Study Design: Literature Review

Objectives: To conduct a comprehensive literature review about the risk factors and preoperative considerations that are related to postoperative venous thromboembolisms (VTEs) in patients who undergo spinal fusion.

Results: Postoperative VTEs are associated with higher costs and longer hospital stays for patients, in comparison to those who did not develop VTEs. Spinal level and multilevel fusion are risk factors for postoperative VTE. The effect of the surgical approach on VTE risk is unclear. Elevated BMI and age, kidney dysfunction, previous VTE, and primary hypercoagulability are preoperative risk factors for developing VTE. Intraoperative and postoperative risk factors for VTE include prolonged procedure time, discharge to inpatient facilities, and length of hospital stay. The effects of hypertension (HTN), sex, and dural tears on VTE risk in spinal fusion patients are uncertain. Chemoprophylaxis reduced the incidence of VTE. Tranexamic acid was not associated with an increase in VTE postoperatively. The American College of Surgeons National Surgical Quality Improvement Program surgical risk calculator served as a poor predictor of VTE incidence in spinal fusion. Preoperative D-dimer levels may help as a predictive tool.

Conclusions: To elucidate the effects of surgical approach, revision surgery, HTN, and dural tears on postoperative VTE risk, further research is warranted. To help identify high-risk patients, a risk calculator sensitive to VTE must be developed.

Background: The study of physiotherapeutic scoliosis-specific exercise (PSSE) for adolescent idiopathic scoliosis (AIS) is rapidly progressing. However, there are limited reports on the medium- to long-term effects of PSSE on scoliosis.

Methods: A systematic review and meta-analysis feasibility study were conducted according to the Cochrane and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. In our exhaustive search, we employed nine search formulas and four search databases according to a preregistered protocol. Identification, screening, eligibility, inclusion, and meta-analysis were performed through repeated meetings involving all coauthors. Each process was conducted by three or more authors.

Results: A total of 1,518 studies were identified in the initial search. After manually reviewing abstracts and full texts, 11 studies were chosen for evaluation and reporting. The overall risk-of-bias was high in approximately half of the studies and moderate in the other half, with none found to have a low risk-of-bias. Only two randomized controlled trials (RCTs) specifically evaluated the therapeutic effect of PSSE on over a 1-year clinical course and the preventive ability of PSSE on surgery. One RCT reported that Cobb angle was substantially smaller in the PSSE group than in the control group at the final follow up, whereas the other found no significant difference between the groups. The methods of exercise intervention, control group selection, and timing of outcome assessments were not standardized in the selected studies. Thus, conducting a meta-analysis of the literature was deemed unfeasible at this time.

Conclusions: The certainty of the evidence that PSSE reduces the progression of Cobb angle in patients with AIS in the short and long term was extremely low. Accordingly, healthcare providers should carefully examine the current evidence when explaining and applying PSSE in such patients. High-quality studies addressing the long-term changes in Cobb angle and Cobb angle at bone maturity as primary outcomes are warranted.

Level of Evidence: Level 1

Introduction: There is a lack of research on the relationship between cervical spinal cord injury (SCI) surgery and symptomatic urinary tract infections (UTIs); hence, this study seeks to fill this critical knowledge gap in postoperative care. This study aims to identify the risk factors for UTIs in patients with traumatic cervical SCI.

Methods: We retrospectively analyzed 187 patients (mean age: 68 years) who underwent cervical SCI surgery between 2017 and 2021. Patients were categorized into UTI and non-UTI groups. Patients with recurrent UTIs were defined as the multiple-UTI group. Preoperative risk factors, including prognostic nutritional index (PNI; 10×serum albumin [g/dL]+0.005×total lymphocyte count [/μL]), were assessed.

