title: Type 3 finger length pattern is associated with total knee replacements due to osteoarthritis but not with hip replacements or hand osteoarthritis in the elderly: the AGES-Reykjavik study.
abstract: BACKGROUND
  Recent case-control studies have shown an association between type 3 finger length pattern (longer ring finger than index finger) and knee osteoarthritis. This large cross-sectional study tests the hypothesis that the type 3 pattern is associated with total joint replacements due to osteoarthritis in a large population based study.
  
  
  METHODS
  Finger length ratios were assessed visually on 5170 hand photographs (2975 females, 2195 males, mean age 76). In this population-based multidisciplinary study of aging in Reykjavik, Iceland, the prevalence of osteoarthritis associated total knee replacements was 223(4.3%) and total hip replacements 316(6.1%). We then performed a binary logistic regression analysis for total knee replacements and total hip replacements, including finger length patterns, osteoarthritis at other sites and other variables with possible association to osteoarthritis such as age, BMI and bone mineral density of the spine.
  
  
  RESULTS
  The prevalence of the type 3 pattern was 50% (43% in females, 58% in males). The regression analysis revealed an odds ratio for total knee replacements of 1.65 (1.24-2.2) p = 0.0007, in the type 3 finger pattern group, similar in both genders. This association was independent of the associations we have previously reported between total knee replacements and BMI and the presence of hand osteoarthritis. No association was seen between finger length patterns and total hip replacements.
  
  
  CONCLUSIONS
  Finger length patterns read from digital photographs in this large study confirm previous radiographic observations with significant associations between the type 3 pattern and total knee replacements but not total hip replacements in both genders in this elderly group.
authors.affiliation: University of Iceland, Reykjavik, Iceland. krs2@hi.is
authors.forename: Kristin
authors.initials: K
authors.lastname: Sigurjonsdottir
authors.forename: Thorir M
authors.initials: TM
authors.lastname: Bjorgulfsson
authors.forename: Thor
authors.initials: T
authors.lastname: Aspelund
authors.forename: Gudny
authors.initials: G
authors.lastname: Eiriksdottir
authors.forename: Sigurdur
authors.initials: S
authors.lastname: Sigurdsson
authors.forename: Thorvaldur
authors.initials: T
authors.lastname: Ingvarsson
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
authors.forename: Lenore
authors.initials: L
authors.lastname: Launer
authors.forename: Vilmundur
authors.initials: V
authors.lastname: Gudnason
authors.forename: Helgi
authors.initials: H
authors.lastname: Jonsson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000639:trends*; D019645:Arthroplasty, Replacement, Knee / Q000639:trends*; D003430:Cross-Sectional Studies; D005260:Female; D005385:Fingers / Q000473:pathology*; D006225:Hand / Q000473:pathology; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D008297:Male; D010003:Osteoarthritis / Q000453:epidemiology / Q000473:pathology / Q000601:surgery; D015207:Osteoarthritis, Hip / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D020370:Osteoarthritis, Knee / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D011159:Population Surveillance / Q000379:methods; D012307:Risk Factors