Comparative Effectiveness of Ultrasound Guided Ozone (O2–O3) and Corticosteroid Injections for Sacroiliac Joint Dysfunction: A Multicenter Clinical Trial

<b>Background/Objectives</b>: Sacroiliac joint (SIJ) dysfunction is a common yet frequently underdiagnosed cause of chronic low back pain. This study aimed to compare the clinical effectiveness of ultrasound-guided corticosteroid and ozone injections in patients with chronic low back pain due to SIJ dysfunction. <b>Methods</b>: This comparative clinical study included 64 patients with chronic sacroiliac joint (SIJ) dysfunction who received ultrasound-guided SIJ injections with either corticosteroid (n = 31) or ozone (n = 33). Participants had a mean age of 45.0 ± 7.7 years, and the sex distribution was 42/22 (female/male). Pain intensity was assessed using the Numeric Rating Scale (NRS), disability using the Oswestry Disability Index (ODI), and quality of life using the Short Form-12 Physical (PCS) and Mental (MCS) Component Summary scores. Outcomes were evaluated at baseline, 3 months, and 6 months. Longitudinal changes were analyzed using two-way repeated-measures ANOVA (group × time) with Bonferroni-adjusted post hoc comparisons. Effect sizes were calculated using Cohen's d. Normality and homoscedasticity were assessed (Shapiro-Wilk and Levene tests), and baseline comparisons were performed using appropriate parametric or non-parametric tests. <b>Results</b>: Both treatments significantly improved pain, disability, and quality of life at 3 months (<i>p</i> < 0.01). However, improvements were significantly greater and more durable in the ozone group across all outcomes at both 3 and 6 months (<i>p</i> < 0.01). At 6 months, between-group differences favored ozone for NRS (mean difference -2.81; Cohen's d = -2.36), ODI (-6.05; d = -1.46), SF-12 PCS (+4.24; d = 1.24), and SF-12 MCS (+4.22; d = 0.83). A ≥50% pain reduction was achieved at 3 months in 97.0% of ozone-treated patients versus 45.2% of corticosteroid-treated patients (<i>p</i> < 0.01) and persisted at 6 months in 18.2% and 0% of patients, respectively (<i>p</i> < 0.05). The magnitude of improvement in the ozone group exceeded commonly reported Minimal Clinically Important Difference (MCID) thresholds for chronic low back pain outcomes, supporting clinical relevance. <b>Conclusions</b>: Ultrasound-guided ozone injection provided greater and more durable improvements in pain relief, functional status, and quality of life compared with corticosteroid injection in patients with SIJ dysfunction.