RATCHETED SPINAL DEVICES
A spinal device ( 10 ) including a variable-length member ( 12 ) including a ratchet mechanism ( 14 ) that has an operative configuration that allows a change in length of the variable-length member ( 12 ) in one direction and prevents a change in length of the variable-length member ( 12 ) in an opposite direction, wherein the variable-length member ( 12 ) includes polyaxial-joint attachment members ( 32 ) for attachment to bone, which permit pivoting movement of the attachment members ( 32 ) about more than one pivoting axis, characterised by a force applicator ( 40 ) operative to adjust or advance the ratchet mechanism ( 14 ).
1 . A spinal device comprising:
a variable-length member comprising a ratchet mechanism that has an operative configuration that allows a change in length of said variable-length member in one direction and prevents a change in length of said variable-length member in an opposite direction, wherein said variable-length member comprises polyaxial-joint attachment members for attachment to bone, which permit pivoting movement of said attachment members about more than one pivoting axis,
and a force applicator operative to adjust or advance said ratchet mechanism.
2 . The spinal device to claim 1 , wherein said force applicator comprises a cam which has a tooth that engages a ratchet rack of said ratchet mechanism.
3 . The spinal device according to claim 1 , comprising a pair of said spinal devices and a connector assembly that forms a jointed connection between said spinal devices that permits multiple degree-of-freedom movement of said spinal devices.
4 . A spinal device comprising:
variable-length members each comprising a ratchet mechanism that has an operative configuration that allows a change in length of each of said variable-length member in one direction and prevents a change in length of each of said variable-length member in an opposite direction, wherein each of said variable-length member comprises polyaxial-joint attachment members for attachment to bone, which permit pivoting movement of said attachment members about more than one pivoting axis,
and a connector assembly that forms a jointed connection between said variable-length members that permits multiple degree-of-freedom movement of said variable-length members.
5 . The spinal device according to claim 4 , wherein said connector assembly comprises a bolt which passes through a first hinge member and a second hinge member adjacent said first hinge member, and pivot pins that pivotally connect said spinal devices to said first hinge member and said second hinge member.
6 . The spinal device according to claim 5 , wherein said connector assembly permits rotation about a longitudinal axis of said bolt, and independently about a longitudinal axis of each pivot pin, which are perpendicular to the longitudinal axis of said bolt.