Tag: Alignment

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Segmental Lordosis After Open Transforaminal Lumbar Interbody Fusion Using Expandable Oblique Versus Static Anterior Banana Cages

Operative Neurosurgery 30:78–89, 2026

This clinical research article compares segmental and lumbar lordosis outcomes after open transforaminal lumbar interbody fusion (TLIF) with posterior column osteotomy using either static anterior “banana” cages or obliquely placed expandable cages. In a single-surgeon retrospective cohort of 210 patients (327 segments), expandable cages produced a significantly greater median change in segmental lordosis (ΔSL) by 2.0° at six months, persisting after multivariate adjustment and propensity matching.

The study also reports inconsistent effects of cage type on overall lumbar lordosis (ΔLL), with subgroup and matched analyses yielding differing results, and found no difference in subsidence or complication rates. Findings emphasize the influence of preoperative segmental lordosis, segment level (notably L5–S1), and construct length on achieved correction, while noting limitations including retrospective design and lack of clinical outcomes.

Expandable Cages: Expandable obliquely placed cages in open transforaminal lumbar interbody fusion (TLIF) with posterior column osteotomy (PCO) produce a significantly greater median increase in segmental lordosis (ΔSL) of 2.0° compared to static anteriorly placed banana cages, representing a 50% increase.

Statistical Robustness: The greater segmental lordosis achieved with expandable cages remained significant after multivariate regression analysis and propensity score matching, confirming the reliability of the finding.

Overall Lumbar Lordosis (ΔLL): No clear advantage was found between cage types regarding the change in overall lumbar lordosis, with results varying depending on the statistical method used.

Surgical Technique Consistency: All surgeries were performed open with a full PCO using a consistent technique, minimizing confounding variables related to surgical approach or technique.

Preoperative Segmental Lordosis Impact: Segments with lower preoperative segmental lordosis (<15°) experienced the greatest increase in lordosis postoperatively, regardless of cage type.

L5-S1 Segment Benefit: Expandable cages were especially favorable at the L5-S1 segment, likely due to anatomical constraints that make insertion of large static cages more challenging at this level.

Complication and Subsidence Rates: No significant differences were observed between cage types in rates of complications, cage subsidence, or spondylolisthesis correction.

Clinical Outcomes Unclear: The study did not assess clinical outcomes, so the impact of the observed radiographic differences on patient-reported outcomes remains unknown.

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The gap between surgeon goal and achieved sagittal alignment in adult cervical spine deformity surgery

J Neurosurg Spine 42:309–319, 2025

This study assessed surgeons’ ability to achieve preoperative sagittal alignment goals in adult cervical spine deformity surgeries. Results showed significant deviations from targets, especially in severe deformities, highlighting the need for improved surgical planning and personalized implants.

Study Overview

• Objective: Assess surgeons’ ability to achieve preoperative sagittal alignment goals in CSD surgery.

• Methods: Prospective study with adult CSD patients across 13 North American centers.

• Patient Demographics: Mean age 63.6 years; 51.1% women; 38.6% had previous cervical fusion.

Key Findings

• Alignment Goals: Surgeons failed to meet goals by 17.2 mm for C2–7 SVA, 10.3° for Cobb angle.

• Factors Affecting Outcomes: Greater baseline TK linked to better Cobb angle achievement.

• Surgical Planning: 60% used PACS, 33.3% used spine-specific software.

• Tools and Criteria: Ames/ISSG criteria used by 33.3% of surgeons; others individualized goals.

Challenges and Recommendations

• Severe Deformities: More challenging to achieve alignment goals in severe cases.

• Need for Advancements: Personalized implants could improve intraoperative goal achievement.

• Alignment Correlations: Strong correlation for C7–S1 SVA, weak for C2–7 SVA.

Statistical Analysis

• Offset Groups: Patients categorized by offset magnitude from goal alignment.

• Significant Associations: Lower baseline TS-CL associated with better TS-CL goal achievement.

