Object: To assess the safety and efficacy of the DIAM implant, the authors compared the mean 12-month outcomes in patients who underwent lumbar surgery with DIAM placement and in those who underwent lumbar surgery only.
Methods: Of 62 patients who underwent simple lumbar surgery (laminectomy and/or microdiscectomy) in a 24-month period, 31 underwent concomitant surgical placement of a DIAM interspinous process spacer (33 devices total). Radiographic imaging, pain scores, and clinical assessments were obtained postoperatively to a mean of 12 months (range 8-25 months). Patients who did not undergo implantation of an interspinous process spacer (Group C) were compared with and stratified against patients who underwent placement of a DIAM implant (Group D). In Group D, no statistically significant differences were noted in anterior or posterior disc height when comparing patients pre- and postoperatively. Compared with Group C, a relative kyphosis of less than 2 degrees was noted on postoperative images obtained in Group D. No statistically significant differences in visual analog scale (VAS) pain scores or MacNab outcomes were noted between Groups C and D at a mean of 12 months of follow up. Complications in Group D included three intraoperative spinous process fractures and one infection.
Conclusions: After simple lumbar surgery, the placement of a DIAM interspinous process spacer did not alter disc height or sagittal alignment at the mean 12-month follow-up interval. No adverse local or systemic reaction to the DIAM was noted. No difference in VAS or MacNab outcome scores was noted between the groups treated with or without the DIAM implants, particularly when the DIAM was used to alleviate low-back pain.