Evaluation of accuracy and reliability of calipers for measuring recumbent knee height in elderly people.

Height measurements in elderly individuals are frequently not feasible and stature must be estimated from knee height. This study compared the accuracy and reliability of a knee-height caliper developed by Ross Laboratories with Mediform and GPN models. Two observers measured 40 elderly ambulatory volunteers with each caliper. Knee height was measured on the left leg from the heel to a point 5 cm proximal to the patella. Intracaliper reliability was similar. Mean absolute differences between repeated measurements ranged from 0.17 to 0.25 cm, technical errors of the estimate ranged from 0.16 to 0.26 cm, and coefficients of reliability exceeded 0.99 for each model. Equations based on knee height predicted subjects' stature to +/- 2.3 cm, an amount unlikely to substantially impair height-based nutrition indices. This comparatively inexpensive caliper was as accurate and reliable as more expensive commercially available models and may be recommended as an alternative to the other calipers.