Objective To compare the short-term clinical outcomes of secondary total hip arthroplasty (THA) after failure of internal fixation with primary THA in elderly patients with displaced femoral neck fractures, and explore the best treatment for displaced femoral neck fractures in the elderly. Methods A total of 300 elderly patients with displaced femoral neck fractures from January 2011 to January 2015 were retrospectively enrolled in this study, of whom 150 underwent primary THA and 150 underwent secondary THA after failure of internal fixation. The operation time, intraoperative bleeding volume, postoperative drainage volume, postoperative ambulation time, length of postoperative hospitalization, incidence of postoperative complications, and score of postoperative hip joint function were compared between the two groups. Results Compared with those in the secondary THA group, in the primary THA group, the operation time was shorter [(54.7±15.3) vs. (70.1±23.4) minutes], the intraoperative bleeding volume was less [(116.9±35.0) vs. (131.7±44.5) mL], the postoperative ambulation was earlier [(1.0±0.3) vs. (1.8±0.6) days], the length of postoperative hospitalization was shorter [(12.0±2.9) vs. (15.2±3.1) days], and the differences were all statistically significant (P<0.05); but there was no statistically significant difference in the incidence of postoperative complications or the Harris scores at 3, 6, 12, and 24 months after operation (P>0.05). Conclusion The secondary THA for femoral neck fracture is more difficult, with longer stay in hospital, but the short-term clinical efficacy is similar to that of the primary THA.