The analysis of segmental lordosis restored by oblique lumbar interbody fusion and related factors: building up preoperative predicting model.

BACKGROUND: Oblique lumbar interbody fusion (OLIF) procedures have the potential to increase the segmental lordosis by inserting lordotic cages, however, the amount of segmental lordosis (SL) changes can vary and is likely influenced by several factors, such as patient characteristics, radiographic parameters, and surgical techniques. The objective of this study was to analyze the impact of related factors on the amount of SL changes in OLIF procedures and to build up predictive model for SL changes. METHODS: This is a retrospective study involving prospectively enrolled patients. A total of 119 patients with 174 segments undergoing OLIF procedure were included and analyzed. The lordotic cages used in all cases had 6-degree angle. Radiographic parameters including preoperative and postoperative segmental disc angle (SDA, preSDA and postSDA), SDA changes on flexion-extension views (ΔSDA-FE), CageLocation and CageInclination were measured by two observers. Interobserver reliability of measurements were ensured by analysis of interclass correlation coefficient (ICC > 0.75). Pearson correlation coefficient analysis and multivariate linear regression were employed to identify factors related to SDA changes and to build up predictive model for SDA changes. RESULTS: The average change of segmental disc angle (ΔSDA, postSDA-preSDA) was 3.9° ± 4.8° (95% confidence interval [CI]: 3.1°-4.6°) with preSDA 5.3° ± 5.0°. ΔSDA was 10.8° ± 3.2° with negative preSDA (kyphotic), 5.0° ± 3.7° with preSDA ranging from 0° to 6°, and 1.0° ± 4.1° with preSDA> 6°. Correlation analysis revealed a significant negative correlation between ΔSDA and preSDA (r = - 0.713, P < 0.001), CageLocation (r = - 0.183, P = 0.016) and ΔSDA-FE (r = - 0.153, P = 0.044). In the multivariate linear regression, preSDA and CageLocation were included in the predictive model, resulting in minimal adjusted R2 change (0.017) by including CageLocation. Therefore, the recommended predictive model was ΔSDA = 7.9-0.8 × preSDA with acceptable fit. (adjusted R2 = 0.508, n = 174, P < 0.001). CONCLUSIONS: The restoration of segmental lordosis through OLIF largely depends on the preoperative segmental lordosis. The predictive model, which utilized preoperative segmental lordosis, facilitates preoperative planning for corrective surgery using the OLIF procedure.

Correcting intervertebral rotation and scoliosis simultaneously by oblique lumbar interbody fusion: a 3D analysis of EOS images.

Purpose: With advancements in minimally invasive techniques, oblique lumbar interbody fusion (OLIF) has gained widespread acceptance and is now commonly performed for adult degenerative scoliosis (ADS). The objective of this research paper is to evaluate three-dimensional (3D) intervertebral motions in EOS models before and after surgery and subsequently assess the efficacy of the 3D correction achieved through staged OLIF. Methods: In this retrospective study, 29 consecutive patients diagnosed with ADS were included, with a mean age of 63.6 years, who underwent staged OLIF surgery between 2018 and 2021. Spinopelvic parameters were assessed using EOS images, and 3D models were reconstructed to measure intervertebral motion angles (IMAs) in 70 surgical intervertebral segments, comprising wedge, lordosis, and axial rotation angles. Regression analysis was conducted to compare IMAs in different planes before and after the staged OLIF surgery. Results: Significant three-dimensional correction was observed in 70 intervertebral segments following the first-stage OLIF. The wedge angles decreased from 5.2°± 4.2° to 2.7°± 2.4° (P < 0.001). The lordosis angles increased from 5.1°± 5.9° to 7.8°± 4.6° (P = 0.014), while the axial rotation angles decreased from 3.8°± 2.6° to 2.3°± 2.1° (P < 0.001). Linear regression analysis revealed a positive correlation between wedge angles and axial angles preoperatively (P < 0.001, r = 0.43), as well as between corrected wedge angles and corrected axial angles (P < 0.001, r = 0.42). Conclusion: This study demonstrated that intervertebral motions had a correlation between coronal and axial planes in lumbar degenerative scoliosis. First-stage OLIF was efficient at correcting segmental scoliosis by inserting cages while correcting rotation deformity simultaneously, as well as improving the sagittal spinopelvic parameters.

Comparisons of oblique lumbar interbody fusion and transforaminal lumbar interbody fusion for degenerative spondylolisthesis: a prospective cohort study with a 2-year follow-up.

