Wallis Interspinous Spacer for Treatment of Primary Lumbar Disc Herniation: Three-Year Results of a Randomized Controlled Trial.

Abstract

Limited data have been reported showing whether the second-generation Wallis interspinous spacer improves function after lumbar spine decompression or discectomy. We evaluated Wallis interspinous spacer placement in patients with low back pain or sciatica secondary to a confirmed diagnosis of primary lumbar disc herniation. The patients were treated from July 2008 to July 2011 at 1 institution. Of the 77 patients, 40 allocated to undergo posterior lumbar discectomy with Wallis implantation and 37 without Wallis implantation. The primary outcomes were the visual analog scale score, Japanese Orthopedics Association score, and Oswestry Disability Index. The secondary outcomes were the intervertebral disc height, range of motion of the operated segments, complications, and operating time. At 3 years, the improvements in the primary outcomes were not different between the 2 groups (P > 0.05). The disc height was significantly greater in the Wallis group than in the control group (P < 0.001). Two patients in the Wallis group and three patients in the control group underwent further surgery to treat repeated prolapse of the index segment or an adjacent segment. No significant difference was found in the complication rate between the 2 groups (P > 0.05). We found that discectomy combined with Wallis implantation was not beneficial for pain relief or lumbar function improvement compared with lumbar discectomy alone. Although the Wallis implant was associated with maintenance of the intervertebral disc height and limited range of motion of the spine, it is probably incapable of preventing recurrent herniation or adjacent segment degeneration.