Treatment of spinal irregularities, including, in one or more embodiments, derotation apparatus and systems that can be used to reduce the rotation of vertebral bodies. Derotation apparatus that may comprise a tube assembly comprising an inner sleeve and an outer sleeve disposed over the inner sleeve. The inner sleeve may have a distal end for attachment to an implant. The tube assembly may further comprise a handle assembly. The tube assembly may further comprise a ball joint assembly disposed between the tube assembly and the handle assembly. The ball joint assembly may comprise a ball joint configured for attachment to a coupling rod. The ball joint assembly further may comprise a reducing extension below the ball joint, the reducing extension being sized to fit in a central bore of the inner sleeve. Orthopedic fixation devices comprising a ball joint are also disclosed.