Category: Spine

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The Timing of Diskectomy as a Predictor of Outcomes in Patients With Lumbar Disk Herniation

Neurosurgery 98:1051–1062, 2026

This prospective cohort study evaluates how the duration of preoperative symptoms influences outcomes after microdiskectomy for lumbar disk herniation. Outcomes measured include radicular pain, low back pain, disability (ODI), and motor and sensory deficits, with follow-up at 6 weeks, 6, 12, and 24 months in 1,120 analyzed patients.

Key finding: surgical intervention within one month of symptom onset yields faster, more pronounced pain relief and neurological recovery, whereas symptoms persisting beyond two years associate with the highest rates of residual motor and sensory deficits at 24 months.

Objective Evaluate how the preoperative duration of low back pain, disability, radicular leg pain, and motor/sensory deficits relates to postoperative outcomes after microdiskectomy for lumbar disk herniation (LDH).

Design/setting Prospective cohort (April 2015–October 2022) of adults undergoing microdiskectomy for symptomatic LDH with imaging-confirmed herniation consistent with symptoms.

Assessments & follow-up Pain measured by NRS, disability by ODI, motor deficit by MRC grading, sensory deficit as present/absent; assessed pre-op and at 6 weeks, 6, 12, and 24 months post-op.

Cohort size 1222 patients enrolled; 69 recurrences and 33 lost to follow-up excluded, leaving 1120 for statistical analyses.

Symptom-duration grouping Patients categorized by symptom duration thresholds ≤1, ≤6, ≤24, and ≥25 months for LDH-related symptoms (pain/disability/neurologic symptomatology).

Key outcome (timing) Surgery performed within 1 month of symptom onset was associated with more favorable outcomes than longer symptom duration, including faster improvement in neurological deficit and more significant radicular pain relief.

Residual deficits at 2 years Residual motor and sensory deficits at 24 months were least common when preoperative neurological symptoms lasted ≤1 month, and more common when symptoms exceeded 1 month.

Worst outcomes with long duration LDH symptoms persisting beyond 2 years were associated with the least favorable postoperative outcomes, including the highest residual motor and sensory deficits at 2 years.

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Long-Term Clinical Benefits of Age-Adjusted Sagittal Correction in Adult Spinal Deformity Surgery

Neurosurgery 98:1040–1050, 2026

This study evaluates long-term clinical outcomes of age-adjusted sagittal alignment correction in adult spinal deformity (ASD) surgery by integrating PI–LL, pelvic tilt, T1 pelvic angle, and SVA. Using hierarchical cluster analysis on 386 patients with long-segment fusion, three postoperative alignment patterns emerged—undercorrected, matched, and overcorrected—correlated with differing radiographic trajectories and complication rates.

Patients in the matched-correction cluster achieved the best balance of clinical improvement (ODI and SRS-22r) and minimized proximal junctional kyphosis/failure, while overcorrection increased mechanical complications despite stronger radiographic correction. The results support a multi-parameter, age-adjusted strategy and propose cluster-derived offset ranges as practical surgical benchmarks.

Aim Evaluate long-term benefits of age-adjusted sagittal alignment in adult spinal deformity surgery by integrating PI–LL, PT, TPA, and SVA using hierarchical cluster analysis.

Cohort Retrospective review of 386 ASD patients undergoing ≥5-level fusion including sacrum/pelvis, with minimum 2-year follow-up (mean follow-up 36.6 months).

Targeting method Postoperative offsets (target − current) for PI–LL, PT, TPA, and SVA were computed using published age-adjusted formulas from 6-week radiographs (or immediate postop if early PJK).

Clustering outcome Patients stratified into 3 clusters (A: 72, B: 211, C: 103) with cluster A undercorrected, cluster B balanced/matched, and cluster C overcorrected trends across all parameters.

Mechanical complications PJK/PJF rates differed by cluster, highest in cluster C (37.9%) vs cluster B (27.5%) and cluster A (20.9%) (P = .046).

Patient-reported outcomes At final follow-up, cluster B had significantly better ODI and SRS-22r outcomes than clusters A and C.

Parameter relationships Offsets showed strong correlations: PI–LL with PT (r = 0.77) and PI–LL with TPA (r = 0.79); weaker with SVA (r = 0.43).

Practical implication A balanced multi-parameter alignment profile (cluster B) best optimized outcomes while reducing complications, supporting integrating multiple sagittal targets rather than relying on a single parameter.

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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.

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Risk Factors and Reoperation Rate in Revision Lumbar Disc Herniation Surgery: A Systematic Review and Meta-Analysis of 1,031,348 Patients

Global Spine Journal 2026, Vol. 16(3) 1633-1647

This systematic review and meta-analysis examines reoperation rates and associated risk factors following primary lumbar disc herniation surgery across 25 studies totaling 1,031,348 patients. Pooled reoperation rate was 8.5% overall (adjusted to 10.3% for publication bias), with rates varying by follow-up: 4% at ≤1 year, 11.1% at 1–5 years, and 8.8% beyond 5 years.

Key risk factors identified include smoking, older age, diabetes, and large annular defects, while sex was not significant. The review highlights heterogeneity across study designs and follow-up durations, recommends careful patient selection, extended conservative management or closer surveillance for high-risk patients, and calls for trials comparing revision techniques.

Objective Estimate the reoperation rate after lumbar disc herniation surgery and identify associated risk factors.

Evidence base 25 studies (including observational studies and 3 RCTs) totaling 1,031,348 patients were included.

Overall reoperation rate Pooled reoperation rate was 8.5% (95% CI 6.2%–11.6%); after trim-and-fill adjustment for publication bias it was 10.3% (95% CI 7.6%–14.0%).

