Effect of acetabular defect on hip stress in adults: three-dimensional finite element analysis / 中国组织工程研究

ABSTRACT

BACKGROUND: Acetabular defect is one of the typical characteristics of adult developmental dysplasia of the hip. The acetabular defect caused an insufficient coverage to the femoral head, which means the contact area between them decreased and the pressure increased. Stress concentration could quicken hip wear and lead to arthritis or dislocation of the hip. Till now, there is no accepted objective criterion about what degree defect could lead to biomechanics changes in the hip. OBJECTIVE: To analyze the influence of different degrees of acetabular defect on the stress distribution of hip joint by using three-dimensional finite element method, and provide theoretical guidance for clinical treatment of hip dysplasia. METHODS: CT thin layer scanning data of normal adult hip were selected. Hip dysplasia models with varying degrees of bone defect were built by using Mimics15.0 and Hypermesh software. Von Mises stress distribution on the subchondral bone of the hip was analyzed by using Ansys10.0 software in the case of single foot touchdown. RESULTS AND CONCLUSION: Each model result was consistent with the actual situation. The maximum Von Mises stress value appeared at the top of the acetabulum dome and medial posterior femoral neck. When simulating one leg standing, the smaller the CE angle, the greater the maximum Von Mises stress on femoral head was; and acetabulum increased from 2.768 MPa and 3.029 MPa with 30° CE angle to 11.075 MPa and 15.322 MPa with 5° CE angle. This change was more obvious when CE angle was less than 15°. These findings confirmed that acetabular defect increases the peak stress of the hip joint, and the greater the defect, the greater the stress was. It is suggested that clinical intervention should be done as early as possible in patients with acetabular defect.