The effect of paraspinal sarcopenia on postoperative sagittal balance: a multivariate analysis following multilevel lumbar fusion surgery

The Spine Journal 26 (2026) 709−719

This clinical study examines how paraspinal sarcopenia influences long-term sagittal alignment and functional outcomes after multilevel posterior lumbar interbody fusion. Using preoperative MRI/CT and serial radiographs, muscle cross-sectional area, fat infiltration, and spinopelvic parameters were measured to compare sarcopenic and nonsarcopenic patients over at least two years.

Results show multifidus atrophy and fatty infiltration, plus inadequate preoperative lumbar and segmental lordosis, independently predict postoperative sagittal imbalance and worse pain and disability. The authors recommend preoperative paraspinal muscle assessment, nutritional and rehabilitation optimization, and tissue-sparing techniques to improve long-term outcomes.

Study aim: Assessed how paraspinal sarcopenia affects long-term sagittal alignment and persistent pain/disability after multilevel posterior lumbar interbody fusion (PLIF), and identified risk factors for postoperative sagittal imbalance.

Design & cohort: Retrospective single-institution study of 213 multilevel PLIF patients with imaging follow-up through ≥2 years; sarcopenic (n=69) vs nonsarcopenic (n=143/144) groups were compared.

Sarcopenia definition: Grouping based on psoas muscle index (MI) at L3 with thresholds <6.36 cm²/m² (men) and <3.92 cm²/m² (women).

Key measurements: Quantified L3 psoas/erector spinae/multifidus muscle MI, fat infiltration (Goutallier grading), and muscle density (CT HU); tracked spinopelvic parameters including LL, SL, PT, PI-LL, SVA plus VAS and ODI outcomes.

Muscle differences by group: Sarcopenic patients had lower muscle indices and higher fat infiltration (especially erector spinae and multifidus), with no significant difference in muscle density reported.

Alignment & outcomes: Sarcopenic patients showed worse long-term sagittal alignment at final follow-up (differences in LL, SL, PT, PI-LL, SVA) and worse long-term VAS and ODI scores, despite similar preoperative clinical scores.

Independent risk factors: Multifidus atrophy (lower MMI) and multifidus fat infiltration plus insufficient preoperative LL and SL were independent predictors of long-term postoperative sagittal imbalance; psoas, erector spinae, and other balance parameters were not independently associated.

Practical implication: Better sagittal-balance maintenance was associated with larger paraspinal MI, reduced fat infiltration, and favorable preoperative LL/SL, supporting preoperative evaluation of muscle health, nutritional status, and alignment.

Spinal versus general anesthesia in robotic minimally invasive transforaminal lumbar interbody fusion: a comparative study on surgical outcomes

J Neurosurg Spine 44:99–107, 2026

This clinical study compares spinal anesthesia (SA) versus general anesthesia (GA) for robot-assisted minimally invasive transforaminal lumbar interbody fusion (RA‑MIS TLIF), reporting retrospective outcomes from 209 patients treated 2018–2024. Primary findings show SA patients had significantly shorter operative times, lower immediate postoperative pain scores, reduced estimated blood loss, and shorter hospital length of stay after propensity score matching and regression adjustment.

The authors contextualize results within advances in robotic spinal surgery and awake spine techniques, discuss safety and potential cost and opioid‑reduction benefits, and acknowledge limitations including retrospective design, single‑center data, and reduced matched cohort size. Conclusions support SA as a safe, efficient approach for RA‑MIS TLIF with calls for larger prospective studies and formal patient‑selection guidelines.

Spinal Anesthesia (SA) vs General Anesthesia (GA): In robot-assisted minimally invasive transforaminal lumbar interbody fusion (RA-MIS TLIF), SA significantly reduces operative times, postoperative pain, and hospital length of stay compared to GA, with no increase in complications or adverse outcomes.

Robotic Assistance Benefits: Robotic technology in spine surgery improves pedicle screw placement accuracy, reduces radiation exposure, and is associated with lower complication and revision rates, enhancing surgical safety and efficiency.

Study Design: A retrospective analysis of 209 patients (31 SA, 178 GA) from 2018–2024, with propensity score matching applied to control for confounders, allowing fair comparison between SA and GA cohorts for single-level procedures.

Key Outcomes (After Matching): SA cohort had shorter median total OR time (159 vs 283 min), procedure time (115 vs 201 min), lower intraoperative blood loss (25 vs 50 mL), lower first postoperative pain scores (median VAS 0 vs 5), and reduced mean length of stay (0.90 vs 2.64 days) compared to GA.

Patient Selection: The choice between SA and GA was based on patient preference and eligibility, with all SA cases being single-level procedures and comparable baseline demographics after matching.

Safety Profile: No increase in intraoperative or postoperative complications was observed with SA; screw placement accuracy remained high with robotic assistance.

Implications for Practice: Combining SA with RA-MIS TLIF offers a safe, efficient, and patient-centered approach that may lower healthcare costs and opioid requirements by reducing pain and hospitalization.

Limitations: Single-center, retrospective design with a relatively small matched cohort may limit generalizability; further prospective, multicenter studies are needed to validate these findings.

Development of a unified and comprehensive definition of successful spinal fusion: a systematic review

J Neurosurg Spine 42:403–412, 2025

The document discusses a systematic review aimed at creating a unified definition of successful spinal fusion by integrating clinical symptoms, imaging modalities, and bone healing processes. It proposes a clinical algorithm for evaluating fusion success, emphasizing the need for standardized assessment criteria.

• A systematic review was conducted to develop a unified definition of successful spinal fusion, incorporating clinical symptoms and imaging modalities.

• The review involved 20 studies evaluating 1,324 spinal fusion procedures, resulting in a clinical algorithm for determining fusion success.

• The algorithm stratifies patients as symptomatic or asymptomatic, using specific imaging techniques based on pain type.

• Successful fusion for asymptomatic patients is considered after 12 months, while persistent symptoms indicate failure regardless of radiographic findings.

• Limitations include reliance on imaging and heterogeneous study data, but the algorithm aims to standardize fusion evaluation and improve outcomes.

• Future directions suggest using AI and machine learning for predictive algorithms and evaluating regional differences in fusion assessment.

• The proposed algorithm aims to improve diagnostic accuracy and provide a shared understanding of successful spinal fusion among clinicians.

• Implementation of the algorithm can enhance outcomes research and assess new developments in spinal fusion.

Can titanium surface technology reduce cost for biologics in anterior lumbar interbody fusion?

J Neurosurg Spine 41:589–595, 2024

Advances in surface architecture and technology have made interbody fusion devices more bioactive, with the hope of facilitating the fusion process more successfully. The advent of these increasingly bioactive implants may reduce reliance on more expensive biologics that have previously been used to achieve high fusion rates.

METHODS A retrospective review of prospectively collected data (August 2018–December 2019) was conducted of consecutively performed anterior lumbar interbody fusions in which an acid-etched, nanosurface-modulated, titanium interbody device packed only with corticocancellous allograft chips and local blood was used. Minimum follow-up was 1 year, and inclusion required available imaging and outcome metrics preoperatively and at 1 year. Fusion and subsidence were assessed via CT scans and/or dynamic radiographs. Health-related quality-of-life measures (Oswestry Disability Index [ODI], visual analog scale [VAS] back/leg) were collected pre- and postoperatively.

RESULTS In total, 55 patients met inclusion criteria (1 year of follow-up, available imaging, and outcome metrics). A total of 69 lumbar levels were treated in these 55 patients. The mean age was 67 ± 12.1 years, with 47% female patients. Roughly one-third (35%) had previous spine surgery, and approximately one-tenth (9.1%) had prior spinal fusion. A total of 20.6% were treated at multiple levels (mean levels per patient 1.2, minimum 1, maximum 3). The mean preoperative patient-reported outcomes were as follows: ODI 39.71 ± 18.15, VAS back 6.49 ± 2.19, and VAS leg 5.41 ± 2.71. One year after surgery, the mean improvements in patient-reported outcomes (vs preoperative scores) were as follows: ODI −22.9 ± 13.08 (p < 0.001), VAS back −3.75 ± 2.03 (p < 0.001), VAS leg −3.73 ± 2.32 (p < 0.001). All levels achieved fusion at 1 year postoperatively based on CT scans (65/69 levels) or dynamic radiographs (4/69 levels, change in score < 5% on flexion-extension radiographs). Four of the 65 levels were assigned to the grade 3 category according to a CT-based grading system, meaning cranial and caudal endplate bone apposition to the implant on both surfaces with no clear intervertebral bone connection through or around the implant. Sixty-one of 65 were found to have contiguous intervertebral bone bridging and thus were assigned to grade 1 (n = 54) or grade 2 (n = 7). Low-grade graft subsidence (Marchi grade 0 or I) occurred in 9 levels (13.0%) and high-grade subsidence (Marchi grade II or III) in 4 levels (5.8%). No patients required reoperation at the level of anterior lumbar interbody fusion and no radiographic or clinical evidence of pedicle screw loosening or failure was observed.

CONCLUSIONS The combination of advances in materials science and surface technology as demonstrated with a nanotechnology titanium cage resulted in the ability to obtain lumbar interbody fusion with allograft chips and local blood alone. Achieving high fusion rates with low-cost biologics/allograft provides for an attractive pathway toward reducing the cost of reconstructive spine care, and a potential incremental benefit for healthcare economics.

Using Novel Segmentation Technology to Define Safe Corridors for Minimally Invasive Posterior Lumbar Interbody Fusion

Operative Neurosurgery 27:14–22, 2024

There has been a rise in minimally invasive methods to access the intervertebral disk space posteriorly given their decreased tissue destruction, lower blood loss, and earlier return to work. Two such options include the percutaneous lumbar interbody fusion through the Kambin triangle and the endoscopic transfacet approach. However, without accurate preoperative visualization, these approaches carry risks of damaging surrounding structures, especially the nerve roots. Using novel segmentation technology, our goal was to analyze the anatomic borders and relative sizes of the safe triangle, trans-Kambin, and the transfacet corridors to assist surgeons in planning a safe approach and determining cannula diameters.