Objective: This study aimed to compare the clinical outcomes between oblique (OLIF) and transforaminal lumbar interbody fusion (TLIF) for patients with degenerative spondylolisthesis during a 2-year follow-up. Methods: Patients with symptomatic degenerative spondylolisthesis who underwent OLIF (OLIF group) or TLIF (TLIF group) were prospectively enrolled in the authors' hospital and followed up for 2 years. The primary outcomes were treatment effects [changes in visual analog score (VAS) and Oswestry disability index (ODI) from baseline] at 2 years after surgery; these were compared between two groups. Patient characteristics, radiographic parameters, fusion status, and complication rates were also compared. Results: In total, 45 patients were eligible for the OLIF group and 47 patients for the TLIF group. The rates of follow-up were 89% and 87% at 2 years, respectively. The comparisons of primary outcomes demonstrated no different changes in VAS-leg (OLIF, 3.4 vs. TLIF, 2.7), VAS-back (OLIF, 2.5 vs. TLIF, 2.1), and ODI (OLIF, 26.8 vs. TLIF, 30). The fusion rates were 86.1% in the TLIF group and 92.5% in the OLIF group at 2 years (P = 0.365). The OLIF group had less estimated blood loss (median, 200 ml) than the TLIF group (median, 300 ml) (P < 0.001). Greater restoration of disc height was obtained by OLIF (mean, 4.6 mm) than the TLIF group (mean, 1.3 mm) in the early postoperative period (P < 0.001). The subsidence rate was lower in the OLIF group than that in the TLIF group (17.5% vs. 38.9%, P = 0.037). The rates of total problematic complications were not different between the two groups (OLIF, 14.6% vs. TLIF, 26.2%, P = 0.192). Conclusion: OLIF did not show better clinical outcomes than TLIF for degenerative spondylolisthesis, except for lesser blood loss, greater disc height restoration, and lower subsidence rate.

Lumbar Lordosis Distribution in Asymptomatic Adult Volunteers: A Systematic Review.

Background: Restoring lumbar lordosis is important for adult spinal deformity surgery. Several reports have suggested that lumbar lordosis distribution has a significant impact on the outcome of surgery, including lumbar distribution index (LDI), proximal lumbar lordosis (PLL), and distal lumbar lordosis (DLL). The features of lumbar lordosis distribution are inconclusive in asymptomatic adults. Questions/Purposes: We sought to evaluate the variation of lumbar lordosis distribution (LDI, PLL, and DLL) and to identify associated factors in asymptomatic adult volunteers. Methods: We performed a systematic review of the Embase and Medline databases to identify studies in asymptomatic adult volunteers to evaluate lumbar lordosis distribution including LDI, PLL, and DLL. Results: Twelve articles met eligibility criteria and were included in our review. The respective pooled estimates of mean and variance, respectively, were 65.10% (95% confidence interval [CI]: 62.61-67.58) and 13.70% in LDI, 16.51° (95% CI: 5.54-27.49) and 11.46° in PLL, and 35.47° (95% CI: 32.79-38.18) and 9.10° in DLL. Lumbar lordosis distribution was associated with race, age, sex, body mass index, pelvic incidence, and Roussouly classification. Conclusions: This systematic review found that despite a wide variation in LDI and PLL, DLL is maintained in a narrower range in asymptomatic adult volunteers, especially in white populations. Distal lumbar lordosis may be a more reliable radiographic parameter to restore the lumbar lordosis distribution in preoperative planning.

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.

Pear-Shaped Disk as a Risk Factor for Intraoperative End Plate Injury in Oblique Lumbar Interbody Fusion.

