Biomechanical Evaluation of Lateral Lumbar Interbody Fusion with Various Fixation Options for Adjacent Segment Degeneration: A Finite Element Analysis.

OBJECTIVE: Adjacent segment degeneration (ASD) is a common phenomenon after lumbar fusion. Lateral lumbar interbody fusion (LLIF) may provide an alternative treatment method for ASD. This study used finite element analysis to evaluate the biomechanical effects of LLIF with various fixation options and identify an optimal surgical strategy for ASD. METHODS: A validated L1-S1 finite element model was modified for simulation. Six finite element models of the lumbar spine were created and were divided into group 1 (L4-5 posterior lumbar interbody fusion [PLIF] + L3-4 LLIF) and group 2 (L5-S1 PLIF + L4-5 LLIF). Each group consisted of 1) cage-alone, 2) cage + lateral screw fixation (LSF), and 3) cage + bilateral pedicle screw fixation (BPSF) models. The range of motion, intradiscal pressure, and facet loads of adjacent segments as well as interbody cage stress were analyzed. RESULTS: The stress on the LLIF cage-superior endplate interface was highest in the cage-alone model followed by the cage + LSF model and cage + BPSF model. The increase in range of motion, intradiscal pressure, and facet loads at the adjacent segment was highest in the cage + BPSF model followed by the cage + LSF model and cage-alone model. However, the biomechanical effect on the adjacent segment seemed similar in the cage-alone and cage + LSF models. CONCLUSIONS: LLIF with BPSF is recommended when performing LLIF surgery for ASD after L4-5 and L5-S1 PLIF. Considering cage subsidence and biomechanical effects on the adjacent segment, LLIF with LSF may be a suboptimal option for ASD surgery.

Full-Endoscopic versus Minimally Invasive Lumbar Interbody Fusion for Lumbar Degenerative Diseases : A Systematic Review and Meta-Analysis.

OBJECTIVE: Although full-endoscopic lumbar interbody fusion (Endo-LIF) has been tried as the latest alternative technique to minimally invasive transforaminal lumbar interobody fusion (MIS-TLIF) since mid-2010, the evidence is still lacking. We compared the clinical outcome and safety of Endo-LIF to MIS-TLIF for lumbar degenerative disease. METHODS: We systematically searched electronic databases, including PubMed, EMBASE, and Cochrane Library to find literature comparing Endo-LIF to MIS-TLIF. The results retrieved were last updated on December 11, 2020. The perioperative outcome included the operation time, blood loss, complication, and hospital stay. The clinical outcomes included Visual analog scale (VAS) of low back pain and leg pain and Oswestry disability index (ODI), and the radiological outcome included pseudoarthosis rate with 12-month minimum follow-up. RESULTS: Four retrospective observational studies and one prospective observational study comprising 423 patients (183 Endo-LIF and 241 MIS-TLIF) were included, and the pooled data analysis revealed low heterogeneity between studies in our review. Baseline characteristics including age and sex were not different between the two groups. Operation time was significantly longer in Endo- LIF (mean difference [MD], 23.220 minutes; 95% confidence interval [CI], 10.669-35.771; p=0.001). However, Endo-LIF resulted in less perioperative blood loss (MD, -144.710 mL; 95% CI, 247.941-41.478; p=0.023). Although VAS back pain at final (MD, -0.120; p=0.586), leg pain within 2 weeks (MD, 0.005; p=0.293), VAS leg pain at final (MD, 0.099; p=0.099), ODI at final (MD, 0.141; p=0.093) were not different, VAS back pain within 2 weeks was more favorable in the Endo-LIF (MD, -1.538; 95% CI, -2.044 to -1.032; p<0.001). On the other hand, no statistically significant group difference in complication rate (relative risk [RR], 0.709; p=0.774), hospital stay (MD, -2.399; p=0.151), and pseudoarthrosis rate (RR, 1.284; p=0.736) were found. CONCLUSION: Relative to MIS-TLIF, immediate outcomes were favorable in Endo-LIF in terms of blood loss and immediate VAS back pain, although complication rate, mid-term clinical outcomes, and fusion rate were not different. However, the challenges for Endo-LIF include longer operation time which means a difficult learning curve and limited surgical indication which means patient selection bias. Larger-scale, well-designed study with long-term follow-up and randomized controlled trials are needed to confirm and update the results of this systematic review.

Safety and Efficacy of Bone Cement (Spinofill®) for Vertebroplasty in Patients with Osteoporotic Compression Fracture : A Preliminary Prospective Study.

