title: Does successful rotator cuff repair improve muscle atrophy and fatty infiltration of the rotator cuff? A retrospective magnetic resonance imaging study performed shortly after surgery as a reference.
abstract: BACKGROUND
  Muscle atrophy and fatty infiltration in the rotator cuff muscles are often observed in patients with chronic rotator cuff tears. The recovery from these conditions has not been clarified.
  
  
  METHODS
  Ninety-four patients were included in this study. The improvement in muscle atrophy and fatty infiltration in successfully repaired rotator cuff tears was evaluated by magnetic resonance imaging at 1 year and 2 years after surgery and was compared with muscle atrophy and fatty infiltration observed on magnetic resonance imaging at 2 weeks after surgery to discount any changes due to the medial retraction of the torn tendon. The patients' muscle strength was evaluated in abduction and external rotation.
  
  
  RESULTS
  Muscle atrophy and fatty infiltration of the supraspinatus were significantly improved at 2 years after surgery in comparison to 2 weeks after surgery. The subjects' abduction and external rotation strength was also significantly improved at 2 years after surgery in comparison to the preoperative values. Patients whose occupation ratio was improved had a better abduction range of motion, stronger abduction strength, and higher Constant score. Patients whose fatty infiltration was improved had a better range of motion in flexion and abduction, whereas the improvements of muscle strength and the Constant score were similar in the group that showed an improvement of fatty infiltration and the group that did not.
  
  
  CONCLUSIONS
  Muscle atrophy and fatty infiltration can improve after rotator cuff repair. The strengths of abduction and external rotation were also improved at 2 years after surgery.
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan. Electronic address: m15702021@gunma-u.ac.jp.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Hamano
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamamoto
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shitara
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ichinose
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shimoyama
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sasaki
authors.affiliation: Department of Physical Therapy, Takasaki University of Health and Welfare, Takasaki, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Department of Orthopaedic Surgery, Maebashi Red Cross Hospital, Maebashi, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Kakuta
authors.affiliation: Department of Orthopaedic Surgery, National Hospital Organization Takasaki General Medical Center, Takasaki, Japan.
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Osawa
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Takagishi
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D000368:Aged; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D009133:Muscular Atrophy / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011184:Postoperative Period; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D017006:Rotator Cuff / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D000070636:Rotator Cuff Injuries / Q000503:physiopathology / Q000601:surgery*; D012785:Shoulder Joint / Q000503:physiopathology; D013997:Time Factors
keywords: Rotator cuff tear; arthroscopic rotator cuff repair; fatty infiltration; magnetic resonance imaging; muscle atrophy; muscle strength