Skeletal Development of the Foot (week 9 - 10 post-ovulation)
Frame 1 - foot supinatus at approximately week 9 post-ovulation. The entire plantar surface of the foot is in supinatus relative to the posterior compartment of the leg. This is a structural relationship, not a positional change.
Frame 2 – skeletal supinatus at approximately week 9 post-ovulation (same picture as Frame 1 but with the skin removed). If the foot stops unwinding at this point, the entire foot remains in supinatus. Podiatrists have identified this foot type as a combination rearfoot/forefoot varum. Rothbart refers to this foot structure as the preclinical clubfoot deformity (both the calcaneus and talus remain in supinatus).
Frame 3 – calcaneal supinatus has unwound into its plantargrade position. Concurrently, this carries the lateral column of the foot (metatarsals 2-5) into a plantargrade position. If the foot stops unwinding at this point, only the medial column of the foot remains in supinatus (e.g., talar supinatus), clinically termed Primus Metatarsus Supinatus. Prior to 2002, this foot structure was not recognized. To view an animated model of talar supinatus, click here.
Frame 4 – foot is completely unwound. When the standing foot is placed in its anatomical neutral position, the entire plantar surface of the foot is plantargrade (on the ground).
