PEM Pearls: Ultrasound for Diagnosing Occult Supracondylar Fractures

Supracondylar humerus fractures are the most common type of elbow fracture in pediatric patients, most often seen in a fall on an outstretched hand (FOOSH) or a fall on a hyper-extended elbow.​1,2​ If there is no obvious fracture on x-rays, the patient may have an occult fracture; look for secondary radiographic signs including a posterior fat pad sign, an enlarged anterior fat pad or ‘sail sign’, or malalignment. Occult supracondylar fractures (those with initial normal radiographs that are later diagnosed in follow up) make up 2-18% of all the fractures we see in kids.​3​ When x-ray findings are nonspecific but the index of suspicion for fracture remains high, ultrasound may aid in your clinical decision making. Technique Probe: High resolution linear probe with frequencies ranging from 6-13 MHz Maximum Depth:6 cm Scanning Scheme: With the elbow bent at 90 degrees, scan along posterior edge of the distal humerus in longitudinal and transverse axes. Findings on Elbow Ultrasound Normal Elbow Identify: Distal humerus without cortical irregularity Posterior fat pad Abnormal Elbow Identify signs of potential occult fracture: Bulging posterior fat pad lipohemarthrosis Elbow Ultrasound vs Radiograph Study 1: European Journal of Trauma and Emergency Surgery 2014 A German study investigated ultrasound accuracy (identifying cortical deformity or a posterior fat pad) compared to standard radiographs in diagnosing supracondylar fractures in 106 pediatric patients.  The test characteristics were as follows:​4​ Sensitivity 100% Specificity 93.5% Negative predictive value 100% Positive predictive value 95.2% Study 2: Orthopaedics & Traumatology: Surgery & Research 2016 A French study of 34 cases of pediatric elbow trauma with suspected occult fracture. Patients with bone deformity diagnosed on initial radiographs were excluded. Patients were splinted until they had an ultrasound performed within 6 days of the injury.​3​ … Continue reading PEM Pearls: Ultrasound for Diagnosing Occult Supracondylar Fractures