Intramedullary nail
The present invention is an intramedullary nail ( 100 ) to be used by being intramedullarily inserted into a bone, having a nail body ( 110 ) comprising an axial hole ( 113 ) extending from an opening formed at a proximal end portion toward a distal end portion along an axis line and a transverse hole ( 114 ) intersecting with the axis line, and having: an engaging member ( 221 ) comprising an engaging portion ( 221 b ) at distal end thereof engageable with a bone fastener inserted through the transverse hole and arranged so as to be shiftable in the axial hole in a manner where the distal end portion is engageable and disengageable with the bone fastener ( 10 ); an adjusting member ( 222 ) controlling the position of the engaging member; and an elastic member ( 125 ) for charging, against the nail body, the engaging member in a direction opposite the controlling direction by the adjusting member.
1. An intramedullary nail for intramedullar insertion into a bone, having a nail body comprising an axial hole extending from an opening formed at a proximal end portion toward a distal end portion along an axis line and a transverse hole intersecting with the axis line, comprising:
an engaging member comprising an engaging portion at distal end thereof engageable with a bone fastener inserted through the transverse hole and arranged so as to be shiftable in the axial hole such that the engaging portion is engageable and disengageable with the bone fastener;
an adjusting member controlling the position of the engaging member from a side of the proximal end portion according to the operation thereof; and
an elastic member for biasing the engaging member to the proximal end portion side in the axis direction against the nail body, and which is arranged between an outer circumferential step provided at the outer circumference of the engaging member and an inner step provided inside the axial hole of the nail body,
whereby a first condition in which the engaging member engages with the bone fastener, by displacement of the engaging member to a side of the distal end portion in the axial direction against the biasing of the elastic member, and a second condition in which the engaging member does not engage with the bone fastener, by displacement of the engaging member to the side of the proximal end portion in the axial direction under the biasing of the elastic member, are selected by operation of the adjusting member.
2. The intramedullary nail as set forth in claim 1 , further comprising a retaining member for retaining the engaging member from the side of the proximal end portion,
the retaining member provided with an aperture in order to enable the adjusting member to contact with the engaging member from the side of the proximal end portion.
3. The intramedullary nail as set forth in claim 1 , wherein the engaging member has an engaging surface for the bone fastener, having a schematic surface form along an inner surface of the transverse hole and comprising an uneven engaging structure superposed on this schematic surface form.
4. The intramedullary nail as set forth in claim 1 , wherein in the nail body, a plurality of transverse holes are formed so as to be arranged along the axis line, and
the engaging member comprises, at a position corresponding to the transverse hole formed at the side of the proximal end portion of the nail body, a transverse opening portion through which another bone fastener is inserted into the transverse hole formed at the side of the proximal end portion.
5. The intramedullary nail as set forth in claim 1 , the adjusting member adapted for rotational operation and the adjusting member having a cam engagement with the engaging member so as to change a controlling position for the engaging member in accordance with the rotational angle of the adjusting member in a condition substantially fixed in the axial direction.