Objective: To compare the clinical and radiologic results between primary total hip replacement arthroplasty (THRA) in patients with avascular necrosis of femoral head (AVN) and secondary THRA in patients with fixation failure of femoral neck fracture.Methods: From March 2014 to February 2021, we retrospectively evaluated a total of 53 patients who underwent either THRA for AVN (33 cases) or THRA for fixation failure of femoral neck fracture (20 cases). Clinical performances and Hemodynamic scales were evaluated. Radiologic analyses were conducted to assess stem alignment, stem stability, the appearance of heterotrophic ossification, stress shielding, and any signs of osteolysis or loosening.Results: THRA for AVN showed a mean blood loss of 881 mL and a 2.1 g/dL preoperative–postoperative (preop–postop) hemoglobin (Hb) difference. Meanwhile, THRA for fixation failure of femoral neck fracture showed a mean blood loss of 1,072 mL and a 3.2 g/dL preop–postop Hb difference (P= 0.017 and P= 0.034, respectively). The mean operation time was 70 minutes in THRA for AVN and 91 minutes in THRA for fixation failure of femoral neck fracture (P= 0.035). Stem alignment was varus 1.50° in AVN and varus 3.50° in fixation failure of femoral neck fracture. There was one case of a varus femoral stem in AVN and six such cases in the fixation failure of femoral neck fractures. This was a statistically significant difference (P= 0.010 and P= 0.020, respectively).Conclusion: Secondary THRA in patients with fixation failure of femoral neck fracture showed longer operation time, larger bleeding, and more varus stem alignment than primary THRA in patients with AVN.