective of this paper was to compare the reoperation rates, timing and causes between decompression alone and decompression plus fusion surgeries for degenerative lumbar diseases through a systematic review of the published data. METHODS: A search of the literature was conducted on PubMed/MEDLINE, EMBASE and the Cochrane Collaboration Library. Reports that included reoperations after decompression alone and/or decompression plus fusion surgeries were selected using designed eligibility criteria. Comparative analysis of reoperation rates, timing and causes between the two surgeries was conducted. RESULTS: Thirty-two retrospective and three prospective studies were selected from 6401 papers of the literature search. The analysis of data reported in these studies revealed that both surgeries resulted in similar reoperation rates after the primary surgery. However, majority of reoperations following the fusion surgeries were due to adjacent-segment diseases, and following the decompression alone surgeries were due to the same-segment diseases. Reoperation rates were not found to decrease in patients operated more recently than those operated in early times. CONCLUSIONS: Reoperation rates were similar following decompression alone or plus fusion surgeries for degenerative lumbar diseases. However, different underlying major causes exist between the two surgeries. There is no evidence showing that the reoperation rate has a trend to decline with newer surgical techniques used. The exact mechanisms of reoperation after both surgeries are still unclear. Further researches are necessary to investigate the mechanisms of reoperation for improvement of surgical techniques that aim to delay or prevent reoperation after lumbar surgery. These slides can be retrieved under Electronic Supplementary Material.

[Percutaneous minimally invasive pedicle screw fixation for cervical fracture using intraoperative three-dimensional fluoroscopy-based navigation].

OBJECTIVE: To retrospectively assess the feasibility and safety of percutaneous minimally invasive pedicle screw fixation for cervical fracture using intraoperative three-dimensional fluoroscopy-based navigation. METHODS: Thirty patients admitted from April 2012 to May 2014 in Beijing Jishuitan Hospital with cervical fracture underwent pedicle screw fixation using intraoperative three-dimensional fluoroscopy-based navigation, with 8 patients using minimally invasive technique (CAOS-MIS group), and the other 22 patients using conventional open approach (CAOS-open group). Operative time, blood loss and postoperative neurovascular complications were recorded. Screw positions were studied by postoperative CT scan. All patients were followed up for at least 6 months. Neck visual analogue score (VAS) and American Spinal Injury Association (ASIA) classification were evaluated preoperatively and at 6-month follow-up. Independent-sample t test and Chi-Square test were used for statistical analysis. RESULTS: Operation time was (139 ± 18) minutes and blood loss was (73 ± 40) ml in CAOS-MIS group and correspondingly (154 ± 42) minutes and (296 ± 171) ml in CAOS-open group. The blood loss in CAOS-MIS group was significantly lower than that in CAOS-open group (t = 5.695, P < 0.01). No screw-related injury to nerve or vertebral artery was observed. Thirty-four screws were placed in CAOS-MIS group with 28 screws (82.4%) classified as Grade I, meanwhile in CAOS-open group 108 screws were placed with 96 screws (88.9%) classified as Grade I. There was no statistical difference between the two groups (χ² = 0.998, P > 0.01). VAS score showed no statistical difference preoperatively (t = 0.334, P > 0.01), however statistical difference existed at 6 months follow-up (t = 4.111, P < 0.01) with (0.4 ± 0.5) in CAOS-MIS group and (1.5 ± 0.7) in CAOS-open group. There were 1 patient from class B to improve to D, 1 case from D to E in CAOS-MIS group, and 1 patient from class A to improve to B, 1 case from B to D, 2 cases from C to D, 3 cases from D to E in CAOS-open group 6 months after surgery. Cervical X-ray demonstrated fractures healed well in all cases at 6 months follow-up. CONCLUSION: It is feasible and safe for percutaneous minimally invasive pedicle screw fixation for cervical fracture using intraoperative three-dimensional fluoroscopy-based navigation, which can also decreases the incidence of postoperative neck pain.

Impact of optical navigation variables on the accuracy of robot-assisted surgery: a study of the TIANJI Robot system.

