Rectangular Tubular Retractor for Microendoscopic Lumbar Decompression.

A cylindrical working tube with a diameter of 16 mm has been used for endoscopic posterior lumbar spinal surgery. However, intraoperative muscle resection is significant when using the current conventional tubular retractor.  To describe a novel tubular retractor for microendoscopic surgery and to analyze the outcomes of lumbar decompressive laminotomy using this retractor.  We devised a novel tubular retractor by changing the medial and lateral sides of the conventional 16-mm cylindrical tubular retractor to planes with a mediolateral dimension of 10 mm (rectangular tubular retractor hereafter). The amount of muscle resection, osteotomy angle on the approach side, and operating time were compared between 25 intervertebral levels treated by bilateral decompression through a unilateral approach using the rectangular tubular retractor and 31 intervertebral levels treated with the same surgery using a 16-mm cylindrical tubular retractor.  Due to the short mediolateral dimension, muscle resection decreased by 86%. The rectangular tubular retractor also decreased early postoperative wound pain. Because the craniocaudal dimension of the tubular retractor was maintained, surgical difficulty did not increase, resulting in only a slight increase in operating time. The facet joint on the approach side could be sufficiently preserved.  The rectangular tubular retractor reduced surgical invasiveness without increasing surgical difficulty.