Fauchelevent had dislocated his kneepan in his fall.
"Les Misérables Complete in Five Volumes" by Victor Hugo
The swelling is seen especially below the kneepan, on each side of the front of the joint, and also often above the kneepan.
"The Home Medical Library, Volume I (of VI)" by Various
Step, now, or I'll crack open yer kneepans, ye robin's egg.
"Red Men and White" by Owen Wister
It most frequently occurs in the stifle joint, where dislocation of the kneepan (patella) takes place.
"Special Report on Diseases of Cattle" by U.S. Department of Agriculture