Full circle: 3D femoral mapping demonstrates age-related changes that influence femoral implant positioning.

The geometry of the femur is important in the final position of an intramedullary implant; we hypothesised that the femoral geometry changes with age and this may predispose the elderly to anterior mal-positioning of these implants. We used CT DICOM data of 919 intact left femora and specialist software that allowed us to defined landmarks for measurement reference - such as the linea aspera - on a template bone that could be mapped automatically to the entire database. We found that older (>80 years) cortical bone is up to 1.