Efficacy of Extracorporeal Shockwave Therapy for Treatment of Trigger Finger: A Systematic Review and Meta Analysis

Background Extracorporeal shockwave therapy (ESWT) has been used as a novel treatment approach for trigger finger, a common condition caused by inflammation of the flexor tendons of the finger and thumb. Trigger finger can lead to significant hand dysfunction and is one of the leading causes of hand pain. ESWT is a conservative treatment modality that has been gaining popularity due to its low associated risks and high success shown in treating a variety of tendinopathies. To date, ESWT has been employed for the treatment of trigger finger, but its efficacy as a treatment option has not yet been proven. Purpose/Hypothesis The purpose of this study is to determine the impact of ESWT on functional outcomes and pain scores when used as a treatment for trigger finger. Study/Design A systematic review and meta-analysis were conducted with strict adherence to PRISMA 2020 guidelines. Methods Five online databases (PubMed, Web of Science, Embase, Scopus, Cochrane) were searched using MeSH key terms to identify studies. Included in the analysis were randomized controlled and non-controlled trials and retrospective cohort studies that utilized ESWT as the sole treatment for trigger finger and reported mean Quick-DASH (qDASH) or Visual Analog Scale (VAS) scores pre- and post-intervention. Two studies, evaluating 40 fingers, met the inclusion criteria for analysis of qDASH, and four studies, evaluating 108 fingers, met the inclusion criteria for analysis of VAS. qDASH scores were compared between baseline and 6 months after treatment to represent the magnitude of disability and symptoms.3 VAS scores were compared between baseline and 7±5 months after treatment to represent pain. Results Statistical analysis was performed using a single group meta-analysis with a random effects approach using IBM SPSS Statistics. This approach allowed for the effect sizes of individual studies to be pooled for collective evaluation of mean changes in qDASH and VAS scores between baseline and follow up. A p-value less than 0.05 was utilized to determine statistical significance. The extent of improvement in scores was represented by the pooled and individual effect size (Cohen’s d) with 95% confidence intervals (95% CI [LL, UL]). For qDASH scores, a large common effect size (Cohen’s d =-1.61 95% CI [-3.45, 0.23]) with considerable heterogeneity (I2 = 0.916) was found, suggesting a substantial treatment effect despite underlying variability in study parameters. However, the p-value was found to be 0.09, suggesting that decreases in qDASH scores 6 months after ESWT treatment (i.e., improvement in magnitude of disability and symptoms) were statistically insignificant. Statistically significant decreases in VAS scores were found (p<0.05) between baseline and 7±5 months after treatment, representing an improvement in pain. A large common effect size (Cohen’s d = -4.74 95% CI [-8.80, -0.68] with considerable heterogeneity (I2 = 0.985) was found, suggesting a large reduction in pain despite underlying variability in study parameters. Conclusion ESWT has demonstrated a large benefit for the treatment of pain associated with trigger finger. Although the effect on functionality (as quantified by qDASH) was statistically insignificant, future randomized controlled trials and high-quality studies are needed to reconcile these findings. A limitation in this study was the number of included studies and the sample sizes utilized to analyze ESWT effects on qDASH and VAS. A larger sample size would make the findings more generalizable and provide greater insight into the effects of ESWT on functional outcomes. An increased number of studies would allow researchers to complete regression-based statistical analyses.