OBJECTIVE: Although several commercialized bone cements are used during percutaneous vertebroplasty (PVP) for patients with osteoporotic vertebral compression fracture (OVCF), there are no reports using domestic products from South Korea. In this study, we investigated the safety and efficacy of Spinofill® (Injecta Inc., Gunpo, Korea), a new polymethyl methacrylate product. METHODS: A prospective, single-center, and single-arm clinical trial of 30 participants who underwent PVP using Spinofill® for painful thoracolumbar OVCF was performed with 6-months follow-up. Clinical and surgical outcomes included the Visual analog scale (VAS), Korean-Oswestry disability index (K-ODI), and Odom's criteria, complication rate, and recurrence rate. Radiological outcomes were evaluated by measuring the findings of postoperative computed tomography and simple radiograph. RESULTS: The pain of VAS (from 8.95±1.05 to 4.65±2.06, p<0.001) and the life quality based on K-ODI (from 33.95±5.84 to 25.65±4.79, p<0.001) improved significantly, and successful patient satisfaction were achieved in 20 patients (66.7%) 1 day after surgery. These immediate improvements were maintained or more improved during the follow-up. There was no surgery- or product-related complications, but OVCF recurred in two patients (6.7%). Favorable cement interdigitation was reported in 24 patients (80.0%), and extra-vertebral cement leakage was reported in 13 patients (43.0%). The mean vertebral height ratio (from 60.49%±21.97% to 80.07%±13.16%, p<0.001) and segmental kyphotic angle (from 11.46°±8.50° to 7.79°±6.08°, p=0.002) improved one day after surgery. However, these short-term radiological findings somewhat regressed at the end. CONCLUSION: The overall outcomes of PVP using Spinofill® were as favorable as those of other conventionally used products.

Comparison of Lateral Interbody Fusion and Posterior Interbody Fusion for Discogenic Low Back Pain.

AIM: To compare lateral (direct [DLIF] or oblique [OLIF]) and posterior (posterior [PLIF] or transforaminal [TLIF]) lumbar interbody fusion results in patients with the same indication of discogenic low back pain. MATERIAL AND METHODS: We enrolled 46 patients who underwent single-level DLIF/OLIF or PLIF/TLIF with at least 1 year of follow-up. Patients were divided into two groups: a lateral group (n=24) who underwent DLIF/OLIF and a posterior group (n=22) who underwent PLIF/TLIF. Clinical, surgical, and radiological outcomes were retrospectively evaluated. RESULTS: Baseline factors, including demographic data, preoperative symptoms, and preoperative radiological findings, were not significantly different between the two groups. In addition, the clinical and radiological outcomes at 1-year post-surgery did not differ between the two groups. However, the DLIF/OLIF procedure conferred significant advantages as follows: favorable postoperative low back pain and patient satisfaction at 1-week and 1-month post-surgery; shorter operation time (mean 173.33 ± 11.54 versus 208.64 ± 17.48 min, p < 0.001); less blood loss during surgery (mean 127.50 ± 41.36 versus 372.73 ± 123.21 mL, p < 0.001); and greater restoration of calibrated disc height at 1-year post-surgery (mean 5.80 ± 1.44 versus 0.50 ± 1.22, p=0.008). There was no statistically significant difference in the incidence of complications between the two groups. However, complications tended to be more frequent in the lateral group; 7 (29.2%) patients in the lateral group and 3 patients (13.6%) in the posterior group. CONCLUSION: Our findings suggest that the lateral group achieved better perioperative outcomes and disc height restoration than the posterior group, although there was no significant difference in the 1-year clinical outcomes.

Comparison of adjacent segment disease after minimally invasive versus open lumbar fusion: a minimum 10-year follow-up.

OBJECTIVE: The object of this study was to compare, after a long-term follow-up, the incidence and features of adjacent segment disease (ASDis) following lumbar fusion surgery performed via an open technique using conventional interbody fusion plus transpedicular screw fixation or a minimally invasive surgery (MIS) using a tubular retractor together with percutaneous pedicle screw fixation. METHODS: The authors conducted a retrospective chart review of patients with a follow-up period > 10 years who had undergone instrumented lumbar fusion at the L4-5 level between January 2004 and December 2010. The patients were divided into an open surgery group and MIS group based on the surgical method performed. Baseline characteristics and radiological findings, including factors related to ASDis, were compared between the two groups. Additionally, the incidence of ASDis and related details, including diagnosis, time to diagnosis, and treatment, were analyzed. RESULTS: Among 119 patients who had undergone lumbar fusion at the L4-5 level in the study period, 32 were excluded according to the exclusion criteria. The remaining 87 patients were included as the final study cohort and were divided into an open group (n = 44) and MIS group (n = 43). The mean follow-up period was 10.50 (range 10.0-14.0) years in the open group and 10.16 (range 10.0-13.0) years in the MIS group. The overall facet joint violation rate was significantly higher in the open group than in the MIS group (54.5% vs 30.2%, p = 0.022). However, in terms of adjacent segment degeneration, there were no significant differences in corrected disc height, segmental angle, range of motion, or degree of listhesis of the adjacent segments between the two groups during follow-up. The overall incidence of ASDis was 33.3%, with incidences of 31.8% in the open group and 34.9% in the MIS group, showing no significant difference between the two groups (p = 0.822). Additionally, detailed diagnosis and treatment factors were not different between the two groups. CONCLUSIONS: After a minimum 10-year follow-up, the incidence of ASDis did not differ significantly between patients who had undergone open fusion and those who had undergone MIS fusion at the L4-5 level.

