The invention relates to a device for minimally invasive attachment of a tracker (20) and/or a registration phantom (30) to a patients bone, comprising a base (10) made of a substantially radiotransparent material, characterized in that the base (10) comprises: - a support surface (11)intended to face the bone, - a plurality of non-parallel through holes (14) for passing a respective percutaneous pin (2) through the base(10) - at least one slot (15) extending from an edge of the base (10) in a direction transversal to the through holes (14),said slot (15) passing throughout the base (10) until the support surface (11) and being intended to engage a percutaneous pin (2) implanted into the patients bone so as to allow the base (10) to slide along said pin (2) and - a reproducible fixationsystem for attaching the tracker (20) and/or the registration phantom(30) to the base.
