Shin splints

Medial Tibial Stress Syndrome
Red area represents tibia. MTSS pain found on inner and lower 2/3rds of tibia.
Classification and external resources
Specialty	Sports medicine
Patient UK	Medial Tibial Stress Syndrome
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Shin splints, also known as medial tibial stress syndrome (MTSS), is defined by the American Academy of Orthopaedic Surgeons as "pain along the inner edge of the shinbone (tibia)." Shin splints are usually caused by repeated trauma to the connective muscle tissue surrounding the tibia. They are a common injury affecting athletes who engage in running sports or other forms of physical activity, including running and jumping. They are characterized by general pain in the lower region of the leg between the knee and the ankle. Shin splints injuries are specifically located in the middle to lower thirds of the anterior or lateral part of the tibia, which is the larger of two bones comprising the lower leg.

Shin splints are the most prevalent lower leg injury and affect a broad range of individuals. It affects mostly runners and accounts for approximately 13% to 17% of all running-related injuries. High school age runners see shin splints injury rates of approximately 13%. Aerobic dancers have also been known to suffer from shin splints, with injury rates as high as 22%. Military personnel undergoing basic training experience shin splints injury rates between 4-8%.

While the exact cause is unknown, shin splints can be attributed to the overloading of the lower leg due to biomechanical irregularities resulting in an increase in stress exerted on the tibia. A sudden increase in intensity or frequency in activity level fatigues muscles too quickly to properly help absorb shock, forcing the tibia to absorb most of that shock. This stress is associated with the onset of shin splints. Muscle imbalance, including weak core muscles, inflexibility and tightness of lower leg muscles, including the gastrocnemius, soleus, and plantar muscles (commonly the flexor digitorum longus) can increase the possibility of shin splints. The pain associated with shin splints is caused from a disruption of Sharpey's fibres that connect the medial soleus fascia through the periosteum of the tibia where it inserts into the bone. With repetitive stress, the impact forces eccentrically fatigue the soleus and create repeated tibial bending or bowing, contributing to shin splints. The impact is made worse by running uphill, downhill, on uneven terrain, or on hard surfaces. Improper footwear, including worn-out shoes, can also contribute to shin splints.

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Wikipedia