Along with other types of shin pain Medial Tibial Stress Syndrome (MTSS) has often been attributed the umbrella term "shin splints". It is now also referred to as Medial Tibial Traction Stress Syndrome.
Both terms refer to the fact that the condition is one of excessive traction and subsequent inflammation of the inner part of the leg.
When we walk or run there are an incomprehensible amount of mechanisms at play to keep us on our feet and moving efficiently; the biomechanics of the legs and feet are at the focus of that.
The process of locomotion is often referred to as the gait cycle. There are several phases to the cycle but the one that is very important in MTSS is "midstance" - the time between the foot flattening to the floor and then pushing off. Pronation occurs during this time period as the foot rolls inward and the inner arch flattens. This action is paramount in providing shock absorption and dealing with varied terrain.
The medial (inner) portion of a muscle called soleus works very hard to resist pronation by pulling upwards during midstance; the tibialis posterior and flexor digitorum longus also assist with this task.
Figure 1: The posterior leg muscles.
a) posterior view of the leg - the calf complex.
b) the second layer of the calf muscles exposing soleus.
c) the deepest layer of calf muscles - tibialis posterior highlighted.
d) Flexor digitorum longus
Certain types of foot posture or overuse combined with repetitive impact can mean that these muscles have excessive force placed upon them. Resultantly the origins of these muscles on the tibia (shin bone) can become irritated.
Classically someone with MTSS will complain of a diffuse pain along the medial border of the tibia, usually at a point between the lower third and upper two thirds. Often the pain will decrease with warming up and exercise but will return afterwards and become worse the following morning.
When to get it looked at:
If left unassisted and untreated MTSS can be the gateway to stress fractures of the tibia. This is obviously something that really needs to be avoided but happens more often than one might think. If the problem has become a recurrent one and you are noticing symptoms regularly then get it checked out. If identified early enough then appropriate rest and footwear modifications can prevent the condition gaining traction (no pun intended). Accurate assessment of foot alignment and gait mechanics is also very important as this can highlight the likely causal factors and lead to appropriate corrective therapy.
If in doubt, get it looked at. This really is something that you do not want becoming entrenched because it could keep you away from sport for much longer than necessary.