title: A single-blind pilot study to determine risk and association between navicular drop, calcaneal eversion, and low back pain.
abstract: OBJECTIVE
  Syndromes causing mechanical low back pain (MLBP) continue to plague the US health care system. One hypothesis is that flatfeet are a risk factor for MLBP. This pilot study evaluated whether subjects with flatter feet are at greater risk for MLBP than subjects without flatter feet.
  
  
  METHODS
  Fifty-eight subjects (16-70 years old) were allocated to a group diagnosed with 2 or more episodes of MLBP or with no history of MLBP. A blind assessor measured navicular drop (ND) using navicular height (NH) and calcaneal eversion (CE). Based on a range of reported data, flatfoot was defined as a possible risk factor for MLBP with ND greater than 3, 8, and/or 10 mm, and/or greater than 6 degrees CE.
  
  
  RESULTS
  According to chi2 analysis, risk of MLBP appeared similar between groups (P > .05). There was no significant difference (P > .05) between continuous variables (t tests, Pearson r and r2) with one exception, correlation of increasing CE with increasing ND (P = .0001). Power was generally low (<0.80). Likelihood ratios and Fisher exact tests supported the chi2 analysis.
  
  
  CONCLUSIONS
  In this study, flatfeet did not appear to be a risk factor in subjects with MLBP. However, small sample size, low power, broader age range, low prevalence of flatfeet (>10 mm ND), and lesser back pain severity make these data tentative. Further research is needed.
authors.affiliation: Cleveland Chiropractic College Los Angeles, Los Angeles, Calif 90004, USA. James.brantingham@cleveland.edu
authors.forename: James W
authors.initials: JW
authors.lastname: Brantingham
authors.forename: Katy Jane
authors.initials: KJ
authors.lastname: Adams
authors.forename: Jeffery R
authors.initials: JR
authors.lastname: Cooley
authors.forename: Denise
authors.initials: D
authors.lastname: Globe
authors.forename: Gary
authors.initials: G
authors.lastname: Globe
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002111:Calcaneus / Q000033:anatomy & histology / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D005413:Flatfoot / Q000503:physiopathology*; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010808:Physical Examination; D010865:Pilot Projects; D012307:Risk Factors; D016037:Single-Blind Method; D013639:Tarsal Bones / Q000033:anatomy & histology / Q000503:physiopathology*