title: Platelet-rich plasma in the treatment of acute hamstring injuries in professional football players.
abstract: OBJECTIVE
  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 platelet-rich 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.
  
  
  METHODS
  Level IV, therapeutic case series.
authors.affiliation: Clinica Ortopedica e Traumatologica, Università degli Studi di Pavia - Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Zanon
authors.affiliation: Athletics National Team Physician, Milan, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Combi
authors.affiliation: Clinica Ortopedica e Traumatologica, Università degli Studi di Pavia - Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Combi
authors.affiliation: Clinica Ortopedica e Traumatologica, Università degli Studi di Pavia - Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: Loris
authors.initials: L
authors.lastname: Perticarini
authors.affiliation: Department of Radiology, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Sammarchi
authors.affiliation: Clinica Ortopedica e Traumatologica, Università degli Studi di Pavia - Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Benazzo
keywords: football; hamstring healing; injuries; muscle; platelet-rich plasma