The efficacy of hyaluronic acid for carpal tunnel syndrome: a randomized double-blind clinical trial.

OBJECTIVES To investigate the effect of hyaluronic acid (HA) in patients diagnosed with mild or moderate carpal tunnel syndrome (CTS). DESIGN A prospective randomized, double-blinded control study with 6 months of follow-up. SETTING Rehabilitation outpatient clinic of one single medical center. SUBJECTS Thirty-five participants with mild or moderate CTS. METHODS Participants were enrolled and randomly assigned to HA or control groups. The HA group received one ultrasound-guided perineural injection of 2.5 ml HA while the control group received 2.5 ml normal saline injection through in-plane, long-axis approach to separate the median nerve from the flexor retinaculum via nerve hydrodissection. Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) scores were the primary outcome, while secondary outcomes included the numeric rating scale (NRS), electrophysiological domains, and the cross-sectional area of the median nerve. The assessment was conducted prior to injection and during the second week and 1-, 3-, and 6-months post-injection. RESULTS Thirty-two patients (17 wrists in HA group and 15 wrists in control group) completed the study. Compared with the control group, the HA group did not show significantly superior outcomes, except in BCTQ and NRS at the second week post-injection (all p < 0.0125). CONCLUSIONS A single ultrasound guided perineural HA injection may have short-term therapeutic efficacy for mild or moderate CTS; however, the 2-weeks superior efficacy was not beneficial for chronic neuropathy. Further studies with larger sample sizes are required to verify its therapeutic efficacy.