Revision Surgery Due to Proximal Junctional Failure and Rod Fracture in Adult Deformity Surgery at a Single Institution in Japan

INTRODUCTION: Proximal junctional failure (PJF) and rod fracture (RF) are the primary reasons for revision surgery after a long corrective fusion for the adult spinal deformity (ASD). However, many recent studies on ASD are multicenter studies from the US and European racial characteristics may differ from those of Asians. Therefore, the risk factors for revision surgery because of PJF and RF after ASD surgery were evaluated in Japanese patients. METHODS: Patients with ASD who underwent corrective surgery from the thoracic vertebrae to the ilium at the authors' institution were reviewed. Demographic, surgical, and radiographic parameters were included in the analysis. Univariate and multivariate regression models were used to analyze the risk factors for PJF and RF. RESULTS: Two hundred and fifty-nine patients were included in the study. A total of 73 patients (28.1%) required revision surgery because of mechanical complications and 15 patients (5.7%) required revision surgery because of PJF on average 380 days after surgery. In PJF cases, body mass index (BMI) and pelvic tilt were significantly higher (p=0.01, p=0.048, respectively). BMI was an independent risk factor for revision owing to PJF (odds ratio [OR], 1.16; p=0.013). A total of 49 patients (18.9%) required revision owing to RF on average 867 days after surgery. Three-column osteotomy (p<0.001), significant blood loss (p=0.048), number of fusion segments (p=0.023), absence of lateral lumbar interbody fusion (p<0.001), and sagittal imbalance (p=0.033) were risk factors for revision surgery owing to RF in the univariate analysis. Three-column osteotomy (OR 4.41; p<0.001) and number of fusion segments (OR 1.21; p<0.009) were independent factors for revision surgery owing to RF. CONCLUSIONS: PJF occurred in a relatively early phase (approximately 1 year) after surgery in patients with ASD with high BMI. Conversely, RF occurred approximately 2.5 years after surgery in three-column osteotomy and spinal fusion cases that involvedlonger fusion range.