Background: The first results from the randomized, controlled iFuse Implant System Minimally Invasive Arthrodesis (iMIA) trial showed that minimally invasive surgical management (MISM) of low back pain originating from the sacroiliac joint (SIJ) by placing transarticular triangular titanium implants reduced pain more effectively than conservative management (CM). We now conducted a separate analysis of the iMIA data to assess whether the referred leg pain (RLP) component of SIJ-associated pain may also be affected by MISM or CM.
Methods: Data from 101 patients, recruited between June 2013 and May 2015 at nine European spine care centers, were included. Forty-nine patients were randomized to CM and 51 patients to MISM. RLP was defined as pain below the gluteal fold and assessed using the visual analogue scale (VAS). Changes in RLP over 6 months were the primary endpoint.
Results: The prevalence of clinically significant RLP was 76.2 %. Over 6 months of follow-up, CM produced no significant change in RLP, which was 51.0 VAS points (interquartile range (IQR) 17.0-75.0) at baseline. In contrast, in the MISM cohort, we found a significant decrease in RLP from VAS 58.0 (IQR 24.5-80.0) at baseline to VAS 13.5 (IQR 0.0-39.3) after 6 months (p < 0.01). Improvement of RLP was associated only with the type of treatment (OR 5.04, p < 0.01), but not with patient age, sex, or different patterns of pain referral.
Conclusions: Our analysis shows that RLP is a frequent phenomenon in patients with SIJ-associated pain. At 6 months of follow-up, MISM helped relieve RLP more effectively than CM. Clinical Trial Registration-URL: http://www.clinicaltrials.gov . Unique identifier: NCT01741025.
Keywords: Conservative pain management; Low back pain; Pain referral patterns; Referred leg pain; Sacroiliac joint fusion.