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Stable Regional and Global Alignment in Patients Treated With Minimally Invasive Lateral Retropleural Thoracic Diskectomy Without Fixation

Operative Neurosurgery 26:511–518, 2024

Thoracic disk herniations are challenging to treat, and open transthoracic or minimally invasive thoracoscopic approaches are associated with significant morbidity, substantial costs, and steep learning curves. The minimally invasive lateral retropleural thoracic diskectomy (MIS-LRP-TD) approach is straightforward and is associated with lower perioperative morbidity. With MIS-LRP-TD, the overlying rib, ipsilateral pedicle, ligamentum flavum, posterior longitudinal ligament, and posterior third of the adjacent vertebral bodies are resected. Adjunct fixation is typically not performed, eliminating hardware-related complications and costs. This radiographic study investigates long-term global and thoracic spine alignment after MIS-LRP-TD without fixation.

METHODS: This study was a single-institution, retrospective evaluation of all patients who underwent MIS-LRP-TD without fixation between November 7, 2017 and July 19, 2022. Preoperative and the most recent postoperative radiographs were used to determine the C7 plumb line to central sacral vertical line, thoracic Cobb angle (TCA), segmental Cobb angle, C7 to sagittal vertical axis, thoracic kyphosis, and segmental kyphosis.

RESULTS: In total, 22 patients with 24 disk herniations underwent MIS-LRP-TD without fixation. The mean (SD) radiographic follow-up was 12.9 (11.2) months. Overall, no significant differences were seen in C7 plumb line to central sacral vertical line (P = .65), C7 to sagittal vertical axis (P = .99), thoracic kyphosis (P = .30), TCA (P = .28), segmental kyphosis (P = .27), or segmental Cobb angle (P = .56) at follow-up. One patient demonstrated a >5°change in TCA but remained asymptomatic.

CONCLUSION: Despite requiring extensive resection of the middle column and ipsilateral costovertebral joint at the index level, MIS-LRP-TD without adjunct fixation does not lead to significant global, regional, or segmental deformity. Thus, MIS-LRP-TD appears to be a safe, effective treatment approach for challenging thoracic disk herniations.

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Novel artificial intelligence algorithm: an accurate and independent measure of spinopelvic parameters

J Neurosurg Spine 37:893–901, 2022

The analysis of sagittal alignment by measuring spinopelvic parameters has been widely adopted among spine surgeons globally, and sagittal imbalance is a well-documented cause of poor quality of life. These measurements are time-consuming but necessary to make, which creates a growing need for an automated analysis tool that measures spinopelvic parameters with speed, precision, and reproducibility without relying on user input. This study introduces and evaluates an algorithm based on artificial intelligence (AI) that fully automatically measures spinopelvic parameters.

METHODS Two hundred lateral lumbar radiographs (pre- and postoperative images from 100 patients undergoing lumbar fusion) were retrospectively analyzed by board-certified spine surgeons who digitally measured lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope. The novel AI algorithm was also used to measure the same parameters. To evaluate the agreement between human and AI-automated measurements, the mean error (95% CI, SD) was calculated and interrater reliability was assessed using the 2-way random single-measure intraclass correlation coefficient (ICC). ICC values larger than 0.75 were considered excellent.

RESULTS The AI algorithm determined all parameters in 98% of preoperative and in 95% of postoperative images with excellent ICC values (preoperative range 0.85–0.92, postoperative range 0.81–0.87). The mean errors were smallest for pelvic incidence both pre- and postoperatively (preoperatively −0.5° [95% CI −1.5° to 0.6°] and postoperatively 0.0° [95% CI −1.1° to 1.2°]) and largest preoperatively for sacral slope (−2.2° [95% CI −3.0° to −1.5°]) and postoperatively for lumbar lordosis (3.8° [95% CI 2.5° to 5.0°]).

CONCLUSIONS Advancements in AI translate to the arena of medical imaging analysis. This method of measuring spinopelvic parameters on spine radiographs has excellent reliability comparable to expert human raters. This application allows users to accurately obtain critical spinopelvic measurements automatically, which can be applied to clinical practice. This solution can assist physicians by saving time in routine work and by avoiding error-prone manual measurements.

