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  • Posterior Ligamentous Augmentation Prevents Acute Proximal Junctional Failure in Upper Thoracic Constructs but not in Lower Thoracic Constructs

    Final Number:

    Randall Hlubek MD; Robert Eastlack MD; Stacie Nguyen; Jakub Godzik MD MSc; Jay D. Turner MD, PhD; Gregory M. Mundis MD

    Study Design:

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2018 Annual Meeting

    Introduction: Posterior ligamentous augmentation (PLA) with polyethylene terephthalate bands at the upper instrumented vertebrae (UIV) -1 to (UIV) +1 is a proximal junctional kyphosis(PJK)/failure(PJF) prevention strategy in adult spinal deformity patients. This study aimed to understand the effect of PLA for long segment constructs terminating in the upper thoracic(UT) and lower thoracic(LT) spine.

    Methods: ASD patients with minimum f/u of 6 mos who underwent PLA were retrospectively reviewed to evaluate the incidence of PJK/PJF. Demographics, operative data, and radiographic parameters were recorded. Preop/postop measurements included pelvic incidence (PI), L1-S1 lumbar lordosis (LL), pelvic tilt (PT), T1 pelvic angle (TPA), C7 sagittal vertical axis (SVA), and UIV to UIV+2 proximal junctional angle (PJA). PJK was diagnosed when:(1)PJA was >= 10 degrees (2) PJA was 10 degrees > than preop. PJF included any of the following: increase PJA of >=15 °, fracture of UIV or UIV + 1, proximal extension of fusion, and/or UIV fixation failure.

    Results: 27 patients (74% female) were identified with a mean age of 67(42-81)yrs, 13 operative levels, and f/u 12(6-18)mos. UIV was UT spine in 19(70%) and the LIV was the ilium in 25(93%). Preop mean SVA(8cm), PI-LL(28.3°), TPA(31.0°), and PT(31.7°) improved to an immediate postop mean SVA(2.8cm), PI-LL (10.8°), TPA(19.1°), and PT(24.5°). 5 patients(19%) developed PJF with 1/19(5%) incidence with UIV in UT and 4/8(50%) incidence with UIV in LT. Compared to UIV in UT, odds ratio of PJF with LT UIV was 4.41(95% CI, 1.64-11.76,p=.01).Failure mode in LT was compression fractures at the UIV in 3/4 patients and hook failure due to a technical error. No patients fit the criteria for PJK.

    Conclusions: PLA resulted in a 19% incidence of PJF(50% LT; 5% UT). Osseous mode of PJF in LT spine may make this technique less effective in constructs that terminate in LT spine vs UT spine.

    Patient Care: PLA appears to be an effective PJK/PJF prevention strategy for long segment constructs that terminate in the upper thoracic spine. It does not appear to be effective when UIV is in the lower thoracic spine due to the osseous mode of failure at the proximal junction.

    Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the technique of posterior ligamentous augmentation. 2) Understand that PLA appears to be an effective PJK/PJF prevention strategy when UIV is in the upper thoracic spine. 3) Understand that PLA may not be effective in the lower thoracic spine due to the osseous method of proximal junctional failure.

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