Introduction. The prevalence of ipsilateral total hip arthroplasty (THA) and total knee arthroplasty (TKA) is rising in concert with life expectancy, putting more patients at risk for interprosthetic femur fractures (IPFF). Our study aimed to assess treatment methodologies, implant survivorship, and clinical outcomes of patients with IPFF. Methods. 77 patients treated for an IPFF from 1985–2017 at a single large referral center were reviewed. Prior to the fracture, at the hip/knee sites respectively 46 femurs had primary/primary, 21 had revision/primary, 3 had primary/revision and 7 had revision/revision components. Mean age and BMI were 74 years and 30 kg/m. 2. , respectively. Mean follow-up after fracture treatment was 7 years. Results. Sixty fractures were classified as Vancouver C (UCS D) while 17 were Vancouver B (UCS B). Fifty-seven patients (74%) were treated with ORIF; 3 developed a non-union, 3 developed a PJI, and 2 developed aseptic loosening. Nineteen patients (25%) were treated with revision arthroplasty including: 13 revision THAs, 4 distal femoral replacements, 1 revision TKA, and 1 total femoral replacement of which 2 developed aseptic loosening and 2 developed a non-union. Survivorship free from any reoperation for the entire cohort was 79% at 2 years. Patients in the ORIF group who went on to union tended to have stemmed components and greater interprosthetic distance (IPD=189mm vs. 163mm, p=0.55) than non-united fractures. Patients who went on to nonunion in the revision arthroplasty group had higher medullary diameter: cortical width ratio (2.5 vs. 1.3, p=0.01) and lower IPD (36mm vs. 202mm, p=0.002). 95% of patients were ambulatory at latest follow-up. Conclusion. Interprosthetic femur fractures are technically and biologically challenging cases. An individualized approach of internal fixation versus revision arthroplasty led to a 79% success rate free of reoperation at 2 years with 95% of patients ambulatory. Continued improvements in management are warranted