Follow-up pattern Reoperation rates differed by follow-up duration: 4% at ≤1 year, 11.1% at 1–5 years, and 8.8% at >5 years (significant subgroup differences).

Smoking risk Smoking was associated with higher odds of reoperation (OR 1.39, 95% CI 1.09–1.78).

Age risk Older age was associated with higher odds of reoperation (OR 1.52, 95% CI 1.25–1.85).

Annular defect risk Larger annular defect size was associated with higher odds of reoperation (OR 2.19, 95% CI 1.07–4.48).

Other factors Diabetes and certain surgical techniques were linked to higher reoperation risk in individual studies; sex was not a significant predictor (OR 1.22, 95% CI 0.96–1.55).

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Which spine surgeries belong in the ambulatory surgical center?

Neurosurg Focus 60(4):E2, 2026

This study uses time-driven activity-based costing (TDABC) to quantify true costs of common cervical and lumbar spine procedures performed in an outpatient hospital setting and compares these costs to Medicare ambulatory surgical center (ASC) reimbursement. Findings show microdiscectomy, lumbar laminectomy/decompression, and ACDF most often fall below Medicare ASC reimbursement, while endoscopic discectomy and posterior lumbar fusion frequently exceed reimbursement.

The analysis identifies supplies and personnel as primary cost drivers, highlights heterogeneity in Medicare ASC facility fees that do not reflect procedural complexity or number of levels, and argues that reimbursement reform is needed to expand the range of spine procedures economically feasible in ASCs.

Objective Identify spine procedures that are economically suitable to move from an outpatient hospital setting to an ambulatory surgical center (ASC) by comparing true costs (via TDABC) with Medicare ASC reimbursement.

Methods Retrospective cohort (2020–2024) of outpatient hospital spine cases with length of stay ≤ 1 day; procedures: cervical disc arthroplasty, ACDF, lumbar laminectomy/decompression, microdiscectomy, endoscopic discectomy, and posterior lumbar fusion; primary outcomes were total costs and proportion of cases with cost below Medicare reimbursement; regression adjusted for age, sex, BMI, and number of levels.

Costing approach (TDABC) Episode mapped across preop, intraop (wheels-in to wheels-out), and recovery phases; costs included supplies (consumables, implants, meds), personnel time (per-minute rates by role), and overhead.

Key cervical finding ACDF was more often below corresponding ASC reimbursement than cervical disc arthroplasty (71.8% vs 40.0%); adjusted odds favored ACDF (OR 5.3, 95% CI 3.0–9.4).

Key lumbar cost levels Mean lumbar episode cost was $4,640 ± $6,475; posterior lumbar fusion had the highest mean cost ($25,042 ± $15,645) and microdiscectomy the lowest ($3,233 ± $2,142).

Key lumbar viability finding Microdiscectomy (95.3%) and laminectomy/decompression (94.5%) most often cost less than reimbursement; endoscopic discectomy (31.0%) and posterior lumbar fusion (30.0%) were least often below reimbursement; adjusted odds were higher for laminectomy/decompression (OR 6.0) and microdiscectomy (OR 4.7), and far lower for endoscopic discectomy (OR 0.01) and fusion (OR 0.02).

Conclusions (procedures best suited for ASC under current payments) Microdiscectomy, lumbar laminectomy/decompression, and ACDF appear most economically suitable for transition from hospital outpatient to ASC in existing payment structures.

Reimbursement implication Broader feasibility in ASCs likely requires reimbursement reform, given mismatches between procedural complexity/resource use and Medicare ASC payment patterns.

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Low Posterior Electromyographic Threshold and Functional Outcomes After L4-5 Lateral Lumbar Interbody Fusion

Operative Neurosurgery 30:566–570, 2026

This single-institution retrospective study evaluates whether low posterior electromyography (EMG) stimulation thresholds during lateral L4-5 lumbar interbody fusion (LLIF) correlate with postoperative femoral nerve motor or sensory neurapraxia. Forty-two lateral-position single-level L4-5 LLIFs with neuromonitoring data showed no significant association between posterior EMG threshold or retractor time and transient postoperative anterior thigh numbness or weakness.

The cohort experienced transient sensory neurapraxia in 38% at six weeks that resolved by six months; only one patient had temporary motor neurapraxia. Limitations include small sample size, retrospective design, and short follow-up, leading authors to conclude no demonstrable link between posterior EMG threshold and plexus injury in this series.

Context: In L4-5 transpsoas LLIF, the retractor is placed near the lumbar plexus; directional EMG stimulation thresholds are used intraoperatively to estimate nerve proximity and potentially reduce injury risk.

Objective: Assessed whether posterior EMG stimulation threshold was associated with lumbar plexus injury/neurapraxia after single-level L4-5 LLIF performed in the lateral position.

Design/criteria: Retrospective, single-institution review of single-level L4-5 LLIF (Jan 2019–May 2022) with available neuromonitoring thresholds and retractor time; excluded cases with additional levels or missing monitoring data.

Cohort/intraop metrics: 42 patients (mean age 66 years); mean retractor time 12.4 minutes; mean posterior EMG threshold 10.4 mA.

Neurologic outcomes: Femoral motor neurapraxia occurred in 1 patient (2%); sensory neurapraxia (anterior thigh numbness) occurred in 16 patients (38%) at 6 weeks and resolved to 0% by 6 months.

Main finding: Posterior EMG threshold was not associated with postoperative motor neurapraxia or sensory neurapraxia at 6 weeks (including logistic regression showing OR 1.00; P=.98 for thigh numbness).