Results: Among 187 patients, 99 (52.9%) experienced a UTI within 90 days postoperatively. The majority of patients in the UTI group, that is, 92 patients (92.9%), had an indwelling catheter as urinary management at the time of the UTI. The UTI group faced higher rates of cardiopulmonary dysfunction, bacteremia, longer hospital stays, and increased medical costs. Multiple UTIs were associated with worse outcomes, including increased complications, longer hospital stays, and higher medical costs. PNI at 3 weeks and 4 weeks postoperatively in the multiple-UTI group was significantly lower than in the single-UTI and non-UTI groups. The American Spinal Injury Association impairment scale grade at admission was independently linked to initial UTI occurrence within 90 days after surgery when adjusting for confounding variables.

Conclusions: We found that 52.9% of patients experienced UTIs within 90 days postoperatively. The risk factors for UTI occurrence included the severity of paralysis, indwelling catheter, and poor improvement in the perioperative nutritional status. Early interventions with intermittent catheterization, appropriate antibiotics, and nutrition might be suggested for patients with severe cervical SCI and malnutrition.

Introduction: Due to global increases in life expectancy, numbers of both super-elderly patients (≥90 years old) and the spine surgeries they undergo are increasing. However, no studies on spine surgery for super-elderly patients have focused on patient-reported outcomes (PROs).

Methods: Subjects were elderly patients (over 75 years old) undergoing spine surgery for degenerative disease (4408 cases) performed at our 13 affiliated centers between April 2017 and August 2021. Surgical procedures, perioperative complications, and PROs were investigated and compared between patients ≥90 years old (SE group) and control patients 75-89 years old (E group).

Results: Although the two groups showed no significant differences in patient background, the SE group showed significantly fewer fusions. The incidence of perioperative complications, including death within 30 days, did not significantly differ between groups. Regarding PROs, there were no significant differences in percentages of patients who achieved minimum clinically important differences in Neck Disability Index, Oswestry Disability Index, or EuroQoL 5 Dimension. There were no significant differences in pre- and postoperative numeric rating scales for each item or patient satisfaction.

Conclusions: There were significant improvements in PROs at 1 year postoperatively in the SE group than in the E group, and there were no significant differences in perioperative complication rates or mortality.

Study Design: Single-institution retrospective study.

Objective: To assess the impact of growing rods (GRs) on postoperative cervical sagittal alignment in patients with early-onset scoliosis (EOS).

Summary of Background Data: Cervical sagittal malalignment is associated with neck and cervical spine dysfunction. The impact of surgery for adolescent idiopathic scoliosis on postoperative changes in cervical spine alignment has been reported by studies. Nevertheless, research on sagittal and spinopelvic parameters in patients with EOS is limited.

Methods: In this study, 28 patients who underwent GR and were followed up until final fusion or bone maturity were included. Standing whole-spine radiographs obtained before GR, after the initial GR surgery, and at the final follow-up were utilized to measure the radiographic parameters. Patients with one or more of the previously reported poor prognostic factors were included in the cervical malalignment (CM) group (n=13), and those with none of the factors were included in the non-CM group (n=15) at the final follow-up, which was followed by correlation analysis and multivariate logistic regression analysis.

Results: No significant change in sagittal alignment between preoperative and final follow-up measurements was found. Pearson correlation analysis revealed a significant positive correlation between the change in the C2-7 angle and T1 slope (T1S) or thoracic kyphosis and a negative correlation between the change in the C2-7 angle and T1S minus C2-7 angle (T1S−CL). The percentage of patients in the CM group increased from 25% preoperatively to 46% at the final follow-up but without significant change. The CM group had significantly smaller preoperative C2-7 angles and lumbar lordosis (LL) and larger T1S−CL and pelvic incidence minus LL (PI−LL) values than the non-CM group.

Conclusion: Smaller preoperative C2-7 angles and larger T1S−CL values were identified as risk factors for CM. Postoperative CM is more likely to occur in patients with reduced compensatory function to maintain preoperative cervical kyphosis.

Introduction: Cervical myelopathy diagnosis is based on specific symptoms, physical signs, and imaging findings. However, information on the accuracy and reliability of physical signs, particularly the Wartenberg reflex and the finger escape sign (FES), is lacking. Therefore, this study aimed to assess the validity and reliability of the Hoffmann and Trömner signs, FES, Wartenberg reflex, and combination of any one positive of these four physical signs.

