Patent ID: 7764985

Claim:
A computer aided surgery navigation system comprising: a. a sensor adapted to sense position of a plurality of indicia on a reference frame attached to an item used in surgery; b. a computing device adapted to receive information from the sensor about position of the indicia and generate information corresponding to position and location of the item to which the indicia are attached; c. a display device adapted to render an image of the item correctly positioned and oriented in correspondence with the position of its indicia as sensed by the sensor; wherein d. the reference frame includes an indicia attachment portion configured to hold the plurality of indicia in an asymmetrical array, a base portion comprising an attachment device configured to secure the base portion to the item used in surgery and a connection portion between the indicia attachment portion and the base portion, the connection portion configured to position the plurality of indicia relative to the base portion at a predetermined position and orientation; e. the connection portion of the reference frame including a fault interface structure with a mating portion having a male mating part and a female mating part, the male and female mating parts causing the indicia attachment portion to attach to the base portion in the predetermined orientation and position, and wherein an additional connection force other than the frictional force between the male and female mating parts is used to hold the indicia attachment portion to the base portion with a strength lower than a strength of other portions of the reference frame, whereby the fault interface permits disconnection of the indicia attachment portion from the base upon application of any inadvertent force to the reference frame regardless of the direction and moment of the inadvertent force; and f. wherein the fault interface structure permits reconnection of the plurality of indicia to the base in the predetermined position and orientation.