Intramedullary Nail Breakage and Mechanical Displacement in Patients with Proximal Femoral Fractures: A Commercial and Medicare Supplemental Claims Database Analysis

OBJECTIVE: This study evaluated the rates and patterns of intramedullary nail (IMN) breakage and mechanical displacement for proximal femur fractures and the factors associated with their occurrence. PATIENTS AND METHODS: Patients with subtrochanteric, intertrochanteric, or basicervical femoral neck fractures treated with IMN from 2016 to 2019 were identified from commercial and Medicare supplemental claims databases and were followed for up to two years. Kaplan–Meier analysis estimated the cumulative incidence of and patterns of breakage/mechanical displacement. Multivariable Cox regression models evaluated the factors associated with breakage/mechanical displacement. RESULTS: A total of 11,128 patients had IMN fixation for subtrochanteric, intertrochanteric, or basicervical femoral neck fractures: (mean SD) age 75.6 (16.4) years, 66.2% female, 74.3% Medicare supplemental vs 26.7% commercial insurance. Comorbidities included hypertension (62.9%), osteoporosis (27.3%), cardiac arrhythmia (23.1%), diabetes (30.7%), and chronic pulmonary disease (16.3%). Most fractures were closed (97.2%), intertrochanteric or basicervical femoral neck (80.1%), and not pathological (91.0%). The cumulative incidence of nail breakage over two years was 0.66% overall, 1.44% for combination fractures, 1.16% for subtrochanteric fractures, and 0.49% for intertrochanteric or basicervical fractures. The cumulative incidence of mechanical displacement was 0.37% overall, 0.43% for subtrochanteric fractures, 0.42% for combination fractures, and 0.36% for intertrochanteric or basicervical femoral neck fractures. Half of the breakages occurred within five months after surgery and half of the mechanical displacements occurred within 75 days. Age 50–64 (vs 75+) and subtrochanteric or pathological fracture were more commonly associated with nail breakage. Complicated hypertension was more commonly associated with mechanical displacement. CONCLUSION: The incidence of IMN breakage and mechanical displacement in US commercial and Medicare supplemental patients with proximal femur fractures from 2016 to 2019 was low (0.66% and 0.37%, respectively up to two years). Age 50–64 (vs 75+) and subtrochanteric or pathological fracture were more commonly associated with breakage. Complicated hypertension was associated with mechanical displacement.