Small lump on tibailis anterior muscle. I play competitive basketball. Only appears when I step with that leg (right leg). Disapears when leg is lifted.

Muscle Hernia. Most muscle hernias occur in the lower leg & affect the tibialis anterior muscle. Swelling appears or enlarges when the affected muscle is contracted & disappears or shrinks during muscle relaxation. Most muscle hernias are treated by reassurance since they are asymptomatic and don't affect function. A few painful hernias need surgery. Ultrasound is diagnostic and can exclude muscle tear or tumor.