Sudden pain and "click" after a very small bump on the street.
Note from a contributor of Imaios :
"The submitted history is more likely attributable to the medial meniscal tear shown on your MR images. You may notice a near complete tear of the posterior root of the medial meniscus. This fits the clinical story well. Tibial enchondromas are typically asymptomatic. The meniscal root tear may be easier to appreciate on coronal imaging, but it is present on the sagital images.
Hope that helps -"
Perry Horwich, M.D.
The Guthrie Clinic
Corning, NY and Sayre, PA