Robotic Surgical System With Density-Based Trajectory Planning And Guidance

A non-transitory computer-readable medium storing instructions to plan preparation of a bone to receive an implant that includes screw openings, wherein the instructions are executable by one or more processors to:

• obtain a surgical plan that includes a planned resection plane of the bone, a planned location of the implant relative to the planned resection plane, and a planned location of the screw openings;
• obtain a bone mineral density (BMD) distribution of the bone comprising a plurality of voxels each associated with a density value;
• identify, from the BMD distribution, a subset of the voxels that encompass a region of the bone below the planned resection plane;
• based on the planned location of each screw opening, group selected voxels of the subset into a plurality of candidate voxel clusters, each candidate voxel cluster comprising adjacent selected voxels extending into the region below the planned resection plane;
• compute, for each candidate voxel cluster, a collective density metric based on the density values of the selected voxels of the candidate voxel cluster;
• select, for each screw opening, the candidate voxel cluster having the collective density metric greater than collective density metrics of other candidate voxel clusters associated with the screw opening;
• and
• determine, based on each selected candidate voxel cluster, a target trajectory for a screw to be inserted through the corresponding screw opening, the target trajectory passing through the selected candidate voxel cluster.

A robotic surgery system for preparing a bone to receive an implant that includes screw openings, wherein the implant secures to the bone with screws that are inserted through the screw openings, the robotic surgery system comprising:

• a robotic manipulator;
• a first cutting tool and a second cutting tool configured to be interchangeably coupled to the robotic manipulator;
• a controller coupled to the robotic manipulator and configured to:
• obtain a surgical plan that includes a planned resection plane of the bone, a planned location of the implant relative to the planned resection plane, and an initial planned location of the screw openings;
• operate the robotic manipulator to control movement of the first cutting tool to resect the bone according to the planned resection plane and to create a resected bone surface;
• obtain a bone mineral density (BMD) distribution of the bone comprising a plurality of voxels each associated with a density value;
• identify, from the BMD distribution, a subset of voxels that encompass a region of the bone below the resected bone surface;
• group selected voxels of the subset into a plurality of candidate voxel clusters, each candidate voxel cluster comprising adjacent selected voxels extending into the region below the resected bone surface;
• compute, for each candidate voxel cluster, a collective density metric based on the density values of the voxels of the candidate voxel cluster;
• select one or more of the candidate voxel clusters having greater collective density metrics than other candidate voxel clusters;
• based on the one or more selected candidate voxel clusters, determine an updated planned location of the screw openings;
• determine, for each screw opening, a target trajectory for the screw to be inserted through the screw opening at the updated planned location, wherein at least one of the target trajectories extends through the one or more selected candidate voxel clusters;
• associate a virtual line haptic object with each target trajectory;
• and
• operate the robotic manipulator to guide movement of the second cutting tool relative to each virtual line haptic object to form pilot holes in the bone for the screws in preparation for securing the implant to the resected bone surface using the screws.