Objective: To assess the functions of intervertebral discs on the lateral bending of the spine in deformed thorax model, and to improve the reliability of the minimally invasive correction surgery for treating pectus excavatum.
Background: Clinical outcomes demonstrate that improvement of scoliosis after surgery correction does not meet expected results if the influences of intervertebral discs have not been taken into account during pre-surgery numerical simulation of pectus excavatum with scoliosis.
Method: Two thorax models were reconstructed based on the computed tomographic (CT) data, which included the deformed (pectus excavatum with scoliosis) models with and without intervertebral discs. In order to study the effects of these discs on the lateral bending of the spine, a 40 mm correcting displacement was applied on the sagittal plane of the sternum of the deformed thorax models.
Results: The result of the lateral displacement of the spine was smaller in the deformed thorax model with discs (2.1 mm) than without discs (2.7 mm). After correction, the Cobb angle of the deformed thorax with discs was 13°, whereas the Cobb angle was 11° in the model without discs. Actually the clinical correction result was 15°.
Conclusion: Intervertebral discs decrease the lateral bending of the spine in the deformed thorax model. The computed results demonstrate that intervertebral discs play a critical role in the lateral bending of the spine of deformed thorax models. Thus, the influence of intervertebral discs should be considered in numerical model and simulation of minimally invasive correction surgery of pectus excavatum with scoliosis.