The tibia is the thicker, inner bone of the lower leg that runs parallel to the fibula. It connects the femur above to the talus and fibula below. The tibia has expanded upper and lower ends connected by a triangular shaft. Common fractures of the tibia include breaks across the shaft from direct blows or at the upper end from knee injuries. Stress fractures can also occur from overuse. Treatment depends on the severity but may involve casting or surgery to stabilize broken bone fragments.