A milling system is disclosed for creating a cavity in a bone. The cavity has a cross section which has a generally triangular profile having a first side generally parallel with an axis of the bone and a second side forming an acute angle with the first side. The cavity is contiguous with a pre-existing conical cavity in the bone. The system comprises a drive shaft, a frame for carrying a cutter and a cutter for cutting the cavity. The drive shaft has a proximal end configured for coupling to a drive means and a distal end configured to form a portion of a drive joint for coupling the drive shaft to a cutter. The frame includes a shaft and a cutter mount for mounting a cutter at a first angle approximating the acute angle with respect to the shaft. The mount includes a bracket extending laterally from the shaft to a bearing configured to receive a portion of a cutter and maintain the received cutter oriented at the first angle during rotation. The cutter has a head configured to form a portion of a drive joint for coupling the cutter to a drive shaft. The drive shaft is coupled to the cutter to form the drive joint. The cutter is received in the mount at the first angle and the drive shaft forms a second angle with the longitudinal axis less than the first angle.