title: Natural progression of osteochondritis dissecans of the humeral capitellum: initial observations.
abstract: OBJECTIVE
  To determine the earliest findings, subsequent changes, and natural course of osteochondritis dissecans of the humeral capitellum.
  
  
  METHODS
  Among 95 patients with osteochondritis dissecans of the humeral capitellum, 16 (mean age, 12.5 years) were selected for this retrospective study because they seemed to have early osteochondritis dissecans and had been followed up without any surgical treatment for 6 months or more (mean, 3.5 years).
  
  
  RESULTS
  The initial imaging appearances of the 16 patients' lesions were divided into two types: localized subchondral bone flattening without fragments in seven, and nondisplaced fragments in nine. Patients with lesion flattening had younger ages and significantly shorter durations of symptoms, and most had open growth plates. In five of the seven with flattening, new bone formed over the flattened bone, and the fragments united after arm motion reduction. In contrast, patients with nondisplaced fragments at clinical presentation had longer durations of symptoms with continued arm motion, and their nondisplaced fragments failed to unite.
  
  
  CONCLUSIONS
  The earliest feature of osteochondritis dissecans is subchondral bone flattening, over which new bone subsequently forms. The new bone then can unite with the underlying bone. However, if subjected to repetitive forces over a given time, unstable fragments develop. These fragments, even if not yet displaced, are unable to unite.
authors.affiliation: Department of Orthopedic Surgery, Yamagata University School of Medicine, Iida-Nishi 2-2-2, Yamagata, Japan. mtakahar@med.id.yamagata-u.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Takahara
authors.forename: T
authors.initials: T
authors.lastname: Ogino
authors.forename: M
authors.initials: M
authors.lastname: Takagi
authors.forename: H
authors.initials: H
authors.lastname: Tsuchida
authors.forename: H
authors.initials: H
authors.lastname: Orui
authors.forename: T
authors.initials: T
authors.lastname: Nambu
mesh_terms: D000293:Adolescent; D002648:Child; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging*; D008297:Male; D010008:Osteochondritis Dissecans / Q000000981:diagnostic imaging*; D011859:Radiography; D012189:Retrospective Studies; D014463:Ultrasonography