Sravisht Iyer

Background: Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is increasingly centralized and performed at high-volume specialized centers. Centralization often requires long-distance travel, but its effect on postoperative outcomes after MI-TLIF is unknown. Purpose: We sought to identify whether travel distance affects outcomes after 1- to 2-level MI-TLIF. Methods: We conducted a retrospective cohort study utilizing data from a prospectively collected registry at a single academic institution. We included adult patients who underwent primary 1- or 2-level MI-TLIF surgery between April 2017 and April 2025 by 3 board-certified orthopedic spine surgeons. Patients with 50 miles from the hospital were classified as travelers. Outcome measures included Oswestry Disability Index, Visual Analog Scale, 12-Item Short Form Survey, and Patient-Reported Outcomes Measurement Information System, and their minimal clinically important difference (MCID) attainment, evaluated at ≤3 and ≥6 months. Other outcomes included 90 day and 1 year readmission and reoperation. Univariate analyses used t -tests and χ ² /Fisher’s exact tests. Multivariable logistic regression identified predictors of long-term MCID non-achievement. Results: Of the 408 patients included, 139 (34.1%) were travelers (mean distance 440.6 vs 19.5 miles for locals). No differences were observed between travelers and locals in all primary patient-reported outcome measures or MCID attainment at both timepoints. Multivariable analysis demonstrated travel distance was not an independent predictor of long-term MCID non-achievement for any outcome 90 day and 1 year readmission and reoperation rates were similar. Conclusions: Our retrospective analysis found that in patients who underwent 1- to 2-level MI-TLIF at our institution, traveling >50 miles was not associated with inferior short- or long-term patient-reported outcomes, likelihood of achieving MCID, or rates of readmission or reoperation through 1 year follow-up. These findings suggest that patients may safely access specialized spine care at high-volume centers without outcome disadvantage from travel burden. Level of Evidence: Level III, retrospective cohort study.

Study Design.: Retrospective cohort. Objective.: To evaluate the associations of 28 preoperative comorbidities with all-cause and etiology-specific revisions (pseudarthrosis, mechanical failure, adjacent segment disease [ASD], infection) following single-level degenerative spinal fusion. Summary of Background Data.: Revision following spinal fusion for degenerative spinal disease remains frequent and costly. While technical factors are well studied, the extent to which preoperative comorbidities differentially predispose to specific revision etiologies is unclear. Materials and Methods.: Using the PearlDiver Mariner170 claims database (2010–2023), we identified adults undergoing single-level degenerative spinal fusion and followed them for 2 years for reoperation. All-cause and etiology-specific revisions were defined by CPT/ICD codes. Preoperative comorbidities were analyzed using multivariable cox proportional hazards models adjusted for age, sex, and all comorbidities. Bonferroni correction set significance at P ≤0.00036. Results.: Among 399,186 patients (mean age 59.7±13.0; 56.7% female; mean CCI 1.4±1.2), anaemia (HR 1.33), osteoporosis (HR 1.31), substance-related disorders (HR 1.25), and depression (HR 1.19) conferred the greatest risk of all-cause revision. Type 2 diabetes (HR 1.07) and essential hypertension (HR 1.14) had smaller but significant effects. Etiology-specific analyses showed that osteoporosis, anaemia, depression, and substance-related disorders were consistently associated with increased risk across pseudarthrosis, mechanical failure, and ASD. Mechanical failure was additionally associated with hypertension (HR 1.20) and diabetes (HR 1.28), which were not significant in the other revision subtypes. In contrast, ASD revisions were uniquely associated with osteoarthritis (HR 1.26). No comorbidity was significantly associated with infection-related revision. All hazard ratios were significant at P <0.001 unless otherwise specified. Conclusion.: In this national cohort of patients, osteoporosis, anaemia, depression, and substance-related disorders emerged as significant predictors of non-infectious revision within two years. Hypertension and type 2 diabetes conferred more modest risks for mechanical failure. These findings support the integration of comorbidity-informed risk stratification into preoperative planning and highlight the potential optimization to minimize revisions and enhance clinical outcomes.

