curled, coiled
踡 centers on being curled or coiled, describing a posture where the body or limbs are drawn in tightly.
踡 combines 足 (foot) with 卷, which likely contributes the sound and the idea of curling or bending. The exact historical development is uncertain.
The foot radical 足 beside 卷 (a shape associated with rolling or curling) suggests a foot curled up or a body coiled tightly.
For ケン, imagine a curled-up cat named Ken: Ken -> ケン, and Ken the cat is always coiled up in a tight ball.