Introduction: This study analyzes the prevalence and risk factors for the development of PJK following lumbar PSO. The hypothesis was that PJK would develop early in the post-operative period at high rates in this population undergoing dramatic sagittal plane realignment, and that risk factors based on baseline and follow-up radiographs would emerge.
Methods: This multi-center, consecutive retrospective analysis was based on patients undergoing PSO surgery for ASD. The rate of patients developing PJK was identified based on 54 cases with 2-year follow- up standing radiographs and at least 1 follow-up at 6 months or 1 year. Risk factors of developing PJK were investigated in 75 patients with 6-month follow-up and short fusion (T10-L2). PJK was radiographically defined as post-operative kyphosis of >10o (between UI and UIV+2) and change in alignment from pre-op of >10o.
Results: The analysis of patients with 2-year radiographs revealed a high rate of PJK (39%), without significant difference between short and long fusions. In 82% of PJK cases, PJK was present at earlier follow-up points. The rate of surgical revisions was 15%, with 4% occurring due to PJK. For patients with 6-month follow-up and short fusion, significant risk factors for PJK were identified: neutral/kyphotic alignment at UIV/UIV+2, age >55, lumbar lordosis ideal correction or overcorrection. For patients with at most one of these risk factors, 0% PJK was noted, while patients with 3 risk factors developed PJK in 42%.
Conclusions: New appearance of PJK after 6 months seems uncommon. The prevalence of PJK following PSO occurs at a high rate radiographically (39% at 2 years) but few require surgical revision (4%). Risk factors for PJK following short fusion that have emerged include UIV alignment, age and lumbar lordosis correction. Future studies will assess the impact of radiographic PJK on health-related quality of life.
Patient Care: This research improves patient care by describing the incidence of and risk factors for proximal junctional kyphosis, a serious and poorly understood complication that can occur with spinal fusion.
Learning Objectives: By the conclusion of this presentation, participants should: (1) recognize the high rate (39%) of proximal junctional kyphosis (PJK) development following pedicle subtraction osteotomy in adult spinal deformity patients, (2) appreciate risk factors for the development of PJK.