OBJECTIVE: Foraminal stenosis (FS) is commonly identified in patients undergoing lumbar decompression, but its clinical significance when deemed "asymptomatic" remains unclear. Minimally invasive surgery techniques for decompression, including unilateral laminotomy for bilateral decompression, aim to relieve neural compression while preserving soft tissue. However, the impact of preoperative FS on postoperative outcomes following minimally invasive decompression is not well-established. The aim of this study was to evaluate the effect of preoperative FS on patient-reported outcome measures (PROMs) and revision surgery rates following single-level minimally invasive lumbar decompression. METHODS: Patients who underwent primary single-level minimally invasive decompression for degenerative lumbar conditions between February 2017 and September 2022 at a single institution were included. Preoperative FS severity was graded from 0 (none) to 3 (severe) on MRI, and patients were stratified into FS+ (any FS ≥ grade 1) and FS− (no FS) groups. Patients in the FS+ and FS− groups were matched 1:1 based on demographic characteristics and preoperative radiographic parameters and compared for all outcome measures. Outcomes included PROMs (Oswestry Disability Index [ODI], visual analog scale [VAS] for back and leg pain, and SF-12 Physical Component Score [PCS]) at short-term and long-term follow-up time points and revision surgery rates. Multivariable logistic regression analysis was conducted for predictors of nonachievement of the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS). RESULTS: Of 320 patients included in the analysis, FS was present in 234 (73.1%, mean age 68.52 years). After matching, the FS+ group (n = 71) and FS− group (n = 71) were compared. Both groups demonstrated significant postoperative improvement in PROMs; however, patients with FS had worse ODI (p = 0.001), VAS-back (p = 0.003), and SF-12 PCS (p = 0.004) outcomes at long-term follow-up. In addition, the FS+ group had higher revision surgery rates at the index level (p = 0.003) and greater likelihood of requiring fusion (p = 0.005). An FS grade of 2 or 3 independently predicted failure to achieve the MCID for ODI, VAS Back, SF-12 PCS and the PASS for ODI. CONCLUSIONS: Radiographic FS, even when deemed asymptomatic, was associated with worse long-term functional outcomes and higher revision rates following minimally invasive decompression. These findings underscore the need for careful preoperative assessment and surgical planning, particularly for patients with moderate-to-severe FS, to optimize long-term outcomes.

Study Design.: Prospective cohort study. Objective.: To evaluate whether bone turnover markers (BTMs) predict pseudarthrosis after cervical spine surgery. Summary of Background Data.: Pseudarthrosis is a major reason for reoperation after ACDF. However, prediction of pseudarthrosis remains elusive. Patient-level factors have proven unreliable, and optimization of modifiable risk factors may be precluded by urgent neurological indications for surgery. Bone turnover markers are directly modifiable and may help predict fusion before and after surgery. Materials and Methods.: Patients undergoing 1–3 level ACDF for degenerative pathology were enrolled. Exclusion criteria included metabolic bone disease, current osteoporosis treatment, inflammatory arthritis, chronic steroid use, and chronic kidney disease. Serum collagen type 1 C-telopeptide (CTX) and procollagen type 1 N-propeptide (P1NP) were used as markers of bone resorption and formation, respectively. Labs were collected preoperatively and at six weeks postoperatively for CTX and P1NP with changes in values (Δ) calculated. The primary outcome was radiographic pseudarthrosis at one year, defined as interspinous distance change >1 mm on dynamic lateral radiographs. Associations between pseudarthrosis and BTMs, demographics, comorbidities, surgical variables, and osteometabolic labs were assessed. A stepwise (Wald) logistic regression model evaluated independent predictors of pseudarthrosis. Results.: Fifty-eight consecutive patients were enrolled, 25 missed six‑week labs, leaving 33 patients (60 levels) for analysis. Pseudarthrosis occurred in 30% of patients. Baseline demographics, surgical factors, and laboratory values were similar between fused and pseudarthrosis cohorts. Six‑week P1NP tended to be higher in the pseudarthrosis group (95.0±84.8 vs. 55.1±23.4, P =0.074), and ΔP1NP was significantly greater (38.5±70.6 vs. −16.9±97.1, P =0.013). Logistic regression identified ΔP1NP as a significant predictor of one‑year fusion status ( P =0.039), whereas BMI, 25‑hydroxyvitamin D, and number of fused levels showed borderline associations. Conclusion.: Patients at risk for pseudarthrosis after ACDF show a larger early increase in P1NP compared to their fused counterparts while CTX levels remained comparable between the groups. Considering that these changes occur early after surgery, there may be a role for trials testing the efficacy of postoperative anabolic agents in preventing pseudoarthrosis in high-risk patients. Evidence level.: Level II (Prospective Cohort Study)

