This is a diagram of the replaced Hip joint and what material is used where in a synthetic hip joint. The diagram shows where polyethlene, cement, and metal are used in a synthetic hip joint.

 These two are diagrams of a Great Hip Joint that is healthy and to the right we have a picture of a hip joint that is worn out and deterriorated. The picture to the right of the worn out hip is a great guide for showing which parts wear out over time and how the artificial hip joint is beneficial. The artificial hip joint is modified so that it takes up the shape of the healthy knee to the left.

Here we see that there is a synthetic knee and a worn out knee. There aer parts of the knee shown in the diagram to the right that show what damage can occur to the knee and what parts are replaced with the artificial knee. The figure to the left showing the artificial knee also shows what material is used to make different parts of the artificial knee.