Detection of Cervical Foraminal Stenosis from Oblique Radiograph Using Convolutional Neural Network Algorithm.

PURPOSE: This study was conducted to develop a convolutional neural network (CNN) algorithm that can diagnose cervical foraminal stenosis using oblique radiographs and evaluate its accuracy. MATERIALS AND METHODS: A total of 997 patients who underwent cervical MRI and cervical oblique radiographs within a 3-month interval were included. Oblique radiographs were labeled as "foraminal stenosis" or "no foraminal stenosis" according to whether foraminal stenosis was present in the C2-T1 levels based on MRI evaluation as ground truth. The CNN model involved data augmentation, image preprocessing, and transfer learning using DenseNet161. Visualization of the location of the CNN model was performed using gradient-weight class activation mapping (Grad-CAM). RESULTS: The area under the curve (AUC) of the receiver operating characteristic curve based on DenseNet161 was 0.889 (95% confidence interval, 0.851-0.927). The F1 score, accuracy, precision, and recall were 88.5%, 84.6%, 88.1%, and 88.5%, respectively. The accuracy of the proposed CNN model was significantly higher than that of two orthopedic surgeons (64.0%, p<0.001; 58.0%, p<0.001). Grad-CAM analysis demonstrated that the CNN model most frequently focused on the foramen location for the determination of foraminal stenosis, although disc space was also frequently taken into consideration. CONCLUSION: A CNN algorithm that can detect neural foraminal stenosis in cervical oblique radiographs was developed. The AUC, F1 score, and accuracy were 0.889, 88.5%, and 84.6%, respectively. With the current CNN model, cervical oblique radiography could be a more effective screening tool for neural foraminal stenosis.

The Perioperative Effects of Preoperative Radiotherapy in Metastatic Spinal Tumor Patients.

OBJECTIVE: Radiotherapy is one of the important treatment options for metastatic spinal tumors but is not the definite intervention in all cases, as there are patients who still require surgical treatment because of severe pain or neurologic events after this treatment. We evaluated the perioperative effects of preoperative radiotherapy in these cases as a future guide for surgeons on critical considerations in this period. METHODS: We included 328 patients in this study who had undergone decompression and fusion surgery for metastatic spinal tumors. Patients who underwent surgery with preoperative radiotherapy were designated as the radiotherapy group (group RT, n = 81), and cases of surgery without preoperative radiotherapy were assigned to the non-radiotherapy group (group nRT, n = 247). We compared the demographic, intraoperative, and postoperative factors between these 2 groups. RESULTS: In terms of intraoperative factors, statistically significant differences were evident in operation time, estimated blood loss, and transfusion (RT vs. nRT: 188.1 ± 80.7 minutes vs. 231.2 ± 106.1 minutes, 607.2 ± 532.7 mL vs. 830.1 ± 1324.7 mL, and 30.9% vs. 43.3%, P < 0.001, P < 0.031, and P < 0.048, respectively). With regard to postoperative factors, the incidence of infection, wound problems, and local recurrence were statistically higher in group RT (RT vs. nRT: 6.2% vs. 0.8%, 12.3% vs. 0.8%, 23.4% vs. 13.7%, P = 0.004, P < 0.001, and P = 0.038, respectively). CONCLUSIONS: Preoperative radiotherapy has the intraoperative advantages of reducing bleeding and shortening the operating time, but postoperative caution is needed because of the possibility of infection, wound problems, and local recurrence increases.

Risk factors of revision operation and early revision for adjacent segment degeneration after lumbar fusion surgery: a case-control study.