BACKGROUND: Intraoperative end plate injury can result in late-onset cage subsidence in oblique lumbar interbody fusion (OLIF). This study aimed to identify risk factors for intraoperative end plate injury and investigate whether a pear-shaped disk correlated with intraoperative end plate injury in OLIF. METHODS: We retrospectively reviewed 102 levels in 82 patients (mean age 60.1 ± 10.0 years) who underwent OLIF for degenerative lumbar diseases. Intraoperative end plate injury was evaluated using midline sagittal computed tomography views at 3 days postoperatively and defined as cage breaching into an adjacent cortical end plate >2 mm. Patient demographics, surgical parameters, radiographic parameters, and cage-related parameters were recorded in all surgical levels. Evaluation of risk factors associated with intraoperative end plate injury was performed. Patient-reported outcome, fusion status, and late-onset cage subsidence were analyzed at a minimum of 1 year after the surgery. RESULTS: Intraoperative end plate injury was observed in 26 levels (25.5%). Multivariate logistic regression analysis identified that bone mineral density (odds ratio [OR] = 0.978), preoperative segmental lordosis (OR = 0.790), and pear-shaped disk were risk factors (OR = 5.837) for intraoperative end plate injury. Intraoperative end plate injury occurred in 45.5% of levels with a pear-shaped disk compared with 16.0% of levels with no pear-shaped disk (P < 0.01). Late-onset cage subsidence was significantly more frequent in the injury group than the no-injury group. Patient-reported outcome and fusion status were unrelated to intraoperative end plate injury. CONCLUSIONS: A pear-shaped disk is the greatest risk factor for intraoperative end plate injury following OLIF.

Accuracy and Reliability of Standing Lateral Lumbar Radiographs for Measurements of Spinopelvic Parameters.

STUDY DESIGN: Retrospective observational study. OBJECTIVE: To assess the accuracy and reliability of standing lateral lumbar radiographs for measurements of spinopelvic parameters, compared with whole-spine EOS® images. SUMMARY OF BACKGROUND DATA: Lateral lumbar radiographs are commonly used for measurements of spinopelvic parameters. However, variable magnifications by fan-beam x-ray projection at margins may cause measurement errors. METHODS: Fifty consecutive patients with standing lateral lumbar radiographs and whole-spine EOS® images were retrospectively reviewed from March to July in 2019. Two orthopedic surgeons (observers) independently measured the spinopelvic parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and lumbar lordosis (LL) on the computers. These spinopelvic parameters of each patient were measured twice on both lateral lumbar radiograph and EOS® image by two observers with the usage of Surgimap software. The measurement difference and agreement of each parameter value between lateral lumbar radiographs and EOS® images were analyzed by paired t test and the interclass correlation coefficient (ICC) respectively. Intra- and inter-observer's reliabilities of both imaging methods were assessed by ICC. RESULTS: The measurement difference of each spinopelvic parameter on EOS® images and lateral lumbar radiographs was less than 1° on average. Only the measurement difference of PI value revealed statistically significant (P = 0.020) with 0.9° discrepancy (95% confidential interval: 0.2-1.6), which indicated no clinical significance. The ICC values of lateral lumbar radiographs and EOS® images were more than 0.870 (range, 0.872-0.976), thus showed good to excellent measurement agreement between both imaging methods. All the ICC values for evaluating intra- and inter-observer reliability were greater than 0.960 (range, 0.963-0.993), indicating excellent reliability for observer's measurements. CONCLUSION: Measurements of spinopelvic parameters (PI, PT, SS, and LL) on standing lateral lumbar radiographs are accurate and reliable, which are comparable to whole-spine EOS® images.Level of Evidence: 3.

Posterior fixation can further improve the segmental alignment of lumbar degenerative spondylolisthesis with oblique lumbar interbody fusion.

BACKGROUND: For patients with degenerative spondylolisthesis, whether additional posterior fixation can further improve segmental alignment is unknown, compared with stand-alone cage insertion in oblique lumbar interbody fusion (OLIF) procedure. The aim of this study was to compare changes of the radiographical segmental alignment following stand-alone cage insertion and additional posterior fixation in the same procedure setting of OLIF for patients with degenerative spondylolisthesis. METHODS: A retrospective observational study. Selected consecutive patients with degenerative spondylolisthesis underwent OLIF procedure from July 2017 to August 2019. Five radiographic parameters of disc height (DH), DH-Anterior, DH-Posterior, slip ratio and segmental lordosis (SL) were measured on preoperative CT scans and intraoperative fluoroscopic images. Comparisons of those radiographic parameters prior to cage insertion, following cage insertion and following posterior fixation were performed. RESULTS: A total of thirty-three patients including six males and twenty-seven females, with an average age of 66.9 ± 8.7 years, were reviewed. Totally thirty-six slipped levels were assessed with thirty levels at L4/5, four at L3/4 and two at L2/3. Intraoperatively, with only anterior cage support, DH was increased from 8.2 ± 1.6 mm to 11.8 ± 1.7 mm (p < 0.001), DH-Anterior was increased from 9.6 ± 2.3 mm to 13.4 ± 2.1 mm (p < 0.001), DH-Posterior was increased from 6.1 ± 1.9 mm to 9.1 ± 2.1 mm (p < 0.001), the slip ratio was reduced from 11.1 ± 4.6% to 8.3 ± 4.4% (p = 0.020) with the slip reduction ratio 25.6 ± 32.3%, and SL was slightly changed from 8.7 ± 3.7° to 8.3 ± 3.0°(p = 1.000). Following posterior fixation, the DH was unchanged (from 11.8 ± 1.7 mm to 11.8 ± 2.3 mm, p = 1.000), DH-Anterior and DH-Posterior were slightly changed from 13.4 ± 2.1 mm and 9.1 ± 2.1 mm to 13.7 ± 2.3 mm and 8.4 ± 1.8 mm respectively (P = 0.861, P = 0.254), the slip ratio was reduced from 8.3 ± 4.4% to 2.1 ± 3.6% (p < 0.001) with the slip reduction ratio 57.9 ± 43.9%, and the SL was increased from 8.3 ± 3.0° to 10.7 ± 3.6° (p = 0.008). CONCLUSIONS: Compared with stand-alone cage insertion, additional posterior fixation provides better segmental alignment improvement in terms of slip reduction and segmental lordosis in OLIF procedures in the treatment of lumbar degenerative spondylolisthesis.

