Risk Factor Analysis of Proximal Junctional Kyphosis after Surgical Treatment of Adult Spinal Deformity with Oblique Lateral Interbody Fusion

Abstract

Study Design: A single-center retrospective study.Purpose: To investigate the prevalence of proximal junctional kyphosis (PJK) and its risk factors after surgical treatment of adult spinal deformity (ASD) with oblique lateral interbody fusion (OLIF).Overview of Literature: Correction of ASD using OLIF has been developed because it is less invasive, and enables correction of severe deformities. Although PJK is a well-recognized complication after the correction of spinal deformity, few studies have evaluated the prevalence and risk factors for PJK after OLIF for ASD.Methods: We reviewed 74 patients who underwent surgery for ASD. PJK was defined as a proximal junction sagittal Cobb angle exceeding 10°, and at least 10° greater than the preoperative measurement. We investigated the following as risk factors: age, sex, body mass index, medical history, number of fused segments, number of interbody fusions, number of OLIFs, number of osteotomies, level of upper instrumented vertebrae, lowest instrumented vertebrae, and radiographic parameters.Results: The mean follow-up duration was 22.4 months and the mean age of the patients was 73.6 years. PJK was present in 19/74 patients (25.7%) and absent in 55/74 (74.3%). In the univariate analysis, those with PJK had a significantly higher proportion of patients with a history of vertebral compression fracture (7/19 patients [36.8%] vs. 6/55 patients [10.9%], p=0.027). Those with PJK had a significantly higher proportion of patients with fusion to the pelvis (18/19 patients [94.7%] vs. 34/55 patients [61.8%], p=0.016). According to the multivariate analysis, fusion to the pelvis was a significant risk factor for PJK.Conclusions: Fusion to the pelvis was the most important risk factor for PJK. A history of vertebral compression fracture served as an additional risk factor for PJK. Clinicians should consider these factors before treating ASD patients with OLIF.