The present application relates to a system for navigation-assisted shoulder operations in which the humeral component is partially replaced with a prosthesis, comprising:a first tracking unit which is configured to be fastened to a section of a bone which is to be removed during the operationa detection unit which is configured to detect landmarks on the bonea second tracking unit which is configured to be attached to another section of the same bonea camera unit which simultaneously detects the first and second tracking unit, in order to determine their respective location anda computational unit which is connected to the camera unit and is configured to: determine a first relative location of the landmarks relative to the first tracking unit from data acquired by means of the detection unit andcalculate a second relative location of the landmarks relative to the second tracking unit on the basis of the first relative locationsuch that additional navigated treatment apparatuses can be exactly positioned during the operation by referring to the second tracking unit.
