Measuring height of bedridden patients can be difficult. One way to estimate height, is by measuring the lower leg length (LLL); the length between the length of a person's foot till the knee. With a special formula, this information can be used to estimate the full body length.
How to measure?The lower leg length (LLL) is measured from the top of the patella (kneecap) to the underside of the foot. The person sits with the knee at an angle of 90 degrees. There is a straight edge which is used to measure so as not to bend the calf muscles. The measurement in this way will be more difficult in bedridden patients, but not impossible.
Formula 1: the lower leg length (LLL)
- Men: length = (2.31 * LLL) + 51.1
- Woman: length = (1.84 * LLL) + 70.2
Formula 2: The lower leg length (LLL) and the age in years
- Men: length = (2.30 x LLL) – (0.063 * age) + 54.9
- Woman: length = (1.91 x LLL) – (0.098 * age) + 71.3
This formula is obtained by taking measurements in a healthy research group of 78 men and 82 women in the age of 17-70 years. Formula 1 is easier to use, however formula 2 is more accurate. According to Han (1996) the length would be approached with a maximum deviation of 6.5 cm as equation 1 is used. Using formula 2 is better (which is not specified).
Alternative formulasThe most widely used and most accurate formula to calculate LLL is that of Chumlea (1998):
- White male: L= 78,31 + (1,94 * LLL) -(0,14 * age)
- White woman: L= 82,21 + (1,85 * LLL) - (0,21 * age)
- White male: L= 74,48 + (2,03 * LLL) -(0,15 * age)
- White woman: L= 68,74 + (2,07 * LLL) - (0,16 * age)
Alternative formulas for the elderlySienkiewicz-Sizer (1997) has developed special formulas for the elderly:
- Men: length = (2.02 x LLL) – (0.04 * age) + 64.19
- Woman: length = (1.83 x LLL) – (0.24 * age) + 84.88