This study aims to explore factors related to optical navigation that interfere with the accuracy of robot-assisted surgery, specifically focusing on the TIANJI Robot system. A measurement model was created to assess the accuracy of the TIANJI Robot system in simulated screw placement. Deviation between actual and planned positions was measured using a three-coordinate machine. Various experiments were conducted to investigate the impact of different optical navigation factors on screw placement accuracy. Deviations were measured at different distances (ranging from 1.2 to 2.2 m) between the optical navigation stereo camera and the tracker, with each distance being tested 50 times. The distance between the optical camera and patient tracker was set at 1.4 m. Deviations were also measured at different angles between the camera and robot tracker, repeated over 25 times for each angle. Data were analyzed using mean and standard deviation, with line charts illustrating deviation changes based on distance and angle details. Within the range of the TIANJI Robot system's optical navigation (1.2-2.2 m), deviation increased as distance increased (χ2 = 479.107, P < 0.001). The robotic system demonstrated high and consistent accuracy (mean deviation: 0.332 mm ± 0.067 mm) when the relative angle between the optical camera and tracker was below 40°. The accuracy of the TIANJI Robot system was found to be influenced by relative distance and angle between the optical camera and tracker during screw placement procedures. Surgeons are recommended to set a relative distance of 1.4-1.5 m between the optical camera and patient tracker, with a relative angle below 40° when placing and adjusting optical tracking devices.

[Posterior C1-C2 transarticular screw fixation for atlantoaxial instability assisted by intraoperative 3-dimensional fluoroscopy-based navigation].

OBJECTIVE: To assess the feasibility, efficacy and indication of posterior C1-C2 transarticular screw fixation for atlantoaxial instability assisted by intraoperative 3-dimensional fluoroscopy-based navigation. METHODS: From November 2005 to October 2012, 58 patients with atlantoaxial instability underwent posterior C1-C2 transarticular screw fixation assisted by intraoperative 3-dimensional fluoroscopy-based navigation. Those with excellent atlantoaxial reduction and no need for decompression underwent percutaneously minimally invasive procedures. Operative duration, blood loss volume, reduction of atlantoaxial joints and postoperative neurovascular complications were recorded. Screw positions were studied by postoperative computed tomography (CT) and divided into 3 categories. The follow-up period was at least 3 months. Local symptoms (assessed by visual analogue scale (VAS) score), neurological conditions (Nurick classification) and bone graft fusion were evaluated. RESULTS: Among them, the procedure was either open surgery (n = 51) or percutaneously minimally invasive surgery (n = 7). A total of 111 screws were placed satisfactorily. Five patients underwent only unilateral C1-C2 transarticular screw fixation. No severe complications were encountered. The mean operative duration was 202.2 ± 54.2 minutes and the average volume of blood loss 412.6 ± 281.2 ml. And the values were comparable to those for the traditional fluoroscopy-guided free-hand procedures. No statistical significance existed between open and percutaneously minimally invasive procedures in operative duration, blood loss volume and precision of screw placement. The patients with incompletely reduced C1-C2 dislocation had comparable clinical outcomes with those with complete reduction. After a 3-month follow-up, all of them showed significant improvements of local symptoms. VAS score decreased from 4.5 ± 1.3 preoperatively to 0.7 ± 0.8 postoperatively while the Nurick classification improved from 2.4 ± 1.1 to 0.6 ± 1.0. And bone graft fusion was satisfactory. CONCLUSIONS: Posterior C1-C2 transarticular screw fixation for atlantoaxial instability assisted by intraoperative 3-dimensional fluoroscopy-based navigation is both feasible and safe. Combined with minimally invasive techniques, this procedure may achieve greater precision and minimal invasion.

Studies on macrofungi diversity and discovery of new species of Abortiporus from Baotianman World Biosphere Reserve.

