Laboratory Studies
No laboratory tests are indicated for the diagnosis of a fracture, though they may be necessary for preoperative clearance. [31]
Imaging Studies
Diagnosis is usually based on standard anteroposterior (AP) and lateral radiographs of the affected elbow (see the images below). [8, 16, 31, 32]
Elbow dislocation associated with medial epicondyle fracture. In this lateral view, fragment is marked with circle.
Distinguishing a fracture of the medial epicondyle (see the image below) from a fracture of the medial condyle can be difficult in the developing elbow. [2, 3, 4, 5, 6, 7, 8, 9, 32] Because cartilaginous structures are usually not visible radiographically, the exact location of injury may not be obvious. With its complicated and variable pattern of ossification, trauma to this region presents a difficult diagnostic challenge.
Because the medial epicondyle lies largely outside the joint capsule, fractures of this structure usually do not produce distention of the capsule. Therefore, if a positive fat-pad sign accompanies soft-tissue swelling, fracture extension distally into the joint capsule to include the trochlear ossification center and medial condyle should be considered.
Radiographic clues to unstable medial condyle fracture in a young child include soft-tissue swelling, a chip or flake of bone from the metaphysis, and the presence of a positive fat-pad sign. [32]
In slightly displaced or nondisplaced fractures of the medial epiphysis, widening or irregularity of the apophyseal physis may be the only sign. If the medial epiphysis is absent, the fragment may be incarcerated totally into the joint or hidden by the overlying ulnar or distal humerus.
The lack of a fat-pad sign cannot be used to exclude medial condyle injury. If the joint capsule is ruptured, no fat-pad sign is exhibited. Therefore, it may be necessary to examine the elbow under anesthesia to determine whether instability is present that would indicate a more extensive injury.
A widely displaced fracture-separation of the medial epicondyle in a patient whose trochlear ossification center has not yet appeared can indicate that the cartilaginous trochlea may also be fractured and attached to the epicondyle. This possibility should be considered and may warrant surgical exploration.
Arthrography may be used to determine the extent of a fracture and to help distinguish an epicondyle fracture from a condyle fracture. [33]
Magnetic resonance imaging (MRI) may be used to evaluate soft-tissue injury and may be helpful in evaluating cartilaginous injury. [34]
Interobserver and intraobserver reliability is poor for the use of plain radiography to assess epicondyle displacement. [35] Three-dimensional computed tomography (CT) is a more accurate means of evaluating displacement of an epicondylar fragment; indeed, plain films may underestimate displacement by up to 1 cm. [36]
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Schematic of two types of medial condyle fractures, as described by Milch.
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Medial epicondyle fracture.
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Displacement patterns as described by Kilfoyle.
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Valgus levering force creating fracture.
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Olecranon acting as a wedge and creating medial condyle fracture.
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Medial condyle fracture caused by traction through flexor pronator origin.
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Epicondyle fractures can be caused by traction forces.
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Positioning for valgus stress radiograph.
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Anteroposterior view of displaced medial epicondyle fracture.
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Anteroposterior view of displaced medial epicondyle fracture after reduction.
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Elbow dislocation associated with medial epicondyle fracture. In this lateral view, fragment is marked with circle.
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Elbow dislocation associated with medial epicondyle fracture. Lateral view after reduction. Reduced fragment is marked. Note normal location somewhat posteriorly on distal humerus.
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Elbow dislocation associated with medial epicondyle fracture. Anteroposterior view after fixation.
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Attachment of medial collateral ligament components is pictured.
