PURPOSE To investigate the short and medium term efficacy and patient outcomes of DIAM spinal stabilization system on back pain, disability, leg pain and quality of life.
METHODS 165 patients were enrolled; 146 patients with a single level disc herniation (L2 to L5) were randomized: 75 investigational (herniectomy and DIAM) and 71 control (herniectomy alone) treated and followed up for 24 months.
RESULTS Significant improvements overtime (P < 0.001) in both groups but not significantly different between groups for visual analog scale (VAS) back pain at 6 months (investigational -3.97 ± 2.55 vs control-3.37 ± 3.15, P = 0.228) and Oswestry Disability Index (ODI) at 12 months (-38.55 ± 20.10 vs -37.19 ± 22.61, P = 0.719). For both outcomes, there was no statistically significant difference between the groups, at all postoperative time points. Although the enrolment ended before the intended sample size (308 patients) was reached, the number of patients reaching the VAS back pain minimally clinically important difference (MCID) of ≥2.2 at 6 months was higher in the investigational (79.4 % vs control 57.1 %, P = 0.008). These results were sustained throughout 24 months (82.8 vs 64.4 %, P < 0.05). In average, surgical duration (P < 0.001), blood loss (P = 0.029) and skin incision (P < 0.001) in the investigational were 10 min longer, 22.5 ml greater and 2.0 cm wider than control group (median values). Improved tertiary outcomes from BL to 24 mo in both groups (investigational vs control): VAS leg pain (mean decrease -6.41 ± 2.57 to -6.41 vs -5.61 ± to -3.30); improved quality of life (SF-36: 20.68 ± 9.44 vs 16.90 ± 10.74); pain medication reduction: 56.7 vs 47.9 %; return to work: 45.7 vs 38.0 %. Adverse event rates: 68.5 % investigational and 66.2 % control.
CONCLUSIONS This is the first randomized controlled trial to report equivalent efficacy and safety of herniectomy with or without DIAM spinal stabilizing device. Leg pain, back pain and the level of disability were not significantly different between groups; however, number of patients reaching the MCID for back pain was significantly higher in the investigational group at 6 through 24 months.