Individual Postoperative And Preoperative Workflow For Patients With Fractures Of The Lower And Upper Extremities

  • Wickert, Kerstin (Saarland University - Applied Mechanics)
  • Andres, Annchristin (Saarland University - Applied Mechanics)
  • Roland, Michael (Saarland University - Applied Mechanics)
  • Braun, Benedikt (University Hospital BG Tuebingen)
  • Histing, Tina (University Hospital BG Tuebingen)
  • Diebels, Stefan (Saarland University - Applied Mechanics)

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Interfragmentary movement (IFM) is a key quantity for fracture healing and determined by the gait cycle and the weight bearing of the patient. Only personalized simulations can identify the effect of different partial weight bearing regimes on the IFM of individual patients. The individual assessment of the postoperative healing situation contributes significantly to the detection of healing disorders, the mechanical stability of implants and the preoperative planning of surgery. Our established workflow consists of the following steps: (1) Monitoring of the patients during the planning and follow-up visits with a motion capturing system as kinematic analysis and sensor insoles for the kinetic gait analysis, (2) transfer of the motion data into the musculoskeletal simulation system (Figure 1 a)) to achieve the corresponding individual muscle and joint forces, as well as moments. (3) Clinical imaging of the patients if available via post-operative computed tomography (CT) scans ideally combined with a six-rod bone density calibration phantom. (4) Segmentation of the CT images and generation of the corresponding adaptive finite element (FE) meshes of the bone-implant systems, including the material parameters based on the Hounsfield units and the calibration phantom. (5) All information from the musculoskeletal simulation and kinetic analysis is transferred as patient-specific constraints to our biomechanical FE simulation process based on the patient-specific mesh. This workflow allows us to simulate individual patient models based on their respective real motion data over their treatment course (Figure 1b) and c)). Thereby pathological processes, which may lead to the development of non-unions, can be detected at an early time point after surgery and may be prevented by early adaption of the postoperative treatment protocol. Furthermore, it is possible to understand the forces that affect the fracture and its healing process permanently in much more detail. The findings of this analysis demonstrate that the individual motion parameters and the individual fracture morphology have a lasting influence on the local healing parameters and to create individual loading recommendations.