Shin Splints (medial tibial stress syndrome) is an inflammation of the muscles, tendons, and bone tissue around the tibia. It is characterized by pain that typically occurs along the inner border of the tibia (shinbone), where the muscles attach to the bone. Shin splints develop when the muscle and bone tissue (periosteum) in the leg become overworked by repetitive activity. When overworked, or fatigued, the muscles and tendons lose their ability to adequately absorb the damaging shock force from physical weight-bearing activities, resulting in the soft tissue being partially torn away from the bone.

The repetitive activities that lead to overworked tissues can come from either overload or biomechanical inefficiencies. Overload includes sudden changes in physical activity, such as increased frequency, duration, or intensity. Biomechanical inefficiencies include flat feet, abnormally rigid arches, or exercising with improper or worn-out footwear. Shin splints are common in runners and in those who participate in activities that require sudden stops and starts, such as basketball, soccer, or tennis.