A surgical guidance system for orthoscopic drilling is disclosed which comprises a probe, the end of which is suitable for locating on the emergence site of a hole to be drilled through body tissue, a targeter comprising one or more sensors for locating the position of the probe, a drill guide, and a control system in communication with the targeter for determining the position of the probe measured by the targeter and providing a real-time visual representation of the relationship between the direction of the drill guide and the tip of the probe to allow the user to align the drill guide to the tip of the probe. The probe comprises an elongate shaft and one or more, preferably two or more markers located at distant positions along the shaft, and wherein further the markers can be detected by the targeter and are each positioned at locations removed from the tip of the probe.
