Abstract
BACKGROUND CONTEXT: It is unknown whether upper instrumented vertebra (UIV) pedicle screw trajectory and UIV screw-rod angle are associated with development of proximal junctional kyphosis (PJK) and/or proximal junctional failure (PJF). PURPOSE: To determine whether (1) the cranial-caudal trajectory of UIV pedicle screws and (2) UIV screw-vertebra angle are associated with PJK and/or PJF after long posterior spinal fusion in patients with adult spinal deformity (ASD). STUDY DESIGN/SETTING: Retrospective review. PATIENT SAMPLE: We included 96 patients with ASD who underwent fusion from T9–T12 to the pelvis (>5 vertebrae fused) between 2008 and 2015. OUTCOME MEASURES: Pedicle screw trajectory was measured as the UIV pedicle screw–vertebra angle (UIV-PVA), which is the mean of the two angles between the UIV superior endplate and both UIV pedicle screws. (Positive values indicate screws angled cranially; negative values indicate screws angled caudally.) We measured UIV rod-vertebra angle (UIV-RVA) between the rod at the point of screw attachment and the UIV superior endplate. METHODS: During ≥2-year follow-up, 38 patients developed PJK, and 28 developed PJF. Mean (± standard deviation) UIV-PVA was −0.9° ± 6.0°. Mean UIV-RVA was 87° ± 5.2°. We examined the development of PJK and PJF using a UIV-PVA/UIV-RVA cutoff of 3° identified by a receiver operating characteristic curve, while controlling for osteoporosis, age, sex, and preoperative thoracic kyphosis. RESULTS: Patients with UIV-PVA ≥3° had significantly greater odds of developing PJK (odds ratio 2.7; 95% confidence interval: 1.0–7.1) and PJF (odds ratio 3.6; 95% confidence interval: 1.3–10) compared with patients with UIV-PVA <3°. UIV-RVA was not significantly associated with development of PJK or PJF. CONCLUSIONS: In long thoracic fusion to the pelvis for ASD, UIV-PVA ≥3° was associated with 2.7-fold greater odds of PJK and 3.6-fold greater odds of PJF compared with UIV-PVA <3°. UIV-RVA was not associated with PJK or PJF.
Original language | English (US) |
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Pages (from-to) | 1072-1079 |
Number of pages | 8 |
Journal | Spine Journal |
Volume | 21 |
Issue number | 7 |
DOIs | |
State | Published - Jul 2021 |
Keywords
- Adult spinal deformity
- Complications
- Fusion
- Pedicle screw
- Pelvis
- Proximal junctional kyphosis
- Scoliosis
- Thoracic kyphosis
- Upper instrumented vertebra
- proximal junctional failure
ASJC Scopus subject areas
- Surgery
- Orthopedics and Sports Medicine
- Clinical Neurology