Connector implant for extending a spinal construct
It is an object of the present invention to overcome at least some of the problems associated with elongating an existing pedicle screw and rod construct. To this end, there is proposed a spinal rod assembly for elongating an in situ spinal posterior rod system by connecting the spinal rod construct to a head of an in situ bone fastener. The spinal rod assembly according to one embodiment comprises a rod connector and at least one rod fastener, wherein the rod connector comprises a first connector head and a second connector head, connected by an elongated bar, and forming a space between the first and second connector heads. The first connector head comprises a first pocket for receiving a first rod end, while the second connector head comprises a second pocket for receiving a second rod end.
1 . A method of extending an in situ spinal construct by using a rod connector, wherein prior to carrying out the method, the in situ spinal construct includes a first spinal rod engaged by at least a first bone fastener and a second bone fastener, wherein a protruding end of the first spinal rod protrudes from the second bone fastener, the rod connector including a first connector head and an elongated bar, the first connector head including a first pocket, a first end entrance, at least a portion of which being opposite to a first pocket end wall, and a first top entrance opposite to a first pocket bottom wall, wherein the elongated bar extends from a first connector head side, which is opposite to at least a portion of the first end entrance, the method comprising:
engaging the elongated bar of the rod connector with a recess of a third bone fastener adjacent to the second bone fastener;
rotating the rod connector about its central axis defined by a longitudinal axis of the elongated bar; and
fixating the rod connector to the third bone fastener and the first spinal rod.
2 . The method according to claim 1 , wherein the rotation angle of the rod connector is at least 60 degrees.
3 . The method according to claim 1 , wherein the first top entrance faces towards the spinal construct when the elongated bar is engaged with the recess of the third bone fastener.
4 . The method according to claim 3 , wherein the rod connector is rotated by flipping over the rod connector once the elongated bar is engaged with the recess of the third bone fastener.
5 . The method according to claim 3 , wherein the first top entrance extends in a direction which is substantially orthogonal to the longitudinal axis of the elongated bar.
6 . The method according to claim 1 , wherein the elongated bar defines a first central axis and the first spinal rod defines a second central axis, and wherein the method comprises aligning the first and second central axes such that the first and second central axes are aligned once the rod connector has been fixated to the third bone fastener and the first spinal rod.
7 . The method according to claim 1 , wherein the rod connector is fixated to the third bone fastener and to the first spinal rod with a respective screw.
8 . The method according to claim 1 , wherein the method further comprises engaging the rod connector with the first spinal rod prior to rotating the rod connector.
9 . The method according to claim 1 , wherein the rod connector further includes a second connector head such that the elongated bar extends from the first connector head to the second connector head, the method further comprising:
engaging the first connector head with the first spinal rod;
engaging a second spinal rod with the second connector head, and with at least a fourth bone fastener adjacent to the third bone fastener; and
fixating the rod connector to the second spinal rod.
10 . The method according to claim 9 , wherein prior to carrying out the method, the method further comprises implanting the fourth bone fastener to a vertebral body.
11 . The method according to claim 1 , wherein prior to carrying out the method, the method comprises cutting off the first spinal rod between the second and third bone fasteners, and removing the cut-off rod portion.
12 . The method according to claim 1 , wherein the elongated bar includes a first elongated bar portion and a second elongated bar portion forming a telescopic structure.
13 . The method according to claim 1 , wherein the elongated bar comprises a transition area between two bar sections having different diameters.
14 . The method according to claim 1 , wherein a cross section of the elongated bar in a first plane perpendicular to an extension direction of the elongated bar is at least partly circular or curved, providing rotational flexibility along the central axis of the connector head when the elongated bar is received within the recess of the third bone fastener.
15 . The method according to claim 1 , wherein the first pocket is defined by the first pocket bottom wall, the first pocket end wall, and opposite first pocket side walls, the first pocket being configured to directly receive, or to indirectly receive by means of a first insert in the first pocket, the first spinal rod of a first rod diameter, the first pocket including a first pocket locking feature, and wherein the elongated bar is sized and shaped to be received by the third bone fastener.
16 . The method according to claim 15 , wherein the first pocket locking feature extends towards the first pocket bottom wall from the first top entrance.
17 . The method according to claim 15 , wherein a minimal first distance between the first side walls defines a first pocket width, and wherein the first pocket width is substantially equal to an elongated bar diameter.
18 . The method according to claim 15 , wherein the rod connector further includes a second connector head connected by the elongated bar to the first connector head, the elongated bar forming a space between the first and second connector heads, the second connector head including a second pocket defined by a second pocket bottom wall, a second pocket end wall, and opposite second pocket side walls, the second connector head including a second end entrance, at least a portion of which being opposite to the second pocket end wall, and a second top entrance opposite to the second pocket bottom wall, the second pocket being configured to directly receive, or to indirectly receive by means of a second insert in the second pocket, a second spinal rod of a second rod diameter, the second pocket including a second pocket locking feature, and wherein the first and second end entrances are located at opposite ends of the rod connector.
19 . The method according to claim 18 , wherein a minimal first distance between the first pocket side walls defines a first pocket width, a minimal second distance between the second pocket side walls defines a second pocket width, and wherein the first and second pocket widths are equal.
20 . The method according to claim 18 , wherein a minimal first distance between the first pocket side walls defines a first pocket width, a minimal second distance between the second pocket side walls defines a second pocket width, and wherein the first and second widths are unequal.