Methods: We reviewed the Hoffmann and Trömner signs, FES, and Wartenberg reflex from the medical records of patients with cervical cord compression who underwent surgery. We included those who underwent lumbar spine surgery as controls, except those with upper extremity symptoms or a history of cerebrospinal disease. Subsequently, we calculated the sensitivity and specificity of cervical cord compression. The primary and secondary observers performed two and one trial, respectively, to measure the intra- and interobserver reliabilities.

Results: This study included 46 cases and 42 controls. The diagnostic sensitivities for the Hoffmann sign, Trömner sign, Wartenberg reflex, FES, and combination of any one positive were 46%, 72%, 63%, 22%, and 83%, respectively; the diagnostic specificities were 98%, 79%, 95%, 98%, and 79%, respectively; the intraobserver kappa value (κ) was 0.80, 0.82, 0.86, 0.66, and 0.95, respectively; and the interobserver κ was 0.84, 0.51, 0.51, −0.02, and 0.60, respectively. Notably, all κ values, except the interobserver κ for the FES, were obtained with P<0.01.

Conclusions: Each physical sign had high specificity but low sensitivity in predicting cervical cord compression. Therefore, they may be useful for definitive diagnosis but not for screening tests. The combination of the four physical signs exhibited improved sensitivity and may be useful for screening tests. However, the results of these physical signs should be carefully interpreted owing to the low level of interobserver reliability.

Introduction: The objective of this study is to investigate the poor recordability characteristics of intraoperative neurophysiological monitoring (IONM) for metastatic spinal tumors, focusing on tumor status or preoperative muscle weakness.

Methods: A total of 132 patients (age 65.3±11.8 years; 82 men) with or without preoperative lower extremity muscle weakness were included in this study. The patients' background characteristics, the presence and degree of pre- and postoperative muscle weakness, and the IONM outcome, including the availability of transcranial motor evoked potential (Tc-MEP) recording and the occurrence of Tc-MEP alarms, were investigated. The data between the groups with and without preoperative muscle weakness were compared. Logistic regression analysis was performed to identify the risk factors for unrecordable Tc-MEP.

Results: Sixty-seven patients with muscle weakness had significantly more unrecordable Tc-MEP (19% vs. 5%, p=0.009) than the 65 patients without muscle weakness. The highest percentage of recordable Tc-MEP in the group with muscle weakness was noted in the plantar muscle (72%). Multivariate analysis identified manual muscle test (MMT) score of ≤3 (odds ratio [OR] 4.529) and ventral spinal cord compression by metastatic tumor (OR 3.924) as independent significant factors for unrecordable Tc-MEP.

Conclusions: IONM for metastatic spinal cord tumors with muscle weakness had a high rate of unrecordable Tc-MEP. Additionally, Tc-MEP may not be detectable in cases of ventral spinal cord compression by a tumor; therefore, preoperative imaging should be thoroughly evaluated.

Introduction: Multimodal intraoperative neurophysiological monitoring (IONM) -such as monitoring muscle-evoked potentials after transcranial electrical stimulation (Tc-MEP) with somatosensory-evoked potential (SEP) after electrical stimulation of the peripheral nerve-is recommended in spine surgeries to prevent iatrogenic neurological complications. However, the effect of using Tc-MEP with SEP to protect against neurological complications, particularly motor function, remains unknown. In clinical settings, changes due to Tc-MEP meeting the alarm points must be a potential neurological injury. This retrospective study, focusing on true-positive (TP) cases, aimed to clarify the change in the SEP waveform simultaneously with the Tc-MEP alarm.