This research focuses on macrofungi in Baotianman Biosphere Reserve and their relationships with plant ecosystems. The findings demonstrate the reserve's macrofungal resources. The study collected 832 specimens, among which 351 macrofungi species were identified, belonging to six classes, 19 orders, 54 familiae, and 124 genera, and one new species of Abortiporus was found. Among them, 11 familiae with a total of 231 species were dominated, accounting for 20.37% of the total number of familiae and 65.81% of the total number of species; 14 genera with a total of 147 species were dominated, accounting for about 11.38% the total number of genera and 41.88% of the total number of species. The richness of macrofungi at the species level was considerably different across the four vegetation types in the reserve, showing that the vegetation types had a bigger influence on macrofungi. In the evaluation of macrofungal resources, a total of 196 species of edible fungi, 121 species of medicinal fungi, 52 species of poisonous fungi, and 37 species of macrofungi with unclear economic value were counted. Abortiporus baotianmanensis is a new species of podoscyphaceae in the genus Abortiporus. The new species display the reserve's richness. Next, the project seeks to generate and conserve macrofungal resources.

Clinical and Radiographic Comparison of Oblique Lateral Lumbar Interbody Fusion and Minimally Invasive Transforaminal Lumbar Interbody Fusion in Patients with L4/5 grade-1 Degenerative Spondylolisthesis.

OBJECTIVES: To compare the clinical and radiographic outcomes of oblique lateral lumbar interbody fusion and minimally invasive transforaminal lumbar interbody fusion in patients with grade-1 L4/5 degenerative spondylolisthesis. METHODS: Based on the inclusion and exclusion criteria, the comparative analysis included consecutive patients with grade-1 degenerative spondylolisthesis who underwent oblique LIF (OLIF, n = 36) or minimally invasive transforaminal LIF (MI-TLIF, n = 45) at the Department of Spine Surgery, Beijing Jishuitan Hospital from January 2016 to August 2017. Patient satisfaction Japanese Orthopaedic Association score, visual analog scale (VAS) scores for back and leg pain, Oswestry disability index (ODI), radiographic outcomes including anterior/posterior disc heights (ADH/PDH), foraminal height (FH), foraminal width (FW), cage subsidence, cage retropulsion, and fusion rate were assessed during a 2-year follow-up. Continuous data are presented as mean ± standard deviation and were compared between groups using the independent sample t-test. Categorical data are presented as n (%) and were compared between groups using the Pearson chi-squared test or Fisher's exact test. Repetitive measurement and analysis of variance was employed in the analysis of ODI, back pain VAS score, and leg pain VAS score. Statistical significance was defined as p < 0.05. RESULTS: The OLIF and MI-TLIF groups comprised 36 patients (age, 52.1 ± 7.2 years; 27 women) and 45 patients (age, 48.4 ± 14.4 years; 24 women), respectively. Satisfaction rates at 2 years post procedure exceeded 90% in both groups. The OLIF group had less intraoperative blood loss (140 ± 36 vs 233 ± 62 mL), lower back pain VAS score (2.42 ± 0.81 vs 3.38 ± 0.47), and ODI score (20.47 ± 2.53 vs 27.31 ± 3.71) at 3 months follow-up (with trends toward lower values at 2 years follow-up), but higher leg pain VAS scores at all postoperative time points than the MI-TLIF group (all p < 0.001). ADH, PDH, FD, and FW improved in both groups post-surgery. At the 2 year follow-up, the OLIF group had a higher rate of Bridwell grade-I fusion (100% vs 88.9%, p = 0.046) and lower incidences of cage subsidence (8.33% vs 46.67%, p < 0.001) and retropulsion (0% vs 6.67%, p = 0.046) than the MI-TLIF group. CONCLUSIONS: In patients with grade-I spondylolisthesis, OLIF was associated with lower blood loss and greater improvements in VAS for back pain and ODI and radiologic outcomes than MI-TLIF. The OLIF is more suitable for these patients with low back pain as the main symptoms are accompanied by mild or no leg symptoms before operation.

Robotic navigation during spine surgery: an update of literature.

INTRODUCTION: The application of robotic navigation during spine surgery has advanced rapidly over the past two decades, especially in the last 5 years. Robotic systems in spine surgery may offer potential advantages for both patients and surgeons. This article serves as an update to our previous review and explores the current status of spine surgery robots in clinical settings. AREAS COVERED: We evaluated the literature published from 2020 to 2022 on the outcomes of robotics-assisted spine surgery, including accuracy and its influencing factors, radiation exposure, and follow-up results. EXPERT OPINION: The application of robotics in spine surgery has driven spine surgery into a new era of precision treatment through a form of artificial intelligence assistance that compensates for the limitations of human abilities. Modularized robot configurations, intelligent alignment and planning incorporating multimodal images, efficient and simple human - machine interaction, accurate surgical status monitoring, and safe control strategies are the main technical features for the development of orthopedic surgical robots. The use of robotics-assisted decompression, osteotomies, and decision-making warrants further study. Future investigations should focus on patients' needs while continuing to explore in-depth medical - industrial collaborative development innovations that improve the overall utilization of artificial intelligence and sophistication in disease treatment.