BACKGROUND CONTEXT: Adjacent segment degeneration (ASD) following lumbar fusion operation is common and can occur at varying timepoints after index surgery. An early revision operation for ASD, however, signifies a short symptom-free period and might increase the risk of successive surgeries. PURPOSE: We aimed to elucidate the overall risk factors associated with revision surgeries for ASD with distinct attention to early revisions. STUDY DESIGN/SETTING: Retrospective, case-control study. PATIENT SAMPLE: The study included 86 patients who underwent revision operations for ASD after lumbar fusion in the revision group and 166 patients who did not for at least 5 years after index surgery. OUTCOME MEASURES: Sagittal parameters, Pfirrmann grading, facet degeneration grading, and disc space height (DSH) of adjacent segments were assessed. METHODS: Revision operations within 5 years postsurgery were defined as early revision. We compared the revision and no-revision groups as well as the early- and late-revision groups. RESULTS: The revision group demonstrated a significantly greater preoperative C7-S1 sagittal vertical axis (SVA) (p=.001), postoperative C7-S1 SVA (p<.001), and postoperative pelvic incidence (PI)-lumbar lordosis (LL) (p<.001) than those in the no-revision group. Preoperative DSH of the proximal adjunct segment (p=.001), postoperative PI-LL (p=.014), and postoperative C7-S1 SVA (p=.037) exhibited significant association with ASD in logistic regression analysis. The early-revision group had a significantly higher patient age (p=.001) and a greater number of levels fused (p=.030) than those in the late-revision group. Multivariate Cox regression analysis demonstrated that old age (p=.045), a significant number of levels fused (p=.047), and a narrow preoperative DSH of the proximal adjacent level (p=.011) were risk factors for early revision. CONCLUSIONS: Postoperative sagittal imbalance, including significant PI-LL and C7-S1 SVA were risk factors for revision operation for ASD but not for early revision. These factors are likely to affect the long-term risk of revision operation due to ASD and thus are not considered risk factors for early revision. Narrow DSH of the proximal adjacent level increased the risks of both revision and early revision surgeries. Moreover, old age and a significant number of levels fused further increased the risk for early revision for ASD.

Reoperation Rates According to Surgical Approach After Operation for Degenerative Cervical Pathology in Patients With Athetoid Cerebral Palsy: A Nationwide Cohort Study.

STUDY DESIGN: National population-based cohort study. OBJECTIVE: The overall complication rate for patients with athetoid cerebral palsy (CP) undergoing cervical surgery is significantly higher than that of patients without CP. The study was conducted to compare the reoperation and complication rates of anterior fusion, posterior fusion, combined fusion, and laminoplasty for degenerative cervical myelopathy/radiculopathy in patients with athetoid cerebral palsy. METHODS: The Korean Health Insurance Review and Assessment Service national database was used for analysis. Data from patients diagnosed with athetoid CP who underwent cervical spine operations for degenerative causes between 2002 and 2020 were reviewed. Patients were categorized into four groups for comparison: anterior fusion, posterior fusion, combined fusion, and laminoplasty. RESULTS: A total of 672 patients were included in the study. The overall revision rate was 21.0% (141/672). The revision rate was highest in the anterior fusion group (42.7%). The revision rates of combined fusion (11.1%; hazard ratio [HR], .335; P = .002), posterior fusion (13.8%; HR, .533; P = .030) were significantly lower than that of anterior fusion. Revision rate of laminoplasty (13.1%; HR, .541; P = .240) was also lower than anterior fusion although the result did not demonstrate statistical significance. CONCLUSION: Anterior fusion presented the highest reoperation risk after cervical spine surgery reaching 42.7% in patients with athetoid CP. Therefore, anterior-only fusion in patients with athetoid CP should be avoided or reserved for strictly selected patients. Combined fusion, with the lowest revision risk at 11.1%, could be safely applied to patients with athetoid CP.

Does Preoperative Radiation Therapy Performed for Metastatic Spine Cancer at the Cervical Spine Increase Perioperative Complications of Anterior Cervical Surgery?

Background: Radiation therapy (RT) performed before anterior cervical spine surgery (ACSS) may cause fascial plane fibrosis, decreased soft-tissue vascularity, and vertebral body weakness, which could increase the risk of esophageal and major vessel injuries, wound complications, and construct subsidence. Therefore, this study aimed to evaluate whether preoperative RT performed for metastatic spine cancer (MSC) at the cervical spine increases perioperative morbidity for ACSS. Methods: Forty-nine patients who underwent ACSS for treatment of MSC at the cervical spine were retrospectively reviewed. All the patients underwent anterior cervical corpectomy via the anterior approach. Patient demographics, surgical factors, operative factors, and complications were recorded. Results of patients who were initially treated with RT before ACSS (RT group) were compared with those who did not receive RT before ACSS (non-RT group). Results: Eighteen patients (36.7%) were included in the RT group, while the remaining 31 (63.3%) were included in the non-RT group. Surgery-related factors, including operation time (p = 0.109), estimated blood loss (p = 0.246), amount of postoperative drainage (p = 0.604), number of levels operated (p = 0.207), and number of patients who underwent combined posterior fusion (p = 0.768), did not significantly differ between the 2 groups. Complication rates, including esophageal injury, dural tear, infection, wound dehiscence, and mechanical failure, did not significantly differ between the RT and non-RT groups. Early subsidence was significantly greater in the non-RT group compared to that in the RT group (p = 0.012). Conclusions: RT performed before surgery for MSC does not increase the risk of wound complication, mechanical failure, or vital structure injury during ACSS. The surgical procedural approach was not complicated by previous RT history. Therefore, surgeons can safely choose the anterior approach when the number of levels or location of MSC favors anterior surgery, and performing a posterior surgery is unnecessary due to a concern that previous RT may increase complication rates of ACSS.

