The value of ultrasonography in predicting the outcomes of simple long bone fractures treated by closed intramedullary nail fixation

Abstract

Purpose

Ultrasonography has been used increasingly in orthopaedic practice credited to its low cost, easy accessibility, non-invasiveness, reproducibility, and safety from radiation. The purpose of this study was to test the validity and efficacy of ultrasonography as an adjunct in the assessment of fracture healing in long bones treated with intramedullary interlocking devices and its predictive value in determining the need for a secondary surgical procedure.

Methods

This was a descriptive longitudinal study of 40 skeletally mature patients from November 2016 to February 2019, who sustained long bone fractures of the tibia or femur treated using intramedullary interlocking nails. Patients with comminuted and segmental fracture patterns were excluded from the study. Each patient was evaluated at 6- and 12-week post-surgery using standard orthogonal radiographs and ultrasonography to assess fracture healing. Patients were then followed up until fracture union. Quantitative data was analyzed using frequency statistics and descriptive data with inferential statistics.

Results

Ultrasonography predicted 87.5% union and 12.5% delayed or non-union as early as 6 weeks after surgery, while radiographs predicted 22.5% union as late as 3 months of follow-up. The sensitivity and specificity of ultrasonography in assessing fracture healing were 100% and 97.2%, respectively, with a positive predictive value of 80.0%. Vascular resistance index was less than 0.5 in all patients who developed delayed or non-union.

Conclusion

Ultrasonography is able to predict fracture outcomes much earlier than standardized radiographs with comparable sensitivity and specificity. Vascular resistance index is an objective parameter in assessing callus quality and predicting fracture outcomes.