[One-stage posterior approach spinal reconstruction for severe lumbar burst fracture].

OBJECTIVE: To evaluate the clinical therapeutic outcomes for severe burst fracture of lumbar vertebrae via a posterior approach for one-stage spinal "three-column" reconstruction. METHODS: An retrospective analysis of data was performed for 21 patients with severe burst fracture of lumbar vertebrae undergoing a posterior approach for one-stage spinal "three-column" reconstruction from 2005 to 2010. It was compared with previous 15 cases undergoing a staged anteroposterior approach. The operative duration, volume of blood loss, pre- and post-operative imaging measurements of kyphosis and vertebral height and nerve function recovery were evaluated. RESULTS: The values of operative duration and volume of blood loss in the one-stage posterior approach group were significantly less than those of the two-stage anteroposterior approach group [(263 ± 72) min vs (439 ± 75) min, t = -5.303, P < 0.01; (1143 ± 296) ml vs (1471 ± 399) ml, t = -2.169, P = 0.042)]. Statistical significance existed in postoperative kyphosis between two groups [(0.5 ± 2.0)° vs (3.9 ± 2.6)°, t = -3.336, P = 0.003]. Vertebral height had no statistical significance pre- and post-operatively between two groups while restoration of vertebral height did [(0.47 ± 0.19) mm vs (0.26 ± 0.15) mm, t = 2.669, P = 0.015]. CONCLUSION: Posterior approach for one-stage vertebral resection, mesh implantation, pedicle screws and rod internal fixation for reconstructing spinal "three-column" structures offers excellent feasibility and safety. And it may avoid complications associated with an anteroposterior approach for two-stage procedures. The median length of hospital stay is also reduced.

Additional lateral plate fixation has no effect to prevent cage subsidence in oblique lumbar interbody fusion.

BACKGROUND: For lumbar degenerative diseases, cage subsidence is a serious complication and can result in the failure of indirect decompression in the oblique lumbar interbody fusion (OLIF) procedure. Whether additional lateral plate fixation was effective to improve clinical outcomes and prevent cage subsidence was still unknown. This study aimed to compare the incidence and degree of cage subsidence between stand-alone oblique lumbar interbody fusion (SA-OLIF) and OLIF combined with lateral plate fixation (OLIF + LP) for the treatment of lumbar degenerative diseases and to evaluate the effect of the lateral plate fixation. METHODS: This was a retrospective comparative study. 20 patients with 21 levels underwent SA-OLIF and 21 patients with 26 levels underwent OLIF + LP. We compared clinical and radiographic outcomes between two groups. Clinical evaluation included Visual Analog Scale (VAS) for back pain and leg pain, Japanese Orthopaedic Association (JOA) scores and Oswestry Disability Index (ODI). Radiographical evaluation included disc height (DH), segmental lordosis angle (SL), and subsidence rate on standing lateral radiographs. Cage subsidence was classified using Marchi's criteria. RESULTS: The mean follow-up duration was 6.3 ± 2.4 months. There were no significant differences among perioperative data (operation time, estimated intraoperative blood loss, and complication), clinical outcome (VAS, ODI, and JOA) and radiological outcome (SH and SL). The subsidence rate was 19.0% (4/21) in SA-OLIF group and 19.2% (5/26) in OLIF + LP group. 81.0% in SA-OLIF group and 80.8% in OLIF + LP group had Grade 0 subsidence, 14.3% in SA-OLIF group and 15.4% in OLIF + LP group had Grade I subsidence, and 4.8% in SA-OLIF group and 3.8% in OLIF + LP group had Grade II subsidence (P = 0.984). One patient with severe cage subsidence and lateral plate migration underwent revision surgery. CONCLUSIONS: The additional lateral plate fixation does not appear to be more effective to prevent cage subsidence in the oblique lumbar interbody fusion, compared with stand-alone technique. If severe cage subsidence occurs, it may result in lateral plate migration in OLIF combined with lateral plate fixation.