Other associations: No significant correlation between posterior EMG threshold and retractor time (Spearman ρ=0.11; P=.50) or postoperative ODI (ρ=0.17; P=.33).

Notable case/interpretation: The single motor neurapraxia case had 27-minute retractor time with posterior EMG 5 mA and recovered by 6 months; median retractor time in the cohort was low (10.8 minutes), limiting conclusions about longer retraction durations.

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Outpatient minimally invasive transforaminal lumbar interbody fusion performed at a single ambulatory surgery center: the Semmes Murphey Clinic experience

Neurosurg Focus 60(4):E5, 2026

This study reports outcomes from 179 patients undergoing single-level minimally invasive transforaminal lumbar interbody fusion (miTLIF) at a single ambulatory surgery center (ASC) between 2012–2024. It presents demographics, surgical details, complications, and validated patient-reported outcomes with 2-year follow-up showing sustained pain reduction, functional improvement, and high satisfaction.

The authors detail selection criteria, perioperative technique using tubular retractors and percutaneous pedicle screws, low complication and 90-day readmission/reoperation rates, and discuss economic and policy implications for ASC-based lumbar fusion care.

Objective Report 2-year outcomes for outpatient minimally invasive TLIF (miTLIF) performed at a single ambulatory surgery center (ASC).

Cohort 485 single-level miTLIFs were performed at the ASC (2012–2024); 179 registry-enrolled patients were analyzed (mean age 54; BMI mean 31).

Selection ASC eligibility exclusions included BMI > 50, weight > 350 lb, cardiac disease not cleared “low risk,” ASA class IIIb or above, family history of malignant hyperthermia, or inability to ambulate; Medicare primary insurance was also excluded for reimbursement reasons.

Disposition 98.3% were discharged within a few hours; 1.1% observed < 23 hours for pain control; 0.56% required hospital transfer for new-onset atrial fibrillation (treated and discharged within 23 hours).

Patient-reported outcomes Mean scores improved from baseline to 3 months and remained improved through 2 years (e.g., back pain NRS 6.98→2.40 at 3 months and 2.86 at 2 years; ODI 44.14→19.37 at 3 months and 13.87 at 2 years; EQ-5D 0.56→0.81 at 3 months and 0.82 at 2 years).

Complications Durotomy occurred in 1.7% (treated with fibrin glue, discharged within hours); superficial surgical site infection 0.56% (oral antibiotics only); postoperative hematoma 0.56%; urinary tract infection 0.56%.

Readmissions/reoperations (90-day) 2.2% readmissions and 1.1% reoperations within 90 days (including hardware failure and delayed hematoma).

Conclusion For carefully selected patients, ASC-based miTLIF showed significant, durable PROM improvement with acceptably low complications, readmissions, and reoperations.

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Impact of lateral plate and screw fixation on long-term radiographic subsidence in lateral lumbar interbody fusion

J Neurosurg Spine 44:493–497, 2026

This clinical study evaluates long-term radiographic subsidence after lateral lumbar interbody fusion (LLIF), comparing stand-alone procedures with those augmented by lateral plate and screw fixation. Retrospective analysis of 146 patients (219 levels) with ≥1-year CT follow-up shows lateral plating significantly reduced subsidence odds, while 3D-printed porous titanium cages trended toward lower subsidence than PEEK.

Results note similar reoperation rates between groups, no grade III subsidence, and rare adverse events including one delayed vertebral fracture with plating; methodology included multivariate logistic regression and Marchi subsidence grading. Conclusions support lateral plate and screw fixation, particularly with porous titanium cages, as protective against severe radiographic subsidence.

Objective Assess whether adding lateral plate and screw fixation changes the long-term rate/grade of radiographic cage subsidence after LLIF (excluding posterior instrumented fusion).

Design/Population Retrospective review (2014–2022) of degenerative lumbar spondylosis LLIF cases at two centers; required ≥1-year postoperative CT; 146 patients/219 levels (45% plated, 55% stand-alone).

Subsidence grading Long-term imaging graded by Marchi criteria (grade 0: 0%–24% disc height loss; I: 25%–49%; II: 50%–74%; III: 75%–100%); no intraoperative subsidence included.

Main finding (plating effect) Lateral plate + screws was significantly associated with reduced long-term radiographic subsidence (multivariable OR 0.484, p = 0.006).

Severity pattern All grade II (severe) subsidence cases occurred in the stand-alone LLIF group (4 patients); no grade III subsidence observed.

Cage material trend 3D-printed porous titanium cages trended toward lower subsidence versus PEEK but did not reach statistical significance (OR 0.401, p = 0.071).

Reoperation/fusion No significant difference in reoperation rate between plated and stand-alone groups; radiographic fusion rates were similar (83.1% plated vs 86.4% stand-alone; p = 0.58).

Noted complications/implant details One lateral-plate patient had a delayed vertebral body fracture; plated cases used 18-mm-wide cages, while nearly all stand-alone cases used 22-mm-wide cages.

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Complications associated with anterior cervical spine surgery: A systematic review of literature

Brain and Spine 6 (2026) 105897

This systematic review examines complications following anterior cervical spine surgery, quantifying incidence rates across studies and identifying major risks such as dysphagia, adjacent segment disease, recurrent laryngeal nerve palsy, infection, pseudarthrosis, esophageal perforation, hematoma, and vertebral artery injury. It synthesizes data from 116 studies (1989–2024) and assesses study quality using the Newcastle–Ottawa Scale.

The review highlights key risk factors—multilevel procedures, revision surgery, OPLL, smoking, older age, and surgeon experience—and emphasizes the importance of preoperative planning, patient selection, standardized prospective monitoring, and timely management to minimize morbidity and guide informed consent and long-term surveillance.

