BACKGROUND:Direct anterior approach has been reported to be associated with a risk of reaming the anterior column of the acetabulum,but there is little evidence supporting this opinion.OBJECTIVE:To reveal differences in the bone stock of the anterior and posterior columns between the direct anterior approach and the posterolateral approach in total hip arthroplasty by CT measurement.METHODS:Sixty cases of primary total hip arthroplasty through direct anterior approach (n=30) or posterolateral approach (n=30) at Fuzhou Second Hospital of Xiamen University from October 2015 to December 2017 were enrolled.The cross-sectional area of the anterior and posterior column of the acetabulum,the height of the anterior and posterior column,acetabular diameter,and anteversion were measured by CT.All researchers had 5-10 years of clinical experience,and the surgeons were associate chief physicians or above.The trial has been approved by the Ethics Committee of Fuzhou Second Hospital of Xiamen University on June 1,2017.All patients signed the written informed consents.RESULTS AND CONCLUSION:(1) The postoperative cross-sectional area of the anterior and posterior column of the acetabulum,and the height of the anterior and posterior column in the two groups were less than those at baseline (P ＜ 0.05),the acetabular diameter was larger than that at baseline (P ＜ 0.01),and the anteversion showed no significant difference (P ＞ 0.05).The area of the anterior column in the direct anterior approach group was higher than that in the posterolateral approach group (P ＜ 0.05),and other parameters were insignificantly different between two groups (P ＞ 0.05).(2) in summary,compared with posterolateral approach in total hip arthroplasty,direct anterior approach leads to increased area of the anterior column,and made no effect on other parameters.Thereafter,direct anterior approach is not a risk factor for eccentric reaming the anterior column of acetabulum,and the conclusion needs to be confirmed by multicenter,prospective randomized controlled trials.