Drilling Speed and Bone Temperature of a Robot-assisted Ultrasonic Osteotome Applied to Vertebral Cancellous Bone.

STUDY DESIGN: An experimental investigation of a robot-assisted ultrasonic osteotome applied to vertebral cancellous bone. OBJECTIVE: The aim of this study was to investigate the effect of various ultrasonic parameter settings on temperature in the drilling site and penetration time and determine the most suitable parameters for efficient and safe robot-based ultrasonically assisted bone drilling in spinal surgery. SUMMARY OF BACKGROUND DATA: A robot-assisted ultrasonic osteotome device may be safe and effective for spinal drilling. METHODS: Sixty specimens of bovine vertebral cancellous were randomly assigned to one of six groups, which varied by mode of ultrasonic vibration (L-T and L) and feed rate (one percent [0.8 mm/s], two percent [1.6 mm/s], and three pecent [2.4 mm/s]). Maximum temperature in the drilling site and penetration time was recorded. RESULTS: Maximum temperature in the drilling site decreased as output power increased for L-T and L modes, was significantly lower for L-T compared to L mode at each feed rate and power setting, was significantly different at feed rates of 1.6 mm/s versus 0.8 mm/s and 2.4 mm/s versus 0.8 mm/s for L-T mode at an output power of 60 W and 84 W, but was not influenced by feed rate for L mode. Penetration time did not significantly improve as output power increased for both L-T and L modes, was significantly decreased with increased feed rates, but was not significantly different between L-T and L modes. CONCLUSION: The optimal parameters for applying a robot-assisted ultrasonic osteotome to vertebral cancellous bone are L-T mode, maximum output power of 120 W, and maximum feed rate of 2.4 mm/s.Level of Evidence: 4.

Placement of pedicle screws using three-dimensional fluoroscopy-based navigation in lumbar vertebrae with axial rotation.

Despite potential advantages of three-dimensional fluoroscopy-based navigation, there still remain a lot of controversies about the indications of this technology, especially whether it is worthy of being used in placement of pedicle screws in lumbar spine. However, according to the inconsistent conclusions reported in the literature and our experiences, the traditional method relying on anatomical landmarks and fluoroscopic views to guide lumbar pedicle screw insertion is unable to meet the requirement of precise screw placement. Based on our observation, screw malposition seems to occur concomitant with vertebral axial rotation which is a ubiquitous phenomenon. Three-dimensional fluoroscopy-based navigation can provide the most valuable axial images in real-time, so it may be useful for placement of pedicle screws in lumbar spine. This study was intended to evaluate the effect of axial rotation of lumbar vertebrae on the accuracy of pedicle screw placement using the traditional method, as well as assess the value of three-dimensional fluoroscopy-based navigation in improving the accuracy. Sixteen lumbar simulation models at different degrees of axial rotation (0°, 5°, 10°, and 20°), with every four assigned the same degree, were equally divided into two groups (traditional method group and three-dimensional fluoroscopy-based navigation group). Random placement of pedicle screws was carried out, followed by CT scan postoperatively. Then the outer pedicle cortex contours were depicted from reconstructed sectional pedicle images using Photoshop. The accuracy of pedicle screw placement was evaluated by determining the interrelationship between screw trajectory and pedicle cortex (quality), and measuring the shortest distance from pedicle screw axis to outer cortex of the pedicle (quantity). Eighty pedicle screws were implanted, respectively, in each group. In traditional method group, statistical difference existed in the accuracy of pedicle screw placement at different axial rotational degrees (P < 0.05). With degrees increasing, the accuracy declined. The accuracy of three-dimensional fluoroscopy-based navigation group was higher than traditional method group in vertebrae with axial rotation (P < 0.01). In qualitative evaluation, the accuracy of the two methods had statistical difference when the degree was 20°, and in quantitative evaluation, statistical difference existed in 5°, 10°, and 20° of vertebral axial rotation.