XFEL structure of carbonic anhydrase II: a comparative study of XFEL, NMR, X-ray and neutron structures.

The combination of X-ray free-electron lasers (XFELs) with serial femtosecond crystallography represents cutting-edge technology in structural biology, allowing the study of enzyme reactions and dynamics in real time through the generation of `molecular movies'. This technology combines short and precise high-energy X-ray exposure to a stream of protein microcrystals. Here, the XFEL structure of carbonic anhydrase II, a ubiquitous enzyme responsible for the interconversion of CO2 and bicarbonate, is reported, and is compared with previously reported NMR and synchrotron X-ray and neutron single-crystal structures.

Connecting the S2 alar-iliac screw head to the satellite rod for surgical correction of degenerative sagittal imbalance.

PURPOSE: The S2AI screw technique has several advantages over the conventional iliac screw fixation technique. However, connecting the S2AI screw head to the main rod is difficult due to its medial entry point. We introduce a new technique for connecting the S2AI screw head to a satellite rod and compare it with the conventional method of connecting the S2AI screw to the main rod. METHODS: Seventy-four patients who underwent S2AI fixation for degenerative sagittal imbalance and were followed up for ≥ 2 years were included. All the patients underwent long fusion from T9 or T10 to the pelvis. The S2AI screw head was connected to the satellite rod (SS group) in 43 patients and the main rod (SM group) in 31 patients. In the SS group, the satellite rod was placed medial to the main rod and connected by the S2AI screw and domino connectors. In the SM group, the main rod was connected directly to the S2AI screw head and supported by accessory rods. Radiographic and clinical outcomes were evaluated in both groups. RESULTS: There were no significant differences in postoperative complications, including proximal junctional failure, proximal junctional kyphosis, rod breakage, screw loosening, wound problems, and infection between the two groups. Furthermore, the correction power of sagittal deformity and clinical results in the SS group were comparable to those in the SM group. CONCLUSION: Connecting the S2AI screw to the satellite rod is a convenient method comparable to the conventional S2AI connection method in terms of radiological and clinical outcomes.

Preoperative Radiographic Simulation for Partial Uncinate Process Resection during Anterior Cervical Discectomy and Fusion to Achieve Adequate Foraminal Decompression and Prevention of Vertebral Artery Injury.

STUDY DESIGN: Retrospective radiographic study. PURPOSE: This study aims to demonstrate the proper resection trajectory of a partial posterior uncinate process resection combined with anterior cervical discectomy and fusion (ACDF) and evaluate whether foraminal stenosis or uncinate process degeneration increases the risk of vertebral artery (VA) injury. OVERVIEW OF LITERATURE: Appropriate resection trajectory that could result in sufficient decompression and avoid vertebral artery injury is yet unknown. METHODS: We retrospectively reviewed patients who underwent cervical magnetic resonance imaging and computed tomography angiography for preoperative ACDF evaluation. The segments were classified according to the presence of foraminal stenosis. The height, thickness, anteroposterior length, horizontal distance from the uncinate process to the VA, and vertical distance from the uncinate process baseline to the VA of the uncinate process were measured. The distance between the uncinate anterior margin and the resection trajectory (UAM-to-RT) was measured. RESULTS: There were no VA injuries or root injuries among the 101 patients who underwent ACDF (163 segments, mean age of 56.3±12.2). Uncinate anteroposterior length was considerably longer in foramens with foraminal stenosis, whereas uncinate process height, thickness, and distance between the uncinate process and VA were not significantly associated with foraminal stenosis. There were no significant differences in radiographic parameters based on uncinate degeneration. The UAM-to-RT distances for adequate decompression were 1.6±1.4 mm (range, 0-4.8 mm), 3.4±1.7 mm (range, 0-7.1 mm), 4.0±1.7 mm (range, 0-9.0 mm), and 4.5±1.2 mm (range, 2.5-7.5 mm) for C3-C4, C4-C5, C5-C6, and C6-C7, respectively. CONCLUSIONS: More than half of the uncinate process in the anteroposterior plane should be removed for adequate neural foramen decompression. Foraminal stenosis or uncinate degeneration did not alter the relative anatomy of the uncinate process and the VA and did not impact VA injury risk.

