Overuse injuries of the lower extremity.

Overuse injuries are a common and important cause of morbidity in elite and recreational athletes. They are increasingly recognized in the sedentary population. This article reviews the major classes of overuse injuries of the lower extremity. The underlying pathologic condition is correlated with the imaging appearances, and the often variable relationship between the imaging appearances and patients' symptoms are reviewed. Attempts at imaged-based grading systems and the ability of imaging to predict patients' prognosis are considered. Image-guided injection therapy for tendinopathy is an important and rapidly changing area; the indications, risks, and potential benefits of these interventions are reviewed.