Pediatric Supracondylar Humerus Fractures Workup

Updated: Aug 27, 2018
  • Author: Jiun-Lih Jerry Lin, MBBS, MS(Orth); Chief Editor: Jeffrey D Thomson, MD  more...
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Workup

Radiography

Radiographic evaluation of a supracondylar humerus fracture (SCHF) consists of an elbow x-ray series that includes anteroposterior (AP) and lateral views of the elbow and any other sites of deformity, pain, or tenderness. [8]  It is essential that a true lateral elbow image be obtained as part of the elbow series. This allows accurate assessment of the anterior humeral line and the anatomic alignment of the distal humerus. [8]  An incorrectly positioned lateral elbow x-ray could potentially lead to misdiagnosis, a missed fracture, or both.

The standard protocol includes an AP image with the patient’s arm supinated in full elbow extension and an orthogonal lateral x-ray. The lateral image should be taken with the patient’s arm flexed at 90º, the humerus horizontal (with the elbow in the same plane as the shoulder), and the wrist in a lateral position. [8, 16]  Achieving the desired position for these projections can be challenging because of the nature of the injury and the presentation of the patient.

Patients who present with an obvious deformity, marked swelling, and severe pain should be considered to have an unstable fracture and should not be moved; repositioning the elbow could result in further soft-tissue injury. The radiographer should angle the beam or use a horizontal beam to obtain required projections. The AP image may have to be obtained with the patient’s arm partially or fully flexed and the humerus against the imaging plate. [16]

On the AP view, the Baumann angle is commonly used to evaluate fractures, in that it maintains an estimation of the carrying angle. The Baumann angle is created by the intersection of a line drawn down the long axis of humeral shaft and a line drawn along the lateral condyle growth plate. A normal Baumann angle is generally considered to be in the range of 70-80º. However, the best assessment involves comparison with the corresponding angle in the contralateral limb. A deviation exceeding 5% indicates coronal plane deformity. This should not be accepted. [9]

On the lateral view, the relation between the anterior humeral line and the ossification center of the capitellum should be examined. In a normal elbow, this line should intersect the middle third of the capitellum. The capitellum moves posteriorly to this reference line in extension-type fractures, whereas it moves anteriorly in flexion-type fractures. [1, 8, 17]  (See the image below.)

(A, B) Anteroposterior (AP) and lateral elbow radi (A, B) Anteroposterior (AP) and lateral elbow radiographs of 6-year-old girl with type 2A supracondylar humerus fracture with no rotational deformity on AP view. Anterior humeral line is crossing anterior to capitellum. (C, D) AP and lateral elbow radiographs of same patient after treatment with collar-and-cuff in elbow hyperflexion. Fracture is now reduced, and anterior humeral line now transects capitellum.

Elbow fat pads are often visible in the case of acute injuries. Hemarthrosis elevates the anterior and posterior fat pads out of the coronoid and olecranon fossa, respectively, making them visible on radiographs. Visualization of fat pads and a clinically painful elbow are suggestive of an occult fracture and warrant treatment as an acute injury with immobilization and orthopedic follow-up. In more than 90% of cases where imaging shows posterior fat pad displacement, a fracture is seen on initial or follow-up radiographs. [18, 19, 9, 8]

As with all pediatric imaging, lead shielding should be used to protect the patient’s gonads.

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CT, MRI, and US

Although radiography is the primary method for evaluating acute elbow injuries in the pediatric population, soft-tissue elbow injuries and inflammatory joint conditions can be further investigated with ultrasonography (US) or magnetic resonance imaging (MRI). For further information about these studies, see Imaging in Pediatric Elbow Trauma.

Computed tomography (CT) and CT angiography (CTA) are not indicated in the workup of pediatric SCHFs, because they do not make a significant contribution to assessment or management. [13]  A pulseless ischemic limb in a pediatric patient with a displaced SCHF should instead be explored surgically with support from vascular surgery. CT is indicated in adult patients with SCHFs to assess the fracture pattern and identify intra-articular extension; however, as noted, adult SCHFs are completely different from pediatric SCHFs and thus are managed differently.

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