Overlapping and underlapping toes occur when toes are out of position. The conditions can be congenital due to inheritance or the fetus’s in-utero position, or they can develop over time from ill-fitting footwear that constricts or pressures the toes, keeping them bunched rather than flat. It can also stem from a bunion.

An overlapping toe lies across the top of an adjacent toe rather than staying in its straight position. This is most common with the fifth toe. An underlapping toe lies behind another toe; this most commonly affects the fourth and fifth toes. Congenital curly toe is a condition where the toes curl and point to the outside of the foot. It is usually congenital and can be worsened by ill-fitting footwear. As a result of toe overlapping or underlapping, blisters, irritation, corns, and calluses may form as the toes rub against one another and footwear.

Treatment for overlapping and underlapping toes involves stretching and taping the toes, which is usually how the condition is treated in infants. However, the mispositioning usually returns. Surgery to release the tendons and soft tissues at the toe joint at the base of the toe may be necessary, and in severe cases, a pin can be temporarily inserted in the toe to correct its position. With underlapping toes that are inflexible and fixed in position, surgery can remove bone in the toe to improve flexibility.