Advanced trial spacers, height measuring tool, and inserter and extractor handle

A trial humeral prosthesis comprising:

• a trial stem configured for implantation into a humerus;
• a trial proximal body configured to couple to a trial articulating component of the trial humeral prosthesis;
• and
• a plurality of trial spacers configured to couple the trial stem to the trial proximal body, the plurality of trial spacers including a first trial spacer and a second trial spacer,
• wherein the first and second trial spacers each include a proximal post, a divot, a shoulder adjacent to the proximal post, and a distal body having a prong extending distally therefrom, the prong including an interior protrusion, and
• wherein the distal body of the first trial spacer is configured to receive the proximal post of the second trial spacer therein, and
• wherein the first trial spacer is configured to be axially pushed onto the second trial spacer such that, when the first trial spacer is axially pushed onto the second trial spacer, the shoulder of the second trial spacer forces the prong of the first trial spacer to flex outwardly and, when the interior protrusion of the prong of the first trial spacer clears the shoulder of the second trial spacer, the prong of the first trial spacer snaps back so that the interior protrusion of the prong of the first trial spacer is received within the divot of the second trial spacer and is in abutment with the shoulder of the second trial spacer.