Patent ID: 8734453

Claim:
An anti-backout stylus instrument assembly comprising: an anterior rough cut guide having an anterior resection slot therethrough, a locking stylus holder supported by said anterior rough cut guide, said locking stylus holder having a stylus bore for receiving a stylus, said stylus bore having a stop member disposed therein, said stop member biased to normally engage a detent of a stylus disposed in said stylus bore, a stylus, said stylus having a substantially flat portion, a tip on a forward end, and a sloped portion between said flat portion and said tip, a lower side of said flat portion of said stylus having a series of detents thereon, said detents configured to depress and pass over said stop member when said stylus is slid forward into said stylus bore, but to engage said stop member when said stylus is slid distally to thereby prevent inadvertent withdrawal of said stylus from said stylus bore, and each of said detents positioned to match a particular femoral size, such that each engagement of a detent by said stop member indicates a femoral size.