with either first or second circumferential recess 58 and 62 in other embodiments bore 70 is only partially threaded about a length thereof referring to fig4 a 4c there is shown another embodiment of glenosphere 50 of the present invention denoted as 50 u2032 glenosphere 50 u2032 includes all of the same features as glenosphere 50 except that the first and second circumferential recesses 58 u2032 62 u2032 are offset from threaded bore 70 u2032 of glenosphere 50 u2032 first circumferential recess 58 u2032 includes a longitudinal axis 63 u2032 and second circumferential recess 62 u2032 includes a longitudinal axis 65 u2032 the longitudinal axes 63 u2032 65 u2032 of first and second circumferential recesses are coaxial glenosphere 50 u2032 includes a hemispherical or semispherical outer surface 52 u2032 having a perimeter 54 u2032 forming an outer diameter of a bottom surface 56 u2032 perimeter 54 u2032 includes a longitudinal axis 67 u2032 that is offset from longitudinal axes 63 u2032 65 u2032 of first and second circumferential recesses 58 u2032 62 u2032 referring to fig5 a 5c there is shown one embodiment of a third component or central screw 80 of the present invention central screw 80 includes a head portion 82 a body portion 84 a neck portion 86 and a longitudinal axis 90 head portion 82 includes a circumferential side surface 83 defining a perimeter with a diameter d 4 body portion 84 of central screw 80 is preferably threaded neck portion 86 is preferably tapered and threaded central screw 80 further includes an engagement portion 88 for receiving an adjustment tool such as a screwdriver for example in reference to fig6 a 6c there is shown one embodiment.