In one aspect, the present invention provides a mounting system (40) for instruments for use in medulloscopy. The mounting system (40) comprises a positioning system (41) adapted for being mechanically attached to a bone (10), and at least one instrument holder (45) attached to the positioning system (41), the instrument holder (45) being adapted for holding one or more instruments for being used during bone surgery in a medullary canal. Due to the positioning system (41) which may be mechanically attached to the bone (10), and due to the instrument holder (45) for holding instruments which is attached to the positioning system (41), a surgeon has both hands available for operating on the patient.