BackgroundHip fracture in older patients leads to high morbidity and mortality. Patients who are treated surgically but fail acutely face a more complex operation with conversion total hip arthroplasty (THA). This study investigated mortalities and complications in patients who experienced failure within one year following hip fracture surgery requiring conversion THA. MethodsPatients aged 60 years or more undergoing conversion THA within one year following intertrochanteric or femoral neck fracture were identified and propensity-matched to patients sustaining hip fractures treated surgically but not requiring conversion within the first year. Patients who had two-year follow-up (91 conversions; 247 comparisons) were analyzed for 6-month, 12-month, and 24-month mortalities, 90-day readmissions, surgical complications, and medical complications. ResultsNonunion and screw cutout were the most common indications for conversion THA. Mortalities were similar between groups at 6 months (7.7% conversion versus 6.1% nonconversion, P = .774), 12 months (11% conversion versus 12% nonconversion, P = .999), and 24 months (14% conversion versus 22% nonconversion, P = .163). Survivorships were similar between groups for the entire cohort and by fracture type. Conversion THA had a higher rate of 90-day readmissions (14% versus 3.2%, P = .001), and medical complications (17% versus 6.1%, P = .006). Inpatient and 90-day orthopaedic complications were similar. ConclusionConversion THA for failed hip fracture surgery had comparable mortality rates to hip fracture surgery, with higher rates of perioperative medical complications and readmissions. Conversion THA following hip fracture represents a potential “second hit” that both surgeons and patients should be aware of with initial decision-making.