Minimally Invasive Sacroiliac Joint Fusion Compared with Sham Operation (SIFSO Trial)

Minimally invasive fusion of the sacroiliac joint (SIJ) as a treatment for SIJ pain remains controversial. The SIFSO trial was a double-blinded, sham-controlled randomized trial with a primary end point of 6 months. Sixty-three patients were randomized to undergo either minimally invasive SIJ fusion or sham surgery. At the 6-month primary end point, a mean reduction of 2.6 points on the Numeric Rating Scale (NRS) was demonstrated in the surgical group, compared with a reduction of 1.7 points in the sham group (group difference: −1.0 point [95% confidence interval (CI), −2.2 to 0.3; p = 0.13]). Patients in the sham group were allowed to cross over to surgery after unblinding at 6 months. The current report describes the 2-year outcomes of all patients, including those who underwent SIJ fusion as part of the initial surgical group, those who crossed over to fusion after sham surgery, and those who remained in the sham group. After unblinding at 6 months, 26 of the 31 patients in the sham group crossed over to fusion. All 63 patients completed the 2-year follow-up. The mean age at baseline was 45 years (range, 26 to 63 years), and 59 of the 63 patients were female. Compared with baseline, the reduction in the NRS score at 2 years was 3.1 (95% CI, 2.0 to 4.1) in the initial fusion group (n = 32), 1.6 (95% CI, −1.8 to 5.0) in the sham group that did not cross over (n = 5), and 3.5 (95% CI, 2.5 to 4.5) in the crossover group (n = 26). In conclusion, surgically treated patients experienced significant pain reduction and improved physical function at the 2-year follow-up, compared with baseline, and the results of SIJ fusion were sustained from 6 months to 2 years. Due to crossover and unblinding, it was not possible to determine the actual effect of minimally invasive SIJ fusion compared with sham surgery at 2 years. Level of Evidence: Therapeutic Level II . See Instructions for Authors for a complete description of levels of evidence.