In an artificial joint that includes a head assembly attached by taper fit to a proximal portion of a surgically implanted stem, it may become necessary to surgically remove the head assembly. A puller can simultaneously apply a force distally to a non-peripheral portion of a proximal side of the head assembly and proximally to several locations spaced apart around a circumference of the distal side of the head assembly. In some examples, the proximal side of the head assembly includes a plug disposed at the non-peripheral portion. The puller can force the plug into contact with the proximal end of the stem, then apply the distal force through the plug to the stem. In other examples lacking a plug, the non-peripheral portion of the head can deform or break in response to the applied distal force, so that the distal force can apply to the stem.