METHODS: The areas of the safe triangle, Kambin, and transfacet corridors were measured using commercially available software (BrainLab, Munich, Germany). For each approach, the exiting nerve root, traversing nerve roots, theca, disk, and vertebrae were manually segmented on 3-dimensional T2-SPACE magnetic resonance imaging using a region-growing algorithm. The triangles’ borders were delineated ensuring no overlap between the area and the nerves.

RESULTS: A total of 11 patients (65.4 ± 12.5 years, 33.3% female) were retrospectively reviewed. The Kambin, safe, and transfacet corridors were measured bilaterally at the operative level. The mean area (124.1 ± 19.7 mm 2 vs 83.0 ± 11.7 mm2 vs 49.5 ± 11.4 mm2 ) and maximum permissible cannula diameter (9.9 ± 0.7 mm vs 6.8 ± 0.5 mm vs 6.05 ± 0.7 mm) for the transfacet triangles were significantly larger than Kambin and the traditional safe triangles, respectively (P < .001).

CONCLUSION: We identified, in 3-dimensional, the borders for the transfacet corridor: the traversing nerve root extending inferiorly until the caudal pedicle, the theca medially, and the exiting nerve root superiorly. These results illustrate the utility of preoperatively segmenting anatomic landmarks, specifically the nerve roots, to help guide decision-making when selecting the optimal operative approach.

“July Effect” in Spinal Fusions: A Coarsened Exact-Matched Analysis

Neurosurgery 92:623–631, 2023

Few neurosurgical studies examine the July Effect within elective spinal procedures, and none uses an exact-matched protocol to rigorously account for confounders.

OBJECTIVE: To evaluate the July Effect in single-level spinal fusions, after coarsened exact matching of the patient cohort on key patient characteristics (including race and comorbid status) known to independently affect neurosurgical outcomes.

METHODS: Two thousand three hundred thirty-eight adult patients who underwent single-level, posterior-only lumbar fusion at a single, multicenter university hospital system were retrospectively enrolled. Primary outcomes included readmissions, emergency department visits, reoperation, surgical complications, and mortality within 30 days of surgery. Logistic regression was used to analyze month as an ordinal variable. Subsequently, outcomes were compared between patients with surgery at the beginning vs end of the academic year (ie, July vs April–June), before and after coarsened exact matching on key characteristics. After exact matching, 99 exactly matched pairs of patients (total n = 198) were included for analysis.

RESULTS: Among all patients, operative month was not associated with adverse postoperative events within 30 days of the index operation. Furthermore, patients with surgeries in July had no significant difference in adverse outcomes. Similarly, between exact-matched cohorts, patients in July were observed to have noninferior adverse postoperative events.

CONCLUSION: There was no evidence suggestive of a July Effect after single-level, posterior approach spinal fusions in our cohort. These findings align with the previous literature to imply that teaching hospitals provide adequate patient care throughout the academic year, regardless of how long individual resident physician assistants have been in their particular role.

Reoperations after primary and revision lumbar discectomy

The Spine Journal 22 (2022) 1983−1989

Published rates for disc reherniation following primary discectomy are around 6%, but the ultimate reoperation outcomes in patients after receiving revision discectomy are not well understood. Additionally, any disparity in the outcomes of subsequent revision discectomy (SRD) versus subsequent lumbar fusion (SLF) following primary/revision discectomy remains poorly studied.

PURPOSE: To determine the 8-year SRD/SLF rates and time until SRD/SLF after primary/revision discectomy respectively.

STUDY DESIGN: Retrospective cohort study.

PATIENT SAMPLE: Patients undergoing primary or revision discectomy, with records in the PearlDiver Patient Records Database from the years 2010 to 2019.

OUTCOME MEASURES: Subsequent surgery type and time to subsequent surgery.

METHODS: Patients were grouped into primary or revision discectomy cohorts based off of the nature of “index” procedure (primary or revision discectomy) using ICD9/10 and CPT procedure codes from 2010 to 19 insurance data sets in the PearlDiver Patient Records Database. Preoperative demographic data was collected. Outcome measures such as subsequent surgery type (fusion or discectomy) and time to subsequent surgery were collected prospectively in PearlDiver Mariner database. Statistical analysis was performed using BellWeather statistical software. A Kaplan-Meier survival analysis of time to SLF/SRD was performed on each cohort, and log-rank test was used to compare the rates of SLF/SRD between cohorts.

RESULTS: A total of 20,147 patients were identified (17,849 primary discectomy, 2,298 revision discectomy). The 8-year rates of SRD (6.1% in revision cohort, 4.8% in primary cohort, p<.01) and SLF (10.4% in revision cohort, 6.2% in primary cohort, p<.01) were higher after revision versus primary discectomy. Time to SLF was shorter after revision versus primary discectomy (709 vs. 886 days, p<.01). After both primary and revision discectomy, the 8-year rate of SLF (10.4% in revision cohort, 6.2% in primary cohort, p<.01) is greater than SRD (6.1% in revision cohort, 4.8% in primary cohort, p<.01).

CONCLUSIONS: Compared to primary discectomy, revision discectomy has higher rates of SLF (10.4% vs. 6.2%), and faster time to SLF (2.4 vs. 1.9 years) at 8-year follow up.