Risk Factors for Postoperative Loss of Lordosis, Cervical Kyphosis, and Sagittal Imbalance After Cervical Laminoplasty.

OBJECTIVE: A retrospective cohort study was undertaken to elucidate the risk factors of loss of cervical lordosis (LCL), kyphotic deformity, and sagittal imbalance after cervical laminoplasty. METHODS: A total of 108 patients who underwent laminoplasty to treat cervical myelopathy and were followed for ≥2 years were included. Logistic regression analysis and multiple regression analysis were performed to identify preoperative risk factors of LCL, kyphotic deformity (cervical lordosis <0°), and sagittal imbalance (sagittal vertical axis >40 mm) at postoperative 2 years. RESULTS: Within multivariate multiple regression analysis, C2-C7 lordosis (P = 0.002), and C2-C7 extension capacity (P<0.001) showed significant association with LCL. Furthermore, age (P = 0.043) and C2-C7 lordosis (P = 0.038) were significantly associated with postoperative kyphosis. Receiver operating characteristic curve analysis for postoperative kyphosis showed that preoperative C2-C7 lordosis of 10.5° had a sensitivity and specificity of 81.3% and 82.4%, respectively. Preoperative K-line tilt (P = 0.034) showed a significant association with postoperative cervical sagittal imbalance at postoperative 2 years. Receiver operating characteristic curve analysis showed that a K-line tilt cutoff value of 12.5° had a sensitivity and specificity of 78.6% and 77.7%, respectively, for predicting postoperative sagittal imbalance. CONCLUSIONS: Higher preoperative C2-C7 lordosis and less preoperative cervical extension capacity were risk factors of LCL. Small preoperative C2-C7 lordosis <10.5° and younger age were risk factors of postoperative kyphosis. Furthermore, a greater K-line tilt would increase the risk of postoperative sagittal imbalance, with a cutoff value of 12.5°.

Atrophy of the Posterior Cricoarytenoid Muscle as an Indicator of a Recurrent Laryngeal Nerve Injury History Before Revision Anterior Cervical Spine Surgery.

STUDY DESIGN: Retrospective study. OBJECTIVES: In our recent study, we observed some cases of symptomatic normal vocal cord motility instead of asymptomatic vocal cord palsy (VCP) in preoperative laryngoscopy of a revision anterior cervical spine surgery (ACSS) cohort. We assumed the intrinsic muscle atrophy caused by recurrent laryngeal nerve injury could cause vocal cord-related symptoms. Thus, radiological examinations were reviewed in relation to the posterior cricoarytenoid (PCA) muscle, one of the intrinsic muscles. METHODS: We retrospectively analyzed 64 patients who underwent a revision ACSS. Patients with vocal cord-related symptoms were classified as symptomatic group (group S, n = 11), and those without symptoms as asymptomatic group (group AS, n = 53). The bilateral size and signal intensity of the PCA muscles in these patients were measured in the axial view with preoperative computed tomography (CT) and magnetic resonance imaging (MRI) evaluations. Since the size and signal intensity values were different on each image, the ratios of the contralateral and ipsilateral muscle values were analyzed for each modality. RESULTS: There was no VCP on laryngoscopy study. However, the mean ratio of the PCA muscle size on CT was 1.40 ± .37 in group S and 1.02 ± .12 in group AS (P = .007). These values on the MRI were 1.49 ± .45 in group S and 1.02 ± .14 in group AS, which was also a significant difference (P = .008). CONCLUSIONS: Evaluating the size of the PCA muscle before revision ACSS may predict a previous recurrent laryngeal nerve injury. Careful planning for the appropriate approach should be undertaken if vocal cord-related symptoms and atrophy of PCA muscle are evident.

Structure-based drug discovery of a corticotropin-releasing hormone receptor 1 antagonist using an X-ray free-electron laser.

Thus far, attempts to develop drugs that target corticotropin-releasing hormone receptor 1 (CRF1R), a drug target in stress-related therapy, have been unsuccessful. Studies have focused on using high-resolution G protein-coupled receptor (GPCR) structures to develop drugs. X-ray free-electron lasers (XFELs), which prevent radiation damage and provide access to high-resolution compositions, have helped accelerate GPCR structural studies. We elucidated the crystal structure of CRF1R complexed with a BMK-I-152 antagonist at 2.75 Å using fixed-target serial femtosecond crystallography. The results revealed that two unique hydrogen bonds are present in the hydrogen bond network, the stalk region forms an alpha helix and the hydrophobic network contains an antagonist binding site. We then developed two antagonists-BMK-C203 and BMK-C205-and determined the CRF1R/BMK-C203 and CRF1R/BMK-C205 complex structures at 2.6 and 2.2 Å, respectively. BMK-C205 exerted significant antidepressant effects in mice and, thus, may be utilized to effectively identify structure-based drugs against CRF1R.

