title: Can positional MRI predict dynamic changes in the medial plantar arch? An exploratory pilot study.
abstract: BACKGROUND
  Positional MRI (pMRI) allows for three-dimensional visual assessment of navicular position. In this exploratory pilot study pMRI was validated against a stretch sensor device, which measures movement of the medial plantar arch. We hypothesized that a combined pMRI measure incorporating both vertical and medial displacement of the navicular bone induced by loading would be correlated with corresponding stretch sensor measurements.
  
  
  METHODS
  10 voluntary participants were included in the study. Both pMRI and subsequent stretch sensor measurements were performed in a) supine, b) standing and c) standing position with addition of 10 % body weight during static loading of the foot. Stretch sensor measurements were also performed during barefoot walking.
  
  
  RESULTS
  The total change in navicular position measured by pMRI was 10.3 mm (CI: 7.0 to 13.5 mm). No further displacement occurred when adding 10 % bodyweight (mean difference: 0.7 mm (CI: -0.7 to 2.0 mm), P = 0.29). The total navicular displacement correlated with stretch sensor measurement under static loading conditions (Spearman's rho = 0.66, P = 0.04) but not with measurements during walking (Spearman's rho = 0.58, P = 0.08).
  
  
  CONCLUSIONS
  Total navicular bone displacements determined by pMRI showed concurrent validity with stretch sensor measurements but only so under static loading conditions. Although assessment of total navicular displacement by combining concomitant vertical and medial navicular bone movements would appear advantageous compared to monoplanar measurement the combined measure did not seem to predict dynamic changes of the medial foot arch during walking, which are among several possible factors depending on different walking patterns.
authors: Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Building 8, 1., Bispebjerg Bakke 23, Copenhagen, DK-2400, Denmark.
authors: Finn
authors: F
authors: Johannsen
authors: Department of Radiology, Copenhagen University Hospital Bispebjerg & Frederiksberg, Nordre Fasanvej 57, vej 4, opg. 5, Frederiksberg, DK-2000 Denmark.
authors: Philip
authors: 0000-0002-6972-7852
authors: P
authors: Hansen
authors: Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Building 8, 1., Bispebjerg Bakke 23, Copenhagen, DK-2400, Denmark.
authors: Sandra
authors: S
authors: Stallknecht
authors: Research Unit for General Practice in Aalborg and Department of Clinical Medicine, Aalborg University, Aalborg, Denmark ; Department of Occupational Therapy and Physiotherapy, Aalborg University Hospital, Aalborg, Denmark.
authors: Michael Skovdal
authors: MS
authors: Rathleff
authors: Department of Radiology, Copenhagen University Hospital Bispebjerg & Frederiksberg, Nordre Fasanvej 57, vej 4, opg. 5, Frederiksberg, DK-2000 Denmark.
authors: Stine
authors: S
authors: Hangaard
authors: Department of Radiology, Copenhagen University Hospital Bispebjerg & Frederiksberg, Nordre Fasanvej 57, vej 4, opg. 5, Frederiksberg, DK-2000 Denmark.
authors: Janus Damm
authors: JD
authors: Nybing
authors: Department of Radiology, Copenhagen University Hospital Bispebjerg & Frederiksberg, Nordre Fasanvej 57, vej 4, opg. 5, Frederiksberg, DK-2000 Denmark ; The Parker Institute, Department of Rheumatology, Copenhagen University Hospital Bispebjerg & Frederiksberg, Copenhagen, Denmark.
authors: Mikael
authors: M
authors: Boesen
mesh_terms: D000328:Adult; D000886:Anthropometry / Q000379:methods; D003430:Cross-Sectional Studies; D005260:Female; D005528:Foot / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010865:Pilot Projects; D011187:Posture / Q000502:physiology; D015203:Reproducibility of Results; D016037:Single-Blind Method; D016683:Supine Position / Q000502:physiology; D013639:Tarsal Bones / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult
keywords: Medial plantar arch; Navicular bone; Positional MRI; Validity