Inefficacy of ultrasound-guided local injections of autologous conditioned plasma for recent epicondylitis: results of a double-blind placebo-controlled randomized clinical trial with one-year follow-up.

OBJECTIVES: The aim was to assess the efficacy of two intra-tendinous injections of platelet-rich plasma (PRP) on epicondylitis of recent evolution (≤3 months).

METHODS: Our study was a double-blind placebo-controlled randomized trial. Two US-guided injections of either PRP (autologous conditioned plasma) or saline solution were performed with an interval of 4 weeks. The exclusion criterion was previous CS infiltration. Patients were monitored by an independent evaluator blinded to treatment at baseline and 1, 3, 6 and 12 months of follow-up. The primary evaluation criterion was the relative improvement from baseline to 6 months in pain score on visual analog scale (0-10). Secondary criteria were the Roles-Maudsley score and the assessment of pain on isometric contraction of extensor carpi radialis brevis and extensor digitorum communis.

RESULTS: Twenty-five patients were randomly assigned to each group. Three patients in each arm dropped out before 6 months. In both groups, the pain score [mean (s.d.)] decreased significantly between two consecutive visits from 6.8 (0.8) (PRP) and 7 (1) (saline) at baseline to 2.5 (1.6) and 1.6 (1.5) (PRP) and to 2.1 (1.6) and 1.8 (2.1) (saline) at 6 and 12 months, respectively. At 6 months, no statistically significant difference was found between groups for relative improvement in pain score [autologous conditioned plasma: -63.2 (22.4%); saline: -69.7 (25.1%); P = 0.24]. No significant difference was found for the secondary criteria.

CONCLUSION: Two US-guided PRP injections for epicondylitis of recent evolution were not more efficacious than saline injections, until 6- and 12-months follow-up.

TRIAL REGISTRATION: ClinicalTrials.gov; https://clinicaltrials.gov/; NCT02378285.