Glattes (2005) — Proximal junctional kyphosis in adult spinal deformity following long instrumented posterior spinal fusion: Incidence, outcomes, and risk factor analysis

Proximal Junctional Kyphosis in Adult Spinal Deformity Following Long Instrumented Posterior Spinal Fusion: Incidence, Outcomes, and Risk Factor Analysis

·Spine·2005·683 citations·Spine

Retrospective cohort study of 81 adult deformity patients (mean follow-up 5.3 years) after long instrumented posterior spinal fusion, examining the incidence of proximal junctional kyphosis (PJK), its effect on SRS-24 patient outcomes and global sagittal balance, and whether any patient, radiographic, or instrumentation variables predict its development.

Study Snapshot

Design

Retrospective cohort

Setting: Single center, St. Louis

Funding: Industry (unspecified)

Objective

Determine whether proximal junctional kyphosis affects outcomes after adult spinal deformity fusion

Outcome(s)

PJK incidence and SRS-24 outcomes scores at final follow-up

Subjects

81 adult deformity patients, minimum 2-year follow-up

Inclusion

Age ≥21 at surgery
Posterior fusion ≥6 motion segments
Complete radiographic follow-up

Exclusion

Revision surgery changing UIV level
Poor proximal junction visualization
Lost to follow-up

Follow-up

Mean 5.3 years (range 2–16)

Statistics

Student t-testChi-square testFisher's exact test

Key Findings

26% of patients developed PJK using a strict dual-criteria definition — proximal junction Cobb >10° AND ≥10° increase from baseline — with a mean junctional Cobb of 19.4° (range 11–33°) among those affected
Radiographic PJK did not translate to worse patient-reported outcomes: SRS-24 total scores were similar between groups (P=0.15), and the pain subscale actually trended better in PJK patients (P=0.08), suggesting this is often a clinically silent radiographic finding
Global sagittal balance was not significantly worse in PJK patients — C7 plumb measured 9.0 mm vs. 20.6 mm (P=0.20) — though large standard deviations (±55 mm) limit confidence in this conclusion
T3 as the UIV carried a 53% PJK rate, more than four times that of T4 (12.5%) and twice that of T2 (25%) among upper thoracic fusions (P=0.02) — the only variable reaching statistical significance, with direct implications for level selection
No patient demographics, pre-existing proximal kyphosis, hook configuration, claw constructs, or supralaminar hooks predicted PJK development, leaving surgeons without reliable patient-level screening tools

Clinical Relevance

When consenting adult deformity patients for long posterior fusion, counsel them that roughly 1 in 4 will develop radiographic PJK — but reassure them that this finding does not consistently worsen pain, self-image scores, or global sagittal balance.

If planning to stop your construct in the upper thoracic spine, recognize that a T3 UIV carries roughly twice the PJK rate of T4, which may factor into your level-selection decision.

Supplemental

Proximal Junctional Kyphosis in Adult Spinal Deformity Following Long Instrumented Posterior Spinal Fusion: Incidence, Outcomes, and Risk Factor Analysis

Proximal Junctional Kyphosis in Adult Spinal Deformity Following Long Instrumented Posterior Spinal Fusion: Incidence, Outcomes, and Risk Factor Analysis

Study Snapshot

Key Findings

Clinical Relevance

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Proximal Junctional Kyphosis in Adult Spinal Deformity Following Long Instrumented Posterior Spinal Fusion: Incidence, Outcomes, and Risk Factor Analysis

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Proximal Junctional Kyphosis in Adult Spinal Deformity Following Long Instrumented Posterior Spinal Fusion: Incidence, Outcomes, and Risk Factor Analysis

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Proximal Junctional Kyphosis in Adult Spinal Deformity Following Long Instrumented Posterior Spinal Fusion: Incidence, Outcomes, and Risk Factor Analysis

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Key Findings

Clinical Relevance

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