General Session: Adult Spinal Deformity

Presented by: S-J. Park - View Audio/Video Presentation (Members Only)


S-J. Park(1), C-S. Lee(1), J-H. Kim(1), J-S. Kim(1)

(1) Samsung Medical Center, Sungkyunkwan University, School of medicine, Orthopedic Surgery, Seoul, Korea, Republic of


Background: The failure modes, time to development, and the clinical relevance are known to be different between proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). However, there are no reports separately studying the risk factors of PJK and PJK.

Objective: To investigate the risk factors for PJK and PJF, separately

Methods: A retrospective study of 160 consecutive patients who underwent a long instrumented fusion to sacrum for degenerative adult spinal deformity with a minimum follow-up of 2 years was conducted. A separate survivorship analysis for PJK and PJF was performed using the Cox proportional hazards model for the three categorical parameters of surgical, radiographic, and the patients' factors.

Results: PJK developed in 27 patients (16.9%) and PJF in 29 patients (18.1%). The median survival time was 17.0 months for PJK and 3.0 months for PJF. Multivariate analyses revealed that high body mass index (BMI) was an independent risk factor for PJK (HR=1.186); whereas the significant risk factors for PJF were older age, the presence of osteoporosis, uppermost instrumented vertebra (UIV) level at the T11-L1, and a greater preoperative SVA (HR=1.082, 6.465, 5.236, and 1.017, respectively). A large correction of sagittal deformity was shown as risk factor for PJF in the univariate analyses, but not in multivariate analyses.

Conclusion: PJK developed at median 17 months and PJF at median 3 months. A high BMI was an independent risk factor for PJK, whereas older age, osteoporosis, UIV level at the thoracolumbar junction, and greater preoperative SVA were risk factors for PJF.