Stress Distributions of Hip Cartilage During Gait Cycle and its Effects in Curved Periacetabular Osteotomy / 医用生物力学

ABSTRACT

Objective To study stress distributions of the cartilage around the hip joint in stress environment of complete gait cycle, and explore the optimal correction angle of bone block in curved periacetabular osteotomy (CPO), so as to provide theoretical references for clinical operation. Methods Based on CT scans from a healthy volunteer and a patient with development dysplasia of hip (DDH), the three-dimensional (3D) model including pelvis and proximal femur was reconstructed. The cortical bone and cancellous bone were distinguished by dividing the masks, and the material attributes were assigned to the finite element model. A total of 100 different postoperative models were obtained by simulating CPO in DDH model, by adjusting lateral center edge angle (LCEA) and anterior center edge angle (ACEA). According to hip joint stresses in complete gait cycle, the model was loaded respectively, and stress changes of normal, preoperative and postoperative acetabular cartilage were analyzed and compared. ResultsThe minimum peak contact stresses of acetabular cartilage of DDH patient at heel landing phase, start phase of single leg support, mid phase of single leg support, end phase of single leg support and double support phase after simulated CPO operation were 5.273, 6.128, 7.463, 6.347, 6.582 MPa, which were decreased by 2.159, 2.724, 2.249, 2.164, 2.119 MPa,respectively, compared with those before operation. The contact area between femoral head and acetabulum was significantly increased after operation, but it was still smaller than that of normal volunteers. Conclusions The optimal correction angle of LCEA and ACEA can be obtained by using finite element method, and the simulation of CPO surgery on different patients is of great significance to improve surgical accuracy and efficiency.