A bone screw has a screw body with a spherical head and a screw rod and a positioning sleeve with a connecting rod fixing seat and a calibration part. An annular cutting slot is defined between the connecting rod fixing seat and the calibration part. At least two pairs of connecting rod calibration openings are formed on a sidewall of the calibration part. An axial cutting slot is formed on a sidewall of an adjacent region of the connecting rod calibration openings. The spherical head is connected to a top portion of the screw rod. The screw body is pivoted to a bottom portion of the positioning sleeve. The spherical head is sleevingly arranged on a spherical pit of the connecting rod fixing seat. The calibration part can be split into two pieces and separated from the connecting rod fixing seat. The calibration part is removable from the positioning sleeve.一種骨釘結構，係於釘本體上軸接定位件，並於該定位件上一體延伸出把持件，且該把持件之側面係為傾斜面，以於進行脊椎固定手術時，可將其中一把持件之弧面靠合相鄰之把持件之傾斜面，使該些把持件相疊合，因而可縮減該些把持件於皮膚表面上所佔用之面積，故能大幅縮小該開口之寬度，以達到傷口範圍最小化之需求。
