What it means
A medial arch lower than normal, measured as navicular height against foot length. Whether that arch is flexible or rigid does not follow from this measurement and needs its own test.
Where it comes from
The medial longitudinal arch lowering under load, with the talus rotating medially and the heel everting.
How it is measured
It is measured on the front view, in the sagittal plane. The defining measurement is archIndexR, and it is reported as a finding from below 0.22°. The number is computed from landmarks on that photograph — not estimated by eye, and not compared against a stock example.
What the numbers mean
| Measurement | Grade |
|---|---|
| up to undefined° | Within normal range |
| undefined–undefined° | Borderline arch |
| undefined–undefined° | Flat foot |
| undefined–undefined° | Severely flat foot |
Source of the bands: NNHt adult bands: <0.17 highly pronated, 0.17-0.21 pronated, 0.22-0.31 normal
What is usually seen alongside it
- How flat the inner arch is (Medial arch angle) — below undefined°
- How flat the inner arch is (Medial arch angle) — below undefined°
- Heel rolls inward (Rearfoot angle) — below undefined°
- Heel rolls inward (Rearfoot angle) — below undefined°
None of these is a diagnosis on its own. Together they corroborate the finding; apart, they do not refute it — a measurement nobody took counts neither for nor against.
What confirms it
This number gives the height of the arch, not its flexibility. The single heel raise separates a flexible flat foot from a rigid one, and the two are not treated alike.
Every number on this page is measured on the skin surface in a photograph. That is not the same as a measurement taken on a radiograph: it correlates with one and does not replace it. Wherever the decision depends on imaging, this page and the report itself say so.
What happens at the clinic
The assessment starts with three standing photographs — front, side and back. Every angle is measured on those photographs, the report prints the number and the grade for each, and the exercise programme is built from those numbers rather than from a template. Posture analysis explains the whole path, and the online assessment can be started from your own photograph now.
Frequently asked questions
At what point is pes planus (by arch height) reported?
When archindexr is below 0.22°, it is reported as a finding. That is where the "Borderline arch" band begins. The bands come from: NNHt adult bands: <0.17 highly pronated, 0.17-0.21 pronated, 0.22-0.31 normal
Can pes planus (by arch height) be assessed from a photograph?
A photograph gives a number, which most assessments do not have. But it is a surface measurement and it does not replace imaging. This number gives the height of the arch, not its flexibility. The single heel raise separates a flexible flat foot from a rigid one, and the two are not treated alike.
What is the most severe grade?
The worst band in this table is "Severely flat foot". The grade is printed beside the measurement itself in the report, so it is always clear which number produced the word.