Can Computed Tomography Hounsfield Units Predict Distal Humerus Fracture Mechanical Complications?

INTRODUCTION: The purpose of this study was to determine whether CT Hounsfield units (HUs) as a proxy for bone quality can predict postoperative mechanical complications following surgical treatment of distal humerus fractures.

METHODS: One hundred fifty-three patients with both column distal humerus fractures who underwent surgical fixation at single institution and had complete radiographic data available were included. Radiographic measurements included the HU value from the surgical distal humerus as determined by measuring the metaphyseal/supracondylar at the midaxial/coronal/sagittal CT image an average of 1 cm from the articular surface using a freehand region of interest. Zones with fracture lines and cortical impaction were avoided for all measurements. Postoperative complications recorded were implant failure, nonunion, and acute periprosthetic fracture. Patients with and without complications were statistically compared, and binary logistic regression was done to determine if CT HU measurements from the distal humerus were predictive of complications.

RESULTS: Five patients (3.3%) developed five mechanical complications, including peri-prosthetic humerus fracture (one), implant failure (two), and nonunion (two). Patients with mechanical complications were more likely to be current smokers (40% vs. 6.8%, P = 0.010). Otherwise, no difference was observed in demographics or AO/Orthopedic Trauma Association classification between the cohorts. Patients with complications had markedly lower HU in the coronal plane ( P = 0.031). Regression analysis found that current smoking was associated with an increased risk of mechanical complications ( P = 0.041, OR = 1.102, 95% confidence interval [CI], 1.087 to 1.710), whereas a higher coronal HU was associated with a decreased risk of complications ( P = 0.048, OR = 0.973, 95% CI, 0.961 to 0.991).

CONCLUSION: A thorough smoking history and CT HU measurements in the coronal plane may identify patients with poorer bone quality at higher risk for postoperative mechanical complications following distal humerus fracture fixation.