An interactive osteotomy platform for automated planning of 3d multiplanar leg malalignment-correcting osteotomies
Quinten Veerman (ET-BDDP, OCON Orthopaedic Centre)
Gabriëlle Tuijthof (ET-BDDP)
Judith olde Heuvel (OCON Orthopaedic Centre)
Roy Hoogeslag (OCON Orthopaedic Centre)
Abstract
Introduction 3D imaging technologies allow for more accurate planning of multiplanar corrective osteotomies around the knee. However, 3D planning introduces complexity. For example, varus/valgus is expressed in the coronal plane of the leg, while posterior tibial slope is expressed in the sagittal plane of the tibia. We present a software platform that deals with this complexity.
Methods A high tibial osteotomy was parametrized using five parameters: hinge axis rotation in axial plane; hinge axis tilt in axial plane; hinge axis position along longitudinal axis; hinge axis distance to cortex; osteotomy opening angle. A MATLAB-algorithm was developed in which the effect of each possible combination of osteotomy parameters was obtained on change in alignment parameters expressed in coordinate systems of the tibia and leg. By finding the set of osteotomy parameters that approaches the predefined change in alignment parameters the closest, a 3D osteotomy planning can be linked to a desired outcome.
Results A digital interactive osteotomy planning platform was developed that automatically computes the required hinge axis orientation and osteotomy opening/closing angle for a given predefined outcome of change in posterior tibial slope and %-weight-bearing-line in the coordinate systems of the tibia and leg, respectively, with an error of <0.1°. During planning, the user is able to manually tweak the osteotomy and is given real-time feedback on the resulting trade-offs.
Conclusion The presented osteotomy planning platform allows for automatic and complex 3D planning of multiplanar leg malalignment correction, while integrating that alignment parameters are measured in different coordinate systems.