Abstract: BACKGROUND: Developmental dysplasia of hip causes groin pain in patients with prolonged activity or standing due to the presence of deformities of the acetabulum and femoral head in terms of structure, size and orientation, and if not effectively treated, patients’ normal activities will be severely limited. 
OBJECTIVE: Finite element model of the hip joint of solid-liquid biphase fiber reinforced cartilage based on FEBio was established to explore the biomechanical properties of the cartilage for patients with developmental dysplasia of hip and the normal hip joint.  
METHODS: A patient with developmental dysplasia of hip and a normal volunteer were chosen to build their left hip models including left pelvis, left femur, and cartilage attached thereto. The solid-liquid biphase fiber reinforced cartilage of normal hip was verified to be effective. The cartilage equal contact stress, fluid pressure, solid effective stress, and fluid support rate differences between the developmental dysplasia of hip patients hip and the normal one in the case of one leg of static load (2 130 N) were compared after establishing finite element models of developmental dysplasia of hip patients.
RESULTS AND CONCLUSION: (1) Compared with the finite element results of the normal hip model, the cartilage contact position of developmental hip dysplasia patient hip showed obvious edge contact, the peak contact stress (3.86 MPa) and peak fluid pressure (3.76 MPa) were both higher than normal hip model. (2) After 1 500 s (stable load-bearing capacity), peak contact stress and peak fluid pressure in both models decreased, but the cartilage contact position of developmental hip dysplasia patient hip moved from the edge of cartilage to the center, and fluid support rate decreased from 97.41% to 91.08%. The fluid support rate in normal hip was decreased by 0.58% from 95.24% to 94.66%. (3) It is indicated that under the physiological load of standing on one leg, the cartilage of developmental dysplasia of hip patients showed obvious edge load, and the decrease of peak contact stress, fluid pressure, and fluid formation rate was greater than that of normal cartilage. Considering the solid-liquid biphasic fiber reinforcement characteristics of cartilage, it is of great clinical significance to evaluate the biomechanical properties of hip cartilage in developmental dysplasia of hip patients, to understand the pathophysiological mechanism of developmental dysplasia of hip, and make preoperative plan.

中国组织工程研究杂志出版内容重点：人工关节；骨植入物；脊柱；骨折；内固定；数字化骨科；组织工程

Key words: developmental dysplasia of hip, cartilage, solid-liquid biphase fiber reinforcement, finite element analysis, biomechanics