# Knee Height Measurement

The measure of knee height may be useful in addition to sitting height and standing height. It is a measurement of the distance from the base of the foot to the top of the knee. Knee height is correlated with stature, and is sometimes used to estimate height in bedridden patients. The proportion of knee height compared to leg length or sitting height may be interesting in a sporting context. Specific body proportions are important attributes for many sports.

purpose: to measure the length of the lower leg to compare to other limb lengths

equipment required: knee height caliper (or less accurately a tape measure)

procedure: The subject lies on their back and bends the left knee and ankle to 90 degrees. Place one end of the caliper under the heel of the foot, the other end down against the thigh about 2 inches behind the patella (kneecap). The shaft of the caliper is held parallel to the long axis of the lower leg. Measure twice to the nearest 0.1 cm.

results: estimated body height can be determined using prediction equations. Here is one such equation (subject group unknown), however you should find an equation derived from the same population as the subject:

males: Height in cm = 84.88 - (0.24 x age) + (1.83 x knee height)
females: Height in cm = 64.19 - (0.04 x age) + (2.02 x knee height)

advantages: this is a simple, cheap (if not using the caliper) and quick test to perform, providing useful information about body proportions.

notes: Just the left knee is usually measured, unless there are reasons to think that there are leg length discrepancies

references:

• Chumlea WC, Roche AF, Steinbaugh ML. Estimating stature from knee height for persons 60 to 90 years of age. J Am Geriatr Soc. 1985 Feb;33(2):116-20.
• Hickson M, Frost G. A comparison of three methods for estimating height in the acutely ill elderly population. J Hum Nutr Diet. 2003 Feb;16(1):13-20.
• Han TS, Lean ME. Lower leg length as an index of stature in adults. Int J Obes Relat Metab Disord. 1996 Jan;20(1):21-7.

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