Background: Lumbosacral canal stenosis is known as the most common cause of back surgery with several complications. Selecting a minimally invasive treatment with high efficacy in such patients is necessary. This study was designed to evaluate the effectiveness of ozone therapy in combination with caudal epidural steroid in patients with lumbar spinal stenosis.

Methods: A double-blind randomized clinical trial was conducted on 50 patients with lumbar spinal stenosis allocated into two study groups. Under ultrasound guidance, the first group received 80 mg of triamcinolone hexavalent with 4 mL of Marcaine 0.5% and 6 mL of distilled water to the caudal epidural space. The second group received an injection similar to the first group, combined with 10 mL of ozone (O2-O3) gas at a concentration of 10 µg/cc. The patients were followed at baseline, one, and six months after injection with clinical outcomes measures using Visual Analog Scale (VAS), Walking Distance (WD) and Oswestry Disability Index (ODI).

Results: The mean age of subjects, 30 males (60%) and 20 females (40%), was reported as 64.51 ± 7.19 years old. Reduction of pain intensity based on VAS score was statistically significant in both groups at follow-up periods (P < 0.001). The VAS changes in the first month and sixth months showed no significant difference between the two groups (P = 0.28 and P = 0.33, respectively). The improvement in disability index (ODI) in both types of treatment during follow-up was significant (P < 0.0001), and there was no difference between the two treatment groups in one month and six months (P = 0.48 and P = 0.88, respectively). As for walking distance, the improvement process with both types of treatment during follow-up periods was significant (P < 0.001). However, after one and six months of treatment, the rate of improvement in patients' walking distance in the caudal epidural steroid injection plus ozone group was significantly higher than in the epidural steroid group (p = 0.026 and p = 0.017, respectively).

Conclusions: In this study, the results of VAS and ODI outcomes showed that caudal epidural steroid injection combined with ozone has no advantage over caudal epidural steroid injection alone. Interestingly, our results demonstrated that the group receiving caudal epidural steroid injection plus ozone scored significantly higher on the walking distance index than the group receiving caudal epidural steroid alone.

Trial registration: IRCT IRCT20090704002117N2 (registration date: 07/08/2019).