The present invention relates to a medical instrumentation, in particular, for implanting an acetabular cup, comprising a medical alignment instrument with a shaped body, which has a patient-specific bone abutment surface facing away from the shaped body and deviating from a spherical surface section, the bone abutment surface being shaped so as to correspond to a bone surface of the patient, wherein the shaped body has at least one viewing edge with a viewing height, and wherein the viewing edge adjoins the patient-specific bone abutment surface, and wherein a transition between the viewing edge and the patient-specific bone abutment surface is tangentially discontinuous.