Study Design: Retrospective cohort study. Objective: This study aims to assess the agreement and differences between EOS imaging and conventional cervical radiographs (cXR) in measuring cervical alignment, and to identify factors associated with their differences. Summary of Background Data: Accurate assessment of cervical spine alignment is essential for effective surgical planning. While cXR has been widely used for this purpose, the EOS imaging system provides a full-body, low-radiation alternative that captures global spinal alignment in a standing position. Despite its advantages, the agreement between EOS and cXR in evaluating cervical alignment parameters remains unclear. Methods: Patients who had both preoperative EOS and cXR images within a 6-month interval were included. The primary outcome measures included cervical alignment parameters in EOS and standing cXR, including C0–C2 Cobb angle, C2–C7 Cobb angle, C2–C7 sagittal vertical axis (SVA), and T1 slope. The humerus angle was measured on EOS imaging as the angle between the humerus and a plumb line to account for arm positioning during imaging. Bland-Altman analysis was used to evaluate the agreement between EOS and cXR. Multiple linear regression identified predictors of measurement differences of cervical alignment. Results: A total of 171 patients were included, with a mean age of 58 years, of which 56% were male. Significant differences were observed in C0–C2 Cobb (EOS, 27.5° versus cXR, 26.6°; P =0.020), C2–C7 SVA (20.9 mm versus 26.3 mm, P P =0.016), while no significant difference was observed for C2–C7 Cobb (EOS, 11.3° versus cXR, 10.4°; P =0.065). The Bland-Altman analysis suggested significant variability for C2–C7 SVA. Multiple linear regression identified humerus angle (B=−0.159, P =0.026), height (B=−0.153, P =0.036), and C2–C7 SVA on cXR (B=−0.515, P <0.001) as significant predictors of C2–C7 SVA measurement differences. Conclusions: EOS and cXR are generally interchangeable for cervical alignment assessment. However, C2-C7 SVA measurements require cautious interpretation due to variability stemming from the humerus angle and the patient’s height.

Study Design: Propensity-matched retrospective cohort. Objective: The objective of this study was to determine whether lumbar disc replacement (LDR) can provide radiographic indirect decompression as effectively as anterior lumbar interbody fusion (ALIF). Summary of Background Data: Isolated lumbar foraminal stenosis can often be treated with indirect decompression via ALIF. More recently, LDR has emerged as a motion-preserving treatment option for lumbar disease; however, its ability to provide indirect decompression has not been studied. Methods: All patients undergoing 1-level ALIF and LDR over a 7-year period were queried. A propensity-matched cohort was then identified utilizing patient-specific factors. This yielded 23 patients undergoing LDR and 44 undergoing ALIF. The primary outcome of this study was the change in radiographic foraminal height (FH) and segmental lordosis (SL) from pre- to postoperatively. All measurements were performed by 2 independent reviewers, and intraclass correlation coefficients (ICC) were calculated. Patient-reported outcome measures, including visual analog scale (VAS) back and leg scores, were collected for comparison at early and late postoperative timepoints. Intercohort comparisons were performed via Mann-Whitney U tests. P -values P 0.75) across both reviewers. Preoperatively, ALIF patients had smaller radiographic FH (13.8 vs. 15.6 mm, P =0.01), but no other differences were seen. Both ALIF and LDR provided significant increases in FH (ALIF: 3.5 mm and LDR: 3.7 mm) and SL (ALIF: 8.0 degrees and LDR: 8.0 degrees). There were no differences in the mean ΔFH ( P =0.56) or ΔSL ( P =0.85) between cohorts. Both groups showed significant improvement in postoperative VAS leg scores at early and late time points. Conclusions: LDR can provide indirect decompression and segmental lordosis restoration as effectively as ALIF.

