Alt Ekstremite Mekanik Aks Değişimleri Sonucu Oluşan Varus ve Valgus Pozisyonlarında Tibia Kıkırdağı Üzerindeki Yük Değişimlerinin Değerlendirilmesi: Sonlu Eleman Model Çalışması

Abstract

Objective: To evaluate changes in the loading of tibial articular cartilage following varus and valgus mechanical axis of lower extremity. Methods: Three- Dimensional (3D) solid models were created on MIMICS® by using DICOM formatted longitudinal computed tomography scans. Respectively 2.5°, 5°, 7.5°, 10°, 12.5° and 15° varus and valgus osteotomies were performed to 3D solid models. ANSYS WorkbenchTM (Version 12) was used to analyze the stress/load distribution, that is to say MES (maximum equivalent stress- von Mises stres), which affect the tibia cartilage in the finite element model obtained by MIMICS. Results: MES of the tibial cartilage was measured 0.860 MPa in the reference model. With regard to the varus models, MES was measured 0.935 MPa in 2.5° varus model, 1.010 MPa in 5°, 1.113 MPa in 7.5°, 1.247 MPa in 10°, 1.388 MPa in 12.5° and 1.530 MPa in 15° varus model. MES was measured 0.813, 0.792, 0.769, 0.745, 0.718 and 0.690 MPa in 2.5°, 5°, 7.5°, 10°, 12.5° and 15° valgus osteotomy models respectively (p=0.028). Conclusion: MES increased in all models of varus position when was compared with reference and valgus models. The decrease of load bearing on tibial articular cartilage in valgus position was lower and statistically different than the reference and varus models. This study clearly showed that tibia cartilage is more sensitive to load bearing in varus position than the valgus positioned lower extremity mechanical axis