Virtual Hip Replacement: "Take on the role of the Surgeon throughout a hip replacement surgery!"Virtual Knee Surgery
The animations, created by Edheads.org, are interactive and well-done. According to the FAQ page, Edheads is a non-profit organization, which creates educational web experiences that are free to teachers, students and parents.
References:
Virtual Hip Replacement: Be a Surgeon! ScienceRoll.com
Image source: Edheads.org