Methods: We included 68 patients with TP who had Tc-MEP changes and new postoperative motor weakness at more than one level of the manual muscle test after surgery. We compared the cases based on the category of spine surgery and paralysis type. We evaluated sex, age at spine surgery (high- or non high-risk), and paralysis type (segmental, long tract, or both). We defined the alarm points as follows: >70% decrease in Tc-MEP wave amplitudes, >50% decrease in wave amplitudes, or 10% extension of SEP latency. Next, we evaluated the SEP wave changes with a Tc-MEP alarm.

Results: All patients showed progressive motor weakness after surgery, and 21 patients (31%) showed SEP changes at the same time as the Tc-MEP alarm. There were no statistically significant differences in the ratio of SEP change between the two groups according to the spine surgery category or among the three groups according to the paralysis type.

Conclusions: Multimodal IONM is an important tool. However, the SEP changes do not necessarily appear immediately after the Tc-MEP alarm. Spine surgeons should appropriately treat Tc-MEP alarms to preserve motor function, regardless of SEP changes.

Introduction: This study investigated the mid- to long-term postoperative outcomes of patients with adult spinal deformity (ASD), focusing on physical function and quality of life (QOL). We also compared age-related changes between patients aged 75 years or older (high elderly) and those younger than 75 years (low elderly).

Methods: A total of 47 patients with ASD underwent thoracic-iliac long spinal fusion between August 2013 and September 2014. The study spanned from the preoperative period to at least 5 years postoperatively. Physical function was assessed using isometric hip flexion and knee extension muscle strength, the 6-min walk distance test, the 10-m walk test, and the timed up and go test. QOL was assessed using the Scoliosis Research Society-22 and Oswestry Disability Index. Repeated-measures analysis of variance with a mixed model approach, corrected for multiple comparisons using Bonferroni, was performed.

Results: Of the 47 patients, 21 participated in the study. Patients with ASD showed improved gait ability postoperatively. Hip flexor strength decreased at more than 5 years postoperatively compared with the preoperative strength. Patient-reported outcome (PRO) scores showed continuous improvement postoperatively, regardless of age. Although older patients had lower preoperative and postoperative physical function, their PRO scores significantly improved and remained favorable for more than 5 years postoperatively.

Conclusions: Patients with ASD experienced sustained improvements in walking ability and PRO for more than 5 years postoperatively. The results of this study showed that even among the elderly, PRO scores consistently improved after surgery and remained positive for an extended period.

Introduction: Gait changes could occur after thoracic to pelvic long-segment corrective fusion surgery, a common procedure for adult spinal deformity (ASD), potentially affecting the occurrence and progression of postoperative hip osteoarthritis. We aimed to clarify postoperative pelvic kinematics in patients with ASD by performing gait analysis using a system based on a smartphone-integrated inertial measurement unit (IMU).

Methods: A total of 21 consecutive outpatients (73.6±4.6 years old, 2 men, 19 women) were enrolled. All had undergone long-segment fusion from the thoracic spine to the pelvis for ASD more than 1 year previously and could walk unassisted. A control group comprised 20 healthy volunteers. The IMU was fixed on the sacrum, and data were collected when subjects walked forward on a flat indoor floor. Acceleration in three axial directions and angular velocity around the three axes were recorded simultaneously during gait, and data were cut out for each gait cycle. Of 1043 features obtained, the top 20 features with the smallest p-value in a statistical comparison were selected. These features, plus gender and age, were classified using gradient boosting machine learning based on the decision tree algorithm. The classification accuracy and relative importance of the feature items were calculated.

Results: The accuracy rate for gait classification between groups was 96.7% and the F1-score was 0.968. The factor that contributed most to the classification of gait in both groups was "y-angular,_change_quantiles,_f_agg=" var",_isabs=True,_qh=0.6,_ql=0.2," which means the variance of the change of the absolute value in the pelvic rotation angular velocity in the horizontal plane in the range of 20%-60% of the gait cycle. Its relative importance was 0.351, which was smaller in the group with fusion.

Conclusions: Patients with ASD following long-segment fusion from the thoracic spine to the pelvis apparently have a gait style characterized by suppressed pelvic rotation in the horizontal plane.

