title: Effects of different heel angles in sleep mode on heel interface pressure in the elderly.
abstract: BACKGROUND
  The heels are one of the most common sites of pressure ulcers, and the incidence rate in the elderly aged 70 years or older is high. Although there is literature on heel interface pressure, the heel interface pressure of the elderly in different postures has not yet been explored, which will be investigated in this study, as well as the effects of different foot positions. Their skin conditions will also be examined.
  
  
  METHODS
  Twenty-five females and twenty-six males, 70 years old or older, are evaluated while lying down, with only their naked foot in its natural position on a mattress, as well as placed on a standard or pressure-relieving mattress in different positions. The moisture, sebum content, and elasticity of the skin of the heel are tested.
  
  
  RESULTS
  The heel of most of the participants is positioned at a 60°-69° or 90°-99° angle to the support surface. The heel interface pressure is the greatest when the foot is upright. The age, weight, and body mass index have no significant impacts. The moisture and sebum content are extremely low while elasticity is normal.
  
  
  CONCLUSIONS
  The relaxed position of the foot is in neutral external rotation and upright positions. A greater amount of pressure is experienced when the foot is upright. The pressure-relieving mattress is more effective for reducing heel pressure but may not apply to all cases. Finally, the skin of the heel is dry and lacks sebum, which implies greater risk of developing heel sores.
authors.affiliation: Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
authors.forename: Shuk-Fan
authors.initials: SF
authors.lastname: Tong
authors.affiliation: Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong. Electronic address: tcjyip@polyu.edu.hk.
authors.forename: Joanne
authors.initials: J
authors.lastname: Yip
authors.affiliation: Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
authors.forename: Kit-Lun
authors.initials: KL
authors.lastname: Yick
authors.affiliation: Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
authors.forename: Marcus Chun-Wah
authors.initials: MC
authors.lastname: Yuen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001513:Beds / Q000009:adverse effects; D004548:Elasticity; D005260:Female; D006365:Heel / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008488:Medical Illustration; D011312:Pressure / Q000009:adverse effects*; D003668:Pressure Ulcer / Q000209:etiology* / Q000503:physiopathology; D012629:Sebum / Q000378:metabolism; D012867:Skin / Q000737:chemistry / Q000503:physiopathology; D012890:Sleep; D016683:Supine Position / Q000502:physiology*
keywords: Elderly; Foot posture; Heel ulcers; Interface pressure; Neutral external rotation; Skin condition; Upright position