1. A surgical device adapted for use with an image guided surgical system to facilitate monitoring inter-dependently mobile bone elements, comprising: a rigidly connected multiple-point anchor assembly releasably engageable to at least two inter-dependently mobile bone elements, immobilizing the bone elements such that no relative movement therebetween is possible, and thereby forming a complex rigid body comprising the immobilized bone elements and the multiple-point anchor assembly; and a trackable member, fastened to the multiple-point anchor assembly and comprising a detectable element adapted to be located and tracked in three dimensional space by the image guided surgical system, thereby defining position and movement of the complex rigid body.