Introduction: Whether the benefits of continued perioperative aspirin therapy in spinal surgery outweigh the risk of perioperative complications remains unclear. This study evaluates the perioperative effects of continuous low-dose aspirin treatment in patients who underwent lumbar decompression alone.

Methods: This single-institute retrospective study included patients who underwent lumbar decompression for L1/2-L5/S1 lesions. The patient characteristics, perioperative parameters, and complications were compared between 103 patients who continued to take 100 mg/day aspirin during the perioperative period (aspirin group) and 653 patients who did not take antiplatelet or anticoagulant drugs (nonaspirin group).

Results: A significantly higher proportion of the patients in the aspirin group were males. The patients in the aspirin group had significantly lower preoperative hemoglobin levels than those in the non-aspirin group (P=0.001 and P=0.044, respectively). No significant differences were detected between the groups in terms of the number of disc decompression levels, duration of surgery, intraoperative blood loss, postoperative drainage volume, number of reoperations required for epidural hematoma formation, or perioperative blood transfusions. No cardiovascular or cerebrovascular ischemic events occurred in either group.

Conclusions: Continuous low-dose aspirin therapy alone during the perioperative period for lumbar decompression did not increase perioperative bleeding or the risk of bleeding-related complications. In conclusion, continuous low-dose aspirin treatment may be acceptable for use in preventing the increased risk of cardiovascular disease caused by aspirin withdrawal in patients undergoing lumbar decompression.

Introduction: This study aimed to compare the biomechanical stress at the proximal junctional aspect between the conventional pedicle screw (PS) fixation (PSF) and the low PS density fixation (LPF) method.

Methods: This study involved 10 patients, half of whom have non-osteoporosis and the other half have osteoporosis. We made two types of intact models (one is from the upper thoracic-to-pelvis model, and the other is from the lower thoracic-to-pelvis model). From the intact models, we constructed two kinds of fusion models: (1) PSF and (2) LPF. The LPF method was as follows: The claw hooks (the combination of the down-going transverse process hooks and facet hooks) were set at the upper instrumented vertebra (UIV) and sublaminar wires at the thoracic spine and PSs at the lumbo-pelvis.

Results: Upper thoracic to pelvis fixation model

In non-osteoporosis, no significant difference between the PSF and LPF is found. In osteoporosis, the von Mises stresses of the vertebra body at UIV, UIV+1, and disc were significantly lower in LPF than in PSF.

Lower thoracic-to-pelvis fixation model

In non-osteoporosis, the average von Mises stress of the vertebral body at UIV+1 and the maximum stress at UIV were lower in LPF than in PSF; however, no significant difference was found in the others. In osteoporosis, the von Mises stress was significantly lower in LPF than in PSF.

Conclusions: The claw hooks stabilized the vertebra body at UIV firmly, and sublaminar wires reduced load translation from the fixed spine.

Introduction: Iron deficiency anemia (IDA) is a common hematological disorder and cause of low hemoglobin. Preoperative anemia has been demonstrated to increase the risk of adverse outcomes after posterior cervical fusion and other spinal surgeries. The need for a transfusion during lumbar fusion has been shown to increase length of stay. This study aimed to assess the impact of IDA on outcomes after spinal fusion for adult spinal deformity (ASD).

Methods: The New York Statewide Planning and Research Cooperative System (SPARCS) database was searched from 2009 to 2013 to identify all patients undergoing ≥2-level thoracolumbar spinal fusion (primary and revision) for ASD with a 2-year follow-up. The patients were then stratified by the presence or absence of IDA. Patients with IDA and patients without IDA were subjected to 1:1 propensity score matching based on age, sex, and obesity. Univariate analysis was employed to compare demographics, hospital parameters, and rates of adverse outcomes. Multivariate binary logistic regression with odds ratio (OR) was employed to identify independent risk factors for adverse postoperative outcomes.

