kneeheight

Knee height is an anthropometric measurement that represents the distance from the floor to the anterior surface of the knee when the leg is extended with the knee flexed at about 90 degrees. It is commonly used to estimate a person’s stature when standing height cannot be measured, such as in bedridden or immobile individuals. The measurement is typically taken with a specialized knee-height caliper or a standard sliding caliper. The subject is positioned supine (lying on the back) or seated with the knee flexed 90 degrees; the caliper is placed on the anterior aspect of the knee, and the measurement is read to the nearest 0.1 cm. Two measurements are usually taken and averaged.

Knee height is then used with population-specific regression equations to estimate stature. These equations often account for sex and age, and have been developed in various populations by researchers such as Chumlea and colleagues. Alternatively, knee height data may be entered into predictive models for nutritional assessment and clinical scoring.

Limitations include disease or deformities of the knee or ankle, edema, amputation, contractures, or recent knee surgery, all of which can affect accuracy. Inter-rater reliability improves with standard protocols and training. In some contexts, seated knee height measurements are used when supine measurements are impractical.

The concept is part of anthropometry, the science of measuring the human body, and remains a practical tool in clinical and field settings for estimating height in populations where direct measurement is not feasible.