title: Evaluation of the prevalence, lesion, and depth of osteoarthritic changes in the patella.
abstract: OBJECTIVE
  The aim of this study was to determine the prevalence, type of lesion, and depth of osteoarthritic (OA) changes in the patella.
  
  
  METHODS
  One hundred and forty-six cadaveric knees were included in this study with an median age of 83 years (54-97). Patella OA lesion was classified using Han's method: Type 1, no or minimal lesion; Type 2, medial facet lesion without involvement of the ridge; Type 3, lateral facet lesion without involvement of the ridge; Type 4, lesion involvement of the ridge; Type 5, medial facet lesion with involvement of the ridge, Type 6, lateral facet lesion with involvement of the ridge; and Type 7, Global lesion. The depth of OA evaluation was performed following Outerbridge's classification.
  
  
  RESULTS
  OA lesions were observed as follows: (Type 1) 31%, (Type 2) 16%, (Type 3) 3%, (Type 4) 12%, (Type 5) 22%, (Type 6) 2%, and (Type 7) 14%. Outerbridge's classification of over Grade 2 OA depth was observed in 63.7% of subjects. A significant difference of patella OA type in gender was observed. Severe patella OA occurred in female subjects. Greater depth of OA was observed in Types 5 and 7. Most OA occurred in the medial facet of the patella including the ridge. Isolated OA in the lateral facet of the patella was observed in only 2% of all knees.
  
  
  CONCLUSIONS
  There is a risk of patella OA in female subjects. Patella OA occurred mainly on the medial side. Isolated OA in the lateral facet of the patella was rare. 63.7% of subjects had patella OA.
  
  
  METHODS
  Controlled laboratory study, Level III.
authors.affiliation: Division of Rehabilitation Medicine, Gunma University Hospital, Maebashi City, Showa-Machi 3-39-15, Gunma, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Iriuchishima
authors.forename: Keinosuke
authors.initials: K
authors.lastname: Ryu
authors.forename: Shin
authors.initials: S
authors.lastname: Aizawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yorifuji
authors.forename: Kenji
authors.initials: K
authors.lastname: Shirakura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000453:epidemiology / Q000473:pathology*; D010329:Patella / Q000473:pathology*; D015995:Prevalence