Robotic system for shoulder arthroplasty using stemless implant components

A method of operating a robotic surgery system for preparing a bone to receive a stemless implant having a proximal body defining a center axis and an eccentric distal projection configured for attachment to the bone, wherein the eccentric distal projection is offset from the center axis by a non-zero offset distance, the robotic surgery system including a robotic manipulator, a cutting tool to be coupled to the robotic manipulator, a localizer configured to track movement of the cutting tool and the bone, and a controller coupled to the robotic manipulator and the localizer, the method comprising the controller performing the steps of:

• operating the robotic manipulator for controlling movement of the cutting tool relative to the bone to resect the bone and to expose a resected bone area;
• determining, based on density data of the bone, a first region of cancellous bone of the resected bone area and an adjacent second region of cancellous bone of the resected bone area, wherein the first region has a greater density than the second region;
• identifying, relative to the resected bone area, a virtual placement circle having a radius corresponding to the offset distance, wherein a plurality of locations are defined along the placement circle, and wherein when the eccentric distal projection is placed at any of the plurality of locations along the placement circle, the proximal body is configured to remain centrally positioned on and configured to cover the resected bone area;
• defining a virtual object relative to the resected bone area, wherein the virtual object is located on the virtual placement circle and within the first region of cancellous bone of the resected bone area;
• and
• operating the robotic manipulator for controlling movement of the cutting tool based on the virtual object to remove additional material from the resected bone area to enable placement of the eccentric distal projection within the first region of cancellous bone of the resected bone area.