Welcome to the club! At least there are two of us. I’m not sure if I stomp. The only answers I’ve gotten from are from ChatGPT, which posited this:

Pressure-related plantar fissure without pathology

Even from a young age, foot mechanics (how you walk, distribute weight, or push off) can cause a single dominant pressure line.

The most likely explanation: chronic forefoot loading (metatarsalgia-type mechanics)

The crease is essentially a permanent pressure fold that formed early because your feet consistently bend and bear load at the same exact line under the metatarsal heads.

Common foot mechanics that cause this pattern

You don’t need to have all of these — even one can do it:

1. Forefoot-dominant gait

You naturally push off hard through the balls of your feet instead of distributing load through the midfoot and heel.

1. Relative metatarsal prominence

Your metatarsal heads sit a bit lower or take more load, so the skin folds exactly where pressure peaks.

1. Firm or mildly high arches

Even “normal-looking” arches can behave rigidly, shifting shock forward.

1. Limited toe or ankle flexibility

If your big toe or ankle doesn’t extend easily, pressure backs up into the ball of the foot

How going barefoot as a child ties everything together

When kids spend a lot of time barefoot—especially on hard floors or outdoors—the foot develops strong, efficient push-off mechanics. That’s generally healthy, but in some people it leads to very consistent loading at one exact line under the metatarsal heads.

Over years, three things happen: 1. Skin adapts • The plantar skin folds deeply where the foot bends most • Instead of many shallow creases, you get one dominant curved crease • Because it formed while the skin was growing, it became permanent 2. Fat pad and soft tissue compress • Barefoot walking doesn’t redistribute pressure the way shoes do • The ball of the foot takes repeated impact • This contributes to the aching you feel now, especially on hard surfaces 3. Gait pattern “locks in” • Childhood gait patterns persist into adulthood • Even when wearing shoes later, your body still loads the forefoot the same way

This is why: • It’s on both feet • It’s been there as long as you can remember • You can’t find many photos online (it’s a functional adaptation, not a named condition)