title: Acceleration of the calcaneus at heel strike in neutrally aligned and pes planus feet.
abstract: OBJECTIVE
  The purpose of this research was twofold: (1) to study the impulsive acceleration of the calcaneus at heel strike in subjects with neutrally aligned (i.e., normal) feet and (2) to explore how the acceleration may differ in subjects with pes planus (i.e., flat) feet. The component of the acceleration vector aligned with the long axis of the tibia was quantified.
  
  
  METHODS
  Subjects with either foot type were instrumented and calcaneal acceleration was quantified during comfortable cadence locomotion.
  
  
  BACKGROUND
  Aberrant peak acceleration has been associated with osteoarthritis. While tibial acceleration has been quantified, calcaneal acceleration has not. Additionally, foot morphology, or foot type, has demonstrated an effect on foot function and thus there may be differences in calcaneal acceleration between foot types.
  
  
  METHODS
  Six subjects with neutrally aligned feet and six with pes planus feet were selected via a clinical exam. Accelerometers were attached to the posterior aspect of the medial surface of the calcanei bilaterally and 10 walking trials were collected.Results. The average baseline-to-peak acceleration for the neutrally aligned and pes planus feet was 4.79 g (SD, 2.14 g) and 5.24 g (SD, 3.28 g), respectively; the peak-to-peak acceleration was 5.03 g (SD, 2.74 g) and 6.75 g (SD, 3.89 g). There were no significant differences (P>0.05) between foot types.
  
  
  CONCLUSIONS
  The calcaneal acceleration at heel strike for neutrally aligned and pes planus feet was not sensitive to foot type.
  
  
  CONCLUSIONS
  Aberrant acceleration has been associated with the development of osteoarthritis [J. Biomech. 5 (3) (1972) 267; J. Biomech. 6 (1) (1973) 51; J. Biomech. 15 (7) (1982) 487]. Osteoarthritis at the subtalar joint, as well as the ankle and midtarsal joints, may be initiated and/or perpetuated by excessive calcaneal acceleration at heel strike.
authors.affiliation: Rehabilitation Research and Development Center, VA Puget Sound Health Care System, MS 151, 1660 South Columbian Way, Seattle, WA 98108, USA. wrledoux@u.washington.edu
authors.forename: W R
authors.initials: WR
authors.lastname: Ledoux
authors.forename: H J
authors.initials: HJ
authors.lastname: Hillstrom
mesh_terms: D000054:Acceleration; D000328:Adult; D001696:Biomechanical Phenomena; D002111:Calcaneus / Q000502:physiology*; D005413:Flatfoot / Q000503:physiopathology*; D005684:Gait; D006801:Humans; D008297:Male; D012815:Signal Processing, Computer-Assisted