The complication trends of adult spinal deformity surgery in Japan – The Japanese Scoliosis Society Morbidity and Mortality survey from 2012 to 2017

Background: The Japanese Scoliosis Society Morbidity & Mortality Committee performed a longitudinal nationwide complication survey of spinal deformity surgery from 2012 to 2017. The present study aimed to analyze the survey results and report the complication trends of adult spinal deformity surgery in Japan. Methods: All Japanese Scoliosis Society members were invited to participate in the survey. Adult spinal deformity was categorized into three groups by age: 20–39 years, 40–64 years and ≥65 years. Complications were grouped into death, blindness, neurological deficits (motor/sensory), infection, massive bleeding, hematoma, pneumonia, cardiac failure, deep vein thrombosis/pulmonary embolism, gastrointestinal perforation, and instrumentation failure. Results: The surveys were performed in 2012, 2014, and 2017. The overall complication rates were 21.6%, 26.0%, and 25.4%, respectively. The complication rates differed significantly by age group in all years such that older patients had a higher complication rate than younger patients. The rate of neurological deficits, particularly motor deficits, significantly increased in 2014 (3.1%–5.5%), and decreased in 2017 (4.3%). Massive bleeding and postoperative hematoma decreased significantly year by year (8.0%, 4.8%, 2.5% and 1.3%, 0.5%, 0.3%, respectively). The complication rate of instrumentation failure remained high, increasing without significant difference (5.2%, 5.8%, 6.5%, respectively), and was more common in the middle-aged and older patients. Conclusions: Surgical complication rates in patients with adult spinal deformity remain high, especially neurological deficits and instrumentation failure in patients aged over 40 years. However, the complication rates of massive bleeding and postoperative hematoma decreased over this period.