title: Classification of the height and flexibility of the medial longitudinal arch of the foot.
abstract: BACKGROUND
  The risk of developing injuries during standing work may vary between persons with different foot types. High arched and low arched feet, as well as rigid and flexible feet, are considered to have different injury profiles, while those with normal arches may sustain fewer injuries. However, the cut-off values for maximum values (subtalar position during weight-bearing) and range of motion (ROM) values (difference between subtalar neutral and subtalar resting position in a weight-bearing condition) for the medial longitudinal arch (MLA) are largely unknown. The purpose of this study was to identify cut-off values for maximum values and ROM of the MLA of the foot during static tests and to identify factors influencing foot posture.
  
  
  METHODS
  The participants consisted of 254 volunteers from Central and Northern Denmark (198 m/56 f; age 39.0 ± 11.7 years; BMI 27.3 ± 4.7 kg/m2). Navicular height (NH), longitudinal arch angle (LAA) and Feiss line (FL) were measured for either the left or the right foot in a subtalar neutral position and subtalar resting position. Maximum values and ROM were calculated for each test. The 95% and 68% prediction intervals were used as cut-off limits. Multiple regression analysis was used to detect influencing factors on foot posture.
  
  
  RESULTS
  The 68% cut-off values for maximum MLA values and MLA ROM for NH were 3.6 to 5.5 cm and 0.6 to 1.8 cm, respectively, without taking into account the influence of other variables. Normal maximum LAA values were between 131 and 152° and normal LAA ROM was between -1 and 13°. Normal maximum FL values were between -2.6 and -1.2 cm and normal FL ROM was between -0.1 and 0.9 cm. Results from the multivariate linear regression revealed an association between foot size with FL, LAA, and navicular drop.
  
  
  CONCLUSIONS
  The cut-off values presented in this study can be used to categorize people performing standing work into groups of different foot arch types. The results of this study are important for investigating a possible link between arch height and arch movement and the development of injuries.
authors.affiliation: Clinic of Physical Therapy and Training, Ikast, Denmark.
authors.forename: Mette Kjærgaard
authors.initials: MK
authors.lastname: Nilsson
authors.affiliation: Department of Orthopaedics, Thy- Mors Center of Head, Orthopaedics and Heart, Aalborg Hospital, Aalborg, Denmark.
authors.forename: Rikke
authors.initials: R
authors.lastname: Friis
authors.affiliation: Clinic of Physical Therapy and Training, Ulfborg, Denmark.
authors.forename: Maria Skjoldahl
authors.initials: MS
authors.lastname: Michaelsen
authors.affiliation: VIA University College, Holstebro, Denmark.
authors.forename: Patrick Abildgaard
authors.initials: PA
authors.lastname: Jakobsen
authors.affiliation: Orthopaedic Surgery Research Unit, The Head, Ortho and Heart Centre, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Rasmus Oestergaard
authors.initials: RO
authors.lastname: Nielsen