Vitrectomy with fovea-sparing ILM peeling versus total ILM peeling for myopic traction maculopathy: A meta-analysis.

PURPOSE: To evaluate the effect and safety of fovea-sparing internal limiting membrane (ILM) peeling (FSIP) for myopic traction maculopathy comparing with that of total ILM peeling (TP). METHODS: PubMed, Web of science, Embase, Cochrane, EBSCO and CNKI, published until January 2020, were searched. Postoperative best-corrected visual acuity (BCVA), postoperative central foveal thickness (CFT), the rate of visual improvement and anatomic success were the main outcome parameters, and the secondary outcome parameters were postoperative complications. Random-effects models were chosen in regard with multi-studies. Standard mean difference (SMD) with 95% confidence interval (CI) and odds ratio (OR) were applied as effect sizes of continuous and binomial data, respectively. RESULTS: Six comparative studies involving 193 eyes were included. Better postoperative BCVA was detected in the FSIP group (SMD = -0.39, 95%CI: -0.69 to -0.09, p = 0.01). The FSIP group had a higher rate of vision improvement with statistical significance (OR = 3.86, 95%CI: 1.36 to 10.97, p = 0.01). Both surgical methods had similar outcomes for postoperative CFT (SMD = 0.07, 95%CI: -0.27 to 0.40, p = 0.70). The FSIP group had a higher rate of anatomic success, though there was no obvious significance (OR = 2.54, 95%CI: 0.96 to 6.74, p = 0.06). For the development of postoperative full-thickness macular hole (FTMH), the rate was lower in the FSIP group (OR = 0.18, 95%CI: 0.05 to 0.64, p = 0.008). CONCLUSION: Vitrectomy with fovea-sparing ILM peeling for myopic traction maculopathy could gain better visual outcomes and decrease incidence of FTMH development, though there was no obvious difference in postoperative CFT and the rate of anatomic success between two groups.

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.

Guideline for Thoracolumbar Pedicle Screw Placement Assisted by Orthopaedic Surgical Robot.

The pedicle screw placement procedure is the most commonly used technique for spinal fixation and can provide reliable three-column stabilization. Accurate screw placement is necessary in clinical practice. To avoid screw malposition, which may decrease the stiffness of the screw-rod construct or increase the likelihood of neural and vascular injuries, the surgeons must fully understand the regional anatomy. Deformities, such as scoliosis, kyphosis or congenital anomalies, may complicate the application of the pedicle screw placement technique and increase the chance of screw encroachments. Incidences of pedicle screw malposition vary in different districts and hospitals and with surgeons and techniques. Today, the minimally invasive spinal surgery is well developed. However, the narrow corridors and limited views for surgeons increase the difficulty of pedicle screw placement and the possibility of screw encroachment. Evidenced by previous studies, robotic surgery can provide accurate screw placement, especially in settings of spinal deformities, anatomical anomalies, and minimally invasive procedures. Based on the consensus of consultant specialists, the literature review and our local experiences, this guideline introduces the robotic system and describes the workflow of robot-assisted procedures and the precautions to take during procedures. This guideline aims to outline a standardized method for robotic surgery for thoracolumbar pedicle screw placement.

