Mechanical Failure and Revision Risk Following Transition from PFNA to TFNA: A Single-Center Cohort Study of 1,970 Patients

Objectives: To compare implant mechanical failure, cut-out rate, and time to failure between two cephalomedullary nail designs following an institutional transition. Methods: Design: Retrospective consecutive cohort study. Setting: Single Level I trauma center, Israel. Patient Selection Criteria: Patients aged >65 years with acute OTA/AO 31A fractures (subtypes 31A1–31A3) treated with a short cephalomedullary nail with helical blade fixation, either the Proximal Femoral Nail Antirotation (PFNA) or the Trochanteric Fixation Nail-Advanced (TFNA), between January 2018 and May 2025 were included. Implant type was determined solely by an institutional transition from PFNA to TFNA in March 2023 for logistical reasons rather than surgeon preference. Outcome Measures and Comparisons: Implant mechanical failure, cut-out rate, time to failure, body mass index (BMI), and Tip-Apex Distance (TAD) were compared between groups. Mortality within the early revision-risk window was compared between groups to exclude survival bias. Results: The PFNA cohort comprised 1,388 patients (mean age 83.1 years, range 65–102; 986 females [71.0%]) and the TFNA cohort 582 patients (mean age 82.9 years, range 65–107; 407 females [69.9%]); baseline demographics were comparable (age, p=0.691; sex, p=0.626). Orthopedic follow-up was 63.9% for the TFNA cohort versus 61.0% for the PFNA cohort (p=0.24), with a shorter maximum observation period for TFNA (TFNA 26 vs. PFNA 88 months).TFNA was associated with a five-fold increase in implant mechanical failure relative to PFNA (TFNA 1.6% vs. PFNA 0.3%; RR=5.36, 95% CI 1.66–17.3; p=0.005), primarily driven by a four-fold increase in cut-outs (1.2% vs. 0.3%; RR=4.18, 95% CI 1.23–14.2; p=0.027). Failures occurred earlier with TFNA (median 80.0 vs. 244.0 days; p=0.027). Among cut-outs, OTA/AO subtype distribution did not differ (31A1: TFNA 57.1% vs. PFNA 50.0%; no 31A3 in either group; p=1.00); TFNA patients had a higher BMI (median 23.9 vs. 20.1 kg/m 2 ; p=0.024), but mean TAD did not differ (TFNA 24.6 vs. PFNA 21.1 mm; p=0.37). Mortality within the revision-risk window did not differ (TFNA 7.2% vs. PFNA 8.8%; p=0.24). Conclusions: The transition to the Trochanteric Fixation Nail-Advanced (TFNA) was associated with five-fold higher mechanical failure and four-fold higher cut-out rates than the Proximal Femoral Nail Antirotation (PFNA) with earlier failures suggesting reduced mechanical stability of the TFNA during early fracture healing. Heightened vigilance is warranted when using TFNA, particularly in patients with higher body mass index early postoperatively. Level of Evidence: Therapeutic Level III.