Optical control of ultrafast structural dynamics in a fluorescent protein.

The photoisomerization reaction of a fluorescent protein chromophore occurs on the ultrafast timescale. The structural dynamics that result from femtosecond optical excitation have contributions from vibrational and electronic processes and from reaction dynamics that involve the crossing through a conical intersection. The creation and progression of the ultrafast structural dynamics strongly depends on optical and molecular parameters. When using X-ray crystallography as a probe of ultrafast dynamics, the origin of the observed nuclear motions is not known. Now, high-resolution pump-probe X-ray crystallography reveals complex sub-ångström, ultrafast motions and hydrogen-bonding rearrangements in the active site of a fluorescent protein. However, we demonstrate that the measured motions are not part of the photoisomerization reaction but instead arise from impulsively driven coherent vibrational processes in the electronic ground state. A coherent-control experiment using a two-colour and two-pulse optical excitation strongly amplifies the X-ray crystallographic difference density, while it fully depletes the photoisomerization process. A coherent control mechanism was tested and confirmed the wave packets assignment.

Does Posterior Cord Compression From the Ligamentum Flavum Influence Clinical Outcomes After Anterior Cervical Discectomy and Fusion?

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To clarify whether outcomes of anterior cervical discectomy and fusion (ACDF) differ according to the presence of posterior cord compression from the ligamentum flavum (CCLF). SUMMARY OF BACKGROUND DATA: Although ACDF effectively addresses anterior cord compression from disc material and bone spurs, it cannot address posterior compression. Whether ACDF could result in favorable outcomes when CCLF is present remains unclear. PATIENTS AND METHODS: A total of 195 consecutive patients who underwent ACDF and were followed up for >2 years were included. CCLF was graded based on magnetic resonance imaging findings. Patients with CCLF grade 2 were classified as such, whereas patients with CCLF grades 0 to 1 were classified as the no-CCLF group. Patient characteristics, cervical sagittal parameters, neck pain visual analog scale, arm pain visual analog scale, and Japanese Orthopedic Association (JOA) score were assessed. Categorical variables were analyzed using a χ 2 test, whereas continuous variables were analyzed using the Student t test. Multivariable logistic regression analysis was performed to elucidate factors associated with JOA recovery rates of >50%. RESULTS: One hundred sixty-seven patients (85.6%) were included in the no-CCLF group, whereas the remaining 28 patients (14.4%) were included in the CCLF group. Among patients in the CCLF group, 14 patients (50.0%) achieved clinical improvement. JOA score significantly improved in the no-CCLF group after the operation ( P < 0.001), whereas improvement was not appreciated in the CCLF group ( P = 0.642). JOA scores at 3 months ( P = 0.037) and 2 years ( P = 0.001) postoperatively were significantly higher in the no-CCLF group. Furthermore, the JOA recovery rate at 2 years after surgery was significantly higher in the no-CCLF group ( P = 0.042). Logistic regression demonstrated that CCLF was significantly associated with a JOA recovery rate of >50% at 2 years after surgery (odds ratio: 2.719; 95% CI: 1.12, 6.60). CONCLUSION: ACDF performed for patients with CCLF grade 2 showed inferior JOA score improvement compared with those with CCLF grade 0 or 1. ACDF cannot remove posterior compressive structures, which limits its utility when ligamentum flavum significantly contributes to cord compression.

Vertebral Body Sliding Osteotomy as a Surgical Strategy for the Treatment of Cervical Myelopathy: Complications and Pitfalls.

