A fixation device for treating an epiphyseal fracture, comprises a shaft extending longitudinally along a central axis from a first end to a second end configured to slidably engage a bone implant opening and a having a maximum radius r and a spherical head element attached to the first end of the shaft and having a radius R>；r, the spherical head element configured to be inserted into a fragmented portion of bone such that the fragmented portion rotates about the spherical head element relative to the central axis of the shaft.
