Midterm Clinical and Radiologic Outcomes after Percutaneous Interspinous Spacer Treatment for Neurogenic Intermittent Claudication.

PURPOSE: To evaluate the midterm clinical and radiologic outcome of percutaneous interspinous process spacer (IPS) treatment for neurogenic intermittent claudication (NIC) in patients who fail conservative treatment. METHODS: Consecutive patients with NIC, lumbar spinal stenosis confirmed on magnetic resonance imaging, failure of conservative management for at least 6 months, and treatment with percutaneous IPS were included. Visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were recorded at baseline, 1 month, 1 year and 3 years after treatment. Spinal canal and foraminal cross-sectional areas were calculated from multidetector computed tomography at baseline and 1 year. RESULTS: There were 80 patients treated with 94 IPS devices; 83% of patients received a single IPS; 78% of IPS devices were placed at L4-L5. An IPS dislocation was the single periprocedural major complication. VAS score of 8.1 ± 2 before treatment was reduced to 4.4 ± 2 at 1 month after treatment (P = .0001); ODI score of 23.3 ± 10 before treatment was reduced to 11.7 ± 8.5 at 1 month after treatment (P = .0001). These significant reductions were durable at 1-year and 3-year follow-up evaluations (P < .01). Spinal canal and foraminal cross-sectional area increased by 15% at 1 year (P = .0001). CONCLUSIONS: Patients with NIC who failed conservative treatment and were treated with percutaneous IPS achieved significant gains in pain relief and reduced disability that remained durable at 3-year clinical follow-up evaluation. This outcome was accompanied by significant increases in spinal canal and foraminal cross-sectional areas at the treated level.