Effectiveness and Safety of Polydioxanone Thread-Embedding Acupuncture as an Adjunctive Therapy for Patients with Chronic Nonspecific Neck Pain: A Randomized Controlled Trial

Objective: To evaluate the effectiveness and safety of treatment with thread-embedding acupuncture (TEA) using polydioxanone in addition to usual care for patients with chronic nonspecific neck pain (CNP) compared with treatment with usual care alone. Methods: A single-center, assessor-blinded, two-armed randomized controlled trial was performed. One hundred and six outpatients with CNP were randomly allocated into the TEA plus usual care (TU) group or the usual care (UC) group in a 1:1 ratio. TEA treatments in the neck region were provided once a week for 4 weeks, and usual care, as needed, was allowed. The primary outcome was the mean Neck Pain and Disability Scale (NPDS) score. Secondary outcomes included clinical relevance measured by using the clinically important difference (CID), pressure pain threshold (PPT), Hospital Anxiety and Depression Scale (HADS), EuroQol-5 Dimension (EQ-5D), and patient global impression of change (PGIC). Participants were assessed at baseline and at weeks 3, 5, and 9. Statistical analyses included analysis of covariance with baseline score as a covariate. Results: The TU group showed significant improvement in NPDS scores compared with the UC group (adjusted group difference, week 5: 13.74 [95% confidence interval: 7.57–19.90]; p < 0.0001 and week 9: 17.46 [11.15–23.76]; p < 0.0001). The proportion of patients with a decrease on the NPDS score of ≥11.5 points (minimal CID) was significantly higher in the TU group at weeks 5 and 9 than in the UC group. At weeks 5 and 9, significant differences were observed on the anxiety/depression subscale of HADS, EQ-5D, and PGIC between the two groups, but not the PPTs at three sites. Temporary stiffness was observed after TEA treatment, but no serious adverse events occurred. Conclusions: The results suggest that polydioxanone TEA is a safe and clinically beneficial adjunctive treatment for patients with CNP.