Aim Quantify frequency, causes, and outcomes of complications associated with anterior cervical spine surgery.

Methods Systematic review following PRISMA; searched CINAHL Plus, MEDLINE, PubMed, Scopus, and EMBASE for English-language studies (1989–2024) in adults; quality assessed with the Newcastle Ottawa Scale.

Evidence base 326 records screened; 116 studies included; study quality ranged from 3/9 to 9/9 on NOS, with frequent weaknesses in external control selection and cohort comparability.

Most common complication (dysphagia) Reported incidence varied widely (2.3%–87.5%); overall rate across all included dysphagia studies was 13%, with higher pooled incidence in prospective vs retrospective cohorts (53.7% vs 12.7%).

Other key complications (ranges) Adjacent segment disease 0.4%–32%; recurrent laryngeal nerve palsy 0.1%–9%; infection 0.39%–8.5%; pseudarthrosis 0.25%–31%; esophageal perforation 0.1%–0.45%; vertebral artery injury 0.3%–7.7%; Horner’s syndrome 0.06%–0.45%; graft failure 2.7%–35.5%; CSF leak 0%–1%; postoperative hematoma 0.21%–7%; new/worsening neurological deficits 0.37%–3.3.

Risk factors (higher complication rates) Multilevel disease, revision surgery, and ossification of the posterior longitudinal ligament (OPLL) were associated with increased complications.

Volume–outcome effect Greater surgeon experience and higher case volume were consistently associated with lower complication rates.

Prevention emphasis Reducing complications depends on thorough preoperative planning, careful patient selection, and proper surgical technique.

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Machine learning models for predicting patient satisfaction after adult spinal deformity surgery

J Neurosurg Spine 44:457–468, 2026

This clinical study develops and internally validates machine learning–guided logistic regression models to predict patient satisfaction 24 months after adult spinal deformity (ASD) surgery, using 213 patients and three feature-selection methods. Nine routinely measurable predictors—including postoperative WOMAC function, frailty, pelvic compensation, imaging MCID achievement, rFCSA, and SVA—were identified and ranked by SHAP for their influence on satisfaction.

The model showed strong discrimination (AUROC 0.846) and calibration, yielded a nomogram for individualized prognostication, and emphasizes modifiable targets for perioperative care and rehabilitation. Limitations include single-center retrospective design, modest sample size, and inclusion of postoperative variables limiting preoperative decision use.

Goal Develop and internally validate models to predict patient satisfaction 24 months after adult spinal deformity (ASD) surgery, using SRS-22r satisfaction (high satisfaction defined as score ≥ 4.5).

Cohort 213 ASD patients met criteria; 128 (60%) used for training and 85 (40%) for internal test validation.

Pipeline Used three ML feature-selection methods—LASSO, recursive feature elimination (RFE), and Boruta—and retained variables consistently selected by all three.

Final predictors Nine key indicators were retained: rFCSA, fatty infiltration, frailty, pelvic compensation, postoperative SVA, imaging MCID achievement, postoperative subtotal score, postoperative WOMAC function, and change in WOMAC function.

Model Built an interpretable logistic regression model from these predictors; binary cutoff optimized via ROC/Youden index, with SHAP used to rank feature importance.

Performance In the test set, the model achieved AUROC 0.846 and accuracy 0.812 (also reported AUPRC 0.894 and Brier score 0.153).

Top drivers (SHAP order) Higher postoperative WOMAC function, absence of frailty, imaging MCID achieved, larger WOMAC function improvement, higher rFCSA, higher postoperative subtotal, lower postoperative SVA, successful pelvic compensation, and lower fatty infiltration increased satisfaction likelihood.

Implication/limitation Intended mainly to identify modifiable factors to guide postoperative rehabilitation; practical preoperative counseling is limited because key inputs include postoperative variables, and external multicenter validation is still needed.

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Utilization of robotic pars repair for early return to activity in adolescents with symptomatic spondylolysis

J Neurosurg Spine 44:349–354, 2026

This case series from a tertiary academic spine center reports outcomes of robot-assisted percutaneous pars repair in nine adolescents with symptomatic lumbar spondylolysis who failed conservative management. The authors describe a single–midline incision technique using CT-based robotic guidance and a single lagged transdefect screw, detailing operative workflow, implant sizes, and a standardized postoperative rehabilitation protocol.

Results show most patients returned to preinjury or higher activity within months, with low complication rates and radiographic evidence of union in those who obtained CT follow-up. The authors conclude that minimally invasive robotic pars repair is a viable option after failed nonoperative care and advocate timely surgical consultation to potentially accelerate return to sport and avoid progressive spondylolisthesis.

Clinical problem Symptomatic lumbar pars interarticularis fractures (spondylolysis) are a common cause of adolescent low-back pain; nonoperative care with activity modification is standard first-line treatment.

Nonunion risk Despite conservative management, about 20% of patients may progress to symptomatic nonunion, and some can later develop spondylolisthesis that may require fusion.

Study aim Robotic surgical guidance was used to enable percutaneous pars screw placement; the series reports the largest cohort of adolescents treated with robot-assisted pars repair to date.

Design & cohort Retrospective review of a prospectively collected database identified 9 adolescents/young adults (13–25 years) treated with a single-screw pars repair technique.

Technique Using Excelsius robotic planning/registration and intraoperative 3D imaging, bilateral screw trajectories were planned to converge so bilateral pars screws could be placed through a single 1–2 cm midline incision; compression was achieved via a “lag-by-technique” preparation without direct pars visualization/grafting.

