摘要：

In one embodiment, a spinal fixation assembly includes an elongated member, such as a spinal rod, configured for placement adjacent the spine and a bone engaging fastener, such as a bone screw having a lower portion configured for engaging a vertebra and a head that is at least partially spherical. The assembly further includes a receiver member defining a bore therethrough from a top end to a bottom end, a recess for receiving the head of the bone screwing fastener therein, and a lower opening at said bottom end of the receiver member through which the bone screw extends. The recess is configured to at permit pivoting of the bone screw within the receiver member until the head is fixed within the recess. The receiver member also includes a channel communicating with the bore and having an upper opening at the top end of the receiver member for insertion of the spinal rod into the channel. In one embodiment, two compression members are provided, each being formed of a temperature responsive material and having a first configuration at a first temperature and a different second configuration at a different second temperature in which the compression member contracts about a portion of the receiver member to thereby compress the receiver member about both the head of the bone screw within the recess and the spinal rod within the channel.

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