US Patent 7107091 Multiple bone tracking

A surgical device adapted for use with an image guided surgical system to facilitate monitoring inter-dependently mobile bone elements. A rigidly connected multiple-point anchor assembly is releasably engageable to at least two inter-dependently mobile bone elements and immobilizes the bone elements such that no relative movement therebetween is possible, and a complex rigid body comprising the immobilized bone elements and the multiple-point anchor assembly is formed. A trackable member is fastened to the multiple-point anchor assembly and comprises 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.