Reoperation rates after fenestration for lumbar spinal canal stenosis: a 20-year period survival function method analysis

Fenestration is the gold standard surgery for lumbar spinal canal stenosis in Japan. Several previous studies have analyzed the reoperation rates in large numbers of patients undergoing several surgical procedures such as laminectomy with or without instrumented spinal fusion; however, there have been few studies focusing solely on fenestration. The purpose of this study was to calculate the reoperation rates after fenestration using the survival function method. Form 1988–2007, 6,998 surgeries for lumbar spinal canal stenosis occurred in Miyagi prefecture, Japan, and these patients were enrolled by the spinal surgery registration system of the Department of Orthopaedic Surgery, Tohoku University. Among these, 5,835 surgeries involved fenestration as a primary surgery and for those who underwent ≥2 lumbar surgeries we analyzed the reoperation rates using the Kaplan–Meier method. Among the 5,835 patients undergoing primary fenestration, 215 patients underwent 221 revisions; 112 included the same spinal levels and 103 were revised only at other levels as primary fenestration. The overall reoperation rates were 0.8 % at 1 year, 2.9 % at 5 years, 5.2 % at 10 years, 7.5 % at 15 years and 8.6 % at >17.7 years. Reoperation rates for those at the same spinal levels were 0.6 % at 1 year, 1.7 % at 5 years, 2.7 % at 10 years, 3.8 % at 15 years, and 4.1 % at >17.0 years. Fenestration can be performed at low cost using standard spinal surgery equipments. The reoperation rates of this procedure were lower than previously reported for several other surgical procedures.