OBJECTIVE: This retrospective cohort study has been aimed at evaluating the incidence of complications after vertebral body sliding osteotomy (VBSO) and analyzing some cases. Furthermore, the complications of VBSO were compared with those of anterior cervical corpectomy and fusion (ACCF). METHODS: This study included 154 patients who underwent VBSO (n = 109) or ACCF (n = 45) for cervical myelopathy and were followed up for > 2 years. Surgical complications, clinical and radiological outcomes were analyzed. RESULTS: The most common surgical complications after VBSO were dysphagia (n = 8, 7.3%) and significant subsidence (n = 6, 5.5%). There were 5 cases of C5 palsy (4.6%), followed by dysphonia (n = 4, 3.7%), implant failure (n = 3, 2.8%), pseudoarthrosis (n = 3, 2.8%), dural tears (n = 2, 1.8%), and reoperation (n = 2, 1.8%). C5 palsy and dysphagia did not require additional treatment and spontaneously resolved. The rates of reoperation (VBSO, 1.8%; ACCF, 11.1%; p = 0.02) and subsidence (VBSO, 5.5%; ACCF, 40%; p < 0.01) were significantly lower in VBSO than in ACCF. VBSO restored more C2-7 lordosis (VBSO, 13.9° ± 7.5°; ACCF, 10.1° ± 8.0°; p = 0.02) and segmental lordosis (VBSO, 15.7° ± 7.1°; ACCF, 6.6° ± 10.2°; p < 0.01) than ACCF. The clinical outcomes did not significantly differ between both groups. CONCLUSION: VBSO has advantages over ACCF in terms of low rate of surgical complications related to reoperation and significant subsidence. However, dural tears may still occur despite the lessened need for ossified posterior longitudinal ligament lesion manipulation in VBSO; hence, caution is warranted.

Fate of pseudarthrosis detected 2 years after anterior cervical discectomy and fusion: results of a minimum 5-year follow-up.

BACKGROUND CONTEXT: Prior study has shown that 70% of cervical pseudarthrosis after anterior cervical discectomy and fusion (ACDF) detected at 1 year will go on to fusion by 2 year. Pseudarthrosis detected 2 years after ACDF may have different bone healing potential compared to nonunion detected 1 year after surgery. Therefore, it might have a different clinical significance. PURPOSE: To examine the radiographic and clinical prognosis of pseudarthrosis detected 2 years after ACDF with a minimum follow-up of 5 years. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENTS SAMPLE: A total of 249 patients who completed a 5-year follow-up after ACDF. OUTCOMES MEASURES: Clinical outcomes such as neck pain visual analogue scale (VAS), arm pain VAS, and neck disability index (NDI) and radiographic assessment such as X-ray, computed tomography (CT) scan. METHODS: A total of 249 patients who completed a 5-year follow-up after ACDF were retrospectively reviewed. Patients who were diagnosed with pseudarthrosis at 2 years postoperatively were included. Fusion, neck pain VAS, arm pain VAS, and NDI were assessed. The results were compared between the union group (patients who achieved union), and the nonunion group (patients with pseudarthrosis) at 5 years postoperatively. RESULTS: Among the patients who had pseudarthrosis at 2 years postoperatively, the fusion rate at 5 years was 32.6% (14/43). While the union group showed continued improvements in neck pain VAS, arm pain VAS, and NDI until 5 years, the nonunion group showed significant worsening of arm pain VAS and NDI at 5 years, with the values of neck pain VAS, arm pain VAS, and NDI being significantly worse than those of the union group at 5 years. CONCLUSION: The incidence of pseudarthrosis detected at 2 years postoperatively after ACDF was 67.4%, and it remained unfused at 5 years postoperatively. Nonunion identified 2 years after ACDF may be considered a poor prognostic factor because it has less potential to achieve fusion with further follow-up and a higher chance of worsening clinical symptoms. Therefore, the presence of fusion at the 2-year follow-up can be considered an indicator of the success of the surgery.

Comparison of Fusion, Subsidence, and Clinical Results Between 3D-Printed Porous Titanium Cage and Polyetheretherketone Cage in Posterior Lumbar Interbody Fusion: A Minimum of 2 Years Follow-Up.

