The exact mechanisms behind shin splints are not fully understood but are thought to involve a variety of different issues.
The causes, however, are relatively clear; shin splints are most commonly associated with repetitive activities that cause stress on the shinbone and the connective tissue that attaches the muscle to the bone.
It is thought that these stresses involve inflammation of the connective tissue that coats the tibia (called the periosteum); this is called periostitis.
Many experts believe that a range of tibial injuries might account for shin splints; some of these could include:
- Tendinopathy: a disease of the tendon.
- Periosteal remodeling: bone growth and regeneration.
Muscle dysfunction: some muscles may also be involved in shin splints, including:
- tibialis posterior (inside of the ankle)
- tibialis anterior (running along the shin and top of the foot)
- soleus (lower calf)
Overpronation as a cause of shin splints
Foot and ankle overpronation is also thought to be a cause of shin splints. Overpronation of the foot/ankle is when the foot steadily moves downward and toward the center of the body.
This change in position places more of the arch of the foot in constant contact with the ground. More weight is placed on the inside of the foot (medial) than the outside edge of the foot (lateral).
This abnormal movement causes muscles to fatigue quicker and may place additional stress on the shinbone.
The symptoms of shin splints are:
- Pain and tenderness along the tibia.
- Potential swelling of the lower legs.
- In chronic cases, there may be lumps or bumps felt along the bones.
- In severe cases, there may be red patches on the skin around painful areas.
Initially, the pain will stop when exercise stops, but if the condition worsens, the pain can become constant.
It is important to have the pain checked by a doctor because other conditions have similar symptoms (see section on diagnosis).