Abstract: Objective To analyze the changes of gait parameters in patients with Crowe type Ⅳ developmental hip dysplasia (DDH) before and after total hip replacement (THA) with anatomic location and subtrochanteric osteotomy.Methods 46 patients with Crowe type Ⅳ DDH from January 2018 to June 2022 were selected as the observation group.THA was performed in all patients with anabular cup and subtrochanteric osteotomy.Gait tests were performed before surgery and 6 months after surgery.The spatio-temporal parameters,kinematic parameters and dynamic parameters (peak joint torque,peak surface reaction force) before and after treatment were analyzed.Meanwhile,according to age,sex and height,46 healthy subjects were matched as control group.They performed the same gait test.Results Six months after operation,multiple spatio-temporal parameters,kinematic parameters and dynamic parameters in the observation group improved compared with those before operation,and bilateral spatio-temporal parameters,joint torque peak and ground reaction force parameters except the medial peak all tended to be consistent.The bilateral step length,stride frequency,swing period,hip flexion moment,hip extension moment,knee flexion moment,ankle plantar flexion moment,longitudinal peak 1,longitudinal peak 2,forward peak,backward peak,hip maximum flexion,hip maximum extension,hip maximum sagittal range of motion,knee maximum flexion,knee maximum dorsalis extension,ankle maximum malleolus and ankle sagittal range of motion of the observation group were lower than that of the control group before and 6 months after surgery.The bilateral Step time,brace period,maximum knee extension  and intraoperative medial peak of operative side before and 6 months after surgery were higher than that of the control group (P<0.05).Conclusion The gait of patients with Crowe type Ⅳ DDH improve significantly after THA anatomic location and subtrochanteric osteotomy with good symmetry,but there are still some differences from normal patients,suggesting that patients still need to strengthen rehabilitation training to further improve their gait.

Key words: Crowe Ⅳ, developmental hip dysplasia, total hip arthroplasty, anatomic position safety cup, subtrochanteric osteotomy, gait parameter