ObjectiveTo retrospectively compare the mid-term effectiveness between by direct anterior approach (DAA) and by posterolateral approach in total hip arthroplasty (THA).MethodsBetween January 2009 and December 2010, 110 patients (110 hips) treated with THA and followed up more than 5 years were chosen in the study. THA was performed on 55 patients by DAA (DAA group), and on 55 patients by posterolateral approach (PL group). There was no significant difference in gender, age, body mass index, types of hip joint disease, and preoperative Harris score between 2 groups (P>0.05). The operation time, amount of bleeding, length of hospital stay, postoperative complications, and the Harris scores were recorded and compared.ResultsThere was no significant difference in operation time and length of hospital stay between 2 groups (t=0.145, P=0.876; t=1.305, P=0.093). The amount of bleeding was significantly less in DAA group than in PL group (t=2.314, P=0.032). All patients were followed up 5-7 years (mean, 5.97 years). Complications happened in 5 cases (9.1%) of DAA group and in 3 cases (5.5%) of PL group, and there was no significant difference in the incidence of complications between 2 groups (χ2=0.539, P=0.463). There was significant difference in Harris scores at 6 months after operation between 2 groups (t=2.296, P=0.014), but no significant difference was found in Harris score at 1 year and 5 years between 2 groups (t=1.375, P=0.130; t=0.905, P=0.087). Further analysis, at 6 months after operation, the joint function score in DAA group was significantly higher than that in PL group (t=1.087, P=0.034), while there was no significant difference in the pain score and range of motion score between 2 groups (t=1.872, P=0.760; t=1.059, P=0.091).ConclusionTHA by DAA has the advantages of less bleeding and faster recovery. The short-term effectiveness is superior to the THA by traditional posterolateral approach, but there is no obvious advantage in the mid-term effectiveness.