[Study of pedicle screw placement assisted by intraoperative three-dimensional navigation in lumbar vertebrae with axial rotation].

OBJECTIVE: To evaluate the effect of axial rotation of lumbar vertebrae on the accuracy of pedicle screw placement using the traditional method, as well as to assess the value of intraoperative three-dimensional (3D) navigation in improving the accuracy. METHODS: Sixteen lumbar simulation models at different degrees of axial rotation (0°, 5°, 10° and 20°), with every four assigned with the same degree, were equally divided into two groups (traditional method group and intraoperative 3D navigation group). Random placement of pedicle screws was carried out, followed by CT scan postoperatively. Then the outer pedicle cortex contours were depicted from reconstructed sectional pedicle images using Photoshop. The accuracy of pedicle screw placement was evaluated by determining the interrelationship between screw trajectory and pedicle cortex (qualitative) and measuring the shortest distance from pedicle screw axis to outer cortex of the pedicle (quantitative). RESULTS: Eighty pedicle screws were implanted respectively in each group. In traditional method group, statistical difference existed in the accuracy of pedicle screw placement at different axial rotational degrees (P < 0.05). With degrees increasing, the accuracy declined. The accuracy of intraoperative 3D navigation group was higher than traditional method group in vertebrae with axial rotation (P < 0.01). In qualitative evaluation, the accuracy of the two methods had statistical difference when the degree was 20°, and in quantitative evaluation, statistical difference existed in 5°, 10° and 20° of vertebral axial rotation. CONCLUSIONS: Screw malposition can be caused by vertebral axial rotation in lumbar spine using traditional method. Accuracy of pedicle screw placement declines with the increase of axial rotational degrees. However, the accuracy can be improved by using intraoperative 3D navigation.

Treatment of L5-S1 Spondyloptosis with Multiple Pedicle Defects Through a Combined Anterior and Posterior Approach.

BACKGROUND: An anterior dislocation of the L5 vertebral body from the sacrum and decent into the pelvis is considered as spondyloptosis. The surgical treatment of L5-S1 spondyloptosis remains challenging and controversial. We present a case of lumbosacral spondyloptosis with multiple pedicle defects treated through a combined anterior and posterior approach. CASE DESCRIPTION: A 38-year-old female patient suffering from L5-S1 spondyloptosis with multiple pedicle defects without any history of trauma presented with lower back pain and bilateral lower leg radiating pain. A 3-stage procedure involving L5 spondylectomy, assisted by intraoperative 3-dimensional (3D) navigation, through a retroperitoneal approach at the first stage was performed. At the second stage, decompression was performed, and pedicle screws and iliac screws were placed into L1-S2, which was assisted by intraoperative 3D navigation. At the third stage, slippage reduction was achieved by placing L4 over onto S1, where a mesh was stuffed with bone from the spondylectomy and was placed into the L4/S1 intervertebral space. The patient experienced transient lower leg weakness but returned to preoperative status soon. Radiography revealed that internal fixation was in good position. No dural tears, postoperative infections, and implantation failure were reported after 3 months of postoperation. CONCLUSIONS: The L5 spondylectomy shortens the spine to reduce the strain on the neural elements and facilitates correction of the lumbosacral kyphosis. When long instrumentation is mandatory, such as in multiple pedicle defects, sacropelvic fixation is recommended. Intraoperative 3D navigation is helpful in such a complex case.

Superior-segment Bilateral Facet Violation in Lumbar Transpedicular Fixation, Part I: A Biomechanical Study of Blocking Superior Facets.

