Inflammation of the muscles of the shin bone, which is located on the inside of the front of the lower leg, is called shin splints. Sometimes, injuries in the lower part of the leg are also referred to as shin splints. Its common symptoms are pain or tenderness along the shin, which may extend to the knee as well. Inflexible calf muscles are a major cause of this problem. The other common causes include Achilles tendons, over pronation, excessive running on hard surfaces, over training, etc.