Postop protocol Patients walked only for 2 weeks, then added stationary biking for 2 weeks, followed by 4 weeks of sport-directed physical therapy; if tolerated symptom-free, they were cleared for activity (cleared to begin return-to-sport training at 4 weeks).

Outcomes Mean preop activity cessation at consultation was 8.6 ± 10.6 months; at mean follow-up 11.4 ± 9.1 months, 78% had returned to baseline activity or were cleared to return to sport.

Safety/efficacy conclusion Robot-assisted pars repair was reported as a safe, effective option after failed nonoperative care, enabling return to activity in as little as 8 weeks; a single lag-style screw may be clinically effective compared with prior open debridement/bone-grafting approaches.

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Comprehensive analysis of biomechanical stability and clinical efficacy in oblique lumbar interbody fusion with distinct anterolateral fixation modalities

J Neurosurg Spine 44:436–448, 2026

This study evaluates how different anterolateral screw angles in oblique lumbar interbody fusion with anterolateral fixation (OLIF-AF) affect cage subsidence, biomechanical stability, and clinical outcomes. A retrospective cohort of 80 L4–5 OLIF-AF patients was grouped by coronal and horizontal screw angles, supplemented by finite element models simulating four screw configurations under physiological loads.

Findings show coronal-plane parallel screw placement reduced cage subsidence, cage stress, displacement, and range of motion versus nonparallel placement, while horizontal bifurcation had no significant effect on subsidence; clinical scores and fusion rates were similar across groups. The authors recommend coronal parallelism with bicortical purchase to optimize stability and lower subsidence risk.

Coronal Plane Parallel Screw Placement: Parallel screw placement in the coronal plane during OLIF-AF significantly reduces the risk of cage subsidence (CS) and enhances biomechanical stability compared to nonparallel placement.

Nonparallel Coronal Screw Placement Risks: Nonparallel coronal screw placement (G2 and G3 groups) is independently associated with higher CS rates, greater reduction in disc height (ΔDH), increased cage stress, displacement, and range of motion (ROM), indicating poorer biomechanical outcomes.

Horizontal Screw Bifurcation: Horizontal screw bifurcation (difference in horizontal plane angle) does not have a statistically significant impact on CS risk or clinical outcomes when coronal plane parallelism is maintained.

Bicortical Purchase Importance: Ensuring that screws penetrate the contralateral vertebral cortex (bicortical purchase) may further reduce the risk of CS, while lack of penetration is associated with earlier and more severe subsidence.

Clinical Outcomes: No significant differences in pain relief (VAS-LBP, VAS-LP) or Oswestry Disability Index (ODI) were observed among the four screw configuration groups at any follow-up point; fusion rates were also similar.

Finite Element Analysis Validation: Finite element modeling confirmed that nonparallel screw configurations increase cage stress and spinal ligament tension, especially during flexion, supporting clinical findings.

Risk Factors for Subsidence: Lower bone mineral density (BMD) and nonparallel coronal screw placement are independent risk factors for cage subsidence after OLIF-AF.

Surgical Recommendation: For optimal biomechanical stability and reduced complication risk, OLIF-AF screws should be placed parallel to the coronal plane and close to the endplates, with bicortical purchase, as this configuration provides better load sharing and fusion environment.

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Incidence of C5 Palsy and Recovery Rate After Cervical Spine Surgery: A Systematic Review and Meta-Analysis

Neurosurgery 98:520–542, 2026

This systematic review and meta-analysis quantifies C5 nerve palsy incidence and recovery following various cervical spine surgeries, comparing anterior and posterior approaches across 155 studies. Pooled rates show higher C5 palsy after posterior procedures (laminectomy 8%, PCDF 7.03%, laminoplasty 5.11%) versus anterior ACDF (2.61%), with overall low permanence rates.

The paper details methods, study selection, heterogeneity, and limitations, and emphasizes the need for standardized diagnostic criteria, prospective cohorts, and treatment algorithms. Findings aim to inform surgical decision-making, patient counseling, and future research priorities to mitigate C5 palsy risk.

C5 palsy incidence: Highest after laminectomy (8%), followed by posterior cervical decompression and fusion (PCDF, 7.03%), laminoplasty (5.11%), corpectomy (4.16%), and lowest after anterior cervical diskectomy and fusion (ACDF, 2.61%).

Permanent C5 palsy rates: Low across all procedures—laminectomy (1.44%), PCDF (1.02%), laminoplasty (0.28%), ACDF (1.06%); no pooled data for corpectomy.

Posterior approaches risk: Posterior decompression procedures (laminectomy, PCDF, laminoplasty) carry a higher risk of C5 palsy than anterior approaches (ACDF, corpectomy).

Resolution and recovery: Most C5 palsy cases are transient and resolve within months; permanent deficits are uncommon with proper follow-up and care.

Surgical decision-making: Choice of approach should consider C5 palsy risk, especially in patients with anatomic risk factors (e.g., narrow foramina, preexisting kyphosis).

Economic impact: C5 palsy increases healthcare costs significantly, with up to $347,000 in the first year and ongoing annual costs of about $42,000 for permanent deficits.

Standardized protocols lacking: There is no consensus on optimal management; most strategies are institution-specific and anecdotal, highlighting the need for standardized treatment protocols.

Research gaps: High study heterogeneity, inconsistent reporting, and lack of long-term data—especially for corpectomy—limit understanding; further prospective studies on risk factors and outcomes are needed.

