title: An Evaluation of Forearm Deformities in Hereditary Multiple Exostoses: Factors Associated With Radial Head Dislocation and Comprehensive Classification.
abstract: OBJECTIVE
  This study attempted to evaluate a series of patients with hereditary multiple exostoses (HME) who could not be categorized according to the widely accepted Masada classification and to identify radiographic variables such as radial bowing, ulnar shortening, ulnar variance, radial articular angle, and carpal slip predictive of deformity.
  
  
  METHODS
  We retrospectively reviewed data on 102 upper limbs of 53 pediatric patients with HME. Demographics, site of forearm involvement, and radiographic parameters were documented. Patients with exostoses of the forearms were categorized into 6 groups based on location of the exostoses and presence or absence of a dislocated radial head. Proportional ulnar shortening was calculated as the ratio of ulnar length to radial length.
  
  
  RESULTS
  According to the Masada classification, 4 limbs were normal, 10 were type I, 2 were type II, and 24 were type III. Sixty-six limbs were unclassifiable. We classified those 66 limbs using a modification of the Masada classification. Of the 106 limbs, 11 (10.3%) had a dislocated radial head. Based on the radiographic analysis, patients with proportional ulnar shortening of less than 0.9 had a higher risk of radial head dislocation than did those with proportional ulnar shortening of 0.9 or greater. Patients with radial bowing greater than 8.1% showed a higher frequency of radial head dislocation than did those with radial bowing of 8.1% or less. Exostoses of both the distal radius and ulna tended to increase the rate of radial head dislocation. A greater amount of negative ulnar variance caused more radial bowing and a greater radioarticular angle.
  
  
  CONCLUSIONS
  We propose a new comprehensive forearm classification for patients with HME. Proportional ulnar shortening less than 0.9 and radial bowing 8.1% or greater can be used to predict the risk of radial head dislocation.
  
  
  METHODS
  Prognostic IV.
authors.affiliation: Department of Orthopedic Surgery, Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Ah Reum
authors.initials: AR
authors.lastname: Jo
authors.affiliation: Department of Orthopedic Surgery, Chonnam National University Hospital, Gwangju, South Korea. Electronic address: stjung@chonnam.ac.kr.
authors.forename: Sung Taek
authors.initials: ST
authors.lastname: Jung
authors.affiliation: Department of Orthopedic Surgery, Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Myung Sun
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Department of Orthopedic Surgery, Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Chang Seon
authors.initials: CS
authors.lastname: Oh
authors.affiliation: Department of Orthopedic Surgery, Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Byung Ju
authors.initials: BJ
authors.lastname: Min
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005097:Exostoses, Multiple Hereditary / Q000150:complications / Q000000981:diagnostic imaging*; D005260:Female; D005542:Forearm / Q000002:abnormalities* / Q000000981:diagnostic imaging; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging*; D008297:Male; D011884:Radius / Q000002:abnormalities / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014457:Ulna / Q000002:abnormalities / Q000000981:diagnostic imaging; D038062:Upper Extremity Deformities, Congenital / Q000145:classification* / Q000000981:diagnostic imaging*; D014955:Wrist Joint / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: Forearm deformity; classification; hereditary multiple exostosis; radial head dislocation