Methods and apparatus using a surgical navigation system during hip joint replacement surgery without separately affixing a marker to the femur. The navigation system acquires the center of rotation of the hip joint as well as at least one point on the femur in the pelvic frame of reference. From these two points, the navigation system calculates the position and length of a first line between the center of rotation of the hip joint and the point on the femur. A prosthetic cup is implanted and its center of rotation is recorded. A tool for forming the bore within which the stem of the femoral implant component will be placed is tracked by the navigation system. The navigation system calculates the position and length of a first line between the center of rotation of the prosthetic cup and the re-palpated first point. The surgical navigation system uses this information to calculate and display to the surgeon relevant information about the surgery.