The thighbone (femur) is the strongest bone in the body. It is usually obvious when the thighbone is broken because it takes so much force to break. But a break in the shinbone (tibia) or in the bone that runs alongside the shinbone (fibula) may be less obvious. Signs and symptoms of a broken leg may include: 
Severe pain, which may worsen with movement
Swelling
Tenderness
Bruising
Obvious deformity or shortening of the affected leg
Inability to walk
 Toddlers or young children who break a leg may start limping or simply stop walking, even if they can't explain why.