Complications of degenerative lumbar spondylolisthesis and stenosis surgery in patients over 80 s

Acta Neurochirurgica (2022) 164:923–931

Degenerative spondylolisthesis (DS) is a debilitating condition that carries a high economic burden. As the global population ages, the number of patients over 80 years old demanding spinal fusion is constantly rising. Therefore, neurosurgeons often face the important decision as to whether to perform surgery or not in this age group, commonly perceived at high risk for complications.

Methods Six hundred seventy-eight elder patients, who underwent posterolateral lumbar fusion for DS (performed in three different centers) from 2012 to 2020, were screened for medical, early and late surgical complications and for the presence of potential preoperative risk factors. Patients were divided in three categories based on their age: (1) 60–69 years, (2) 70–79 years, (3) 80 and over. Multiple logistic regression was used to determine the predictive power of age and of other risk factors (i.e., ASA score; BMI; sex; presence or absence of insulin-dependent and -independent diabetes, use of anticoagulants, use of antiaggregants and osteoporosis) for the development of postoperative complications.

Results In univariate analysis, age was significantly and positively correlated with medical complications. However, when controls for other risk factors were added in the regressions, age never reached significance, with the only noticeable exception of cerebrovascular accidents. ASA score and BMI were the two risk factors that significantly correlated with the higher numbers of complication rates (especially medical).

Conclusion Patients of different age but with comparable preoperative risk factors share similar postoperative morbidity rates. When considering octogenarians for lumbar arthrodesis, the importance of biological age overrides that of chronological.

Transforaminal lumbar interbody fusion using a novel minimally invasive expandable interbody cage

J Neurosurg Spine 35:170–176, 2021

The goal of this study was to evaluate the clinical and radiographic outcomes of a novel multidirectional in situ expandable minimally invasive surgery (MIS) transforaminal lumbar interbody fusion (TLIF) cage.

METHODS A retrospective analysis of 69 consecutive patients undergoing a 1- or 2-level MIS TLIF using an expandable cage was performed over a 2-year period. Standard MIS techniques with pedicle screw fixation were used in all cases. Upright lateral dynamic flexion/extension radiographs were reviewed prior to and at 1 year after surgery. Clinical metrics included numeric rating scale for back and leg pain, Oswestry Disability Index, and the SF-12 and VR-12 physical and mental health surveys. Radiographic parameters included anterior and posterior disc height, neuroforaminal height, spondylolisthesis, segmental lordosis, lumbar lordosis, and fusion rate.

RESULTS A total of 69 patients representing 75 operative levels met study inclusion criteria. The mean patient age at surgery was 63.4 ± 1.2 years, with a female predominance of 51%. The average radiographic and clinical follow-ups were 372 and 368 days, respectively. A total of 63 patients (91%) underwent 1-level surgery and 6 patients (9%) underwent 2-level surgery. Significant reductions of numeric rating scale scores for back and leg pain were observed—from 6.1 ± 0.7 to 2.5 ± 0.3 (p < 0.0001) and 4.9 ± 0.6 to 1.9 ± 0.2 (p < 0.0001), respectively. A similar reduction in Oswestry Disability Index from 38.0 ± 4.6 to 20.0 ± 2.3 (p < 0.0001) was noted. Likewise, SF-12 and VR-12 scores all showed statistically significant improvement from baseline (p < 0.001). The mean anterior and posterior disc heights improved from 8.7 ± 1.0 mm to 13.4 ± 1.5 mm (p = 0.0001) and 6.5 ± 0.8 mm to 9.6 ± 1.1 mm (p = 0.0001), respectively. Neuroforaminal height improved from 17.6 ± 2.0 mm to 21.9 ± 2.5 mm (p = 0.0001). When present, spondylolisthesis was, on average, reduced from 4.3 ± 0.5 mm to 1.9 ± 0.2 mm (p = 0.0001). Lumbar lordosis improved from 47.8° ± 5.5° to 58.5° ± 6.8° (p = 0.2687), and no significant change in segmental lordosis was observed. The overall rate of radiographic fusion was 93.3% at 1 year. No perioperative complications requiring operative revision were encountered.

CONCLUSIONS In this series of MIS TLIFs, use of this novel interbody cage was shown to be safe and effective. Significant improvements in pain and disability were observed. Effective and durable restoration of disc height and neuroforaminal height and reduction of spondylolisthesis were obtained, with concurrent gains in lumbar lordosis. Taken together, this device offers excellent clinical and radiographic outcomes via an MIS approach.

Outcome of unilateral versus standard open midline approach for bilateral decompression in lumbar spinal stenosis: is “over the top” really better?

J Neurosurg Spine 31:236–245, 2019

In this retrospective analysis of a prospective multicenter cohort study, the authors assessed which surgical approach, 1) the unilateral laminotomy with bilateral spinal canal decompression (ULBD; also called “over the top”) or 2) the standard open bilateral decompression (SOBD), achieves better clinical outcomes in the long-term follow-up. The optimal surgical approach (ULBD vs SOBD) to treat lumbar spinal stenosis remains controversial.

