Ultrasound for the Diagnosis of Occult Elbow Fractures in the Adult Population

CASE

A 53-year-old woman with a past medical history of hypertension arrived to the Emergency Department with left arm pain shortly after a mechanical fall on an outstretched hand. She denied any other symptoms or injuries from the fall. Her vital signs were within normal limits. Her physical exam was notable for an obvious deformity with bony tenderness and swelling over her left elbow, but her motor, sensory, and vascular exams were intact. Her exam was otherwise unremarkable. 

DIAGNOSIS

A point of care ultrasound (POCUS) was performed while the patient waited for her x-ray, showing cortical disruption over the radial head in both the transverse and sagittal planes.

Figure 1. Cortical disruption over the radial head, in transverse and sagittal planes respectively.

The patient’s plain film report noted a posterior dislocation of the elbow. It also noted extensive soft tissue swelling with a punctate linear ossific process just proximal to the radial head which was thought to be a fracture fragment. Given the bone fragment which was seen on x-ray but no clear fracture, the patient then had a CT scan of her elbow to better characterize the injury. CT imaging redemonstrated the bone fragment next to the lateral epicondyle suspicious of avulsion fracture, but without a clear source.

The patient was diagnosed with a left elbow dislocation with possible occult, proximal radial head avulsion fracture.

DISCUSSION

Extremity injuries and concern for fractures are common reasons for patient visits to the Emergency Department. However, radiographs are often negative for fracture in these injuries (50% for upper extremities and 85% for ankle injuries). [1] With the advent of ultrasound availability across Emergency Departments, there may be benefits for using POCUS as an adjunct in diagnosis or exclusion of fractures. In particular, bedside ultrasound may be superior to x-ray for diagnosis of occult fractures such as nondisplaced fractures, buckle fractures, and Salter Harris I fractures. [1]

Identifying fractures of the elbow using POCUS includes visualizing cortical disruption, subperiosteal hematomas, posterior fat pad elevation or lipohemarthrosis. [2, 3] A meta-analysis by Joshi et al. reviewing the sensitivity and specificity for ultrasound diagnosis of upper extremity fractures completed by Emergency Medicine physicians compared to x-ray was 83-100% and 73-91% respectively. [1] In another study evaluating POCUS as compared to CT (the gold standard), for the diagnosis of elbow fractures not adequately visualized on x-ray, POCUS had a sensitivity of 97% and a specificity of 88%. [4] The authors speculate that this is due to easy detection of cortical deformity and real time correlation with bony tenderness on exam with ultrasound. [4]

Figure 2. Visualization of normal (A and B) and abnormal, elevated (C and D) posterior fat pads. [2]

Figure 3. Abnormal, elevated posterior fat pad with layering lipohemarthrosis. [2]

Additional benefits for ultrasound diagnosis of fractures and extremity trauma includes the additional visualization of injury to ligaments or soft tissue that are often poorly visualized on x-ray and CT scan. [3] There are limitations to ultrasound utilization in fractures including view limitations around bony contours in the joint regions, individual provider familiarity, and surgical planning. [1]

CASE RESOLUTION

The patient’s elbow was reduced in the emergency department after which she was seen by an orthopedic consult for splinting. She was discharged with orthopedic outpatient follow up in one week. 

TAKE-AWAYS

·       Ultrasound has been shown to be sensitive and specific for diagnosing fractures in multiple locations, including the elbow in both pediatric and adult populations.

·       Positive findings for an elbow fracture with ultrasound include cortical disruption, cortical deformity or angulation, elevated posterior fat pad, and lipohemarthrosis.

·       In some studies, ultrasound has been shown to have very strong sensitivity and specificity as compared to CT for viewing nondisplaced or occult fractures of the elbow. This may be especially helpful in correlating immediate ultrasound findings with POCUS to bony point tenderness on exam. 

·       Limitations of ultrasound in elbow fractures include difficulty viewing bony contours in the joint, variable operator familiarity, and utility for plain films for surgical planning in non-EM specialties.

AUTHOR: Katherine Stewart, MD is a first-year Emergency Medicine resident at Brown University/Rhode Island Hospital.

FACULTY REVIEWER: Kristin Dwyer, MD is the Director of Ultrasound Division of Brown Emergency Medicine

SOURCES

[1] Joshi N, Lira A, Mehta N, Paladino L, Sinert R. Diagnostic accuracy of history, physical examination, and bedside ultrasound for diagnosis of extremity fractures in the emergency department: a systematic review. Acad Emerg Med. 2013;20(1):1-15.

[2] Rabiner JE, Khine H, Avner JR, Friedman LM, Tsung JW. Accuracy of point-of-care ultrasonography for diagnosis of elbow fractures in children. Ann Emerg Med. 2013;61(1):9-17.

[3] Pourmand A, Shokoohi H, Maracheril R. Diagnostic accuracy of point-of-care ultrasound in detecting upper and lower extremity fractures: An evidence-based approach. Am J Emerg Med. 2018;36(1):134-136.

[4] Avcı M, Kozacı N, Beydilli İ, Yılmaz F, Eden AO, Turhan S. The comparison of bedside point-of-care ultrasound and computed tomography in elbow injuries. Am J Emerg Med. 2016;34(11):2186-2190.