Study Design: Systematic Review. Objectives: Lumbar foraminal stenosis (LFS) is a common finding on spine imaging. While surgery is indicated for symptomatic LFS, the clinical impact of incidentally found asymptomatic LFS (aLFS) on surgical outcomes remains unclear. This study aims to evaluate the influence of aLFS on reoperation rates and functional outcomes following lumbar spine surgery. Methods: A systematic search of PubMed, Embase, MEDLINE, and the Cochrane Library was conducted. Eight of 795 records met inclusion criteria and encompassed 1,744 adult patients undergoing lumbar spinal surgery, of whom 468 (26.8%) had aLFS. Due to heterogeneity in LFS classification, surgical procedures, follow-up duration, and patient-reported outcome measures (PROMs), quantitative pooling was not feasible and a structured narrative synthesis was performed. Study characteristics, patient demographics, surgical details, LFS classification methods, PROMs, and reoperation events were assessed. Results: aLFS was associated in some studies with less postoperative improvement in Oswestry Disability Index and greater residual back and leg pain. Several studies suggested that preoperative aLFS at the surgical level was associated with increased index-level reoperations following decompression (low-moderate certainty). However, no association was found at adjacent levels or with fusion procedures. Conclusions: Evidence regarding the prognostic significance of incidental aLFS remains limited, heterogeneous, and low certainty. Association between index-level aLFS and later reoperation should be interpreted cautiously because instability-related factors may be stronger drivers of failure than stenosis severity alone. Current evidence does not support prophylactic treatment of radiographically asymptomatic foraminal stenosis, particularly at adjacent levels in the absence of instability or symptom correlation.

Study Design: Retrospective cohort study. Objectives: To assess the impact of preoperative symptom duration on patient-reported outcomes following percutaneous transforaminal endoscopic discectomy (PTED). Summary of Background Data: Lumbar disc herniation and foraminal stenosis are common conditions that can lead to debilitating radiculopathy and functional limitations. Percutaneous transforaminal endoscopic discectomy (PTED) has emerged as a minimally invasive surgical option to address these pathologies, offering potential advantages in recovery and patient satisfaction. However, the duration of preoperative symptoms has been suggested as a critical factor influencing surgical outcomes. Prolonged symptom duration may lead to nerve root inflammation, fibrosis, and chronic pain syndromes, potentially diminishing the effectiveness of surgical intervention. Materials and Methods: Patients who underwent primary 1-level or 2-level PTED with a single surgeon between 2020 and 2023 were included. Patients were grouped into shorter (P P =0.002). The shorter symptom duration cohort achieved MCID for ODI at a significantly greater rate in the early postoperative period (85.2% vs. 44.4%, P P P =0.037). Conclusions: Our study demonstrates improved clinical outcomes for patients with shorter preoperative symptom duration undergoing endoscopic lumbar discectomy, suggesting that delayed surgical intervention may result in poorer outcomes and greater postoperative disability. These findings may help inform the approach to counseling patients on postoperative expectations and outcomes based on their preoperative symptom duration. Level of Evidence: Level III.

Study Design/Setting: Prospective cohort study. Objectives: To test whether the novel Forgotten Spine Surgery Score-Cervical (FS3-C) better differentiates outcomes between motion-preserving cervical disc replacement (CDR) and fusion via anterior cervical discectomy and fusion (ACDF) compared with the NDI. Methods: The FS3-C was derived from a 20-item pool and reduced to 12 items after pilot testing in 41 CDR patients. Validation cohorts included 127 CDR and 112 ACDF patients who completed FS3-C and NDI. Internal consistency, ceiling/floor effects, and convergent validity were assessed. Group comparisons used appropriate parametric and nonparametric tests. Multivariable linear regression adjusting for age, Charlson Comorbidity Index, sex, and number of operated levels, as well as propensity score matching, were performed to address baseline differences. Results: A total of 239 patients were included. Cronbach α was 0.95 (FS3-C) and 0.88 (NDI). FS3-C correlated inversely with NDI (r = −0.606, P < 0.001). Mean FS3-C was higher after CDR (59.9 ± 19.6) than ACDF (53.2 ± 22.2; P = 0.012), while NDI did not differ ( P = 0.074). In multivariable analysis, CDR remained independently associated with higher FS3-C scores (β = 8.94, P = 0.009), with no association for NDI ( P = 0.239). Propensity-matched analysis yielded consistent results (mean difference 9.22, P = 0.008), while NDI remained nonsignificant ( P = 0.289). Conclusions: The FS3-C detected differences between CDR and ACDF not detected by the NDI. Findings were consistent across adjusted and propensity-matched analyses, supporting its strong performance and greater discriminatory capacity as a cervical spine PROM.