Houston Methodist. Leading Medicine

Foot FAQ


I've heard there's a way to measure a flat foot in degrees. How do I do this?


You may be referring to the navicular drop test (NDT). In this test the person stands with the feet about shoulder width apart. The navicular tuberosity is felt and marked. This is a boney projection along the side of the navicular bone. The navicular bone is the bone on top of your foot above your arch.

With the ankle joint in the middle (neutral), the distance from the navicular bone to the floor is measured. The person with a flat foot then relaxes the foot and the same measurement is taken again. The difference between these two measures is called the navicular drop.

Movement of 10 mm or less is considered "normal." More than 10 mm suggests too much rolling in of the ankle and drop of the arch called pronation. Pronation isn't really divided into degrees except perhaps mild, moderate, or severe.

Belinda Lange, BSc, B Physiotherapy (Hons), et al. The Effect of Low-Dye Taping on Plantar Pressures, During Gait, in Subjects with Navicular Drop Exceeding 10 mm. In Journal of Orthopaedic & Sports Physical Therapy. April 2004. Vol. 34. No. 4. Pp. 201-208.

*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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