title: Cortical Atrophy Related to Tumor Prosthesis in Skeletally Immature Osteosarcoma Patients.
abstract: BACKGROUND
  Cortical atrophy is commonly observed after prosthetic reconstruction for bone sarcomas. However, relevant literature regarding this phenomenon in skeletally immature patients is limited. Therefore, in this study, we evaluated the incidence and patterns of cortical atrophy. We then assessed its predisposing factors. Finally, we analyzed whether cortical atrophy was associated with poor prosthesis survival.
  
  
  METHODS
  We retrospectively reviewed 31 stems in 19 skeletally immature osteosarcoma patients who were treated with resection and tumor prosthesis surgery. We measured the cortical thickness using plain radiographs annually. The mean patient age was 11 years (range, 6 to 14 y) and the mean follow-up period was 10 years (range, 2 to 14 y).
  
  
  RESULTS
  Cortical atrophy developed in 13 stems, all within 3 years. There were 3 gross types of cortical atrophy: hourglass in 5, sharpening in 4, and shortening atrophy in 4. On multivariate analysis, stem-cortex diameter ratio of ≥0.5 and age of less than 10 years were significantly associated with cortical atrophy (P=0.002 and P=0.019, respectively). Cortical atrophy was significantly associated with eventual prosthesis failure (9/13 in the cortical atrophy group vs. 4/18 in the nonatrophy group, P=0.035).
  
  
  CONCLUSIONS
  Cortical atrophy is common in the skeletally immature patients with tumor prosthesis and is associated with prosthesis failure. Patients with cortical atrophy should be closely monitored for prosthesis failure and appropriately managed to prevent failures.
  
  
  METHODS
  Level IV-therapeutic study.
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Hospital, Jongno-gu, Seoul.
authors.forename: Wanlim
authors.initials: W
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Hospital, Jongno-gu, Seoul.
authors.forename: Ilkyu
authors.initials: I
authors.lastname: Han
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Bundang-gu, Seongna-si, Gyeonggi-do, Korea.
authors.forename: Hwan-Seong
authors.initials: HS
authors.lastname: Cho
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Hospital, Jongno-gu, Seoul.
authors.forename: Seungcheol
authors.initials: S
authors.lastname: Kang
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Hospital, Jongno-gu, Seoul.
authors.forename: Han-Soo
authors.initials: HS
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D001284:Atrophy / Q000209:etiology; D001696:Biomechanical Phenomena; D001859:Bone Neoplasms / Q000601:surgery*; D001842:Bone and Bones / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005266:Femoral Neoplasms; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D012516:Osteosarcoma / Q000601:surgery*; D011183:Postoperative Complications / Q000473:pathology*; D011474:Prosthesis Design; D011475:Prosthesis Failure / Q000009:adverse effects*; D019919:Prosthesis Implantation / Q000009:adverse effects / Q000379:methods*; D011859:Radiography; D012189:Retrospective Studies; D013977:Tibia / Q000000981:diagnostic imaging / Q000473:pathology; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult