Computer-assisted method and system for planning an osteotomy procedure

A system for planning an osteotomy procedure on at least one bone selected from a tibia and a femur of a patient's lower limb to correct a misalignment of said lower limb, in which said bone is to be partially cut into two bone portions articulated by a hinge zone, said bone portions are to be distracted or closed until a deformed configuration of the bone and an implant is to be screwed to said bone portions to maintain the bone in said deformed configuration, said system comprising at least one processor and at least one user interface coupled to the at least one processor,

• wherein the at least one processor is configured to:
• obtain an at least partial 3D model of the tibia and the femur and a 3D model of the implant;
• receive at least one user input via the user interface comprising at least one target alignment parameter;
• based on the at least partial 3D model of each bone and the at least one user input, implement a dynamic simulation of each cut and of distraction or closing of the bone portions to compute a deformed model of each bone to be cut resulting from the simulated cut(s) and distraction or closing taking into account predefined rules relating to a ration between cut and uncut areas, said dynamic simulation comprising a simulation of the movement of the bone portions from an initial position prior to each bone cut to a final position defining the deformed configuration of the bone achieving a corrected alignment of the limb and preserving a hinge zone connecting the bone portions;
• and
• based on the deformed bone model(s) and the at least partial 3D model of the implant, compute an optimal placement of the implant onto the deformed bone.

A computer-assisted method for planning an osteotomy procedure on at least one bone selected from a tibia and a femur of a patient's lower limb to correct a misalignment of said lower limb, in which said bone is to be partially cut into two bone portions articulated by a hinge zone, said bone portions are to be distracted or closed until a deformed configuration of the bone and an implant is to be screwed to said bone portions to maintain the bone in said deformed configuration, comprising:

• obtaining, at a processor of a computer, an at least partial 3D biomechanical model of the tibia and/or the femur and a 3D model of the implant;
• receiving, at the processor, at least one user input comprising at least one target alignment parameter;
• based on the at least partial 3D biomechanical model of each bone and the at least one user input, implementing by the processor a dynamic simulation of each cut and of distraction or closing of the bone portions to compute a deformed model of each bone to be cut resulting from the simulated cut(s) and distraction or closing, said dynamic simulation comprising a simulation of the movement of the bone portions from an initial position prior to each bone cut to a final position defining the deformed configuration of the bone achieving a corrected alignment of the limb;
• and
• based on the deformed bone model(s) and the at least partial 3D model of the implant, computing by the processor an optimal placement of the implant onto the deformed bone;
• wherein the dynamic simulation and the computation of the optimal placement of the implant are based on the at least partial 3D biomechanical model so as to take into account influence of soft tissues onto the deformed bone.

A computer-assisted method for planning an osteotomy procedure on at least one bone selected from a tibia and a femur of a patient's lower limb to correct a misalignment of said lower limb, in which said bone is to be partially cut into two bone portions articulated by a hinge zone, said bone portions are to be distracted or closed until a deformed configuration of the bone and an implant is to be screwed to said bone portions to maintain the bone in said deformed configuration, comprising:

• obtaining, at a processor of a computer, an at least partial 3D model of the tibia and/or the femur and a 3D model of the implant;
• receiving, at the processor, at least one user input comprising at least one target alignment parameter;
• based on the at least partial 3D model of each bone and the at least one user input, implementing by the processor a dynamic simulation of each cut and of distraction or closing of the bone portions to compute a deformed model of each bone to be cut resulting from the simulated cut(s) and distraction or closing, said dynamic simulation comprising a simulation of the movement of the bone portions from an initial position prior to each bone cut to a final position defining the deformed configuration of the bone achieving a corrected alignment of the limb, the movement being decomposed into N phases, N being an integer greater than or equal to 2;
• and
• based on the deformed bone model(s) and the at least partial 3D model of the implant, computing by the processor an optimal placement of the implant onto the deformed bone;
• wherein the dynamic simulation comprises, for each phase:
• computing a transformation matrix to be applied to the position of each point of the at least partial 3D model of the bone to be cut at the beginning of said phase to determine the position of said point at the end of said phase;
• monitoring anatomical features to determine whether a relative position of the bone portions at the end of said phase allows reaching the at least one target alignment parameter.