Apparatus and methods for measuring spacing between first and second bone screws engaged with first and second bone structures are provided. An apparatus comprises first and second arms operably engaged with a single pivot pin. The first arm includes a distal end adapted to engage the first bone screw, and a proximal end comprising a graduated scale. The second arm, operably engaged with the first arm via the single pivot pin, includes a distal end adapted to engage the second bone screw, and a proximal end comprising an indicator segment slidably engaged with the graduated scale. A position of the indicator segment relative to the graduated scale is therefore indicative of a spacing between the first and second bone screws.