A stable foot is a essential for normal walking running or jumping. The foot is really a big lever wrench that our strong calf muscles can act upon.
The Lisfranc ligament (named after a napoleonic surgeon) is a really strong ligament that holds the midfoot together and makes it rigid, which means that it can act as a solid lever and doesn't bend in the middle.
If the Lisfranc ligament is injured, the midfoot becomes unlocked and the foot can no longer function as a stable lever, this can be greatly debilitating, and limits function quite dramatically.
Lisfranc injuries often present with a great deal of swelling in the foot, and the foot shape often looks slightly odd. There is often very little to see on simple X-rays, and this is why diagnosis of these injuries can be delayed.