Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024
Influence of surgical mobilization strategies in adolescent idiopathic scoliosis on the range of motion (#227)
INTRODUCTION
The surgical correction of adolescent idiopathic scoliosis (AIS) involves multiple resections steps to mobilize the spine. The amount and severity of the resected structures varies strongly between surgeons, while the efficacy of resections have shown contradictory results in literature. Particularly for in-vitro investigations only non-deformed spines are usually available. The goal of this study was, therefore, to quantify the effect of different surgical mobilization strategies using finite element models of AIS-deformities.
METHODS
In a previous study we have documented the different surgical mobilization strategies of thirty-two surgeons on specific AIS-patient cases using a questionnaire. Theses mobilization strategies were now analyzed using parametric Finite-Element models of healthy and five AIS-deformities. First, the FE-model was calibrated with in-vitro experiments, which performed on non-deformed human spines. Then, FE-models of AIS-curvatures of different AIS-patients were modeled. The efficacy of the resection steps was quantified using the range of motion (ROM) under pure moments of 2.5 Nm in flexion-extension, lateral bending and axial rotation. In addition, the morphology of the spinal deformities was quantified and correlated with the calculated ROM.
RESULTS
Facetectomies of non-deformed spines increased the ROM in axial rotation to 110% (+/- 10%) compared to the intact state, which is in line with in-vitro data. Facetectomies performed at the apex level (here T8) of the AIS-deformities, increased the ROM to 200% (+/- 68%) in axial rotation to the left. The higher the cobb-angle, the stronger was the effect of the facetectomy. Main influence on the ROM had the facet angle within the transverse plane of the facet joint on the concave side (figure 1).
DISCUSSION
The results indicate that the effect of mobilization depend on the severity of the deformity. Main reasons for the decreased ROM seem to be morphological characteristics, such as facet angle. Therefore, it is important to consider curve-severity when planning and conducting mobilization strategies.