Background: Standalone interspinous process devices (IPDs) to treat degenerative lumbar spinal stenosis with neurogenic intermittent claudication (NIC) have shown ambiguous results in the literature.
Objective: To show that a minimally invasive percutaneous IPD is safe and noninferior to standalone decompressive surgery (SDS) for patients with degenerative lumbar spinal stenosis with NIC.
Methods: A multicenter, international, randomized, controlled trial (RCT) was con- ducted. One hundred sixty-three patients, enrolled at 19 sites, were randomized 1:1 to treatment with IPD or SDS and were followed for 24 mo.
Results: There was significant improvement in Zurich Claudication Questionnaire physical function, as mean percentage change from baseline, for both the IPD and the SDS groups at 12 mo (primary endpoint) and 24 mo (-32.3 ± 32.1, -37.5 ± 22.8; and -37.9 ± 21.7%, -35.2 ± 22.8, both P < .001). IPD treatment was not significantly noninferior (margin: 10%) to SDS treatment at 12 mo (P = .172) but was significantly noninferior at 24 mo (P = .005). Symptom severity, patient satisfaction, visual analog scale leg pain, and SF-36 improved in both groups over time. IPD showed lower mean surgical time and mean blood loss (24 ± 11 min and 6 ± 11 mL) compared to SDS (70 ± 39 min and 189 ± 148 mL, both P < .001). Reoperations at index level occurred in 18.2% of the patients in the IPD group and in 9.3% in the SDS group.
Conclusion: Confirming 3 recent RCTs, we could show that IPD as well as open decompression achieve similar results in relieving symptoms of NIC in highly selected patients. However, despite some advantages in secondary outcomes, a higher reoperation rate for IPD is confirmed.