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Coronal balance with circumferential minimally invasive spinal deformity surgery for the treatment of degenerative scoliosis

J Neurosurg Spine 34:879–887, 2021

Coronal malalignment (CM) in adult spinal deformity is associated with poor outcomes and remains underappreciated in the literature. Recent attempts at classifying CM indicate that some coronal shifts may be more difficult to treat than others. To date, outcomes for circumferential minimally invasive surgery (cMIS) of the spine in the context of these new CM classifications are unreported.

METHODS A retrospective evaluation of patients with degenerative scoliosis (Cobb angle > 20 ) consecutively treated with cMIS at a single institution was performed. Preoperative and 1-year postoperative standing radiographs were used to make the comparisons. Clinical outcome measures were compared. Patients were subgrouped according to the preoperative distance between their C7 plumb line and central sacral vertical line (C7-CSVL) as either coronally aligned (type A, C7-CSVL < 3 cm); shifted ≥ 3 cm toward the concavity (type B); or shifted ≥ 3 cm toward the convexity (type C) of the main lumbar curve.

RESULTS Forty-two patients were included (mean age 67.7 years). Twenty-six patients (62%) were classified as type A, 5 patients (12%) as type B, and 11 patients (26%) as type C. An average of 4.9 segments were treated. No type A patients developed postoperative CM. All type B patients had CM correction. Six of the 11 type C patients had CM after surgery. Overall, there was an improvement in the C7-CSVL (from 2.4 to 1.8 cm, p = 0.04). Among subgroups, only type B patients improved (from 4.5 to 0.8 cm, p = 0.002); no difference was seen for type A patients (from 1.2 to 1.4 cm, p = 0.32) or type C patients (from 4.3 to 3.1 cm, p = 0.11). Comparing type C patients with postoperative CM versus those without postoperative CM, patients with CM had worse visual analog scale back scores at 1 year (5 vs 1, p = 0.01). Moreover, they had higher postoperative L4 tilt angles (11  vs 5 , p = 0.01), indicating inadequate correction of the lumbosacral fractional curve.

CONCLUSIONS cMIS improved coronal alignment, curve magnitudes, and clinical outcomes among patients with degenerative scoliosis. It did not result in CM in type A patients and was successful at improving the C7-CSVL in type B patients. Type C patients remain the most difficult to treat coronally, with worse visual analog scale back pain scores in those with postoperative CM. Regional coronal restoration of the lumbosacral fracture curve should be the focus of correction in cMIS for these patients.

 

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Contribution of Lordotic Correction on C5 Palsy Following Cervical Laminectomy and Fusion

Neurosurgery 79:816–822, 2016

C5 palsy is a well-reported complication of cervical spine surgery. The implication of sagittal cervical alignment parameters and their changes after surgery on the incidence of C5 palsy remains unclear.

OBJECTIVE: We review cervical alignment changes in our cases of C5 palsy after cervical laminectomy and fusion.

METHODS: Cases of C5 palsy were retrospectively compared with a control group. Preoperative and postoperative upright plain film radiographs were analyzed in blinded fashion.

RESULTS: Spine registry analysis identified 148 patients who underwent cervical laminectomy and fusion by the senior author over 5 years. There were 18 (12%) cases complicated by postoperative C5 palsy. Nine of these 18 patients had prerequisite upright films and were compared with a randomly constructed case control group of 20 patients. There were no statistically significant differences between the 2 groups in age, proportion of males, and preoperative Nurick score. Measures of sagittal alignment did not differ significantly between the 2 groups on preoperative and postoperative imaging. When comparing the amount of alignment change between preoperative and postoperative upright imaging, however, patients with C5 palsy had a statistically higher amount of average C4-C5 Cobb angle change (22.53 vs 0.78; P = .01). Logistic regression analysis demonstrated that lordotic change in both C4-C5 and C2-C7 Cobb angles were associated with development of palsy.

CONCLUSION: Lordotic cervical correction, as measured on upright imaging, was statistically larger in patients who had C5 palsy. The role of deformity correction in C5 palsy deserves further study and may inform intraoperative decision making.

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