A joint system enables pivotable coupling between a first frame member and a second frame member. The joint system includes a mounting ball assembly affixable to the first frame member, and a connector engageable with the mounting ball assembly at one end and affixable to the second frame at an opposite end. The connector is constructed such that it is movable on the mounting ball assembly in a folding plane and through a clearance amount in a clearance plane substantially perpendicular to the folding plane. A continuous passage is defined through the mounting ball assembly and the connector.