Biomechanical effects of surgical muscle damage on spinal stability and the stress acting on adjacent segments following lumbar spinal fusion

• Applicant: Professor Dr. Hans-Joachim Wilke
• Subject Area: Orthopaedics, Traumatology, Reconstructive Surgery ; Clinical Neurology; Neurosurgery and Neuroradiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 558083832

Accelerated degeneration of the adjacent spinal segments after surgical fusion, also known as Adjacent Segment Degeneration (ASD), is one of the most common postoperative complications in spine surgery. In many cases, additional surgery is necessary to treat the consequences of ASD. Moreover, the mechanisms by which ASD develops are still an unresolved problem in spine research. While various causes are being discussed, the most common hypothesis is that segmental fusion leads to increased movement and stress in the adjacent segments if the patient moves postoperatively to the same extent as preoperatively. However, it is still unclear which role the muscles injured during surgery play in the development of ASD. To develop strategies for the prevention of ASD, biomechanical models are therefore required that adequately consider the complex loading of the individual segments by muscle forces and body weight. The aim of this research project is therefore to investigate the influence of healthy and damaged back muscles on the stability of the lumbar spine and the relevance of the musculature for ASD clinically, experimentally, and numerically. For this purpose, clinical MRI images of ASD patients are analyzed regarding their muscle integrity using artificial intelligence and compared with a control group of volunteers without any previous spine surgeries. In addition, in vitro studies will be performed on human donor specimens to investigate the influence of muscle forces and the influence of fusion and motion-preserving implants on the stability and kinematics of the spine. The findings from the clinical data analysis on muscle integrity will be experimentally simulated to biomechanically investigate the influence of surgically induced muscle trauma. In addition, the in vitro studies are used to create specimen-specific finite element models and to validate their biomechanical properties. The numerical replication of the in vitro studies makes it possible to analyze the stresses and strains in the spinal structures in detail and to draw conclusions about possible overloading. The muscle forces required for the in vitro and in silico studies are calculated as part of a collaboration with the University of British Columbia using musculoskeletal multi-body models to guarantee physiological loads on the spine. The multimodal approach of this research project aims to better understand the mechanisms of ASD development and create a biomechanical basis for the prevention of ASD.

• DFG Programme: Research Grants