title: Hamstring muscle function after tendon harvest for anterior cruciate ligament reconstruction: evaluation with T2 relaxation time of magnetic resonance imaging.
abstract: BACKGROUND
  Regeneration of the semitendinosus and gracilis tendons after harvesting for anterior cruciate ligament reconstruction has been reported; however, muscle belly function after tendon regeneration has not been well documented.
  
  
  OBJECTIVE
  The semitendinosus and gracilis muscles are highly activated during knee flexion if their tendons are well regenerated after anterior cruciate ligament reconstruction.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Hamstring muscle activation in 11 patients who had undergone anterior cruciate ligament reconstruction with semitendinosus and gracilis tendons was evaluated by measuring the increase of T2 relaxation time measured via magnetic resonance imaging after knee flexion exercise. Tendon regeneration was evaluated via magnetic resonance imaging.
  
  
  RESULTS
  Both muscles increased T2 relaxation time after knee flexion exercise in the operated legs, and there was no significant difference in those values between the operated and nonoperated legs. All the semitendinosus tendons were regenerated at or below the joint line, but no gracilis tendons were observed beyond the joint line. The results indicated that both muscles were highly recruited during knee flexion, regardless of the degree of their tendon regeneration.
  
  
  CONCLUSIONS
  The semitendinosus and gracilis muscles are able to restore or maintain their contractile capability after harvest of their tendons for anterior cruciate ligament reconstruction, regardless of the degree of regeneration.
authors.affiliation: Department of Orthopaedic Surgery, Tokushima Red Cross Hospital, Chuden-cho, Komatsushima City, Japan. ytakeda@tokushima-med.jrc.or.jp
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Takeda
authors.forename: Shinji
authors.initials: S
authors.lastname: Kashiwaguchi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Matsuura
authors.forename: Takeshi
authors.initials: T
authors.lastname: Higashida
authors.forename: Akira
authors.initials: A
authors.lastname: Minato
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001178:Arthroplasty / Q000379:methods; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000503:physiopathology / Q000601:surgery* / Q000628:therapy; D007719:Knee Joint / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery*; D016059:Range of Motion, Articular; D012038:Regeneration / Q000502:physiology*; D013709:Tendon Transfer; D013710:Tendons / Q000502:physiology*; D016896:Treatment Outcome