A system for assessing an intervertebral disc space comprises an elongated catheter with proximal and distal ends and an expandable body carried at the distal end of the elongated catheter. The expandable body includes a distal cap portion. The system further includes a mandrel extending through the elongated catheter and the expandable body and attached to the distal cap portion. The mandrel is movable within the elongated catheter and the expandable body to reposition the distal cap portion relative to the distal end of the elongated catheter while the expandable body is positioned within the intervertebral disc space.