Methods The investigators conducted a non-randomized comparative study to compare component positioning and clinical outcomes of the consecutive unilateral primary THA patients operated with DAA techniques and that of those operated with micro-PA techniques by a single surgeon. The investigators used DAA techniques with standard operation table and micro-PA techniques featuring indirect-contracture-releasing capsulotomy, preservation of short external rotators except piriformis and conjoint tendon, and tendon-to-bone capsulotendinous repair. The investigators used propensity-score matching analysis to compare the postoperative THA component positioning and clinical outcomes in DAA and micro-PA groups.