The Modified 11-Item Frailty Index and Postoperative Outcomes in Patients Undergoing Lateral Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The aim of this study was to analyze postoperative complications and recovery patterns in different modified 11-item frailty index (mFI-11) groups after lateral lumbar interbody fusion (LLIF) surgery. SUMMARY OF BACKGROUND DATA: The relationship between the mFI-11 score and LLIF surgery has not been previously reported. METHODS: A single-center, consecutive series of patients who underwent LLIF with at least two years of follow-up were retrospectively reviewed. Complications after LLIF surgery were recorded. Clinical outcomes, including the visual analog scale (VAS) for back/leg pain and the Oswestry Disability Index (ODI), were evaluated preoperatively and at 1 and 2 years postoperatively. The proportions of patients who achieved substantial clinical benefit (SCB) for the VAS-B, VAS-L, and ODI were also analyzed. RESULTS: One hundred fifty-two patients included in the present study were grouped according to their mFI-11 score: 0 (n = 39), 0.09 (n = 69), 0.18 (n = 31), and ≥0.27 (n = 13). An mFI-11 score ≥0.27 was a significant predictor of urinary complications (adjusted odds ratio: 3.829, P = 0.013). At 2 years postoperatively, patients in all frailty categories experienced improvements in the VAS for back pain, VAS for leg pain, and ODI, without significant differences between the four groups (p = 0.182, 0.121, and 0.804, respectively). There were also no significant differences in the proportions of patients achieving SCB for back/leg pain and the ODI between the four groups (P = 0.843, 0.957, and 0.915, respectively). CONCLUSION: An mFI-11 score was found to be independently associated with urologic complications in patients who underwent LLIF. Patients in all frailty categories experienced significant improvements in back pain, leg pain, and the ODI at 1 year and 2 years postoperatively. LLIF surgery may be useful for patients with high frailty index.Level of Evidence: 4.

The irony of the transforaminal approach: A comparative cohort study of transforaminal endoscopic lumbar discectomy for foraminal versus paramedian lumbar disc herniation.

ABSTRACT: Transforaminal endoscopic lumbar discectomy (TELD) is useful for soft lumbar disc herniation (LDH). Although the transforaminal approach can reach the foraminal disc zone, the risk of exiting nerve root irritation along the path is considerable. Few studies have assessed the difficulties of TELD for foraminal LDH. The objective of this study is to compare the clinical results of TELD between foraminal or far-lateral LDH and paramedian LDH.Between June 2016 and July 2017, 135 consecutive patients with single-level LDH were treated with TELD for 2 years. Among them, 25 patients had foraminal or far-lateral LDH (foraminal group), and the remaining 110 patients had central or subarticular LDH (paramedian group). Perioperative data and clinical outcomes were evaluated using the visual analog pain scale, Oswestry Disability Index, and modified Macnab criteria.The foraminal group showed a higher rate of significant access pain (24.00% vs 8.19%, P < .05). The foraminal group also had a longer duration of surgery, length of hospital stay, and return to work (all P < .05). Pain scores and functional status were significantly improved in both groups. Although there were no differences in the outcomes at 2 years postoperatively, early pain and disability at 6 weeks were higher in the foraminal group.Ironically, the early clinical results of TELD for foraminal LDH may be less favorable than those for paramedian LDH. Therefore, great care should be taken during TELD for foraminal or far-lateral LDH.

Effects of Total Psoas Area Index on Surgical Outcomes of Single-Level Lateral Lumbar Interbody Fusion.

OBJECTIVE: We evaluated the effect of the total psoas area index (TPAI = total psoas muscle area [cm2]/height squared [m2]) on neurological complications and clinical outcomes after lateral lumbar interbody fusion and identified the appropriate TPAI to achieve a substantial clinical benefit (SCB). METHODS: A consecutive series of 123 patients who had undergone single-level lateral lumbar interbody fusion at a single center with ≥2 years of follow-up were retrospectively reviewed. The patient characteristics and operative data were evaluated. The neurological complications were classified as transient and persistent symptoms. The visual analog scale score for back pain was assessed preoperatively and at 1 and 2 years postoperatively. RESULTS: The present study included 31 men and 92 women. The mean TPAI was 8.97 cm2/m2 for the men and 5.04 cm2/m2 for the women. The mean TPAI was not significantly different between the patients with and without perioperative neurological complications. Multiple logistic regression analysis showed that solid interbody fusion was the most significant factor for achieving an SCB regarding back pain in men (odds ratio [OR], 2.453; P = 0.019) and women (OR, 2.906; P = 0.042). The TPAI was one of the predictors for achieving an SCB in men (OR, 1.251; P = 0.038) and women (OR, 1.795; P = 0.023). The optimal cutoff point of the TPAI for an SCB was 8.18 cm2/m2 for the men and 4.43 cm2/m2 for the women. CONCLUSIONS: The TPAI had little effect on the incidence of perioperative neurological complications. However, the TPAI was identified as one of the predictors for achieving an SCB regarding back pain.

