Abstract: A surgical instrument (10) serves to cut bone by vibrating at ultrasonic frequencies ranging between 22 kHz and 36 kHz. The instrument includes a titanium alloy body with a straight tang (11), a straight distal length (12) having a sharp free end (13), and an intermediate length (14) between the tang (11) and the distal length (12). The intermediate length has three successive curved portions (14a, 14b, 14c) with concavities facing towards alternate directions which are alternately opposite and perpendicular to a central axis (x) of the instrument. The intermediate (14) and distal (12) lengths are progressively flattened and get thinner from the tang (11) towards the end (13).