ObjectivesThe purpose of this study was to analyze mid- to long-term outcomes of total hip arthroplasty (THA) following failed internal fixation of femoral neck fracture.MethodsThis study retrospectively analyzed 345 patients with femoral neck fracture who underwent THA after failure of internal fixation at our hospital between January, 2003 and December, 2019. Patients older than 55 years (n = 175) and patients no older than 55 years (n = 170) were compared in terms of complications and survival rates during follow-up, which lasted a mean of 6 years.ResultsThe two age groups showed similarly low incidence of complications and similarly long periods of survival without revision surgery. Only three younger patients and two older patients underwent revision surgery during follow-up. The two groups showed similarly high survival rates at the end of follow-up (> 93%). Younger patients showed significantly bettter Harris hip score at last follow-up (90.2 vs. 88.1 points, p < 0.001) without clinically significant difference, but they required THA significantly earlier after internal fixation (4.4 vs. 6.8 years, p < 0.001).ConclusionsTHA after failed internal fixation of femoral neck fracture is a well tolerated and effective procedure in older and younger patients.