Factors Predicting the Clinical Outcome After Trans-sacral Epiduroscopic Laser Decompression for Lumbar Disc Herniation.

OBJECTIVE: Previous literatures have demonstrated widely variable clinical results after transsacral epiduroscopic laser decompression (SELD) and the factors predicting outcomes are not yet established. Therefore, we analyzed the clinical outcome and associated predictive factors of SELD in patients with lumbar disc herniation. METHODS: Between 2015 and 2018, 82 patients who underwent single-level SELD and followed up at least 6 months were enrolled. The overall success rate (excellent or good results at final follow-up) was 58.5% according to Odom's criteria. Based on this result, patients were divided to 2 groups: a favorable group (n = 48) and an unfavorable group (n = 34). A retrospective review of the baseline characteristics and clinical outcome were conducted to reveal the predictive factors. RESULTS: As expected, improvement of pain and patient satisfaction, was more favorable in the favorable group (p < 0.05). Moreover, the rate of additional procedure was lower in the favorable group (4.2%, 2 of 48 patients) than in the unfavorable group (35.3%, 12 of 34 patients) (p = 0.011). Among the various baseline characteristics, the only significant predictive factor for favorable outcome was the presence of a high-intensity zone (HIZ) on preoperative magnetic resonance imaging (50.0% [24 of 48 patients] in the favorable group vs. 11.8% [4 of 34 patients] in the unfavorable group; odds ratio, 15.67; p = 0.024). CONCLUSION: Although SELD for lumbar disc herniation resulted in a less favorable clinical outcome than that reported in previous studies, in patients with a HIZ, SELD can be an effective minimally invasive surgery to relieve low back pain and/or leg pain.

Dynamic Stabilization Surgery in Patients with Spinal Stenosis: Long-term Outcomes and the Future.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: The purpose of this study was to analyze the long-term results for patients with lumbar spinal stenosis (LSS) treated with dynamic stabilization (DS) and to consider how we can improve the results. SUMMARY OF BACKGROUND DATA: Few studies have reported long-term outcomes of DS surgery for LSS with or without spondylolisthesis. METHODS: A single-center, single-surgeon consecutive series of LSS patients who underwent DS surgery with at least 5 years of follow-up were retrospectively reviewed. Twenty-seven patients were included in the LSS group and 38 patients in the spondylolisthesis group. Patient characteristics, operative data, radiographic parameters, clinical outcomes, and complications were analyzed at baseline and follow-up. RESULTS: In the LSS group, all radiographic parameters (e.g., disc height, segmental lordosis, segmental range of motion [ROM] at the index level and proximal adjacent level, global lordosis, and global ROM) were maintained well until the last follow-up. In the spondylolisthesis group, global lordosis decreased from 36.5°â€Š±â€Š8.2° to 32.6°â€Š±â€Š6.0° at the last follow-up (P = 0.039), and global ROM decreased from 22.1°â€Š±â€Š6.9° to 18.8°â€Š±â€Š7.1° at the last follow-up (P = 0.012). In both groups, back pain, leg pain, and Oswestry Disability Index scores showed significant and sustained improvements. Screw loosening occurred in three patients (11.1%) in the LSS group and five patients (13.2%) in the spondylolisthesis group. Symptomatic adjacent segment degeneration (ASD) occurred in two patients (7.4%) in the LSS group and three patients (7.9%) in the spondylolisthesis group. CONCLUSION: Decompression and DS surgery for LSS with or without spondylolisthesis showed favorable long-term surgical outcomes with an acceptable rate of complications and ASD. However, an improved physiological DS system should be developed.Level of Evidence: 4.

Learning curve of percutaneous endoscopic transforaminal lumbar discectomy by a single surgeon.

