The safety and effectiveness of lumbar transforaminal injection of sterile amniotic fluid filtrate compared to steroid for lumbosacral radicular pain due to spinal stenosis: a phase I/II double-blinded randomized trial.

BACKGROUND

Radicular symptoms from lumbosacral spinal stenosis (LSS) are commonly managed with conservative measures, including transforaminal epidural steroid injection (TFESI). However, repeated use may cause systemic side effects in some patients. Human amniotic fluid filtrate (hAF), containing anti-inflammatory, neuroprotective, and regenerative factors, has shown therapeutic potential in pre-clinical models and other medical conditions.

OBJECTIVES

Compare the safety and effectiveness of transforaminal epidural injections with hAF versus dexamethasone for treating radicular pain from LSS.

DESIGN

Double-blinded, prospective, randomized comparative trial.

METHODS

Fifty-eight participants were included, with outcomes assessed at 3 weeks, 6 weeks, 3 months (primary endpoint), and 6 months. Primary outcomes were adverse events (AEs) and proportions of participants reporting ≥50% numerical pain rating scale (NPRS) back and leg pain reductions at 3 months. Secondary outcomes included Oswestry Disability Index (ODI), Swiss Spinal Stenosis Questionnaire (SSSQ), and PROMIS Physical Health Summary (PHS). Linear mixed-effects models evaluated between-group differences while accounting for repeated measures.

RESULTS

At 3 months, a significantly greater proportion of participants receiving dexamethasone achieved ≥50% reductions in back pain (45.8% [95%CI = 27.9%-64.9%] vs. 15.0% [95%CI = 5.2%-36.0%]; P = .050) and leg pain (60.0% [95%CI = 40.7%-76.6%] vs. 25.0% [95%CI = 11.2%-46.9%]; P = .034) compared with hAF. Secondary outcome trends similarly favored dexamethasone at 3 months. Mixed-effects models showed greater improvements to 6-week pain and function scores with dexamethasone relative to hAF. Group AE rates were comparable, and no serious intervention-related AEs occurred.

CONCLUSION

Dexamethasone demonstrated significantly greater short- and intermediate-term benefits over hAF across multiple clinical outcome domains for radicular pain due to LSS, prompting early trial discontinuation.

TRIAL REGISTRATION: ClinicalTrials.gov (NCT04537026); September 3, 2020.