title: Early MRI and intraoperative findings in rapidly destructive osteoarthritis of the hip: A case report.
abstract: BACKGROUND
  The pathophysiology of rapidly destructive hip osteoarthritis (OA) of the hip is still unclear. Also, there have been only few reports on the initial stage of the disease. We report a case of an initial-stage rapidly destructive hip OA, documented by magnetic resonance imaging and intraoperative findings.
  
  
  METHODS
  A 77-year-old woman reported left hip pain without any antecedent trauma. Initial radiographs showed no obvious abnormality. After 4 months of conservative therapy, radiographs showed progressive joint-space narrowing and T1-weighted magnetic resonance images revealed a bone-marrow edema pattern not only on the femoral head but also on the lateral side of the acetabulum. Then during total hip arthroplasty, we found extensive inversion of the anterosuperior portion of the acetabular labrum, and the location was mostly consistent with the bone-marrow edema lesions in the femoral head and acetabulum.
  
  
  CONCLUSIONS
  Several theories for the etiology of rapidly destructive hip OA have been proposed, including idiopathic chondrolysis, abnormal immunoreaction, intra-articular deposition of hydroxyapatite crystals, and subchondral insufficiency fracture. One of the reasons rapidly destructive hip OA is still considered idiopathic is the lack of reports regarding the initial stage of the disease. Our report is the first to demonstrate magnetic resonance imaging for initial-stage disease with intraoperative findings before collapse of the femoral head.
  
  
  CONCLUSIONS
  Inversion of the acetabular labrum may be a mechanism of rapidly destructive hip OA.
authors.affiliation: Department of Orthopaedic Surgery, Kanazawa Medical University, Kahoku-gun, Japan. Electronic address: 66406kf@kanazawa-med.ac.jp.
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Fukui
authors.affiliation: Department of Orthopaedic Surgery, Kanazawa Medical University, Kahoku-gun, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Kaneuji
authors.affiliation: Department of Pathology and Medical Laboratory, Kanazawa Medical University, Kahoku-gun, Japan.
authors.forename: Mana
authors.initials: M
authors.lastname: Fukushima
authors.affiliation: Department of Orthopaedic Surgery, Kanazawa Medical University, Kahoku-gun, Japan.
authors.forename: Tadami
authors.initials: T
authors.lastname: Matsumoto
keywords: Bone marrow edema; Early findings; Inverted acetabular labrum; Rapidly destructive hip osteoarthritis