ABSTRACT: To evaluate the learning curve of percutaneous endoscopic transforaminal lumbar discectomy (PETLD) from the novice stage to the proficient stage, we performed retrospective study for patients with lumbar disc herniation who underwent PETLD performed by a single surgeon and evaluated the surgeon's learning curve and the effect of surgical proficiency on outcomes.A total of 48 patients who underwent PETLD at the lower lumbar level (L3-S1) with a minimum 1-year follow-up were enrolled. The learning curve of the surgeon was assessed using cumulative study of operation time and linear regression analyses to reveal the correlation between operation time and case series number.Because the cutoff of familiarity was 25 cases according to the cumulative study of operation time, the patients were allocated into two groups: early group (n = 25) and late group (n = 23). The clinical, surgical, and radiological outcomes were retrospectively evaluated and compared between the two groups.According to linear regression analyses, the operation time was obtained using the following formula: operation time (minutes) = 69.925-(0.503 × [case number]) (P < .001).As expected, the operation time was significantly different between the two groups (mean 66.00 ±â€Š11.37 min in the early group vs 50.43 ±â€Š7.52 min in the late group, P < .001). No differences were found between the two groups in demographic data and baseline characteristics. Almost all clinical outcomes (including pain improvement and patient satisfaction), surgical outcomes (including failure, recurrence, and additional procedure rates), and radiological outcomes (including change of disc height and sagittal angles) did not differ between the two groups.However, the late group demonstrated a more favorable postoperative volume index of the remnant disc (362.91 mm3 [95% confidence interval, 272.81-453.02] in the early group vs 161.14 mm3 [95% confidence interval, 124.31-197.97] in the late group, P < .001), and a lower complication rate related to exiting nerve root (16.0% in the early group vs 0% in the late group, P = .045).The learning curve of PETLD is not as difficult as that of other minimally invasive spine surgery technique. Although the overall outcomes were not different between the groups, the risks of incomplete decompression and exiting root injury-related complication were higher in the novice stage.

Surgical Impacts of Metastatic Non-small Cell Lung Cancer to the Thoracic and Lumbar Spine.

BACKGROUND: Surgery for spinal metastasis is rapidly increasing in frequency with procedures ranging from laminectomy to spondylectomy combined with stabilization. This study investigated the effect of various surgical procedures for spinal metastasis of non-small cell lung cancer (NSCLC). METHODS: A single-center consecutive series of patients who underwent surgery for spinal metastasis of NSCLC were retrospectively reviewed. Patients' characteristics, radiographic parameters, operative data, clinical outcomes, and complications were analyzed. Surgical outcomes were assessed according to pain and performance status before and after surgery. Overall survival (OS) rate was estimated using the Kaplan-Meier method. Multivariate analysis was performed to detect factors independently associated with OS using a Cox proportional hazards model. RESULTS: Twenty-one patients were treated with laminectomy, 24 with corpectomy, 13 with spondylectomy (piecemeal or total en bloc fashion), and all procedures were combined with stabilization. Back pain and performance status improved significantly after surgical treatment among the three groups. Revision surgery due to tumor progression at the index level or spinal metastasis at another level were four patients (19.0%) in the laminectomy group, six patients (25.0%) in the corpectomy group, and one patient (7.7%) in the spondylectomy group. A Charlson comorbidity index and the number of spinal metastasis negatively affected OS (hazard ratio [HR], 19.613 and 2.244). Postoperative chemotherapy, time to metastasis, spondylectomy, and corpectomy had favorable associations with OS (HR, 0.455, 0.487, 0.619, and 0.715, respectively). CONCLUSION: Postoperative chemotherapy was the most critical factor in OS of patients with metastatic NSCLC to the spine. An extensive surgical procedure (corpectomy/spondylectomy) with stabilization also could be beneficial for limited patients with spinal metastasis of NSCLC.

Prognosis of Symptomatic Pseudarthrosis Observed at 1 Year After Lateral Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The aim of this study was to investigate the prognosis of symptomatic pseudarthrosis observed at 1 year after lateral lumbar interbody fusion (LLIF) surgery and to analyze the risk factors for persistent pseudarthrosis for 2 years postoperatively. SUMMARY OF BACKGROUND DATA: Few articles have evaluated the prognosis of symptomatic pseudarthrosis following LLIF surgery. METHODS: One hundred fifty-two patients with a minimum follow-up of 2 years were screened. Fusion status was assessed at 1 year postoperatively, and unfused segments were reevaluated at 2 years postoperatively. Dynamic x-rays and computed tomography images were acquired to evaluate the fusion status. Demographic data were evaluated to identify the risk factors associated with persistent pseudarthrosis. Clinical outcomes, including the visual analog scale (VAS) for back/leg pain and the Oswestry disability index (ODI), were evaluated preoperatively and at 1 and 2 years postoperatively. RESULTS: Symptomatic pseudarthrosis was detected in 42 patients at 1 year postoperatively. Among them, 23 patients (54.8%) exhibited solid bony fusion 2 years postoperatively without further intervention. Fourteen patients (33.3%) showed asymptomatic pseudarthrosis, and the remaining five patients (11.9%) showed symptomatic pseudarthrosis. Multivariable analysis showed that diabetes (adjusted odds ratio [OR]: 2.817, P = 0.007), smoking (adjusted OR: 6.497, P = 0.008), and fusion at more than three levels (adjusted OR: 2.525, P = 0.031) were risk factors for persistent pseudarthrosis. Improvements in the VAS scores for back pain and ODI scores were significantly lower in the persistent pseudarthrosis group than in the final solid fusion group at 2 years postoperatively. CONCLUSION: It is not necessary to intervene for all patients in whom symptomatic pseudarthrosis is detected at 1 year postoperatively because only 11.9% of them will show persistent symptomatic pseudarthrosis. However, early revision surgery should be considered when severe symptomatic pseudarthrosis associated with diabetes, smoking, and fusion at more than three levels is present.Level of Evidence: 4.

Disc height discrepancy between supine and standing positions as a screening metric for discogenic back pain in patients with disc degeneration.

BACKGROUND CONTEXT: The diagnosis of discogenic low back pain (LBP) from disc degeneration of the lumbar spine is often evaluated with discography. Noninvasive, simple screening methods other than invasive discography are useful, as evidence supporting clinical findings and magnetic resonance imaging (MRI) have come to the forefront. PURPOSE: To investigate disc height (DH) discrepancy between supine and standing positions on simple radiography to clarify its clinical screening value in individuals with discogenic LBP. STUDY DESIGN/SETTINGS: Retrospective matched cohort design. PATIENT SAMPLE: Ninety-two patients with early to middle stage disc degeneration (Pfirrmann grade II, III, or IV). OUTCOME MEASURES: Each subject underwent simple radiographs and MRI. Baseline characteristics, including demographic data and MRI findings, and radiological findings, including DH discrepancy, segmental angle, and sagittal balance, were analyzed. DH discrepancy ratio was calculated as (1 - [calibrated DH on standing radiography/calibrated DH on supine radiography]) × 100%. METHODS: We matched LBP group of 46 patients with intractable discogenic pain (≥7 of visual analog scale scores) confirmed by discography with control group of 46 patients with similar stage disc degeneration with mild LBP (≤4 of visual analog scale scores). Binary regression analysis, receiver operating characteristic curve analysis, and cut-off value for diagnosis were used to evaluate and clarify diagnostic value of various factors. RESULTS: There was no significant difference between the two groups in terms of baseline characteristics, including age, sex, body mass index, pathological level, and magnetic resonance findings such as disc degeneration, high intensity zone, and para-spinal muscle volume. Among the various radiological findings, the calibrated mean DH in the standing position (20.87±5.65 [LBP group] vs. 26.95±3.02 [control group], p<.001) and the DH discrepancy ratio (14.55±6.13% [LBP group] vs. 1.47±0.75% [control group], p=.007) were significantly different between the two groups. The cut-off value for DH discrepancy ratio to screen discogenic LBP was ≥6.04%. Additionally, as a compensation for pain, sagittal vertical axis (3.43±2.03 cm [LBP group] vs. -0.54±3.05 cm [control group], p=.002) and pelvic incidence (54.74±6.76° [LBP group] vs. 43.98±8.67° [control group]; p=.006) were different between the two groups. CONCLUSIONS: The results suggest that DH discrepancy between the supine and standing positions could be a screening metric for discogenic LBP in early to middle stage disc degeneration of the lumbar spine.

Intraoperative Radiographs in Single-level Lateral Lumbar Interbody Fusion Can Predict Radiographic and Clinical Outcomes of Follow-up 2 Years After Surgery.

MINI: Some of the improvements in DH, FH, and SLL achieved intraoperatively during lateral lumbar interbody fusion surgery were lost by the postoperative 1-week follow-up. An intraoperative radiograph can predict radiographic and clinical outcomes of the 2-year follow-up. The difference between preoperative DH and intraoperative DH should be >4.18 mm.

Retrospective cohort study The aim of this study was to evaluate whether the intraoperatively estimated parameters, as calculated on a cross-table lateral radiograph, are maintained in an upright position at discharge and at 2 years postoperatively and to identify the appropriate disc height (DH) to achieve substantial clinical benefit. The amount of correction retained following lateral lumbar interbody fusion (LLIF) surgery had not been reported. A single-center, consecutive series of patients who underwent single-level LLIF with at least 2 years of follow-up were retrospectively reviewed. Upright standardized preoperative, 1-week, and 2-year postoperative radiographs, as well as intraoperative lateral radiographs, were analyzed for DH, foraminal height (FH), and segmental lumbar lordosis (SLL) at the index level. Clinical outcomes were compared between preoperatively and 1 week and 2 years postoperatively. In total, 89 patients were evaluated (mean follow-up, 42.8 months [range, 24­83 months]). DH decreased from 12.5 ±â€Š2.7 mm intraoperatively to 11.7 ±â€Š3.1 mm at 1 week postoperatively, FH decreased from 15.9 ±â€Š3.6 mm to 15.1 ±â€Š3.6 mm, and SLL decreased from 13.6°â€Š±â€Š1.7° to 12.4°â€Š±â€Š1.7°. A linear correlation between intraoperative and 2-year postoperative parameters was found ( R2  = 0.552, 0.518, and 0.616, respectively). Clinical outcomes, including back pain, leg pain, and Oswestry Disability Index (ODI), significantly improved 2 years postoperatively. The optimal cutoff point for substantial clinical benefit thresholds for the ODI was a 4.18 mm increase in DH (sensitivity, 64.3%; specificity, 80.3%; area under the curve, 0.793; 95% confidence interval, 0.642­0.855). Some of the improvements in DH, FH, and SLL achieved intraoperatively during LLIF surgery were lost by the postoperative 1-week follow-up. An intraoperative radiograph can predict radiographic and clinical outcomes of the 2-year follow-up. The difference between preoperative DH and intraoperative DH should be >4.18 mm. Level of Evidence: 4.