Results: A total of 524 patients (262 with IDA and 262 without IDA) were identified. Patients with IDA experienced higher rates of overall surgical complications (50.4% vs 23.7%, P<0.001), wound complications (3.4% vs 0.4%, P=0.011), and blood transfusion (10.3% vs 6.5%, P<0.001). No difference was observed in the rate of overall medical complications. Patients with and without IDA had comparable rates of readmission (8.0% vs 13.0%, P=0.064), although patients with IDA had lower rates of reoperation (7.6% vs 13.0%, P=0.044). There was no mortality in either cohort. IDA was independently associated with wound complications (OR=10.6, P=0.028), blood transfusion (OR=3.9, P<0.001), and surgical complications (OR=3.5, P<0.001).

Conclusions: Baseline IDA was predictive of increased wound complications, postoperative blood transfusion, and overall surgical complications after thoracolumbar fusion surgery for ASD. Our findings could inform potential medical interventions to mitigate the risks of adverse outcomes in patients with IDA.

Level of Evidence: III, retrospective cohort

Introduction: During spinal surgery, management of intraoperative bleeding and effective hemostasis are required to clearly visualize the surgical field and to safely perform procedures and positive postoperative outcomes. However, it is challenging to stop bleeding from the venous plexus around the dural sac due to the potential risk of neural tissue damage. We aimed to develop hemostatic sheets with appropriate characteristics for spinal surgery, such as softness, appropriate thickness, biodegradability, thrombin bioactivity, and minimal water-induced expansion.

Methods: Hemostatic sheets were made by dissolving bovine bone-derived gelatin in water and aerating it to form foam, followed by freeze-drying, crosslinking, and thrombin-soaking. Sheets A to H were produced with different gelatin concentrations, foam densities, and crosslinking times by additional heat treatment. The sheets were then soaked in thrombin solution for enhanced hemostasis. Material properties, such as density, tensile strength, biodegradability, and hemostatic capacity, were evaluated. Sheet efficacy was further assessed with liver bleeding and spinal venous plexus bleeding models in a miniature pig.

Results: High-density gelatin sheets showed stable shape retention in wet conditions and robust tensile strength. Sheets with higher density and more crosslinking had prolonged persistence in the pepsin test and lower biodegradability in vivo. Sheet B, produced from a 4% gelatin solution with heating at 155°C for 4 h, showed the best balance of properties, such as no deformation cracks, rapid water absorption, minimal expansion, and faster degradation within 10 weeks, compared with TachoSil and other sheets. In hemostasis models, Sheet B outperformed Avitene and TachoSil, achieving higher success rates in spinal (four out of six sites) and liver bleeding (five out of five sites) models.

Conclusions: A thrombin-loaded hemostatic sheet produced from 4% gelatin solution with a short heating time for crosslinking demonstrated well-balanced material properties, such as shape retention, biodegradability, and wet expansion rate, which resulted in effective hemostasis in in vivo models. These advances may contribute to surgical hemostatic applications.

Introduction: There is ongoing debate over whether to remove or retain posterior spinal implants following the successful union of thoracolumbar fractures. This study aimed to compare clinical and radiographic outcomes following removal versus retention of posterior spinal implants in patients with healed thoracolumbar fractures.

Methods: All patients who underwent posterior short segment fixation for thoracolumbar (T11-L2) fractures and presented to the outpatient clinic of our institution (level I trauma center) from October 2020 to October 2022 were enrolled in the study. The participants were randomly assigned to one of the two groups. The EQ-5D-5L was the primary outcome of the study. The secondary outcomes were the Oswestry Disability Index (ODI), loss of correction, and incidence of complications.

Results: A total of 52 patients were included in the final analysis with 26 patients in each group. During the 6-month and 1-year follow-up visits, the implant removal group had a statistically significant improvement in the EQ-Index, EQ-VAS, and ODI, while there were no significant differences in these parameters in the implant retention group. There was no significant difference between the two groups regarding loss of correction (P=0.109).

