Medial tibial stress syndrome (MTSS) is an overuse injury characterised by pain along the posteromedial border of the tibia due to repetitive stress and microtrauma to the tibial periosteum and adjacent musculature. It is clinically important as a common cause of exertional leg pain in athletes and military recruits, often requiring activity modification to prevent progression. MTSS is closely associated with biomechanical factors such as excessive pronation, which can increase strain on the tibial cortex and delay recovery.