Acute Disc Herniation at the Proximal Junctional Segment (UIV/UIV + 1) Following Long Segment Spinal Fusion…

Cohort studyInternational journal of spine surgery· Jul 2026

Acute Disc Herniation at the Proximal Junctional Segment (UIV/UIV + 1) Following Long Segment Spinal Fusion With Cement-Augmented Instrumentation: A Retrospective Study.

Dana Saleh, Ahmad Zayd Alkadri, Sadegh Bagherzadeh … Puya Alikhani

SpineCohort studyQ1IF 1.9

Acute disc herniation after spinal fusion linked to sharp increase in junctional Cobb angle

Acute Disc Herniation at the Proximal Junctional Segment (UIV/UIV + 1) Following Long Segment Spinal Fusion With Cement-Augmented Instrumentation: A Retrospective Study.

Dana Saleh … Puya Alikhani

International journal of spine surgery · Jul 2026 · Q1 in Surgery

Background

Prophylactic cement augmentation at the uppermost instrumented vertebra (uppermost instrumented vertebra) and the adjacent supravertebra (uppermost instrumented vertebra + 1) is commonly used during long-segment fusion for adult spinal deformity to reduce the risk of proximal junctional failure.

Methods

In this retrospective cohort study, 173 patients underwent long-segment posterior spinal fusion (≥5 levels) with prophylactic polymethylmethacrylate (polymethylmethacrylate) cement augmentation at uppermost instrumented vertebra/uppermost instrumented vertebra + 1 between January 2016 and January 2024.

n = 173 patients

Results

junctional angle worsened sharply, far more than in patients without herniation

ADH group

20.3°

Controls

1.2°

More results

Baseline characteristics were well balanced between matched groups, with no significant differences observed for matched or unmatched variables (all P > 0.05) except for smoking, which was more prevalent in the acute disc herniation group ( P = 0.03).

More results

Acute disc herniation patients presented with acute neurological deterioration, including lower-extremity weakness, gait instability, myelopathy, and urinary dysfunction, often requiring urgent revision surgery.

Disc slope change was similar between groups ( P = 0.42).

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Conclusion · 1 of 2

Despite preserved bone quality, acute disc herniation was associated with profound junctional collapse and rapid neurological decline, suggesting a biomechanical failure mechanism driven by polymethylmethacrylate-related overstiffening.

Conclusion · 2 of 2

Strategies that preserve a gradual stiffness transition at the proximal junction may be necessary to mitigate this risk.

Acute Disc Herniation at the Proximal Junctional Segment (UIV/UIV + 1) Following Long Segment Spinal Fusion With Cement-Augmented Instrumentation: A Retrospective Study.

Acute Disc Herniation at the Proximal Junctional Segment (UIV/UIV + 1) Following Long Segment Spinal Fusion With Cement-Augmented Instrumentation: A Retrospective Study.

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