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A Validation of the Tarlov Cyst Quality-of-Life Survey in Men Surgically Treated for Symptomatic Spinal Tarlov Cysts

Operative Neurosurgery 30:379–384, 2026

This article validates the 11-item Tarlov Cyst Quality-of-Life (TCQoL) scale for male patients undergoing surgical treatment of sacral Tarlov cysts, demonstrating good internal consistency (Cronbach α = 0.85), significant postoperative improvement on nine items, and strong concurrent validity with ODI and SF-36 physical function and pain subscales. The TCQoL showed large responsiveness (SRM = 0.81) and correlated with VAS pain measures.

Methods include prospective preoperative and 3-month postoperative administration of TCQoL, ODI, SF-36, and VAS in 46 male patients treated surgically between 2016–2023, with detailed psychometric analyses assessing discriminative validity, construct validity, and responsiveness; limitations noted include small sample size, single-surgeon single-center design, and 20% attrition.

TCQoL Validation in Men: The Tarlov Cyst Quality-of-Life (TCQoL) scale, previously validated in women, was successfully validated for male patients undergoing surgical treatment for symptomatic sacral Tarlov cysts, demonstrating good internal consistency (Cronbach α = 0.85) and discriminative validity.

Study Population: The study included 46 male patients (final sample) with an average age of 48.4 years, mostly presenting with multiple sacral cysts and a median symptom duration of nearly 35 months.

Surgical Technique: Surgery involved a posterior approach with laminectomy, cyst drainage, and wrapping of the nerve root with a bovine pericardium sleeve to prevent refilling, followed by closure with a resorbable plate.

Symptom Improvement: Significant improvement was observed in 9 of 11 TCQoL items postoperatively, especially for discomfort while sitting, sacral pain, lower extremity pain, and weakness; sexual function items showed no significant change.

Correlation with Established Measures: The TCQoL showed strong positive correlation with the Oswestry Disability Index (ODI) (r = 0.63, P < .001) and moderate to strong negative correlations with key SF-36 subscales (physical function, bodily pain, vitality, and social functioning), indicating good concurrent validity.

Scale Responsiveness: The standardized response mean (SRM) for TCQoL was 0.81, indicating a large effect size and sensitivity to clinical change after surgery.

Limitations: The study is limited by a small sample size (reflecting the rarity of Tarlov cysts in men), single-center and single-surgeon design, and a 20% attrition rate; findings may not generalize to non-sacral or non-Tarlov cysts.

Clinical Utility: The TCQoL can now be used as a disease-specific HRQoL tool for both male and female patients with symptomatic sacral Tarlov cysts, supporting standardized outcome measurement in future research and clinical practice.

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Cage migration in multilevel stand-alone lateral lumbar interbody fusion: incidence and clinical correlations

J Neurosurg Spine 44:426–435, 2026

This clinical case series compares the incidence and outcomes of lateral interbody cage migration (LCM) following multilevel stand-alone lateral lumbar interbody fusion (LLIF) versus LLIF with posterior pedicle screw instrumentation in 87 age-matched patients. The retrospective analysis reports similar LCM rates (7% vs 5%), no significant differences in complications, and comparable improvements in Oswestry Disability Index and pain scores at ≥1 year follow-up.

The report details patient selection, radiographic assessment methods, operative characteristics, and risk-factor analysis, emphasizing meticulous selection for multilevel stand-alone LLIF. Authors conclude multilevel stand-alone LLIF can be safe in selected patients but call for prospective studies to validate findings and clarify factors contributing to cage migration.

Lateral Cage Migration (LCM) Incidence: LCM occurred in 7% of multilevel stand-alone LLIF cases and 5% of LLIF cases with posterior instrumentation; this difference was not statistically significant.

Patient Selection Criteria: Optimal candidates for multilevel stand-alone LLIF have neutral sagittal and coronal balance, mild to moderate facet arthropathy, stable grade 1 spondylolisthesis, absence of severe central canal stenosis, normal or mildly reduced bone mineral density, and comorbidities or age that increase surgical risk with posterior fixation.

Clinical Outcomes: Both cohorts (stand-alone and posterior instrumentation) showed significant postoperative improvement in Oswestry Disability Index (ODI) and visual analog scale (VAS) scores, with no significant differences between groups.

Complication Rates: Postoperative complication rates were similar between groups (23% stand-alone vs. 20% posterior instrumentation), and no intraoperative complications were reported in either group.

Biomechanical Considerations: Supplemental posterior instrumentation increases construct stability, but clinical significance in preventing LCM in well-selected patients remains unclear; stand-alone LLIF can be safe with meticulous patient selection.

Role of Lateral Plates: Adding lateral plates to stand-alone LLIF does not significantly improve stability or reduce cage migration/subsidence in multilevel constructs and may increase cost and risk.

Risk Factors for LCM: No significant demographic, radiographic, or procedural risk factors for LCM were identified in this study; all patients with LCM had normal bone density, and meticulous surgical technique and patient selection are emphasized.

Study Limitations: Retrospective design, single institution, and small sample size may limit generalizability; prospective studies are needed for further validation.

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Contrast-Enhanced Ultrasound Perfusion Imaging of the Spinal Cord Before and After Surgical Decompression for Cervical Spondylotic Myelopathy

Neurosurgery 98:688–697, 2026

Contrast-enhanced ultrasound (CEUS) was applied intraoperatively to acquire spinal cord perfusion metrics before and after posterior decompression in 16 patients with cervical spondylotic myelopathy (CSM). The study details a reproducible surgical ultrasound window, CEUS acquisition parameters, time–intensity curve analysis, and statistical correlation of wash-in-time (WIT) with modified Japanese Orthopedic Association (mJOA) scores.

The technique proved feasible and safe, yielding pre- and postdecompression perfusion data without complications. Predecompression and postdecompression WIT correlated significantly with preoperative, 1-month, and 6-month mJOA scores, suggesting CEUS WIT may have prognostic utility for postoperative neurologic recovery.