Conclusions: In patients who have undergone posterior instrumentation for thoracolumbar fractures, the removal of implants following fracture consolidation demonstrates enhanced clinical outcomes when compared to retaining the implants. Although loss of correction is marginally higher in the implant removal group than in the retention group, this disparity did not attain statistical significance, nor did it correlate with inferior clinical outcomes. Furthermore, the incidence of complications following implant removal remained minimal. These findings emphasize the favorable efficacy and safety profile of implant removal procedures within this patient population.

Introduction: This study aims to determine whether Patient-Reported Outcomes Measurement Information System (PROMIS) domain scores can predict elective spine surgery within 1 year of initial clinic evaluation.

Methods: A retrospective query for all new patient spine clinic visits with diagnosis codes related to lower back pain was carried out at a single academic institution. A chart review was conducted to collect sociodemographic variables, clinic visit details, and PROMIS domain scores (PF [Physical Function], PI [Pain Interference], Depression, and Global Health-Physical and Global Health-Mental). Patients were divided into Surgery and No Surgery, and for time to surgery, a subanalysis was also carried out.

Results: Overall, 116 (8.4%) of 1,387 new patients underwent surgery within 1 year. Race, Surgeon vs. Advanced Practice Provider (APP), and whether advanced imaging (MRI or CT myelogram) was available for interpretation were statistically associated with undergoing surgery. Patients in the Surgery group had statistically significant worse PROMIS scores in all domains when compared with the No Surgery group, and PROMIS PI was additionally associated with Time to Surgery. Multivariate analysis identified PROMIS PI, race, presence of advanced imaging interpretation, and Surgeon vs. APP as independent predictors of Surgery vs. No Surgery; however, only race and PROMIS PI were independent predictors of Time to Surgery.

Conclusions: Worse new patient PROMIS PI scores were associated with undergoing surgery within one year of initial evaluation. To determine if PROMIS scores may help in a triage capacity to identify which patients are most appropriate for a surgeon visit versus a nonsurgical provider, further research is needed, thereby improving the efficiency of surgical care delivery.

Introduction: Lumbar microdiscectomy is a commonly conducted surgical procedure for treating symptomatic lumbar disc herniations. Recurrence of herniation is a common cause of poor outcomes and the need for revision surgery, which occurs in as many as 21% of patients following primary discectomy. Identifying factors that are associated with the recurrence of herniation may be valuable for risk stratification and patient counseling. This study aimed to explore the relationship between various patient demographic variables and comorbidities and rates of reoperation after primary lumbar microdiscectomy.

Methods: The American College of Surgeons National Surgical Quality Improvement Program database was queried for patients who were undergoing single-level primary lumbar microdiscectomy between 2016 and 2022. Eligibility for inclusion was determined by age >18 years and current procedural terminology codes 63030 and 63042. Patients with preoperative sepsis or cancer were excluded. Patient demographics, including age, race, ethnicity, and body mass index (BMI), and various comorbidities were compared between cohorts. To determine factors independently associated with the need for revision microdiscectomy, multivariable Poisson regressions were utilized.

Results: In this study, a total of 65,121 primary discectomy patients were included, with a separate cohort of 6,971 patients undergoing revision discectomy. In comparison with primary patients, the revision cohort was older and had higher proportions of female and non-Hispanic White patients (all c0.001). The odds ratio for revision discectomy was greater in patients aged ≥65 years (1.577, 95% CI [1.480, 1.680]) than in those aged <45 years (p>0.001). The odds ratio for revision was lower in Black (0.821, 95% CI [0.738, 0.914]) and Hispanic patients (0.819, 95% CI [0.738, 0.909]) when compared with non-Hispanic White patients (p<0.001). Obese patients with BMI ≥35 (1.193, 95% CI [1.103, 1.290]) were at greater risk of revision than those with BMI <25 (p<0.001). Diabetes (1.326, 95% CI [1.242, 1.416], p<0.001), functional dependence (1.411, 95% CI [1.183, 1.683], p<0.001), chronic obstructive pulmonary disorder (1.315, 95% CI [1.137, 1.512], p<0.001), hypertension (1.398, 95% CI [1.330, 1.470], p<0.001), and smoking (1.082, 95% CI [1.018, 1.151], p=0.012) were associated with greater risk of revision. Poisson log-linear regression demonstrated sex (χ²=19.9, p<0.001), race (χ²=39.5, p<0.001), diabetes (χ²=10.1, p=0.001), smoking (χ²=18.5, p<0.001), hypertension (χ²=16.4, p<0.001), age (χ²=102.4, p<0.001), and BMI (χ²=4.7, p=0.029) as significant predictors of revision, with steroid use (χ²=3.5, p=0.061) and functional status (χ²=3.7, p=0.055) approaching significance.

