1. A computer assisted surgical navigation system for registering the position of prosthetic hip joint components, the system comprising: a first reference element applied to the pelvis that generates a first three-dimensional dynamic reference array, which is independently registered in the system; a second reference element applied to the femur that generates a second three-dimensional dynamic reference array, which is independently registered in the system; a three-dimensional dynamic reference point representing the native anatomical center that is independently registered in the system and derived from the first and second dynamic arrays; a tracking device that generates a third three-dimensional dynamic reference array, which is independently registered in the system, the device having a pre-determined shape and dimensions that precisely articulate with an acetabular component and a further shape and dimensions that independently articulate precisely with a neck portion of a femoral component, representing a prosthetic joint center independently registered in the system; and wherein the tracking device concurrently registers in the system the three dimensional positions of the femoral and acetabular prosthetic components, the prosthetic joint center and the native anatomical joint center, respectively, to intraoperatively represent alterations in three dimensional location of the leg length and offset prior to any reduction of the prosthetic joint.