OBJECTIVE: The occurrence of early osteointegration and reduced modulus of elasticity have been proved with 3-dimensinally (3D) printed porous titanium (3DP-titanium) cages used for posterior lumbar interbody fusion (PLIF). The present study was conducted to demonstrate the fusion rate, subsidence, and clinical outcomes for the 3DP-titanium cage in PLIF and to compare its results with those of the polyetheretherketone (PEEK) cage. METHODS: A total of 150 patients who underwent 1-2-level PLIF and were followed up for >2 years were retrospectively reviewed. The fusion rates, subsidence, segmental lordosis, visual analog scale (VAS) score for back pain, VAS score for leg pain, and Oswestry disability index were assessed. RESULTS: A higher 1-year (3DP-titanium, 86.9%; PEEK, 67.7%; P = 0.002) and 2-year (3DP-titanium, 92.9%; PEEK, 82.3%; P = 0.037) fusion rate could be achieved with 3DP-titanium cages for PLIF than with PEEK cages. The amount of subsidence (3DP-titanium, 1.4 ± 1.6 mm; PEEK, 1.9 ± 1.8 mm; P = 0.092) and incidence of significant subsidence (3DP-titanium, 17.9%; PEEK, 23.4%; P = 0.389) was not significantly different between the 2 materials. Furthermore, the VAS score for back pain and leg pain and Oswestry disability index were not significantly different between the 2 groups. On logistic regression analysis, cage material (P = 0.027) showed a significant association with fusion, and the number of levels fused (P = 0.012) was associated with subsidence. CONCLUSIONS: The 3DP-titanium cage resulted in a higher fusion rate than the PEEK cage when used for PLIF. The subsidence rate did not differ significantly between the 2 cage materials. Therefore, the 3DP-titanium cage can be safely used for PLIF, considering its stable construct.

Surgical complications and incomplete canal widening of the vertebral body sliding osteotomy to treat cervical myelopathy.

OBJECTIVE: Vertebral body sliding osteotomy (VBSO) is a surgical technique that anteriorly translates the vertebral body with compressive lesions and achieves cord decompression through canal widening. However, data on the surgical complications of VBSO are lacking. Furthermore, it has not been known whether VBSO could be a viable alternative in the treatment of cervical myelopathy even when the preoperative canal-occupying ratio (COR) is large, which seems to frequently result in incomplete canal widening. This study aimed to describe the incidence of VBSO-associated surgical complications and to evaluate the incidence and risk factors of incomplete canal widening. METHODS: A total of 109 patients who underwent VBSO to treat cervical myelopathy were retrospectively reviewed. Neck pain visual analog scale, Neck Disability Index, Japanese Orthopaedic Association (JOA) scores, and surgical complications were evaluated. For radiological evaluation, C2-7 lordosis, C2-7 sagittal vertical axis, and COR were measured. Patients with a preoperative COR < 50% (n = 60) and those with a COR ≥ 50% (n = 49) were compared and logistic regression analysis was performed to identify factors associated with incomplete canal widening. RESULTS: The most frequent complication in the patients was mild dysphagia (7.3%). Dural tears were observed during posterior longitudinal ligament resection (n = 1) and foraminotomy (n = 1). Two patients underwent reoperation due to radiculopathy from adjacent-segment disease. Incomplete canal widening occurred in 49 patients. According to logistic regression analysis, high preoperative COR was the only factor associated with incomplete canal widening. The amount of canal widening and JOA recovery rate in the COR ≥ 50% group were significantly higher than in the COR < 50% group. CONCLUSIONS: Mild dysphagia was the most common complication following VBSO. Although VBSO aims to decrease the complication rate of corpectomy, it was not free of dural tears. Special care would be required during the posterior longitudinal ligament resection. Incomplete canal widening occurred in 45.0% of patients, and high preoperative COR was the only risk factor for incomplete canal widening. However, high preoperative COR would not be a contraindication for VBSO, given that favorable clinical outcomes were presented in the COR ≥ 50% group.

Risk factors for postoperative complaints in patients following lumbar decompression and fusion: Analyses focusing on preoperative symptoms.

BACKGROUND: Several patients complained of residual symptoms following lumbar decompressive surgery for lumbar degenerative disease (LDD). However, few studies analyze this dissatisfaction by focusing on preoperative patients' symptoms. This study was conduct to determine the factors that could predict the patients' postoperative complaints by focusing on their preoperative symptoms. METHODS: Four hundred and seventeen consecutive patients who underwent lumbar decompression and fusion surgery for LDD were included. Postoperative complaint was defined by at least twice same complaint during the outpatient follow-up of 6,12, 18 and 24 months after surgery. A comparative analysis was performed between complaint group (group C, N = 168) and non-complaint group (group NC, N = 249). Demographic, operative, symptomatic, and clinical factors were compared between the groups by univariate and multivariate analyses. RESULTS: The main preoperative chief complaints were radiating pain (318/417, 76.2%). However, most common postoperative complaint was residual radiating pain (60/168, 35.7%) followed by tingling sensation (43/168, 25.6%). The presence of psychiatric disease (adjusted odds ratio [aOR], 4.666; P = 0.017), longer pain duration (aOR, 1.021; P < 0.001), pain to below the knee (aOR, 2.326; P = 0.001), preoperative tingling sensation (aOR, 2.631; P < 0.001), preoperative sensory and motor power decrease (aOR, 2.152 and 1.678; P = 0,047 and 0.011, respectively) were significantly correlated with postoperative patients' complaints in multivariate analysis. CONCLUSIONS: The postoperative patients' complaints could be predicted and explained in advance by checking the preoperative characteristics of patients' symptoms, including the duration and site carefully. This could be helpful to enhance the understanding of the surgical results preoperatively, which could control the anticipation of the patients.

