Transforaminal epidural steroid injection for lateral recess stenosis: subpedicular approach versus Kambin's triangle approach – a randomized single-blinded study

Purpose Transforaminal epidural steroid injections (TFESI) are commonly used to treat patients with lumbar spinal stenosis. It is the aim of our study to prospectively evaluate the effectiveness of TFESI using subpedicular and Kambin's triangle approach in patients with radiculopathy due to lateral recess stenosis. Methods Participants undergoing TFESI were randomized into two groups: the subpedicular approach group ( n = 24) and the Kambin's triangle approach group ( n = 24). The primary outcome measure was the numerical rating scale (NRS) pain score at 3 and 6 weeks post-injection. A ≥50% reduction in the NRS pain score from baseline indicated a successful therapeutic effect. The secondary outcome measure was the requirement of surgery at 6 months post-injection. Results All participants reported a significant reduction in the NRS pain score at 3 and 6 weeks after the injection ( P < 0.05). The proportion of patients who experienced pain reduction ≥50% in the Kambin's triangle approach group was higher than that in the subpedicular approach group at 3 and 6 weeks post-injection. The difference was statistically significant at 3 weeks ( P < 0.05) and borderline significant ( P = 0.057) at 6 weeks. There was no significant difference in the proportion of patients eventually requiring surgery at 6 months and the complication rate between the two groups. Conclusions These results suggest that TFESI using Kambin's triangle approach is more effective in providing short-term pain alleviation for patients with radiculopathy due to lateral spinal stenosis.