PhD Scientific Days 2021

CL_VII_L: Clinical Medicine VII. Lectures

Finite Element Study of the Closed Loop Reconstruction Technique Method Following Total Sacrectomy

Text of the abstract

Introduction
Chordoma is often resistant to radiation- and chemotherapy. In order to achieve an optimal oncological result, en bloc resection is required via a surgical procedure. After total sacrectomy the connection between the lumbar spine and the pelvis must be re-established. The surgical stabilization implemented in this study uses the closed loop technique (CLT) developed at the National Center for Spinal Disorders, Budapest.
Aims
The aim of this study was to develop a complex finite element (FE) model of CLT and to compare the lumbo-pelvic motion and the implant stresses to the results of different reconstruction systems.
Method
The geometry of the lumbar spine and the pelvis of a 24 years old male patient were developed using a series of computed tomography scans. The position of the ilia were modified in accordance to the surgery. Subsequently the osseoligamentous FE model of the lumbar spine was developed and validated. CLT was implemented into the model and was tested against multiple defined load cases from the literature.
Results
The simulation results were compared to previously published values. The maximum von Mises stress at CLT is in the same range as the previously published results. Vertical displacement and rotations show broader variety among the different models.
Conclusion
The limitations of this FE study are well known. In order to compare all reconstruction systems to the CLT own calculations are required. The results of the analysis show that the lumbo-pelvic motion can be reduced with the application of CLT. Higher stress values may induced, but remain under the yield strength of the implant material. The developed model can help choosing the right reconstruction system individually for patients undergoing total sacrectomy.
Funding
Prepared with the professional support of the doctoral student scholarship program of the co-operative doctoral program of the ministry of innovation and technology financed from the national research, development and innovation fund.

University and Doctoral School

Semmelweis University, Károly Rácz Doctoral School of Clinical Medicine