Biomechanical Design of an Intervertebral Disc Arthroplasty Implant

Date

2026-1-19

Author

Ngabonziza Hirwa, Jean Aimé Tony

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The intervertebral disk acts as a joint situated between each of the 26 bones comprising the vertebral column. This column provides support for the trunk and safeguards the spinal cord. Furthermore, the intervertebral disk is critical in providing flexibility to the vertebral column and cushioning impact from common activities such as walking, running, and jumping. The intervertebral disc ages and degenerates faster than any other connective tissue in the body, resulting in back pain. Current therapies include surgical interventions (total disc replacement) to restore functional joints, similar to knee replacement procedures known as arthroplasty. The new intervertebral disc that replaces the degenerated one needs to be biomechanically designed to sustain all the functions that the old one brought to the spine and body. The new intervertebral disc is known as an implant. This study consists of designing an intact disc and an implant (Mobi-C), using Finite element modelling with a simple vertebra disc FE model approach inspired by Lee et al. (2000), the models are meshed within MSC Marc/Mentat software where the boundary conditions are applied and different parameters are recorded. The most notable parameter in this study is range of motion (ROM). Apply similar boundary conditions to both FE models, a pure moment of 1.5 N.m at a node point on the C5 vertebra and a preload of 57.879 N on the C5 top surface while the C6 vertebra is entirely fixed, to observe the change in their kinematic motion needed at the C5-C6 segment. The main objective is to validate the implant FE model with experimental results of a real-life disc. The intact FE model predicted 11.60°/10.07° flexion/extension, 9.38˚–9.39° lateral bending, and 8.61° axial rotation while the implant FE model predicted 9.10°/8.18°, 10.82°–12.39°, and 9.40°–10.69°, respectively, indicating 15–20% lower flexion–extension, 10–30% increase in lateral bending and axial rotation when comparing with the intact FE model. These ROM values lay within published experimental corridors for intact/normal C5–C6 disc, supporting the primary experimental validation objective.

Subject Keywords

Arthroplasty, C5-C6 Disc, Finite Element Analysis, Implant, Mobi-C

URI

https://hdl.handle.net/11511/118755

Collections

Northern Cyprus Campus, Thesis