title: Association of flat feet with knee pain and cartilage damage in older adults.
abstract: OBJECTIVE
  To assess the cross-sectional relation of planus foot morphology to ipsilateral knee pain and compartment-specific knee cartilage damage in older adults.
  
  
  METHODS
  In the Framingham Studies, we adapted the Staheli Arch Index (SAI) to quantify standing foot morphology from pedobarographic recordings. We inquired about knee pain and read 1.5 T magnetic resonance image (MRI) scans using the Whole-Organ MRI Score. Logistic regression compared the odds of knee pain among the most planus feet to the odds among all other feet, and estimated odds within categories of increasing SAI. Similar methods estimated the odds of cartilage damage in each knee compartment. Generalized estimating equations adjusted for age, sex, body mass index, and nonindependent observations.
  
  
  RESULTS
  Among 1,903 participants (56% women, mean ± SD age 65 ± 9 years), 22% of knees were painful most days. Cartilage damage was identified in 45% of medial tibiofemoral (TF), 27% of lateral TF, 58% of medial patellofemoral (PF), and 42% of lateral PF compartments. Compared with other feet, the most planus feet had 1.3 times (95% confidence interval [95% CI] 1.1-1.6) the odds of knee pain (P = 0.009), and 1.4 times (95% CI 1.1-1.8) the odds of medial TF cartilage damage (P = 0.002). Odds of pain (P for linear trend = 0.05) and medial TF cartilage damage (P for linear trend = 0.001) increased linearly across categories of increasing SAI. There was no association between foot morphology and cartilage damage in other knee compartments.
  
  
  CONCLUSIONS
  Planus foot morphology is associated with frequent knee pain and medial TF cartilage damage in older adults.
authors: Massachusetts General Hospital Institute of Health Professions and Boston University School of Medicine, Boston, Massachusetts 02118, USA. grossd@bu.edu
authors: K Douglas
authors: KD
authors: Gross
authors: David T
authors: DT
authors: Felson
authors: Jingbo
authors: J
authors: Niu
authors: David J
authors: DJ
authors: Hunter
authors: Ali
authors: A
authors: Guermazi
authors: Frank W
authors: FW
authors: Roemer
authors: Alyssa B
authors: AB
authors: Dufour
authors: Rebekah H
authors: RH
authors: Gensure
authors: Marian T
authors: MT
authors: Hannan
mesh_terms: D000368:Aged; D002357:Cartilage Diseases / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D002358:Cartilage, Articular / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D005413:Flatfoot / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007717:Knee / Q000473:pathology / Q000503:physiopathology; D007719:Knee Joint / Q000473:pathology* / Q000503:physiopathology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000150:complications* / Q000473:pathology / Q000503:physiopathology