Purpose: muscle injuries have a high incidence in professional football and are responsible for the largest number of days lost from competition. several in vitro studies have confirmed the positive role of plateletrich plasma (PRP) in accelerating recovery and in promoting muscle regeneration, and not fibrosis, in the healing process. this study examines the results of intralesional administration of PRP in the treatment of primary hamstring injuries sustained by players belonging to a major league football club. Methods: twenty-five hamstring injuries (grade 2 according to MRi classification) sustained by professional football players during a 31-months observation period were treated with PRP and analyzed. sport participation absence (sPA), in days, was considered to correspond to the healing time, and we also considered the re-injury rate, and tissue healing on MRi. the mean follow-up was 36.6 months (range 22-42). Results: there were no adverse events. the mean sPA for the treated muscle injuries was 36.76±19.02 days. the re-injury rate was 12%. tissue healing, evaluated on MRi, was characterized by the presence of excellent repair tissue and a small scar. Conclusions: this study confirmed the safety of PRP in treating hamstring lesions in a large series of professional football players. PRP-treated lesions did not heal more quickly than untreated lesions described in the literature, but they showed a smaller scar and excellent repair tissue. Level of evidence: Level iV, therapeutic case series.

III.

Level V, expert opinion.

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