A fixation assembly includes an anchor, a cam, and a shaft. The anchor defines a longitudinal axis and includes a spine that extends along the longitudinal axis. The spine has a first projection and a second projection that extend from the spine in a direction transverse to a longitudinal axis. The anchor defines a slot between the first and second projections. The cam is disposed with the slot and is positioned to rotate about the longitudinal axis between first and second positions to enable the first and second projections and the cam to secure the anchor to osseous tissue. The shaft is rotatably disposed within the anchor and positioned to rotate the cam between the first and second positions. In the first position, the cam is aligned with the first and second projections, and in the second position, the cam is misaligned with the first and second projections.