A surgical bone milling instrument, suited to operate in a hole formed in a bone, comprising a milling element (10), with longitudinal axis (A) and with the forward end portion (11) rotating around a longitudinal axis (A), and milling the bone. The instrument comprises a tubular element (30) of circular external cross-section and provided with a thread engaging, by helical coupling, a hole formed in the bone. The milling element (10) is associated with the tubular element (30), arranged so that the forward end portion (11) thereof is located ahead of the tubular element (30) andcan rotate around the longitudinal axis (A) thereof and translate axially relative to the tubular element (30). The milling element (10) has a rear portion (14) which passes coaxially through the tubular element (30), while the forward end portion (11) projects beyond the front of the tubular element (30). The milling procedure of a bone cavity can be completed while maintaining control of the position of the device relative to the hole. Furthermore, in each phase in which the milling element is rotated, while the instrument is axially stationary inside the hole, a groove is created on the end of the hole (or an extension of the entire hole) the depth of which is constant and predetermined. Further, by way of axial pressure applied to the milling head by the drive element, a detachment of residual bone wall can be achieved as soon as this has reached a breaking resistance which is lower than a force applied by the drive element.Linvention porte sur un instrument de type fraise chirurgicale à os adapté à la pratique dinterventions dans une cavité formée dans un os, et comprenant un élément de fraisage (10) avec un axe longitudinal (A) et une partie dextrémité antérieure (11) en rotation autour de laxe longitudinal (A), permettant ainsi le fraisage de los. Linstrument comprend un élément tubulaire (30) de section extérieure circulaire et dont le filet vient en prise par couplage hélicoïdal avec
