BackgroundIndications for total hip arthroplasties (THA) differ from primary osteoarthritis (OA), which allows elective surgery through femoral neck fractures (FNF), which require timely surgical care. The aim of this investigation was to compare mortality and revisions in THA for primary OA and FNF.MethodsData collection for this study was performed using the German Arthroplasty Registry (EPRD) with analysis THA for the treatment of FNF and OA. Cases were matched 1:1 according to age, sex, body mass index (BMI), cementation, and the Elixhauser score using Mahalanobis distance matching.ResultsOverall 43,436 cases of THA for the treatment of OA and FNF were analyzed in this study. Mortality was significantly increased in FNF, with 12.6% after 1 year and 36.5% after 5 years compared with 3.0% and 18.7% in OA, respectively (p< 0.0001). The proportion for septic and aseptic revisions was significantly increased in FNF (p< 0.0001). Main causes for an aseptic failure were mechanical complications (OA: 1.1%; FNF: 2.4%;p< 0.0001) and periprosthetic fractures (OA: 0.2%; FNF: 0.4%;p= 0.021). As influencing factors for male patients with septic failure (p< 0.002), increased BMI and Elixhauser comorbidity score and diagnosis of fracture (allp< 0.0001) were identified. For aseptic revision surgeries, BMI, Elixhauser score, and FNF were influencing factors (p< 0.0001), while all cemented and hybrid cemented THA were associated with a risk reduction for aseptic failure within 90 days after surgery (p< 0.0001).ConclusionIn femoral neck fractures treated with THA, a significant higher mortality, as well as septic and aseptic failure rate, was demonstrated compared with prosthesis for the therapy of osteoarthritis. Increased Elixhauser comorbidity score and BMI are the main influencing factors for development of septic or aseptic failure and can represent a potential approach for prevention measures.Level of evidence: Level III, Prognostic.