Boney shin splints affects the major bone in the lower leg, the tibia (shin bone). Microscopic fractures (micro fractures) occur within the bone itself. The resulting inflammatory process (the body's way of repairing itself) causes pain and localised swelling along the bone itself. The muscular regions of the lower leg are not usually affected.
Again this form of injury is caused by poor biomechanics during the contact phase of gait (when the foot strikes the ground). Unlike its muscular cousin this type of injury is caused by poor shock absorption usually (but not always) in an athlete with a rigid foot type.