Guideline for Posterior Atlantoaxial Internal Fixation Assisted by Orthopaedic Surgical Robot.

Atlantoaxial transarticular facet screw fixation (Magerl technique) and C1 lateral mass screws combined with C2 pedicle screws fixation (Harms technique) are the most commonly used techniques for posterior internal fixation in the upper cervical spine. Upper cervical spinal surgery is a technically demanding and challenging procedure because of complicated anatomical structures and frequent occurrence of anomalies. Accurate insertion of screws allows for stable and secure internal fixation, which is necessary for both techniques. Traditional methods under fluoroscopic assistance in this region cannot meet the requirements of high levels of accuracy and security during the procedure. Robot-assisted spinal surgery can provide accurate and reliable guidance during the screw insertion, which is evidenced in the literature. As a recently developed technique, robot-assisted surgery is supposed to be performed by skilled surgeons who have received standard training for robotic surgery. The standardized upper cervical spinal surgery assisted by the robot system needs to be introduced to these surgeons. Based on the consensus of consultant specialists, the literature review, and our local experience, this guideline included the introduction of the robotic system, the workflow of robot-assisted procedures, and the precautions to take during procedures. This guideline aims to provide a standardization of the robotic surgery for posterior atlantoaxial internal fixation.

Robot-assisted Percutaneous Transfacet Screw Fixation Supplementing Oblique Lateral Interbody Fusion Procedure: Accuracy and Safety Evaluation of This Novel Minimally Invasive Technique.

OBJECTIVES: Percutaneous transfacet screw fixation (pTSF) is a minimally invasive posterior fixation technique supplementing oblique lateral interbody fusion (OLIF) for lumbar spinal disorders. Accurate screw insertion is difficult to achieve and technically demanding under 2-D fluoroscopy. Recently developed robot-assisted spinal surgery demonstrated a high level of accuracy of pedicle screw insertion and a low complication rate. No published study has reported this combination technique. The aim of our study was to evaluate the accuracy and safety properties of the combination of both minimally invasive techniques: robot-assisted pTSF supplementing the OLIF procedure. METHODS: This was an experimental and prospective study. Selected consecutive patients with lumbar degenerative disorders received robot-assisted pTSF supplementing the OLIF procedure using the TianJi Robot system operated by one senior surgeon from March to October 2018. The accuracy of screw insertion and perioperative screw-related complications were evaluated. Assessment of the accuracy of screw insertion included intraoperative robotic guidance accuracy and incidence of screw encroachments. Intraoperative robotic guidance accuracy referred to translational and angular deviations of screws, which were assessed by comparing the planned and actual screw trajectories guided by the robot on reconstructed images using TianJi Robot Planning Software. Screw encroachments were evaluated on postoperative CT images and classified by a grading system (A, excellent; B, good; C, poor). Screw-related complications including intraoperative pin skidding, screw malposition and adjustment, together with postoperative neurological symptoms that correlated with screw malposition were recorded. RESULTS: Ten patients, with an average age of 60.2 years, were selected and recruited in this study. All cases were degenerative lumbar spinal disorders, out of which there were 6 cases of Meyerding Grade I degenerative spondylolisthesis. Twenty-four transfacet screws were inserted by robotic assistance. Instrumented levels included nine segments at L4-5 level and three segments at L3-4 level. Two patients had both L4-5 and L3-4 level fixation. The average surgical time was 3.3 h (SD, 0.8 h). The mean blood loss was 90 mL (SD, 32 mL). Intraoperative guidance accuracy showed 1.09 ± 0.17 mm (ranging from 0.75 to 1.22 mm) translational deviation and 2.17° ± 0.39° (ranging from 1.47° to 2.54°) angular deviation. The gradings of screw encroachment were: 17 screws (71%) with Grade A, 6 screws (25%) with Grade B, and 1 screw (4%) with Grade C. Only one pin skidding occurred intraoperatively and revised subsequently. No postoperative neurological complications were found. CONCLUSION: Our preliminary study of robot-assisted pTSF supplementing the OLIF procedure showed a high level of accuracy for screw insertion and this minimally invasive combination technique was found to be a feasible and safe procedure.

Clinical evaluation of the polymethylmethacrylate-augmented thoracic and lumbar pedicle screw fixation guided by the three-dimensional navigation for the osteoporosis patients.