Conclusions: Patient demographics, comorbidities, and rehabilitative status may be significantly associated with rates of reherniation and revision surgery following lumbar microdiscectomy. We found that the significant predictors of revision surgery are functional dependence, advanced age, male sex, White race, obesity, diabetes, smoking, and hypertension. Early identification and attendance to the modifiable risk factors will aid patient guidance and outcomes following primary lumbar microdiscectomy.

Introduction: Condoliase-based chemonucleolysis and microendoscopic discectomy (MED) are considered to be minimally invasive treatments for lumbar disc herniation (LDH). The aim of this study was to compare the clinical outcomes of both treatments, specifically focusing on whether the outcomes vary by age group.

Methods: Patients with LDH who received intradiscal condoliase injections (condoliase group) or underwent MED (MED group) with 1-year follow-up were enrolled in this study. A numerical rating scale (NRS) was developed for leg and back pains. Using magnetic resonance imaging, changes in disc height and degeneration were evaluated. The data were assessed at baseline and at 3-month and 1-year follow-ups. The therapy was considered effective in patients whose NRS for leg pain improved by ≥50% at 1 year from baseline and for whom surgery was not required. Comparative analyses were conducted between the condoliase and MED groups and among the <20, 20-39, 40-59, and ≥60 year age groups.

Results: In this study, a total of 345 patients (condoliase group, n=233; MED group, n=112) were enrolled. Subsequent surgery was required in 23 patients (9.9%) in the condoliase group because of the ineffectiveness of the condoliase therapy. Because of herniation recurrence, reoperation was required in five patients (4.5%) in the MED group. The efficacy rates were respectively 74.4% and 74.6% in the condoliase and MED groups, and no intergroup or age-group differences were found. The condoliase group had a significantly higher decrease in disc height when compared with the MED group (9.0% vs. 4.4%, p<0.05). Compared with the older age group, the younger age group had a greater decrease in disc height and disc degeneration; however, their recovery was better than that of the older age group. Among the age groups, the herniation reduction rate did not significantly vary.

Conclusions: Condoliase and MED had equivalent 1-year outcomes, with no differences observed in efficacy across age groups. For informed decision-making, the advantages and disadvantages of each treatment must be understood.

Introduction: Endoscopic Spine Surgery (ESS) has begun to gain traction as an alternative to traditional microscopic spine surgery, particularly for lumbar decompression. However, one of the challenges associated with this approach is the steep learning curve. A recent advancement in this field aims to flatten the learning curve by incorporating navigation into ESS. This technology provides valuable information on the extent of decompression, confirms the working level, and reduces radiation exposure.

Technical Note: We aimed to describe our experience using electromagnetic navigation in biportal endoscopic spine surgery (BESS). The surgical technique is initiated by positioning the patient prone on a radiolucent table. The navigation field generator is positioned over the caudal end of the patient. The navigation system is set up with patient mappers at the desired working levels. The patient tracker is implanted. The final fluoroscopy images are captured in anteroposterior and lateral views. Subsequently, standard incisions are made, and endoscopic decompression is performed. When required, various instruments can be used to confirm the level, angulation, and extent of decompression.

Conclusions: Our experience showed that this approach reduced the need for intraoperative imaging and provided an accurate alternative to repeated intraoperative imaging. However, it does involve a significantly long setup. Further trials of larger scale are required to determine its efficacy.