The battle of ultrasound vs X-ray: Diagnosis of a finger fracture
By Kerrin Boyle, University College Dublin
Background
Phalangeal fractures are a common pathology seen in the emergency department, however they are typically diagnosed using X-ray and not ultrasound. Ultrasound is useful in the detection of a radiolucent foreign body or a tendon injury post trauma. It is not the modality of choice if a fracture is suspected.
A 29 year old male presented to the emergency department with a swollen and tender left index finger after an injury at work. The patient was referred for an X-ray of their hand which was reported by the radiologist as no bony injury seen. The patient was subsequently discharged from the emergency department. However, the patient represented with an infected and swollen distal phalanx. An ultrasound examination was requested to out rule the presence of a radiolucent foreign body.
Ultrasound Findings
The ultrasound examination revealed a hypoechoic defect in the bony cortex at the tip of the distal phalanx with mild periosteal elevation. This hypoechoic defect demonstrated a sonographic appearance of a double contrast sign in the transverse plane, which is indicative of a fracture. There was also evidence of oedema noted at the distal phalanx. However, there was no sonographic evidence of a foreign body present. These findings represented an undisplaced healing fracture of the distal phalanx of the left index finger which was retrospectively identified on X-ray.
Discussion
A fractured finger is often clinically diagnosed in the emergency department through X-ray. However, ultrasound was an accessory tool in the diagnosis of a missed distal phalanx fracture. Dynamic sonographic imaging of the distal phalanx ensured there was no tendon pathology present or evidence of a radiolucent foreign body.
Conclusion
Ultrasound is not the modality of choice for diagnosing a fracture dueto not being readily available. However, it is a beneficial accessory tool when an occult fracture is suspected.