title: Scheuermann kyphosis in nonhuman primates.
abstract: METHODS
  A cadaveric survey of the thoracic spines of extant species of nonbipedal primates for the presence of Scheuermann kyphosis.
  
  
  OBJECTIVE
  To determine the presence and prevalence of Scheuermann kyphosis in quadrupedal species of the closest living relatives to humans to demonstrate that bipedalism is not an absolute requirement for the development of Scheuermann kyphosis.
  
  
  BACKGROUND
  The etiology of Scheuermann kyphosis remains poorly understood. Biomechanical factors associated with upright posture are thought to play a role in the development of the disorder. To date, Scheuermann kyphosis has been described only in humans and extinct species of bipedal hominids.
  
  
  METHODS
  Thoracic vertebrae from 92 specimens of Pan troglodytes (chimpanzee) and 105 specimens of Gorilla gorilla (gorilla) from the Hamann-Todd Osteological Collection at the Cleveland Museum of Natural History were examined for Scheuermann kyphosis on the basis of Sorenson criteria and the presence of anterior vertebral body extensions and for the presence of Schmorl nodes.
  
  
  RESULTS
  Two specimens of P. troglodytes (2.2%) were found to have anatomic features consistent with Scheuermann kyphosis including vertebral body wedging greater than 5° at 3 or more adjacent levels and the presence of anterior vertebral body extensions. One of the affected specimens (50%) demonstrated the presence of Schmorl nodes whereas 2 of the unaffected specimens (2.2%) had Schmorl nodes. None of the specimens of G. gorilla (0%) were found to have anterior vertebral body extensions characteristic of Scheuermann kyphosis or Schmorl nodes.
  
  
  CONCLUSIONS
  Thoracic kyphotic deformity consistent with Scheuermann kyphosis exists in quadrupedal nonhuman primates. Bipedalism is not a strict requirement for the development of Scheuermann kyphosis, and the evolutionary origins of the disease predate the vertebral adaptations of bipedal locomotion.
authors.affiliation: St. Mary's Medical Center, San Francisco, CA 94117, USA. bmfm38a1@yahoo.com
authors.forename: Brian M
authors.initials: BM
authors.lastname: Farrell
authors.forename: Calvin C
authors.initials: CC
authors.lastname: Kuo
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Tang
authors.forename: Steven
authors.initials: S
authors.lastname: Phan
authors.forename: Jenni M
authors.initials: JM
authors.lastname: Buckley
authors.forename: Dimitriy G
authors.initials: DG
authors.lastname: Kondrashov
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D018420:Ape Diseases / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D005075:Biological Evolution; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D006071:Gorilla gorilla; D008124:Locomotion; D008297:Male; D002679:Pan troglodytes; D011187:Posture; D012307:Risk Factors; D012544:Scheuermann Disease / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000662:veterinary*; D013904:Thoracic Vertebrae / Q000473:pathology* / Q000503:physiopathology