Radiographic diagnostics of bone fractures

Standard projections and forced alternatives

A baseline requirement of diagnostic imaging is obtaining images in two projections. However, in practice, physicians regularly encounter physical limitations. For example, in extension fractures of the distal humerus, the patient is unable to straighten the arm for correct positioning in the anteroposterior view due to pain and a biomechanical block.

If a standard examination is impossible or its results are doubtful, alternative methods are used. These include computed tomography (CT) or comparative radiographs of the symmetrical healthy joint. The final diagnosis, especially when impacted fractures of the humeral head or dislocations are suspected, is made exclusively after imaging, as clinical symptoms are often smoothed out.

Specifics of pediatric X-ray diagnostics

In children, the imaging picture has a number of critically important features, ignorance of which leads to overdiagnosis or missed injury:

• Epiphysiolysis in newborns: Most commonly, this is an obstetrical injury of the distal humerus. Diagnosis in the first days of life is practically impossible if there is no fragment displacement. This is due to the complete absence of radiopaque bone tissue in the epiphyseal region.
• Age 3–6 years: Reliable identification of growth plate injury is only possible through careful comparison with an image of the uninjured limb.
• Isolated fractures of the humeral trochlea: Normally, the ossification center of this zone in children is frequently fragmented. An inexperienced specialist may mistake these natural multiple fragments for bone fragments.
• Injuries of the capitulum: The fracture line rarely passes exclusively through the growth zone ("pure" epiphysiolysis); much more often, osteoepiphysiolysis is visualized on images, where the fracture plane obliquely intersects the distal metaepiphysis.

X-ray anatomical landmarks and injury "masking"

Pronounced edema and hematoma often conceal the true joint deformity during visual inspection, making the radiograph the only objective criterion.

In intra-articular condylar fractures (type B), the bone fragment is displaced upward and rotated by muscle pull. The images are used to assess the disruption of important biomechanical lines:

1. The Marx sign is disrupted — the axis line of the humerus ceases to be perpendicular to the line drawn through the condyles.
2. Asymmetry of Hüter's triangle is visualized.

Fractures of the head and anatomical neck of the humerus require special attention. A massive hematoma in this area can physically displace the head. On a radiograph, such a picture may falsely resemble a traumatic shoulder dislocation. In fractures with significant displacement of the humeral trochlea, the longitudinal axis of the arm intersects the epicondylar line lateral to the midpoint at an inward-facing angle.

Differential diagnosis of fractures and dislocations

Radiography plays a decisive role in differentiating supracondylar fractures from forearm dislocations. Although a dislocation can be clinically suspected by the forced limb position, springy resistance sign, and absence of bone crepitus, it is the radiograph that establishes the definitive diagnosis.

In children, traumatic dislocations occur significantly less often than fractures due to the high elasticity and strength of the ligamentous-capsular apparatus. Frequently, what clinically appears to be a dislocation turns out to be a traumatic epiphysiolysis on the radiograph.

In posterior and posterolateral dislocation of both forearm bones, the image will show posterior (or posterior and lateral) displacement of the bones, while the distal end of the humerus is displaced anteriorly. The tip of the olecranon is thus located above the line connecting the humeral epicondyles.

Class and exam questions

What else to study on this topic

• Classification of humeral condyle fractures (types A, B, C) and mechanisms of their occurrence.
• Complications in humeral fractures: diagnostics of neurovascular bundle injuries.
• Conservative and surgical treatment of fractures of the surgical neck of the humerus.
• Methods for closed reduction of traumatic shoulder dislocation (by Chaklin, Kocher, Bairov).
• Prevention of post-traumatic contractures of the shoulder joint.

Other topics in the "Specialized Adult Traumatology" section

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