52 Year Old Dancer
Findings:
(1) Plantarflexed 1st Metatarsal, Left > Right
(2) PMs Values:  12mm Left,  08mm Right
(3) Positive Knee Bend Test
Dx:  Primus Metatarsus Supinatus foot type, Left > Right

Knee Bend Test (top figure left)
Frame 1 - knees extended
Frame 2 - knees extended, superimposed grid
Frame 3 - knee flexed, superimposed grid
Frame 4 - arrows demonstrating asymmetry in pronation pattern (left > right)

Positive KBT- feet are more pronated with knees flexed (weight over the forefoot) than with knees extended (weight over the heels). 

A positive KBT and PMs values greater than 10mm are pathognomonic for the Primus Metatarsus Supinatus foot type. Note: A
plantarflexed 1st metatarsal masks the true PMs value (see bottom figure left, arrows point to the plantarflexed 1st metatarsals).