Contrast-Enhanced Ultrasound (CEUS) Feasibility: CEUS can safely and effectively acquire spinal cord perfusion data both before and after surgical decompression in patients with cervical spondylotic myelopathy (CSM).

Wash-In Time (WIT) as Key Perfusion Parameter: WIT, defined as the time between initial appearance and peak concentration of contrast microbubbles, is the most relevant CEUS-derived perfusion metric and inversely correlates with neurologic status measured by modified Japanese Orthopedic Association (mJOA) scores.

Correlation with Neurologic Outcomes: Lower WIT values (indicating faster perfusion) are significantly associated with better preoperative and postoperative neurologic function at 1 and 6 months, suggesting potential as a prognostic biomarker.

No Significant Correlation with MRI Signal Change: Preoperative spinal cord signal changes on MRI, previously considered prognostic, did not correlate with WIT or other perfusion indices in this cohort.

Technical Approach: A small bony trough is created at the lateral lamina border to allow direct insonation of the compressed spinal cord, enabling both pre- and post-decompression CEUS imaging without interfering with standard surgical workflow.

No Major Complications: The technique was free of adverse events related to ultrasound contrast administration or the imaging process itself.

Small Sample and Pilot Nature: The study’s findings are limited by its small sample size (16 patients), and further multicenter, prospective studies are needed to validate CEUS as a predictive tool for surgical outcomes in CSM.

Clinical Implication: CEUS, and specifically preoperative WIT, shows promise for intraoperative prognostication and may help identify patients at risk for poor recovery or reperfusion injury after cervical decompression surgery.

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Postoperative loss in segmental lumbar lordosis following L5–S1 anterior lumbar interbody fusion

J Neurosurg Spine 44:420–425, 2026

This clinical study evaluates predictors and thresholds for postoperative loss of L5–S1 segmental lordosis following anterior lumbar interbody fusion (ALIF) in 94 adults treated for degenerative disc disease. Multivariate analyses identified baseline obesity, absence of posterior fixation, and larger immediate lordotic correction as independent predictors of 6-week to 1-year segmental lordosis loss, which related to higher rates of cage subsidence and revision.

The authors derived 6-week postoperative L5–S1 lordosis thresholds (overall range 21.6°–26.8°, PI-specific: low 19.0°–24.8°, average 21.0°–26.4°, high 24.1°–28.7°) that minimized subsequent loss and need for revision. Findings support targeted preoperative planning to achieve sustainable correction while balancing risks of overcorrection and subsidence.

Segmental Lordosis Restoration: L5–S1 anterior lumbar interbody fusion (ALIF) provides strong and durable correction of segmental lumbar lordosis and disc height, with most correction maintained at 1 year postoperatively.

Predictors of Lordosis Loss: Baseline obesity, lack of posterior fixation, and larger initial correction in L5–S1 lordosis are independent predictors of postoperative segmental lordosis loss within 1 year.

Complications: Loss of segmental lordosis increases the risk of cage subsidence and revision surgery, particularly due to pseudarthrosis.

Optimal Correction Thresholds: Achieving 6-week postoperative L5–S1 segmental lordosis between 21.6° and 26.8° minimizes the risk of lordotic loss and need for revision; PI-specific thresholds are 19.0°–24.8° (low PI), 21.0°–26.4° (average PI), and 24.1°–28.7° (high PI).

Risks of Overcorrection/Undercorrection: Overcorrection (>26.8°) increases risk of cage subsidence and mechanical complications, while undercorrection (<21.6°) may predispose to implant failure and adjacent segment disease.

Surgical Planning Importance: Preoperative planning should target lordosis correction within these thresholds and consider modifiable risk factors to optimize outcomes and reduce complications.

Comparison to Other Techniques: ALIF offers greater segmental correction than other lumbar interbody fusion techniques such as TLIF or XLIF.

Clinical Implications: Nearly half of patients experience some degree of lordosis loss post-ALIF, highlighting the need for careful patient selection, surgical technique, and postoperative monitoring.

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Unraveling the cause of microspurs in spontaneous intracranial hypotension type 1: discogenic origin or calcified Hofmann’s ligament?

J Neurosurg Spine 44:315–319, 2026

This clinical study investigates the origin of ventral spinal microspurs causing spontaneous intracranial hypotension (SIH) type 1, comparing discogenic lesions with fibrotic tissue consistent with Hofmann’s ligament. Retrospective histopathological reanalysis of 27 surgically resected microspurs showed both discogenic and fibrotic origins, with 13 discogenic, 9 fibrotic, and 5 unclassifiable cases, and no significant differences in spur length, location, or CT density.

The authors conclude that ventral CSF leaks can arise from calcified intervertebral discs as well as calcified or fibrotic Hofmann’s ligaments, expanding the pathophysiological understanding of SIH and highlighting limitations from retrospective design, small sample size, and histological classification challenges.

Etiology of Microspurs: Microspurs causing ventral CSF leaks in spontaneous intracranial hypotension (SIH) type 1 can originate from both calcified intervertebral discs (discogenic) and calcified fibrous tissue associated with Hofmann’s ligament, not exclusively from disc material.

Histopathological Classification: Microspurs were histopathologically classified as either discogenic (cartilage/fibrocartilaginous tissue, often with secondary calcification) or fibrotic (hypercellular fibrous tissue with or without calcification, suggestive of Hofmann’s ligament).

Distribution: Most microspurs were located in the thoracic spine, with about one-third found at the cervicothoracic or thoracolumbar junctions, and the rest in the midthoracic region.

