Navicular Drop Test

The navicular drop test is a method used to assess the degree to which the talus plantar flexes in space on a calcaneus that has been stabilized by the ground, during subtalar joint pronation.

This test was introduced firstly by Brody in 1982 to assess the amount of foot pronation in runners.

See Also: Foot Anatomy

How do you do the Navicular Drop Test?

The clinician palpates the position of the navicular tubercle as the patient’s foot is non–weight-bearing but resting on the floor surface, with the subtalar joint maintained in neutral.

The clinician then attempts to quantify the amount of inferior displacement of the navicular tubercle, as the patient assumes 50% weight-bearing on the tested foot (relaxed standing).

The two measurements are recorded.

What is a positive Navicular Drop Test?

A navicular drop that is greater than 10 mm from the neutral position to the relaxed standing position suggests excessive medial longitudinal arch collapse of abnormal pronation.

Test Accuracy

Navicular Drop Test has been found to have an intratester reliability that ranged from ICC = 0.61 to 0.79 and intertester reliability of ICC = 0.57.

However, it is questionable whether a significant drop is also indicative of dysfunction.

Feiss Line Test

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

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 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 line. The patient is then asked to stand with their feet approximately 3–6 inches apart.

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

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

Note

The navicular drop test, considered to be an estimate of the extent of pronation, assesses the change in navicular position between weight-bearing and non–weightbearing positions. Note that the body weight should be evenly distributed between the two feet.

Navicular height can be measured by making Navicular tuberosity while the patient is in weight-bearing
position. Distance from ground to navicular tuberosity is measured.

A strong relationship exists between excessive forefoot varus (>8°) and an increased navicular drop.

The low interrater reliability associated with the navicular drop test is related to the low reliability of assessing subtalar joint neutral. The height of the navicular in weight bearing (the second measurement of the navicular drop test) is highly correlated with radiographic measurements of navicular height in weight bearing.

References

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