title: The natural history of donor hamstrings unit after anterior cruciate ligament reconstruction: a prospective MRI scan assessment.
abstract: OBJECTIVE
  The aim of this prospective study was to assess the natural history of the donor hamstrings, compared to the contralateral knee and thigh.
  
  
  METHODS
  In 47 patients who had ACL reconstruction (hamstrings technique), bilateral knees and thighs were investigated using MRI scans, up to 2 years post-operatively.
  
  
  RESULTS
  Tendon regeneration below the knee joint line of the semitendinosus occurred in 30/47 (64 %) patients and of the gracilis tendon in 17/47 (36 %) patients. Insertion of both tendons at the "pes anserinus", with normal anatomic relations, was observed in 5/47 (11 %) patients. Semitendinosus and gracilis donor muscles were found retracted in 41/47 (87 %) patients. In 25/47 (53 %) patients, there was evidence of fatty infiltration of the semitendinosus muscle. All (47/47) (100 %) patients showed semitendinosus muscle atrophy and 41/47 (87 %) patients showed gracilis muscle atrophy, compared to the contralateral limb. High signal intensity on STIR images was observed in the semitendinosus in 22/47 (46 %) patients and in the gracilis muscle in 30/47 (64 %) patients, on MRI examination performed up to 24 months post-operatively.
  
  
  CONCLUSIONS
  The "regenerated" hamstrings tendons most commonly do not regenerate fully anatomically, so they should not be considered as a first choice for re-harvesting in revision ACL reconstruction. The "donor hamstrings muscles" are found to be shorter, contracted, thinner and with a long-term abnormal MRI signal, features which are considered to be related to reduced muscle performance (knee flexion and internal rotation) post-operatively.
  
  
  METHODS
  II.
authors.affiliation: 424 Military General Hospital, Thessaloniki, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Tsifountoudis
authors.affiliation: 424 Military General Hospital, Thessaloniki, Greece. ibisbinas@hotmail.com.
authors.forename: Ilias
authors.initials: I
authors.lastname: Bisbinas
authors.affiliation: Asclepios Diagnostic Centre, Thessaloniki, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kalaitzoglou
authors.affiliation: 424 Military General Hospital, Thessaloniki, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Markopoulos
authors.affiliation: AHEPA University Hospital, Thessaloniki, Greece.
authors.forename: Aphrodite
authors.initials: A
authors.lastname: Haritandi
authors.affiliation: Asclepios Diagnostic Centre, Thessaloniki, Greece.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Dimitriadis
authors.affiliation: District General Hospital, Agios Pavlos, Thessaloniki, Greece.
authors.forename: Stergios
authors.initials: S
authors.lastname: Papastergiou
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007717:Knee / Q000601:surgery; D007719:Knee Joint / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009133:Muscular Atrophy / Q000000981:diagnostic imaging / Q000209:etiology*; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology*; D011446:Prospective Studies; D012038:Regeneration; D013710:Tendons / Q000000981:diagnostic imaging / Q000502:physiology* / Q000637:transplantation; D013848:Thigh / Q000601:surgery; D055815:Young Adult
keywords: Anterior cruciate ligament reconstruction; Hamstrings unit; Natural history