Individual postoperative and preoperative workflow for patients with fractures of the lower extremities.

Background: The individual assessment of the postoperative healing situation contributes significantly to detecting healing disorders, ensuring the mechanical stability of implants, and planning revision surgeries.

Methods: Our established workflow consists of the following steps: (1) Monitoring of the patients during their treatment course with a motion capturing system as kinematic and sensor insoles for the kinetic gait analysis, (2) transfer of the motion data into the musculoskeletal simulation system AnyBody™ to achieve the corresponding individual muscle and joint forces. (3) Clinical imaging of the patients via postoperative computed tomography 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 meshes of the bone-implant systems, including the material parameters based on Hounsfield units and calibration phantom via the software ScanIP™. (5) Based on the patient-specific model, all information from the musculoskeletal simulation and gait analysis is transferred to our biomechanical simulation process as patient-specific constraints.

Findings: This workflow allows us to simulate individual patient models based on their respective actual motion data over their treatment course. Thus, pathological processes that may lead to non-healing fractures can be detected early after surgery and prevented by adapting the postoperative treatment protocol. Furthermore, it is possible to understand the forces that affect the fracture and its healing process permanently in more detail.

Interpretation: The findings demonstrate that the individual motion parameters and fracture morphology influence the local healing parameters and create individual weight-bearing recommendations.