METHODS The main outcomes of this study were changes in a spinal stenosis measure (SSM) symptoms score, SSM function score, and quality of life (sum score of the 3-level version of the EQ-5D tool [EQ-5D-3L]) over time. These outcome parameters were measured at baseline and at 12-, 24-, and 36-month follow-ups. To obtain an unbiased result on the effect of ULBD compared to SOBD the authors used matching techniques relying on propensity scores. The latter were calculated based on a logistic regression model including relevant confounders. Additional outcomes of interest were raw changes in main outcomes and in the Roland and Morris Disability Questionnaire from baseline to 12, 24, and 36 months.

RESULTS For this study, 277 patients met the inclusion criteria. One hundred forty-nine patients were treated by ULBD, and 128 were treated by SOBD. After propensity score matching, 128 patients were left in each group. In the matched cohort, the mean (95% CI) estimated differences between ULBD and SOBD for change in SSM symptoms score from baseline to 12 months were -0.04 (-0.25 to 0.17), to 24 months -0.07 (-0.29 to 0.15), and to 36 months -0.04 (-0.28 to 0.21). For change in SSM function score, the estimated differences from baseline to 12 months were 0.06 (-0.08 to 0.21), to 24 months 0.08 (-0.07 to 0.22), and to 36 months 0.01 (-0.16 to 0.17). Differences in changes between groups in EQ-5D-3L sum scores were estimated to be -0.32 (-4.04 to 3.40), -0.89 (-4.76 to 2.98), and -2.71 (-7.16 to 1.74) from baseline to 12, 24, and 36 months, respectively. None of the group differences between ULBD and SOBD were statistically significant.

CONCLUSIONS Both surgical techniques, ULBD and SOBD, may provide effective treatment options for DLSS patients. The authors further determined that the patient outcome results for the technically more challenging ULBD seem not to be superior to those for the SOBD even after 3 years of follow-up.

 

Intrathecal Morphine Following Lumbar Fusion: A Randomized, Placebo-Controlled Trial

Neurosurgery, Volume 85, Issue 2, August 2019, Pages 189–198

Despite the potential for faster postoperative recovery and the ease of direct intraoperative injection, intrathecal morphine is rarely provided in lumbar spine surgery.

OBJECTIVE: To evaluate the safety and efficacy of intrathecal morphine following lumbar fusion.

METHODS: We randomly assigned 150 patients undergoing elective instrumented lumbar fusion to receive a single intrathecal injection of morphine (0.2 mg) or placebo (normal saline) immediately prior to wound closure. The primary outcome was pain on the visual- analogue scale during the first 24 h after surgery. Secondary outcomes included respiratory depression, treatment-related side effects, postoperative opioid requirements, and length of hospital stay. An intention-to-treat, repeated-measures analysis was used to estimate outcomes according to treatment in the primary analysis.

RESULTS: The baseline characteristics of the 2 groups were similar. Intrathecal morphine reduced pain both at rest (32% area under the curves [AUCs] difference, P < .01) and with movement (22% AUCs difference, P < .02) during the initial 24 h after surgery. The risk of respiratory depression was not increased by intrathecal morphine (hazard ratio, 0.86; 95% confidence interval, 0.44 to 1.68; P = .66). Although postoperative opioid requirements were reduced with intrathecal morphine (P < .03), lengths of hospital stay were similar (P = .32). Other than a trend towards increased intermittent catheterization among patients assigned to intrathecal morphine (P = .09), treatment-related side effects did not significantly differ. The early benefits of intrathecal morphine on postoperative pain were no longer apparent after 48 h.

CONCLUSION: A single intrathecal injection of 0.2 mg of morphine safely reduces postoperative pain following lumbar fusion.

The impact of adding posterior instrumentation to transpsoas lateral fusion

J Neurosurg Spine 30:211–221, 2019

Transpsoas lateral interbody fusion is one of the lateral minimally invasive approaches for lumbar spine surgery. Most surgeons insert the interbody cage laterally and then insert pedicle or cortical screw and rod instrumentation posteriorly. However, standalone cages have also been used to avoid posterior instrumentation. To the best of the authors’ knowledge, the literature on comparison of the two approaches is sparse.

METHODS The authors performed a systematic review and meta-analysis of the available literature on transpsoas lateral interbody fusion by an electronic search of the PubMed, EMBASE, and Scopus databases using PRISMA guidelines. They compared patients undergoing transpsoas standalone fusion (TP) with those undergoing transpsoas fusion with posterior instrumentation (TPP).

RESULTS A total of 28 studies with 1462 patients were included. Three hundred and seventy-four patients underwent TPP, and 956 patients underwent TP. The mean patient age ranged from 45.7 to 68 years in the TP group, and 50 to 67.7 years in the TPP group. The incidence of reoperation was found to be higher for TP (0.08, 95% confidence interval [CI] 0.04–0.11) compared to TPP (0.03, 95% CI 0.01–0.06; p = 0.057). Similarly, the incidence of cage movement was found to be greater in TP (0.18, 95% CI 0.10–0.26) compared to TPP (0.03, 95% CI 0.00–0.05; p < 0.001). Oswestry Disability Index (ODI) and visual analog scale (VAS) scores and postoperative transient deficits were found to be comparable between the two groups.

CONCLUSIONS These results appear to suggest that addition of posterior instrumentation to transpsoas fusion is associated with decreased reoperations and cage movements. The results of previous systematic reviews and meta-analyses should be reevaluated in light of these results, which seem to suggest that higher reoperation and subsidence rates may be due to the use of the standalone technique.

