A joint assembly of an adapter defines a first longitudinal axis and includes first and second hinges, first and second rings, a joint cover, and a biasing mechanism. The joint cover has first and second cover portions. The first ring is pivotally coupled to the first hinge and the first cover portion is pivotally coupled to the first hinge to define a first joint center. The second ring is pivotally coupled to the second cover portion and the second hinge is pivotally coupled to the second ring to define a second joint center that is spaced from the first joint center. The first and second joint centers define a cover axis of the joint cover. The biasing mechanism is engaged with the first ring and the joint cover to bias the joint cover towards an aligned configuration in which the cover axis is aligned with the first longitudinal axis.