title: Hamstring Tendon Regeneration After Harvest for Anterior Cruciate Ligament Reconstruction: A Systematic Review.
abstract: To assess whether the portions of the semitendinosus and gracilis tendons harvested for anterior cruciate ligament reconstruction have the potential to regenerate and, if so, to evaluate the histologic properties and actual function of this newly formed tissue.
  
  
  
  We performed a comprehensive search of CINAHL (Cumulative Index to Nursing and Allied Health Literature), Embase, Medline, the Cochrane Central Registry of Controlled Trials, and SPORTDiscus from inception of the databases to July 2014, using various combinations of keywords. Studies focusing on hamstring tendon and muscle regeneration through imaging and histology, as well as on the related functional outcomes, were selected. We included studies assessing evidence of tissue regeneration with imaging (magnetic resonance imaging, 3-dimensional computed tomography, ultrasonography) or with histologic examination of biopsy samples (or a combination thereof).
  
  
  
  Nineteen articles were included in this review, with a total of 400 patients observed. The overall rate of tissue regeneration was 86.0%, with similar values shown in most studies regardless of the methodology of the assessment. Biopsy confirmed that the tissue found at the site in 74% of the cases showed typical histologic features of the tendon. The mean modified Coleman Methodology Score of the studies included was 52.7 points, showing a modest methodologic quality for the studies published to date.
  
  
  
  In over 85% of the cases analyzed, regeneration signs of the harvested tendon were found through different imaging and histologic methodologies. A torque deficit in deep knee flexion is always present postoperatively, but the cause for this is still unclear. There is a need for better-designed trials featuring a higher level of evidence to further investigate this matter, and the effects of postoperative care and the surgical approach used on the regeneration process should be analyzed in the future.
  
  
  
  Level IV, systematic review of Level II, III, and IV studies.
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Campus Bio-Medico University of Rome, Rome, Italy.
authors.forename: Rocco
authors.initials: R
authors.lastname: Papalia
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Campus Bio-Medico University of Rome, Rome, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Franceschi
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Campus Bio-Medico University of Rome, Rome, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: D'Adamio
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Campus Bio-Medico University of Rome, Rome, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Diaz Balzani
authors.affiliation: Department of Musculoskeletal Disorders, Faculty of Medicine and Surgery, University of Salerno, Salerno, Italy; Centre for Sports and Exercise Medicine, Barts and The London School of Medicine and Dentistry, Mile End Hospital, London, England. Electronic address: n.maffulli@qmul.ac.uk.
authors.forename: Nicola
authors.initials: N
authors.lastname: Maffulli
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Campus Bio-Medico University of Rome, Rome, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Denaro
mesh_terms: D016118:Anterior Cruciate Ligament / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D006801:Humans; D012038:Regeneration; D013710:Tendons / Q000637:transplantation*