Reverse shoulder surgery and method

An offset tool for determining a desired size of an adapter for use with a humeral implant, the offset tool comprising:

• a trial tray configured to be coupled with a humeral implant site, the trial tray comprising an opening at a distal portion thereof;
• an outer shaft having a distal end and a proximal end, the distal end having an aperture to a channel within the outer shaft, the distal end having a dimension larger than a dimension of the opening such that the distal end is configured to abut the trial tray at a proximal surface thereof, and
• an inner shaft having an inner shaft proximal portion and an inner shaft distal portion, the inner shaft proximal portion configured to move telescopically within the channel of the outer shaft, such that the inner shaft is configured to extend from the outer shaft and through the opening towards a stem disposed in a humeral stem;
• wherein, when the inner shaft distal portion abuts an inner surface of a cavity of the stem and the outer shaft distal end abuts the trial tray coupled to the implant site, the desired size of the adapter corresponds with a depth therebetween.