The two bones in the lower leg between the knee and the ankle are the tibia and the fibula. The tibia, larger and heavier, is the primary weight bearer of the two. The fibula, smaller, lies alongside the tibia on the lateral side of the lower leg, and is joined to the tibia at top and bottom by ligaments. Between them is the interosseous membrane. An injury to either bone or to their connecting tissues may affect the efficient working of the biomechanics of the lower extremity. The patella, or kneecap, glides in a groove on the upper front of the tibia.
