Incidence of de novo sacroiliac joint pain following adult spinal deformity surgery with pelvic fixation

OBJECTIVE The aim of this study was to determine the rate of postoperative new-onset sacroiliac joint pain (SIJP) following adult spinal deformity (ASD) surgery with pelvic fixation. METHODS Patients undergoing ASD surgery with pelvic fixation, without baseline SIJP, and with a minimum 1-year follow-up were included. Patients were screened for SIJP by self-reported buttock/groin pain and/or posterior superior iliac spine (PSIS) pain scores ≥ 4. Patients with positive results on questionnaires were indicated for an SIJ examination consisting of 5 provocative maneuvers with ≥ 3 positive examination findings considered to be indicative of SIJP. Types of pelvic fixation were then compared for rates of postoperative SIJP. RESULTS A total of 346 patients were identified, with mean age of 65 (SD 10) years and BMI of 28 (SD 5); 71% of patients were female. Thirteen patients (4%) underwent SIJ fusion at the index procedure. At the 1-year follow-up, 82 patients (24%) had positive screening responses for SIJP on the questionnaire; 63 underwent an SIJ examination and only 3 patients (1%) had a positive result. At the 2-year follow-up, 138 patients were administered the SIJP screening questionnaire; 31 (22%) had a positive questionnaire response for SIJP, 17 underwent an SIJ examination, and only 2 patients (1%) had a positive result. There was no difference in SIJP between patients with traditional iliac fixation (n = 162, 0% at 1 and 2 years) and S2-alar-iliac screws (n = 184), where 2% developed SIJP by 1 (p = 0.25) and 2 (p = 0.52) years, respectively. There was also no difference in SIJP between patients with 4 points of pelvic fixation (n = 85, 0% at 1 and 2 years) and patients with fewer than 4 points of pelvic fixation (n = 261), where 1% (p = 0.57) and 2% (p > 0.99) developed SIJP at 1 and 2 years, respectively. Of the 79 patients with iliac crest harvesting, none developed SIJP at the 1- or 2-year follow-up. CONCLUSIONS Based on examination, the incidence of de novo SIJP following ASD surgery with pelvic fixation is low: only 1% at the 1- and 2-year follow-ups. The large discrepancy between at least moderate regional reported pain but a negative provocative examination warrants further investigation as to the source of substantial pain in nearly one-quarter of ASD patients postoperatively.