Objective:To determine the operation procedure of THA for Crowe type-Ⅳ developmental dysplasia of hip and its relationship with nerve injury.Methods:A consecutive series of 39 THAs was performed for Crowe type-Ⅳ developmental dyaplasia of hip in 35 patients(all female).The mean age of the patients at the time of surgery was 49.l years(range 36~ 56years).Thirty-five hips in 31 patients were followed up.The average follow-up period of the whole series was 4.2 years (range 1~ 7.5years).Each patient was evaluated clinically and by radiographs before the operation and during the follow-up period,according to the Harris hip score(HHS),All procedures were carried out through a lateral-posterior approach.In 33 of 35 hips,the cup was inserted in the "true" acetabulum.All the prostheses used were cementless,except for 5 cemented femoral stems in 5 patients.