Vertebral Body Sliding Osteotomy as a Surgical Strategy for the Treatment of Cervical Myelopathy: Outcomes at Minimum Five years Follow-up.

STUDY DESIGN: A retrospective cohort study. OBJECTIVE: To evaluate the outcomes of vertebral body sliding osteotomy (VBSO) with a minimum follow-up of five years and compare the results with those of anterior cervical discectomy and fusion (ACDF) and anterior cervical corpectomy and fusion (ACCF). SUMMARY OF BACKGROUND DATA: VBSO reportedly results in fewer complications, better lordosis restoration, and faster bone union than corpectomy. Although previous studies demonstrate the outcomes of VBSO with follow-up of two years or longer, results in longer term surveillance remain unknown. METHODS: This study included 128 patients who underwent VBSO (n=38), ACDF (n=62), or ACCF (n=28) as a treatment for cervical myelopathy and was followed up for five years or more. Fusion, subsidence, C0-2 lordosis, C2-7 lordosis, segmental lordosis, C2-7 sagittal vertical axis, surgical complications, and neck pain visual analog scale, Neck Disability Index, and Japanese Orthopedic Association (JOA) scores were assessed. Comparisons between continuous variables in each group were made using independent sample t tests. For nominal variables, the Fisher exact test or the χ 2 test was used. Paired t test was used to analyze the changes in postoperative values compared with preoperative values. RESULTS: The reoperation rate (0.0%) after VBSO was significantly lower than that after ACCF (14.3%; P =0.028). VBSO had a higher fusion rate at six-month and one-year follow-up, but the fusion rate at five years (97.4%) was not significantly different from that of ACDF (85.5%; P =0.054) and ACCF (85.7%; P =0.077). Segmental lordosis at the five-year follow-up was significantly higher in the VBSO group (16.1°) than in the ACDF (11.9°; P =0.002) and ACCF (6.5°; P <0.001) groups. C2-7 lordosis at five-year follow-up was significantly higher in the VBSO group than in the ACCF group ( P =0.017). Neck pain visual analog scale, Neck Disability Index, and JOA scores and the JOA recovery rate did not show significant intergroup differences during the five-year study period. CONCLUSIONS: VBSO showed promising long-term results in terms of low revision rate, fast solid union, and effective segmental lordosis restoration when compared with other anterior reconstruction techniques.

Risk Factors and Exit Strategy of Intraoperative Neurophysiological Monitoring Alert During Deformity Correction for Adolescent Idiopathic Scoliosis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To elucidate the risk factors of intraoperative neurophysiological monitoring (IONM) alert during deformity correction surgery for adolescent idiopathic scoliosis (AIS) and to describe the outcomes of patients who underwent staged correction surgery due to IONM alert during the initial procedure. METHODS: We reviewed 1 024 patients with idiopathic scoliosis who underwent deformity correction and were followed-up for ≥1 year. The pre-and postoperative Cobb angle of the major structural curve, operative time, estimated blood loss (EBL), number of levels fused, event that caused the IONM alert, and intervention required for the recovery of the signal were recorded. Patients who received IONM alerts (alert group) and those who did not (non-alert group) during the operation were compared. RESULTS: Compared to the non-alert group, the alert group had a significantly greater preoperative Cobb angle of the major structural curve (P < .001), number of levels fused (P = .003), operative time (P < .001), and EBL (P < .001). The percentage of correction did not significantly differ between the 2 groups (P = .348). Eight patients (.8%) underwent a staged operation because the IONM signal alert hindered correction of the deformity. The percentage of correction of patients who underwent staged operation was 64.9 ± 15.1%, and no permanent neurologic deficits occurred. CONCLUSIONS: A greater magnitude of preoperative deformity and surgical extent increases the risk of cord injury identified by IONM alerts during correction of deformities in patients with AIS. However, in patients in whom the IONM alert cannot be recovered or reproduced by proceeding with deformity correction, surgeons can minimize the risk by aborting the initial procedure and completing the correction using staged operations.