STUDY DESIGN: This is an in vitro biomechanical study. OBJECTIVES: The aim of this study was to investigate the biomechanical variations of lumbar spine motor units and that under different moments after screw heads blocking superior-adjacent bilateral facets through the cadaver specimen biomechanical experiment. SUMMARY OF BACKGROUND DATA: Facet joint violation by pedicle screws is not a rare adverse event in instrumented lumbar fusion surgery, and one of the most common types is the screw head blocking the superior-adjacent facet. However, its contribution to biomechanical instability at the supradjacent level is unknown. METHODS: The range of motion (ROM) of 12 lumbar spines (L4-S1) were measured in flexion-extension, lateral bending, and axial rotation for L4/5. All specimens were randomly divided into two groups: the control group and the blocking group, each with 6 specimens. Spine were tested on intact and instrumented specimens, respectively. The relative ROM changes were compared between the blocking and control groups. RESULTS: In the blocking group, the supradjacent-level flexion-extension ROM significantly decreased under all moments (7.5, 6.0, 4.5 Nm) relative to the intact spine and a significant decrease in the lateral bending relative ROM was found at 4.5 Nm. In the control group, no significant change of supradjacent-level ROM was found relative to the intact noninstrumented spine at each moment. When performing flexion-extension, the relative ROM change between the 2 groups was significantly different at 4.5 Nm. When performing lateral bending, the relative ROM change between the 2 groups was significantly different at moments of 6.0 and 4.5 Nm. CONCLUSION: When screw heads blocked superior-adjacent bilateral facets, the supradjacent-level flexion-extension ROM and lateral bending ROM decreased. In the long run, this may be a risk of persistent low-back pain due to frequent impingement. LEVEL OF EVIDENCE: N/A.

Superior-segment Bilateral Facet Violation in Lumbar Transpedicular Fixation, Part III: A Biomechanical Study of Severe Violation.

MINI: In controls, adjacent-level range of motion (ROM) did not change relative to noninstrumented spine at each moment. In severe violation, flexion-extension and rotation ROM of adjacent vertebrae decreased at each moment (7.5, 6.0, 4.5 Nm); lateral bending ROM decreased at 4.5 Nm. Significant differences in movements were found except lateral bending (7.5 Nm). STUDY DESIGN: This is an in vitro biomechanical study. OBJECTIVES: This study aimed to investigate the biomechanical variations of lumbar spine motor units after bilateral facet joint severe violation in cadaver specimens and analyze the biomechanics under different moments. SUMMARY OF BACKGROUND DATA: The incidence of facet joint violation (FJV) is highly variable, and one of the most important factors is the lack of awareness of protection. Until now, the biomechanical effects of FJV remain unclear. METHODS: Biomechanical testing was performed on 12 human cadaveric spines under flexion-extension, lateral bending, and axial rotation loading. After intact analysis, pedicle screws were inserted at L5, and the biomechanical testing was repeated. Full range of motion (ROM) at the proximal adjacent levels under different moments was recorded and normalized to the intact (100%) noninstrumented spine. The relative ROM changes were compared between the control and severe violation groups. RESULTS: The adjacent-level ROM (flexion-extension, lateral bending, axial rotation) did not change significantly in the control group at each moment (7.5, 6.0, 4.5 Nm) compared with the intact noninstrumented spine. In the severe violation group, the supradjacent-level ROM decreased significantly under all moments relative to the intact noninstrumented spine (P < 0.05) except for the ROM of lateral bending at moments of 7.5 and 6.0 Nm. When comparing the ROM between the two groups, there were significant differences in all movements except lateral bending at 7.5 Nm. CONCLUSION: When superior-segment bilateral facet joints are severely violated by screws, the flexion-extension and axial rotation ROM of adjacent vertebrae decreases at each moment (7.5, 6.0, 4.5 Nm), and the lateral bending ROM decreases at 4.5 Nm. LEVEL OF EVIDENCE: N/A.

This is an in vitro biomechanical study. This study aimed to investigate the biomechanical variations of lumbar spine motor units after bilateral facet joint severe violation in cadaver specimens and analyze the biomechanics under different moments. The incidence of facet joint violation (FJV) is highly variable, and one of the most important factors is the lack of awareness of protection. Until now, the biomechanical effects of FJV remain unclear. Biomechanical testing was performed on 12 human cadaveric spines under flexion-extension, lateral bending, and axial rotation loading. After intact analysis, pedicle screws were inserted at L5, and the biomechanical testing was repeated. Full range of motion (ROM) at the proximal adjacent levels under different moments was recorded and normalized to the intact (100%) noninstrumented spine. The relative ROM changes were compared between the control and severe violation groups. The adjacent-level ROM (flexion-extension, lateral bending, axial rotation) did not change significantly in the control group at each moment (7.5, 6.0, 4.5 Nm) compared with the intact noninstrumented spine. In the severe violation group, the supradjacent-level ROM decreased significantly under all moments relative to the intact noninstrumented spine (P < 0.05) except for the ROM of lateral bending at moments of 7.5 and 6.0 Nm. When comparing the ROM between the two groups, there were significant differences in all movements except lateral bending at 7.5 Nm. When superior-segment bilateral facet joints are severely violated by screws, the flexion-extension and axial rotation ROM of adjacent vertebrae decreases at each moment (7.5, 6.0, 4.5 Nm), and the lateral bending ROM decreases at 4.5 Nm. Level of Evidence: N/A.

