Carbon fiber has a theoretical advantage over other materials for hip arthroplasty. It has a modulus of elasticity closer to that of bone than other materials. This property has been used in the production of a femoral component for use in hip arthroplasty. Isoelasticity could avoid the problems of stress shielding prevalent with other uncemented metal prostheses; however, the early failure of one such prosthesis due to implant breakage at the neck-body junction is reported.