Comparison of Spinal Canal Expansion Following Cervical Laminoplasty Based on the Preoperative Lamina Angle : A Simulation Study.

OBJECTIVE: Expansion in the spinal canal area (SCA) after laminoplasty is one of the critical factors to relieve the preoperative symptoms. No previous study has compared the increases in SCA achieved by open-door laminoplasty (ODL) and double door laminoplasty (DDL) according to the preoperative lamina angle (LA). This study was designed to clarify the relationship between the laminoplasty opening angle (OA)/laminoplasty opening size (OS) and increases in the SCA following ODL and DDL according to the preoperative LA using a simulation model. METHODS: The simulation model was constructed and validated by comparing the clinical data of 64 patients who had undergone C3-C6 laminoplasty (43 patients with ODL and 21 patients with DDL). SCA expansion was predicted with a verified simulation model at various preoperative LAs (from 28° to 32°) with different OAs (40° to 44°) and OSs (10 mm to 14 mm) recruited from patient data. RESULTS: The constructed simulation model was validated by comparing clinical data and revealed a very high degree of correlation (r=0.935, p<0.001). In this validated model, at the same OA, the increase in SCA was higher following ODL than following DDL in the usual LA (p<0.05). At the same OS, the increase in SCA was slightly larger following DDL than following ODL, but the difference was not significant (p>0.05). The difference was significant when the preoperative LA was narrower or much wider. CONCLUSION: Based on clinical data, a simulation model was constructed and verified that could predict increases in the SCA following ODL and DDL. When applying this model, prediction in SCA increase using the OS parameter was more practical and compatible with clinical data. Both laminoplasties achieved enough SCA, and there was no significant difference between them in the usual range.

A prospective study of non-surgical versus surgical treatment for lumbar spinal stenosis without instability.

OBJECTIVE: Even if analyzed through meta-analyses or systemic reviews ensued lately, we could say that at least it is inconclusive which of the surgical or non-surgical treatment to lumbar spinal stenosis is better particularly in short to intermediate-term. This study compared non-surgical and surgical outcomes in surgical candidates for lumbar spinal stenosis (LSS). METHODS: Surgical candidates for LSS were prospectively screened. Patients were offered the option to be enrolled in a randomized cohort, an observational cohort, or not to participate. Patient-reported outcomes were evaluated at baseline, and at 1, 3, 6, and 12 months. The primary outcomes were measures of pain and functional outcomes such as the Korean version of the Oswestry Disability Index (K-ODI), the EuroQol 5-Dimension instrument (EQ-5D), and 36-Item Short-Form Health Survey (SF-36). RESULTS: One hundred and ten patients were enrolled in the randomized cohort and 37 patients in the observational cohort. Among them, 97 patients received non-surgical treatment, and 50 patients underwent surgical treatment. At 12 months, the non-surgical treatment group had less improvements in the primary outcome measures of back pain (mean change: non-surgery, 2.34 vs. surgery, 3.99), leg pain (2.92 vs. 3.40), K-ODI (5.12 vs. 8.31), EQ-5D utility index (0.19 vs. 0.25), and EQ-5D VAS (9.68 vs. 16.0). Most SF-36 section parameters also showed less improvement in the non-surgical treatment group than in the surgical treatment group throughout the 12-month follow-up. CONCLUSIONS: In LSS patients without instability, non-surgical treatment resulted in less pain improvement and functional recovery through 1 year.

Durability and Failure Types of S2-Alar-Iliac Screws: An Analysis of 312 Consecutive Screws.