 

Predictors of Poor Outcome in Patients Submitted to Minimally Invasive Transforaminal Lumbar Interbody Fusion

World Neurosurg. (2018) 119:488-493

Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) has become an increasingly popular method for lumbar arthrodesis. While having similar long-term outcomes when compared with open TLIF, it decreases the amount of intraoperative blood loss and iatrogenic muscle damage, the intensity of postoperative pain, and the duration of hospital stay. However, uncertainty remains about which factors contribute to outcomes in these patients. The purpose of this study was to retrospectively analyze a cohort of patients submitted to MI-TLIF and to identify factors that can be associated with a worse postoperative outcome.

METHODS: Clinical records from 283 patients were assessed and, according to Odom’s criteria, postoperative clinical outcome at 12 months was classified as excellent, good, fair, and poor. Demographic variables, clinical data, and surgery-related data were analyzed, looking for associations between them and clinical outcome. A binomial logistic regression analysis was then performed to include those associations.

RESULTS: The main variables associated with worse prognosis (“poor” class according to Odom’s criteria) were a period of sick leave longer than 3 months before the surgery, age younger than 50 years, lytic spondylolisthesis, L5-S1 level, and occurrence of complications. These 5 conditions were included in a logistic regression analysis, and 3 of them were independently associated with poor outcome: operative complications, age younger than 50 years, and sick leave longer than 3 months before surgery. –

CONCLUSIONS: Younger patients, those on a sick leave for more than 3 months before surgery, or those who suffered surgical complications tended to have less satisfactory results after MI-TLIF.

Pelvic retroversion: a compensatory mechanism for lumbar stenosis

J Neurosurg Spine 27:137–144, 2017

The flexed posture of the proximal (L1–3) or distal (L4–S1) lumbar spine increases the diameter of the spinal canal and neuroforamina and can relieve symptoms of neurogenic claudication. Distal lumbar flexion can result in pelvic retroversion; therefore, in cases of flexible sagittal imbalance, pelvic retroversion may be compensatory for lumbar stenosis and not solely compensatory for the sagittal imbalance as previously thought. The authors investigate underlying causes for pelvic retroversion in patients with flexible sagittal imbalance.

METHODS One hundred thirty-eight patients with sagittal imbalance who underwent a total of 148 fusion procedures of the thoracolumbar spine were identified from a prospective clinical database. Radiographic parameters were obtained from images preoperatively, intraoperatively, and at 6-month and 2-year follow-up. A cohort of 24 patients with flexible sagittal imbalance was identified and individually matched with a control cohort of 23 patients with fixed deformities. Flexible deformities were defined as a 10° change in lumbar lordosis between weight-bearing and non–weight-bearing images. Pelvic retroversion was quantified as the ratio of pelvic tilt (PT) to pelvic incidence (PI).

RESULTS The average difference between lumbar lordosis on supine MR images and standing radiographs was 15° in the flexible cohort. Sixty-eight percent of the patients in the flexible cohort were diagnosed preoperatively with lumbar stenosis compared with only 22% in the fixed sagittal imbalance cohort (p = 0.0032). There was no difference between the flexible and fixed cohorts with regard to C-2 sagittal vertical axis (SVA) (p = 0.95) or C-7 SVA (p = 0.43). When assessing for postural compensation by pelvic retroversion in the stenotic patients and nonstenotic patients, the PT/PI ratio was found to be significantly greater in the patients with stenosis (p = 0.019).

CONCLUSIONS For flexible sagittal imbalance, preoperative attention should be given to the root cause of the sagittal misalignment, which could be compensation for lumbar stenosis. Pelvic retroversion can be compensatory for both the lumbar stenosis as well as for sagittal imbalance.

 

The Influence of Pelvic Incidence and Lumbar Lordosis Mismatch on Development of Symptomatic Adjacent Level Disease Following Single-Level Transforaminal Lumbar Interbody Fusion

Neurosurgery 80:880–886, 2017

Annual incidence of symptomatic adjacent level disease (ALD) following lumbar fusion surgery ranges from 0.6% to 3.9% per year. Sagittal malalignment may contribute to the development of ALD.

OBJECTIVE: To describe the relationship between pelvic incidence-lumbar lordosis (PI-LL) mismatch and the development of symptomatic ALD requiring revision surgery following single-level transforaminal lumbar interbody fusion for degenerative lumbar spondylosis and/or low-grade spondylolisthesis.

METHODS: All patients who underwent a single-level transforaminal lumbar interbody fusion at either L4/5 or L5/S1 between July 2006 and December 2012 were analyzed for pre- and postoperative spinopelvic parameters. Using univariate and logistic regression analysis,we compared the spinopelvic parameters of those patients who required revision surgery against those patients who did not develop symptomatic ALD. We calculated the predictive value of PI-LL mismatch.

RESULTS: One hundred fifty-nine patients met the inclusion criteria. The results noted that, for a 1◦ increase in PI-LL mismatch (preop and postop), the odds of developing ALD requiring surgery increased by 1.3 and 1.4 fold, respectively, which were statistically significant increases. Based on our analysis, a PI-LL mismatch of >11◦ had a positive predictive value of 75% for the development of symptomatic ALD requiring revision surgery.

