Tibial Stress Injuries

A potpourri of terms have been coined to refer to injuries that share many etiologic, clinical and imaging characteristics, perhaps because they are part of a spectrum ranging from micro-trabecular disruption to frank stress fractures.

'Shin splints' have been renamed 'posteromedial tibial stress syndrome' - a term that points to the site of origin of the pain and its proposed etiology: Periosteal avulsive changes mediated by the soleus at its origin.

'Posteromedial tibial stress syndrome' is also know as 'medial tibial stress syndrome', which has evolved into the initialism 'MTSS.'

MTSS is simply a spectrum from tibial stress reaction to frank stress fractures with manifestations on bone scan and MR. An MR classification has been devised to parallel this continuum:

Grade O: Normal MR

Grade 1: Periosteal high signal

Grade 2: Bone marrow signal on T2

Grade 3: Bone marrow signal changes on T1

Grade 4: Visible fracture line

The differential diagnosis for leg pain in athletes includes not only MTSS, but also muscle and tendon injuries and exertional compartment syndrome, vascular etiologies (popliteal artery entrapment syndrome, claudication, deep venous thrombosis), and neurogenic pain from lumbosacral pathology or nerve entrapment.

Pronators are at risk for MTSS.

Posteromedial and posterolateral stress reactions are more common, but they can also occur at the anterior aspect of the tibia. Fatigue phenomena with biomechanical overload have been implicated: leg-length discrepancy, pronation, muscle imbalance; similarly bone insufficiency in the context of osteoporosis has been considered.

Anterior tibial stress fractures are more commonly transverse, but they can also be longitudinal along the dyaphysis.


Typical posteromedial stress reaction with periosteal and endosteal reaction. The central dot of high signal is a penetrating vessel.

Bone aposition is noted on the CT-scan along the posteromedial cortex. On the right, a sagittal STIR scan shows the longitudinal extent of the findings.

Similar findings noted along the anterior aspect of the tibia. A small break is noted on the T1 scan to the right.