title: Volume Increases of the Gluteus Maximus, Gluteus Medius, and Thigh Muscles After Hip Arthroplasty.
abstract: BACKGROUND
  Muscle atrophy in osteoarthritis (OA) patients is expected to recover after total hip arthroplasty (THA) because of the increase in activity levels. Although some reports have shown an increase in the thigh muscles (Th) after THA, no reports of increases in the gluteal muscles and of analyses of the factors related to muscle recovery have been published. In this study, the changes in the gluteal and Th volumes after THA were quantitatively evaluated using computed tomography (CT) images, and the factors related to muscle recovery were analyzed.
  
  
  METHODS
  The subjects were 40 OA hips with CT images taken 3 weeks after THA (first postoperative [postop] CT) and more than 2 years after THA (second postop CT). The cross-sectional areas of gluteus maximus (G-max), gluteus medius (G-med), and Th were measured in both CT images. The factors related to muscle recovery that were measured and evaluated were age, gender, days from operation, surgical approach, Kellgren-Lawrence grades, and hip functional score (Japanese Orthopaedics Association hip score).
  
  
  RESULTS
  All measured cross-sectional areas of the operated side increased significantly from the first postop CT to the second postop CT (G-max, 40%; G-med, 11%; and Th, 20%). In the analysis of the factors related to muscle recovery, the increase rate of G-max correlated significantly with patient age, and the increase rate of G-med correlated significantly with the increase in Japanese Orthopaedics Association hip score.
  
  
  CONCLUSIONS
  Hip OA can lead to atrophy of the gluteal and Th, but the muscle volume can recover more than 2 years after THA.
authors.affiliation: Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, Suita City, Osaka, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Uemura
authors.affiliation: Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Suita City, Osaka, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Takao
authors.affiliation: Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Suita City, Osaka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Sakai
authors.affiliation: Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, Suita City, Osaka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishii
authors.affiliation: Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, Suita City, Osaka, Japan. Electronic address: n-sugano@umin.net.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Sugano
mesh_terms: D000368:Aged; D019412:Anatomy, Cross-Sectional; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006621:Hip Joint / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000473:pathology*; D009133:Muscular Atrophy / Q000209:etiology; D009929:Organ Size; D015207:Osteoarthritis, Hip / Q000150:complications / Q000601:surgery*; D013848:Thigh; D014057:Tomography, X-Ray Computed
keywords: CT images; cross-sectional area; hip arthroplasty; muscle atrophy; muscle recovery