CONCLUSIONS: A high PI-LL mismatch is strongly associated with the development of symptomatic ALD requiring revision lumbar spine surgery. The development of ALD may represent a global disease process as opposed to a focal condition. Spine surgeons may wish to consider assessment of spinopelvic parameters in the evaluation of degenerative lumbar spine pathology.

 

Impact of obesity on complications and outcomes: a comparison of fusion and nonfusion lumbar spine surgery

J Neurosurg Spine 26:158–162, 2017

Prior studies have shown obesity to be associated with higher complication rates but equivalent clinical outcomes following lumbar spine surgery. These findings have been reproducible across lumbar spine surgery in general and for lumbar fusion specifically. Nevertheless, surgeons seem inclined to limit the extent of surgery, perhaps opting for decompression alone rather than decompression plus fusion, in obese patients. The purpose of this study was to ascertain any difference in clinical improvement or complication rates between obese and nonobese patients following decompression alone compared with decompression plus fusion for lumbar spinal stenosis (LSS).

Methods: The Quality Outcomes Database (QOD), formerly known as the National Neurosurgery Quality and Outcomes Database (N 2 QOD), was queried for patients who had undergone decompression plus fusion (D+F group) versus decompression alone (D+0 group) for LSS and were stratified by a body mass index (BMI) ≥ 30 kg/m 2 (obese) or < 30 kg/m 2 (nonobese). Demographic, surgical, and health-related quality of life data were compared.

Results: In the nonobese cohort, 947 patients underwent decompression alone and 319 underwent decompression plus fusion. In the obese cohort, 844 patients had decompression alone and 337 had decompression plus fusion. There were no significant differences in the Oswestry Disability Index score or in leg pain improvement at 12 months when comparing decompression with fusion to decompression without fusion in either obese or nonobese cohorts. However, absolute improvement in back pain was less in the obese group when decompression alone had been performed. Blood loss and operative time were lowest in the nonobese D+0 cohort and were higher in obese patients with or without fusion. Obese patients had a longer hospital stay (4.1 days) than the nonobese patients (3.3 days) when fusion had been performed. In-hospital stay was similar in both obese and nonobese D+0 cohorts. No significant differences were seen in 30-day readmission rates among the 4 cohorts.

Conclusions: Consistent with the prior literature, equivalent clinical outcomes were found among obese and non-obese patients treated for LSS. In addition, no difference in clinical outcomes as related to the extent of the surgical procedure was observed between obese and nonobese patients. Within the D+0 group, the nonobese patients had slightly better back pain scores at 2 years postoperatively. There may be a higher blood product requirement in obese patients following spine surgery, as well as an extended hospital stay, when fusion is performed. While obesity may influence the decision for or against surgery, the data suggest that obesity should not necessarily alter the appropriate procedure for well-selected surgical candidates.

Benefit of Transforaminal Lumbar Interbody Fusion vs Posterolateral Spinal Fusion in Lumbar Spine Disorders

tlif-x-ray-lat

Neurosurgery 79:397–405, 2016

Despite increasing use and potential benefits of transforaminal lumbar interbody fusion (TLIF) compared with posterolateral spinal fusion (PSF), previous studies have not documented improved clinical outcomes with TLIF vs PSF.

OBJECTIVE: To compare the outcomes of TLIF with PSF in patients with spondylolisthesis, spinal stenosis, and adjacent level disease.

METHODS: The National Neurosurgical Quality and Outcomes Database was queried for patients who had a lumbar fusion. Eighty-five percent (1722) of enrolled cases had 12-month follow-up data. There were 306 PSF patients and 1230 TLIF patients. PSF cases within each diagnostic subgroup were propensity-matched to patients who had TLIF. Sufficient propensity-matched controls were available for patients with spondylolisthesis (109), spinal stenosis (63), and adjacent segment disease (47).

RESULTS: Operating room time, estimated blood loss, and length of stay were similar between PSF and TLIF in all 3 propensity-matched groups. In the spondylolisthesis group, there was a greater improvement in Oswestry Disability Index (ODI) with TLIF vs PSF at 3 months (19.4 vs 26.0, P = .009), 12 months (20.8 vs 29.3, P = .001), and in percentage reaching minimal clinically important difference at 12 months (80% vs 62%, P = .007). There were no differences in ODI improvement between PSF and TLIF in the stenosis or adjacent segment disease groups.

CONCLUSION: TLIF generated more favorable ODI outcomes than PSF for patients with spondylolisthesis, but not for patients with spinal stenosis or adjacent segment disease. There was also equivalence in operating room time and estimated blood loss between TLIF and PSF, potentially altering the long-standing assumption that PSF is a simpler procedure.

ALIF and total disc replacement versus 2-level circumferential fusion with TLIF: a prospective, randomized, clinical and radiological trial

ALIF-TDR vs TLIF

Eur Spine J (2016) 25:1558–1566

Study design: Prospective, randomized trial.