Imaging Findings: There was no statistically significant difference in microspur length or CT density (Hounsfield units) between discogenic and fibrotic (Hofmann’s ligament) origins, limiting the ability of imaging to distinguish between them preoperatively.

Clinical Implications: Both discogenic and fibrotic origins should be considered in the diagnosis and surgical planning for SIH with ventral CSF leaks, as relying solely on the discogenic theory may overlook alternative etiologies.

Pathophysiological Mechanism: Calcified microspurs, whether from discs or Hofmann’s ligament, may cause dural tears due to mechanical stress at spinal junctions or in regions with a narrow spinal canal.

Limitations: The study’s retrospective design, small sample size, and challenges in histopathological classification (lack of specific markers, possible sampling errors) limit the generalizability and precision of findings

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Are there distinct patterns of clinical deficits in cervical deformity? A discriminant analysis of health-related quality of life measures

J Neurosurg Spine 44:242–252, 2026

This clinical study analyzes preoperative health-related quality of life (HRQOL) measures in 134 adults with cervical deformity (CD) to identify distinct clinical deficit patterns and their association with radiographic morphotypes. Using factor and cluster analyses on NDI, mJOA, and SWAL-QOL items, four patient clusters emerged: sleep/fatigue, low neck disability, dysphagia with severe neck disability, and myelopathy.

These HRQOL-derived clusters correlated with specific radiographic types among severe deformities: cervicothoracic, focal, and flat-neck morphotypes. The findings support integrating patient-reported clinical dimensions into CD classification systems to guide tailored surgical planning and outcome assessment.

Distinct HRQOL Patterns: Four distinct patterns of health-related quality of life (HRQOL) deficits were identified in patients with cervical deformity: sleep/fatigue impairment, low neck disability, severe dysphagia and neck disability, and predominant myelopathy.

Cluster Analysis: Principal component and cluster analyses using NDI, mJOA, and SWAL-QOL questionnaires grouped patients into four homogeneous outcome clusters, each reflecting a unique constellation of clinical deficits.

Radiographic Associations: Each HRQOL deficit pattern was significantly associated with specific cervical deformity morphotypes: severe dysphagia/neck disability with cervicothoracic deformity, myelopathy with focal deformity, and sleep/fatigue or low disability with flat neck deformity.

Clinical Implications: Recognizing these HRQOL patterns may inform tailored management strategies, surgical planning, and prognosis for different cervical deformity subtypes.

Measurement Tools: The study utilized validated patient-reported outcome measures: Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA) scale, and Swallowing Quality of Life (SWAL-QOL) questionnaire.

Radiographic Parameters: Comprehensive imaging assessments included cervical and spinopelvic alignment measures, such as cervical SVA, T1 slope, C2–7 lordosis, and T1S-CL mismatch.

Demographic Factors: No significant differences in age, sex, BMI, or most comorbidities were found across clusters, except for higher rates of depression and prior spine surgery in those with the most severe clinical deficits.

Classification Framework: Findings support integrating HRQOL measures with radiographic parameters for a more comprehensive, patient-centered cervical deformity classification system.

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Minimal Clinically Important Difference and Relative Change in Patient-Reported Outcomes After Surgery for Cervical Spondylotic Myelopathy: A Nationwide Study of 1,700 Patients

Neurosurgery 98:358–364, 2026

This nationwide registry study of 1,756 patients evaluates minimal clinically important difference (MCID) versus minimal clinically important relative change (MCIRC) for patient-reported outcomes after surgery for degenerative cervical myelopathy. Using anchor-based ROC analyses, the authors derive MCID and MCIRC thresholds for NRS neck/arm pain, EQ-5D index, EQ VAS, and NDI, and compare predictive accuracy for patient satisfaction at one year.

Key findings show MCIRC outperforms absolute MCID for NRS neck and arm pain and NDI, while MCID is superior for EQ-5D index and EQ VAS; selected thresholds are reported (e.g., NRS neck MCID −3 and MCIRC −47%). The study recommends incorporating MCIRC in future spine outcome guidelines to improve individualized assessment.

Minimal Clinically Important Difference (MCID): MCID represents the smallest absolute change in patient-reported outcome measures (PROMs) that signifies meaningful improvement for the patient after cervical spondylotic myelopathy surgery.

Minimal Clinically Important Relative Change (MCIRC): MCIRC is a proportional measure that reflects the minimum relative change in PROMs from baseline, making it more sensitive to changes in patients with extreme baseline values.

Calculation Methods: MCID and MCIRC values were determined using anchor-based approaches (with patient satisfaction as the anchor), ROC curve analysis with the Youden index, minimal detectable change (MDC), and mean change methods.

Key Thresholds Identified: MCID values were −3 for NRS neck pain, −2 for NRS arm pain, 0.09 for EQ5D index, 7 for EQ VAS, and −12 for NDI; MCIRC values were −47% for NRS neck pain, −40% for NRS arm pain, 386% for EQ5D index, 52% for EQ VAS, and −32% for NDI.

Predictive Accuracy: Relative change (MCIRC) provided greater predictive accuracy for identifying patient satisfaction in NRS neck/arm pain and NDI, while absolute difference (MCID) was superior for EQ5D index and EQ VAS.

Clinical Implication: MCIRC is recommended for PROMs influenced by baseline severity (like pain and disability scores), as it better accounts for individual variability and may enhance individualized patient assessment.

Study Population: The study analyzed 1,756 patients from the Swedish Spine Registry who underwent surgery for degenerative cervical myelopathy, with 59% reporting satisfaction at one year postoperatively.

Practical Recommendation: Incorporating MCIRC thresholds into future spine surgery outcome guidelines could improve evaluation of individualized patient recovery.

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