PURPOSE: To evaluate the safety and efficacy of three-dimensional (3D) navigation-guided polymethylmethacrylate (PMMA)-augmented thoracic and lumbar pedicle screw fixation for the osteoporotic patients. METHODS: 27 consecutive osteoporosis patients with a variety of spinal disorders who underwent 3D navigation-guided PMMA-augmented pedicle screw fixation were evaluated clinically and radiologically in the perioperative and 1-year follow-up period. The improvement of Japanese Orthopaedic Association (JOA) scores was analyzed. PMMA leakage and other complications were inspected intraoperatively and postoperatively. Screw loosening and bone fusion were evaluated radiographically during follow-up. RESULTS: 8 patients had thoracic and lumbar fractures; 18 patients had degenerative spinal disorders; one patient had revision surgery. One patient died of postoperative pneumonia. Each of the other 26 patients was followed up regularly at 3, 6, 12 and 18 months postoperatively. The mean therapeutic improvement rate is 39.6% evaluated by JOA scores. 2 patients (7.4%) had leakage into the spinal canal in front of the posterior longitudinal ligament and two patients (7.4%) had leakage into the prevertebral soft tissue inspected by the postoperative CT scans. No pedicle cortex breach and cement leakage surrounding pedicle cortex were observed. None of patients complained of dyspnoea and showed evidence of pulmonary embolism. Bone fusions were found in 20 patients (bony fusion rate 76.9%) at the 12-month follow-up and no screw loosening occurs. CONCLUSION: The results show favorable outcome using 3D navigation-guided PMMA-augmented thoracic and lumbar pedicle screw fixation for the osteoporosis patients both clinically and radiologically.

[Use sagittal reconstruction CT for making decisions regarding the surgical strategy for cervical ossification of the posterior longitudinal ligament].

OBJECTIVE: Use sagittal reconstruction CT to verify the surgical strategy for cervical ossification of the posterior longitudinal ligament (OPLL). METHODS: A retrospective study of 161 patients (106 males and 55 females) who had undergone surgery for OPLL from July 2007 to November 2010 was performed. The mean age at surgery was 54.5 years (range from 26 to 77 years). The mean follow-up period was 28 months (12 - 54 months). There were 40 patients accept anterior approach surgeries (anterior group) which include 14 cases of anterior cervical corpectomy and fusion and 26 cases of anterior cervical discectomy and fusion. There were 120 patients accept posterior approach surgeries (posterior group) which was spinous process-splitting laminoplasty for cervical myelopathy using coralline hydroxyapatite. One patient accepted combined anterior and posterior approach. According to the sagittal reconstruction CT, the main reason for spinal cord compression was cervical disc herniation in anterior group, and OPLL in posterior group. The level of spinal cord compression was 1 to 2 levels in anterior group, and 1 to 5 levels in posterior group with a major of 2 to 4 levels. As the classification of OPLL, segmental type and circumscribed type were major of segmental type in anterior group and all of the four types were in posterior group, the distribution of each type was average. The patients of posterior group were classified into two groups according to the modified K-line classification, and clinical results were compared between the two groups. The modified K-line was defined as a line that connects the midpoints of the spinal canal at C(2) and C(7) on sagittal CT myelography. Compression to the spinal cord did not exceed the K-line in the modified K-line(+) group and did exceed it in the modified K-line(-) group. Clinical data were compared using t-test or χ(2) test. Correlation analysis was used to determine the relationships of C(2)-C(7) angulation between sagittal reconstruction CT and neutral position X-ray. RESULTS: The patient of anterior group had better recovery rate of the JOA score (72% ± 27%) than the posterior group (59% ± 35%) at the latest follow-up (t = 2.238, P = 0.027). In posterior group, the patients of modified K-line(+) group had better recovery rate of the JOA score (63% ± 37%) than the K-line(-) group (49% ± 30%) at the latest follow up (t = 2.150, P = 0.034). The C(2)-C(7) angulation on sagittal reconstruction CT was 11° ± 9° which has significantly correlated with the C(2)-C(7) angulation on neutral position X-ray which was 10° ± 10° (r = 0.947, P < 0.01). CONCLUSIONS: Considering the selection of surgical approach, it should be combined with the main clinical diagnosis for spinal cord compression, the level of compression, the classification of OPLL and the kyphotic alignment of the cervical spine. The modified K-line is a simple and practical tool for making decisions regarding the surgical strategy for cervical OPLL patients.