title: Muscle and tendon injuries: the role of biological interventions to promote and assist healing and recovery.
abstract: OBJECTIVE
  To summarize clinical studies after platelet-rich plasma (PRP) therapy for tendinopathy, plantar fasciopathy, and muscle injuries; to review PRP formulations used across studies; and to identify knowledge deficits that require further investigation.
  
  
  METHODS
  After a systematic review in PubMed, we identified clinical studies assessing PRP efficacy in tendon and muscle during the past decade. We standardized data extraction by grouping studies based on anatomic location; summarized patient populations, PRP formulations, and clinical outcomes; and identified knowledge deficits that require further investigation.
  
  
  RESULTS
  Overall, 1,541 patients had been treated with PRP in 58 clinical studies; of these, 26 addressed upper limb tendinopathies and 32 addressed the lower limb (810 patients and 731 patients treated with PRP, respectively). The quality of research is higher for the upper limb than for the lower limb (23 controlled studies, of which 17 are Level I, v 19 controlled studies, of which 6 are Level I, respectively). Patients have been treated mostly with leukocyte-platelet-rich plasma, except in the arthroscopic management of the rotator cuff. The safety and efficacy of PRP for muscle injuries has been addressed in 7 studies including 182 patients. Differences across results are mainly attributed to dissimilarities between tissues and different stages of degeneration, numbers of PRP applications, and protocols.
  
  
  CONCLUSIONS
  Given the heterogeneity in tendons and tendinopathies, currently, we are not able to decide whether PRP therapies are useful. Despite advances in PRP science, data are insufficient and there is a clear need to optimize protocols and obtain more high-quality clinical data in both tendinopathies and muscle injuries before making treatment recommendations.
  
  
  METHODS
  Level IV, systematic review of Level I through IV studies.
authors.affiliation: Regenerative Medicine Laboratory, BioCruces Health Research Institute, Cruces University Hospital, Barakaldo, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Andia
authors.affiliation: Department of Musculoskeletal Disorders, University of Salerno School of Medicine and Dentistry, Salerno, Italy; Queen Mary University of London, London, England; Barts and The London School of Medicine and Dentistry, London, England; Centre for Sports and Exercise Medicine, Mile End Hospital, London, England. Electronic address: n.maffulli@qmul.ac.uk.
authors.forename: Nicola
authors.initials: N
authors.lastname: Maffulli
mesh_terms: D001182:Arthroscopy; D036981:Fasciitis, Plantar / Q000628:therapy; D006801:Humans; D018482:Muscle, Skeletal / Q000293:injuries* / Q000502:physiology; D053657:Platelet-Rich Plasma; D012038:Regeneration; D013708:Tendon Injuries / Q000628:therapy*