The condition known as Shin Splints involves a muscular over-use scenario. There are Anterior Shin Splints and Posterior Shin Splints. Anterior Shin Splints involve the Tibialis anterior muscle of the anterior compartment of the leg, and Posterior Shin Splints involve the Tibialis posterior muscle of the posterior compartment of the leg.
Both of these muscles are involved in slowing down pronation during the stance phase of gait. Tibialis anterior functions early in the stance while Tibialis posterior functions a little later. If the patient over-pronates or pronates too rapidly, either or both of these muscles may be called upon to work harder than normal. As a result, fatigue sets in, leading to inefficient force production which leads to micro-tearing of the soft tissue and therefore and inflammatory reaction. Since the muscle is wrapped in a fascial covering, the swelling that occurs from the aforementioned problem is restricted by this covering. Beyond the fact that much pain results from the entire process, the presuure within the fascial covering can be suffiecient to “choke-off” the blood supply to the involved musculature, further added to the insult on the tissue. In severe circumstances the swelling can be severe enough to damage the deep peroneal nerve resulting in a permanent “foot drop,” as this nerve supplies the dorsiflexors of the foot. The scenario that typically brings on “shin splints” is a sedentary individual that suddenly starts running or walking long distances. When that individual is also an over-pronator, the combination of having weak muscles from lack of activity and having this biomechanical fault increase the likelihood of injury. Even changing the type of shoe worn during walking or running can be sufficient to increase the pronation of the subtalar and transverse tarsal joints and lead to tissue injury.