BACKGROUND: S2-alar-iliac (S2AI) screws improve stability across the lumbosacral junction in spinopelvic fixation procedures by crossing the cortical surfaces of the sacroiliac joint (SIJ), thereby increasing the biomechanical strength of the instrumentation. OBJECTIVE: To investigate the durability and failure types of S2AI screws after spinopelvic reconstruction surgery. METHODS: A single-center, single-surgeon consecutive series of patients who underwent spinopelvic fixation using bilateral S2AI screws with a ≥1-yr follow-up and at least 1 postoperative computed tomographic scan were retrospectively reviewed. Patient characteristics, radiographic parameters, operative data, clinical outcomes, and complications were analyzed. RESULTS: In total, 312 S2AI screws in 156 patients were evaluated (mean follow-up, 26.1 mo; range 12-71 mo). There were no significant differences in screw diameter, length, or insertion angle between right-side and left-side screws. Visual analogue scale scores for back pain, ambulatory status, and Oswestry Disability Index scores significantly improved. A total of 10 patients (3.2%) experienced SIJ pain after S2AI screw installation. SIJ pain improved in 8 of them following SIJ block. In total, 7 screws (2.2%) showed partial periscrew lucency. Set screw dislodgement occurred in 7 screws (2.2%). Screw fracture occurred in 6 screws (1.9%): 5 neck fractures and 1 shaft fracture. A total of 5 patients (1.6%) underwent revision surgery for S2AI screw failure. Distal device (L4-pelvis region) breakage occurred in 5 patients. CONCLUSION: The radiographic and clinical outcomes of S2AI screw fixation were acceptable. However, S2AI screw fixation has several drawbacks, including screw fracture and dislodgement of the set screw. SIJ irritation symptoms after S2AI screw fixation occurred with considerable frequency.

Surgical Outcomes and Complications Following All Posterior Approach for Spinal Deformity Associated with Neurofibromatosis Type-1.

OBJECTIVES: The purpose of this study was to evaluate surgical outcomes and complications of spinal deformity associated with neurofibromatosis type-1 (NF-1). METHODS: From 2012 to 2018, patients suffering from spinal deformity associated with NF-1 who underwent surgical correction were identified. Demographic data and radiographic measures were retrospectively reviewed. Pre- and postoperative whole spine radiograph images were used to determine both coronal and sagittal Cobb angles. All of patients underwent 3-dimentional computed tomographic scan and magnetic resonance imaging scan to confirm dystrophic features. For evaluation of clinical outcomes, we surveyed the pre- and postoperative scoliosis research society-22r (SRS-22r) score. RESULTS: Seven patients with spinal deformity associated with NF-1 were enrolled in this study. The mean age of patients was 29.5±1.2 years old. The mean follow-up period was 2.8±1.4 years. The apex of the deformity was located in cervicothoracic (n=1), thoracic (n=4), and lumbar region (n=2). Most patients have poor bone quality and decreased bone mineral density with average T-score of -3.5±1.0. All patients underwent surgical correction via posterior approach. The pre- and postoperative mean coronal and sagittal Cobb angle was 61.6±22.6° and 34.6±38.1°, 56.8±18.5° and 40.2±9.1°, respectively. Mean correction rate of coronal and sagittal angle was 44.7% and 23.1%. Ultimate follow-up SRS-22r score (average score, 3.9±0.4) improved comparing to preoperative score (average score, 3.3±0.9). Only one patient received revision surgery due to rod fracture. No serious complication occurred, such as neurological deficit, and viscerovascular injury. CONCLUSION: The surgical correction of patients having spinal deformity associated with NF-1 is challenging, however the radiographic and clinical outcomes are satisfactory. The all posterior approach can be a safe and effective surgical option for patients having dystrophic curves associated with NF-1.

Comparison of the use of opioids only and pregabalin add-on for the treatment of neuropathic pain in cervical myelopathy patients: a pilot trial.

Among patients with cervical myelopathy who were diagnosed with neuropathic pain (NP) by the LANSS test, the study participants were randomly assigned to one of the two study groups. The participants in one study group received opioids only, while those in the other group received opioids and pregabalin. Thirty-nine patients were analyzed in the study (20 patients in the opioid-only group and 19 in the pregabalin add-on group). The LANSS, neck pain, and arm pain scores in the pregabalin add-on group improved significantly compared with those in the opioid-only group after the first 4 weeks (p = 0.005, 0.001 and 0.035, respectively), but there was no significant difference between the two groups during the next 4 weeks (p = 0.615, 0.377 and 0.716, respectively). There was no significant difference in the neck disability index and EuroQol-5Dimension scores after four weeks and eight weeks of follow-up. Adverse events were reported by four patients (20.0%) in the opioid-only group and five patients (26.3%) in the pregabalin add-on group (p = 0.716). However, over time, the occurrence of side effects and dropouts increased in the pregabalin add-on group. This exploratory pilot study suggests that pregabalin add-on treatment is more efficient than the use of opioids alone at the beginning of NP treatment in cervical myelopathy patients. However, prescribing pregabalin add-on treatment for more than four weeks should be done cautiously.