If you sit around a bar in small town Alaska with your artificial leg and let a friend stab it occasionally to show women how tough Alaska guys are, it's useful if he doesn't miss one night and put the knife in the wrong one. (The markings reflect all the times his aim was better.)
On the other hand, when you get your new titanium leg, you can give your old plastic one to a former girlfriend and she can display it on her porch to show off the results.
(The photograph's tag is one year off--the picture was taken yesterday about 200 miles north of Anchorage.)