Feiss Line Test

What is the "Feiss Line Test" used for?

• The Feiss line test is used to assess the height of the medial arch, using the navicular position

How to perform the "Feiss Line Test"?

• With the patient non–weight-bearing, the clinician marks the apex of the medial malleolus and the plantar aspect of the first MTP joint, and a line is drawn between the two points the so called (Feiss Line). 
• The navicular is palpated on the medial aspect of the foot, and an assessment is made of the position of the navicular relative to the imaginary Feiss line. 
• The patient is then asked to stand with their feet approximately 3–6 inches apart.

What is the positive result?

In weight-bearing, the navicular normally lies on or very close to the Feiss line.

The degree of flatfoot deformity is defined as following:

• If the navicular falls one-third of the distance to the floor, it represents a first-degree flatfoot;
• if it falls two thirds of the distance, it represents a second-degree flatfoot;
• if it rests on the floor, it represents a third-degree flatfoot.

References

• No diagnostic accuracy studies have been performed to determine the sensitivity and specificity of Feiss line test.