A surgical apparatus comprising: a base unit; an arm coupled to the base unit, the arm comprising a first section and a second section which are moveable with respect to each other about a joint, the arm being configured to receive a guide-tube; a tracking un it coupled to the joint and configured to track movement of the first section of the arm with respect to the second section of the arm; and a processor configured to: receive intra-operative image data relating to the guide-tube and the anatomy of a patient from which an initial position and orientation of the guide-tube relative to the anatomy of the patient can be determined, the image data including image data relating to a target location within the patient, receive tracking information from the tracking unit, and track the position and orientation of the guide-tube based on the initial position and orientation and the tracking information such that the guide-tube may be aligned with respect to the target location within the patient using the tracked position and orientation of the guide-tube to allow the delivery of a surgical instrument to the target location.