Purpose: The treatment of degenerative disc disease (DDD) with two-level fusion has been associated with a reasonable rate of complications. The aim of the present study was to compare (Hybrid) stand-alone anterior lumbar interbody fusion (ALIF) at L5/S1 with total disc replacement at L4/5 (TDR) as an alternative surgical strategy to (Fusion) 2-level circumferential fusion employing trans- foraminal lumbar interbody fusion (TLIF) with transpedicular stabilization at L4–S1.

Methods: A total of 62 patients with symptomatic DDD of segments L5/S1 (Modic ≥2°) and L4/5 (Modic ≤2°; positive discography) were enrolled; 31 were treated with Hybrid and 31 with Fusion. Preoperatively, at 0, 12, and a mean follow-up of 37 months, clinical (ODI, VAS) and radiological evaluations (plain/extension-flexion radiographs evaluated for implant failure, fusion, global and segmental lordosis, and ROM) were performed.

Results: In 26 of 31 Hybrid and 24 of 31 Fusion patients available at the final follow-up, we found a significant clinical improvement compared to preoperatively. Hybrid patients had significantly lower VAS scores immediately postoperatively and at follow-up compared to Fusion patients. The complication rates were low and similar between the groups. Lumbar lordosis increased in both groups. The increase was mainly located at L4–S1 in the Hybrid group and at L1–L4 in the Fusion group. Hybrid patients presented with increased ROM at L4/5 and L3/4, and Fusion patients presented with increased ROM at L3/4, with significantly greater ROM at L3/4 compared to Hybrid patients at follow-up.

Conclusions Hybrid surgery is a viable surgical alternative for the presented indication. Approach-related inferior trauma and the balanced restoration of lumbar lordosis resulted in superior clinical outcomes compared to two-level circumferential fusion with TLIF.

Impact of Age on Short-term Outcomes After Lumbar Fusion

Three-Dimensional Computed Tomography-Based Spinal Navigation in Minimally Invasive Lateral Lumbar Interbody Fusion4

Neurosurgery 77:347–354, 2015

The safety and efficacy of spinal fusion in the elderly population remains uncertain with conflicting data.

OBJECTIVE: To determine if elderly patients undergoing instrumented lumbar fusion have increased 30-day complication rates compared to younger patients.

METHODS: The American College of Surgeons National Surgical Quality Improvement Program was used to identify all patients undergoing instrumented posterolateral lumbar fusion between 2005 and 2011. Patients were stratified by decade cohorts as follows: ,65, 65 to 75, 75 to 85, and $85 years old. All 30-day complications were grouped as overall composite morbidity and were compared using multivariate analysis.

RESULTS: A total of 1395 patients were identified and the overall 30-day complication rate was 11.47%. The complication rates were 9.04% and 14.05% for patients younger than 65 and older than 65, respectively. When stratified by decade cohorts, the complication rates were 9.04% for the ,65 cohort, 13.46% for the 65 to 75 cohort, 16.17% for the .75 to 85 cohort, and 4.00% for the $85 cohort. Multivariable regression analysis revealed no statistically significant difference between the ,65 and $65 age cohorts (odds ratio = 1.26; 95% confidence interval: 0.87-2.19). After stratifying into age cohorts, multivariable analyses revealed no difference in odds of postoperative complication occurrence for any age cohort when compared with the referent group (,65 years of age).

CONCLUSION: Patients older than 65 years of age have significantly higher rates of complications after lumbar fusion when compared to younger patients. However, multivariable analysis revealed that age was not an independent risk factor for complication occurrence after lumbar fusion.

Impact of Body Mass Index on Adjacent Segment Disease After Lumbar Fusion for Degenerative Spine Disease

Impact of Body Mass Index on Adjacent Segment Disease After Lumbar Fusion for Degenerative Spine Disease

Neurosurgery 76:396–402, 2015

Adjacent segment disease is an important complication after fusion of degenerative lumbar spines. However, the role of body mass index (BMI) in adjacent segment disease has been addressed less.

OBJECTIVE: To examine the relationship between BMI and adjacent segment disease after lumbar fusion for degenerative spine diseases.

METHODS: For this retrospective study, we enrolled 190 patients undergoing lumbar fusion surgery for degeneration. BMI at admission was documented. Adjacent segment disease was defined by integration of the clinical presentations and radiographic criteria based on the morphology of the dural sac on magnetic resonance images.

RESULTS: Adjacent segment disease was identified in 13 of the 190 patients, accounting for 6.8%. The interval between surgery and diagnosis as adjacent segment disease ranged from 21 to 66 months. Five of the 13 patients required subsequent surgical intervention for clinically relevant adjacent segment disease. In the logistic regression model, BMI was a risk factor for adjacent segment disease after lumbar fusion for degenerative spine diseases (odds ratio, 1.68; 95% confidence interval, 1.27- 2.21; P < .001). Any increase of 1 mean value in BMI would increase the adjacent segment disease rate by 67.6%. The patients were subdivided into 2 groups based on BMI, and up to 11.9% of patients with BMI ≥25 kg/m2 were diagnosed as having adjacent segment disease at the last follow-up.

CONCLUSION: BMI is a risk factor for adjacent segment disease in patients undergoing lumbar fusion for degenerative spine diseases. Because BMI is clinically objective and modifiable, controlling body weight before or after surgery may provide opportunities to reduce the rate of adjacent segment disease and to improve the outcome of fusion surgery.