Risk Factors of Diaphyseal Femoral Nonunions: A Systematic Review and Meta-analysis.

Abstract

Intramedullary nailing of diaphyseal femur fractures often results in reliable union, with union rates ranging from 96% to 100%. However, femoral nonunions (FNUs) can be a debilitating clinical condition for patients. The purpose of this review was to identify and characterize the predictors of nonunion after femoral midshaft fractures. A systematic search was conducted using key terms "femoral shaft non-union," "femoral diaphyseal non-union," "femoral shaft fracture," "femoral diaphysis fracture," and "femoral midshaft fracture" published before June 2024. Human studies describing risk factors associated with development of FNUs were included. Articles were excluded if not able to assess risk factors of FNUs. Data synthesis summarized outcome measures and study designs appropriately in the results. SPSS meta-analysis function was used to calculate the mean effect size estimate (MESE) and 95% confidence intervals for each outcome. This search yielded a total of 7,879 studies, and after exclusion criteria were assessed, 26 articles comprising 14,170 patients with diaphyseal femoral fractures were included. These studies included 973 fractures developing nonunions after surgical intervention. A total of 25 factors were assessed. Age (MESE = 1.33 [0.92 to 1.74]; P < 0.001) and type 2 diabetes (MESE = 1.77 [1.03 to 2.52]; P < 0.001) were significant patient-specific risk factors. Arbeitsgemeinschaft Osteosynthesefragen/Orthopaedic Trauma Association 32B (MESE = 0.94 [0.35 to 1.53]; P < 0.001) and Winquist-Hansen type 3 (MESE = 1.45 [0.63 to 2.26]; P < 0.001) were significant injury-specific factors, along with butterfly fragment size and displacement and open fractures. Open reduction (MESE = 0.80 [0.30 to 1.30]; P < 0.001) and postoperative nonsteroidal anti-inflammatory drug use (MESE = 1.17 [0.08 to 2.27]; P = 0.04) were significant surgical-specific and management-specific risk factors, along with external fixation and iatrogenic comminution. Age, diabetes, fracture classification grading, and postoperative nonsteroidal anti-inflammatory drug use were among the factors placing patients at the highest risk of femoral diaphyseal nonunions, including other patient-specific, injury-specific, surgical, and management factors. Future studies are warranted to use a prospective study design, identify diaphyseal nonunion-specific risk factors, and implement evidence-based prevention strategies. III.