Introduction: Proximal junctional kyphosis (PJK) is a frequent complication after long segment thoraco-lumbar fusion for adult spinal deformity (ASD) with potentially significant impact on clinical outcome. The reported incidence of PJK is wide-ranging, while the etiology and risk factors of PJK remain poorly understood. The purpose of this study, therefore, was to determine the incidence and radiographic predictors for PJK occurrence after adult spinal deformity surgery at a single institution, neurosurgical department.
Methods: We performed a retrospective analysis of consecutive adults (age >=21 years) that underwent long segment thoraco-lumbar fusion (>=7 vertebrae) for ASD at a single institution, neurosurgical department between 2008-2013. Pre-operative and post-operative clinical and radiographic data were evaluated. Radiographic measurements included thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS).
Results: Sixty-five patients met inclusion criteria with a mean age of 65 years. Average follow up was 1.2 years. Thirty-eight (59%) patients developed PJK at last follow up, with four (11%) requiring additional surgery to treat PJK. Older age at time of surgery and greater pre-operative thoracic kyphosis predicted post-operative PJK occurrence (p<0.0001 and p<0.042, respectively). Not surprisingly, fracture at the proximal level of the construct was also associated with PJK (p<.0001). Radiographic parameters of ideal deformity correction such as SVA <50 mm, PT <200, and PT-LL < ±100 were not associated with lower incidence of PJK.
Conclusions: Radiographic PJK occurs commonly after long segment thoraco-lumbar surgery for adult spinal deformity. Older age and greater pre-operative thoracic kyphosis are associated with higher risk of PJK. Incidence of revision surgery to treat clinically significant PJK, however, remains low.
Patient Care: This study will further contribute to understanding and literature about the incidence and clinical significance of PJK – as well as improve our ability to best manage these complex surgical patients.
Learning Objectives: 1. To study the incidence and risk factors of PJK in spinal deformity surgery.
2. To identify radiographic predictors of PJK in spinal deformity surgery
3. To assess the clinical implications of PJK