Sickled feet is a term used to describe a dancers specific foot position where the toes of the dancers foot curve inward, and his or her heel drops back. This position is a problem for several reasons. Over time, sickling destabilizes a dancers ankles, increases the risk of slips, twists, sprains, and tendinitis. Sickling is a common problem among dance students, and it can happen in almost any dance movement or position. Weakness in the foot and ankle is the main cause of sickling, particularly in the muscles on the outside of the ankle. Poor motor control and genetic variations can also contribute to sickling. To prevent sickling, dancers must worry about inward or outward sickling and avoid it to prevent injury. Teachers prevent sickling with proper form, and dancers can check for sickling in their foot by drawing an "X" on the front of their ankle and again at the base of their 2nd toe, then drawing a line to connect the two. A strong ankle will consistently produce a vertical line in the foot, while in a sickled foot, the line will veer outward, indicating that more strength is needed.