A medical data processing method for determining the spatial relationship of a positioning guide connected to a medical implant relative to a tool, wherein the positioning guide is for positioning the tool relative to the implant and has a predetermined position relative to the implant, the method being constituted to be executed by a computer and comprising the following steps: a) acquiring first medical device position data comprising first medical device position information describing the position of the positioning guide relative to the implant, wherein the first medical device position data is acquired based on detecting a graphical pattern on a marker device having a fixed spatial relationship relative to the positioning guide, wherein the graphical pattern encodes the first medical device position information or information which allows access to the first medical device position information; b) acquiring, by detecting said marker device with a detection unit having a predetermined and advantageous fixed spatial relationship with the tool, second medical device position data comprising second medical position information describing the position of the tool with respect to the positioning guide; c) determining, based on the first medical device position data and the second medical device position data, relative position data comprising relative position information describing the spatial relationship of the tool relative to the positioning guide, characterised in that determining the relative position data comprises determining graphical position output data comprising graphical position output information describing the position of the tool with respect to an implant attachment unit of the implant in a graphical output, in that it is determined whether the position of the tool relative to an implant attachment unit of the implant fulfils a predetermined condition, and in that the graphical position output information is highlighted if the predetermined condition is fulfilled. a) acquiring first medical device position data comprising first medical device position information describing the position of the positioning guide relative to the implant, wherein the first medical device position data is acquired based on detecting a graphical pattern on a marker device having a fixed spatial relationship relative to the positioning guide, wherein the graphical pattern encodes the first medical device position information or information which allows access to the first medical device position information; b) acquiring, by detecting said marker device with a detection unit having a predetermined and advantageous fixed spatial relationship with the tool, second medical device position data comprising second medical position information describing the position of the tool with respect to the positioning guide; c) determining, based on the first medical device position data and the second medical device position data, relative position data comprising relative position information describing the spatial relationship of the tool relative to the positioning guide, in that determining the relative position data comprises determining graphical position output data comprising graphical position output information describing the position of the tool with respect to an implant attachment unit of the implant in a graphical output, in that it is determined whether the position of the tool relative to an implant attachment unit of the implant fulfils a predetermined condition, and in that the graphical position output information is highlighted if the predetermined condition is fulfilled.