Normal intervertebral segment rotation of the subaxial cervical spine: An in vivo study of dynamic neck motions.

BACKGROUND: Accurate knowledge of the intervertebral center of rotation (COR) and its corresponding range of motion (ROM) can help understand development of cervical pathology and guide surgical treatment. METHODS: Ten asymptomatic subjects were imaged using MRI and dual fluoroscopic imaging techniques during dynamic extension-flexion-extension (EFE) and axial left-right-left (LRL) rotation. The intervertebral segment CORs and ROMs were measured from C34 to C67, as the correlations between two variables were analyzed as well. RESULTS: During the EFE motion, the CORs were located at 32.4 ± 20.6%, -2.4 ± 11.7%, 21.8 ± 12.5% and 32.3 ± 25.5% posteriorly, and the corresponding ROMs were 13.8 ± 4.3°, 15.1 ± 5.1°, 14.4 ± 7.0° and 9.2 ± 4.3° from C34 to C67. The ROM of C67 was significantly smaller than other segments. The ROMs were not shown to significantly correlate to COR locations (r = -0.243, p = 0.132). During the LRL rotation cycle, the average CORs were at 85.6 ± 18.2%, 32.3 ± 25.3%, 15.7 ± 12.3% and 82.4 ± 31.3% posteriorly, and the corresponding ROMs were 3.5 ± 1.7°, 6.9 ± 3.8°, 9.6 ± 4.1° and 2.6 ± 2.5° from C34 to C67. The ROMs of C34 and C67 was significantly smaller than those of C45 and C56. A more posterior COR was associated with a less ROM during the neck rotation (r = -0.583, p < 0.001). The ROMs during EFE were significantly larger than those during LRL in each intervertebral level. CONCLUSION: The CORs and ROMs of the subaxial cervical intervertebral segments were segment level- and neck motion-dependent during the in-vivo neck motions. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: Our study indicates that the subaxial cervical intervertebral CORs and ROMs were segment level- and neck motion-dependent. This may help to improve the artificial disc design as well as surgical technique by which the neck functional motion is restored following the cervical arthroplasty.

Comparison of the One-Time Accuracy of Simulated Freehand and Navigation Simulated Pedicle Screw Insertion.

OBJECTIVE: To compare one-time accuracy rate between simulated freehand (SFH) and navigation simulated (NS) pedicle screw insertion, assuming no second chance to correct screws. METHODS: A simulated, comparative, cross-sectional study was conducted on 69 patients undergoing lumbar spine surgery. An intraoperative registration system captured the planned point of entry and trajectory of pedicle screws for both SFH under direct visualization and NS under navigation-aided visualization. Pedicle screw insertion was simulated for each captured image (370 screws) using Surgimap. Rajasekaran's method helped evaluate the point of entry accuracy and trajectory. RESULTS: Accuracy rate was better for the NS method (97.8%) than for the SFH method (63.8%). Of 370 screws in the SFH group, 134 penetrated the cortex, with 31 resulting in >4 mm penetration. Of 370 screws in the NS group, 8 penetrated the cortex, <4 mm penetration. Of 134 misplaced screws in the SFH group, 64 were due to error in the point of entry, 63 were due to error in the trajectory angle, and 7 were due to both errors. Of 8 errors in the NS group, 7 were due to the point of entry. CONCLUSIONS: Intraoperative navigation had significantly better one-time accuracy of pedicle screw insertion than freehand insertion and should be used to avoid injury to the pedicle and surrounding tissue from screw reinsertion.