System and method for fixing bone. An exemplary system may comprise a clamping instrument, a first fastener, and a second fastener. The clamping instrument may include a first tube and a second tube. The tubes may have an adjustable separation from one another while remaining coaxially aligned with one another on an axis, and may be configured to apply pressure to opposite sides of a bone to compress the bone. The first fastener may be configured to pass through the first tube on the axis. The second fastener may be configured to attach to the first fastener and to pass through the second tube on the axis. In some embodiments, the system also may comprise an insertion tool configured to carry the second fastener into the second tube and prevent the second fastener from turning.
