The invention features bone screws having a threaded screw body and a screw head attached to one end of the screw body, the bone screw further including: a) an interior channel extending longitudinally through the screw head and through at least a portion of the screw body, wherein the interior channel has a width of less than 5.0 millimeters; and b) a plurality of radially-disposed delivery channels connecting the interior channel to the exterior of the screw body, each delivery channel having exterior openings. The invention further features devices that include a bone screw and a delivery manifold detachably attached to the screw head of the bone screw. In addition, the invention features methods of treating a patient having a bone defect by using a bone screw described herein.