Laboratory Studies
Preoperative laboratory studies should be patient-specific. They should be performed to medically clear the patient for an operative procedure if one is justified.
Studies should include coagulation studies and hemoglobin level. If the patient's medical condition is in question, then a medical team consultation may be appropriate. Whereas blood loss can be minimized with the intraoperative use of a tourniquet, typing and screening can be performed if the patient is unable to tolerate blood loss.
Plain Radiography
The fracture personality, including the bone quality, fracture pattern, level of comminution, articular involvement, displacement, and associated injuries, must be understood completely before treatment is attempted. [14] Multiplane radiographs, including anteroposterior (AP) and lateral views, are appropriate. (See the images below.)
Lateral radiograph of a distal humerus fracture of the left elbow. Only the intra-articular portion of the lateral condyle is involved.
Anteroposterior radiograph following a distal humerus fracture of the right elbow.
AP radiographs should be obtained with the elbow flexed approximately 40° and with the radiographic beam directed perpendicular to the distal humeral surface. This allows disengagement of the olecranon from its fossa and permits a better view of the distal humerus. In the pediatric population, the Baumann angle—defined as the angle between the lateral condylar physeal line and the axis of the humerus—is often measured by using AP radiographs. It must be compared with the angle on the contralateral side.
In addition, displacement of the anterior, posterior, or supinator fat pad can suggest a fracture. The posterior fat pad is the most sensitive for pathology. Skaggs et al demonstrated a 76% incidence of occult elbow fracture with a positive posterior fat pad sign. [15] A medial epicondylar fracture should be suspected if a fragment is visible within the joint and the epicondyle is not visible.
Oblique radiographs can aid in assessing multiplane involvement of the fracture lines and comminution.
In many instances, traction views allow better visualization of the fracture lines and fragments. Mobile fluoroscopy can be helpful as well, especially in cases associated with seemingly minor fractures and instability.
Other radiographic views of the elbow can be obtained to exclude associated injuries. A radial head–capitellar view is a semilateral view of the elbow with the beam aimed 45° toward the ipsilateral shoulder joint. With the thumb of the hand pointed upward, the radial head can be magnified without any overlap of the proximal ulna. The coronoid view can be obtained to define the coronoid process. The radiographic beam is directed at the lateral elbow and pointed 45° away from the ipsilateral shoulder.
Computed Tomography
Computed tomography (CT) of the distal humerus can be performed to further analyze the fracture pattern. Thin-cut coronal and axial cuts at 1 mm intervals should be obtained. Three-dimensional reconstructions can be obtained but rarely contribute much to the overall assessment of the fracture. The integrity of the central column, as well as comminution and preexisting arthritic changes within the joint surfaces, should be observed. Often, CT scans reveal details that cannot be viewed on simple radiographs.
A study suggested that additional CT could improve intraobserver reliability but did not improve interobserver agreement, indicating that interpretation is a reflection of training, knowledge, and experience. [14] Another study found that although adding CT to radiography did not improve interobserver reliability, it did change fracture classification and treatment planning. [16]
Other Imaging Studies
If questions regarding vascular status arise, duplex Doppler ultrasonography (US) or angiography can be performed. US has also been shown to be helpful in differentiating stable from unstable pediatric lateral condylar fractures. Vocke-Hell et al showed US to be effective in determining which nonossified fractures involved the joint surface and required operative intervention. [17]
Staging
No perfect classification system has been developed for distal humerus fractures that allows accurate direction for treatment considerations and prognostic outcome. The many classifications that have been proposed often overlap.
Mehne and Jupiter separated fractures on the basis of column involvement and whether the fractures are intra-articular, intracapsular, or extracapsular. [9, 18] Their classification system incorporates features of many previously described fracture types.
For single-column involvement, the Milch classification is often used. It classifies fracture patterns as having medial or lateral condylar involvement and further characterizes them as either low (type I) or high (type II), depending on how proximally the fracture started before traveling obliquely across the trochlea. These fractures usually occur from an abduction or adduction force.
Kuhn et al described a divergent bicolumn fracture pattern that can occur with an axial force from the olecranon in patients with fenestrated olecranon/coronoid fossae. [19]
Capitellar and trochlear fractures are seen infrequently, occur in the coronal plane, and can be classified into one of the following subtypes:
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Type I - These are isolated capitellar fractures involving a large portion of cancellous bone; they are known as Hahn-Steinthal fractures
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Type II - These are fractures involving the anterior cartilage, with a thin-sheared layer of subchondral bone; they are known as Kocher-Lorenz fractures
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Type III fractures - These are comminuted osteochondral fractures
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Type IV fractures - Classified by McKee et al, these involve the capitellum and one half of the trochlea; they often result in the double-arc sign observed on lateral radiographs
For bicolumn variants, the classification system introduced by Mehne and Matta takes into consideration the height of the fracture through each column, as follows:
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Y and T fractures begin in the center of the trochlea, secondary to trochlear impaction into the olecranon-trochlear ridge, causing propagation of the fracture vertically and across each column; if a fracture involves both columns at a distal level, it may enter the olecranon and coronoid fossae and produce comminuted articular fragments too small to reconstruct
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H-type fractures may produce a free-floating trochlear fragment, with the medial column fractured in two places; this can increase the risk of avascular necrosis of the articular fragment; the system does not identify comminution or fragment displacement
Many have continued to use the simple classification proposed by Riseborough and Radin, [20] which differentiates fractures on the basis of displacement and rotation. The use of this classification system is limited because it does not account for the large variety of fracture patterns. Riseborough and Radin's classification is as follows:
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Type I - Fractures involving minimally displaced articular fragments
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Type II - Fractures involving displaced fragments that are not rotated
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Type III - Fractures involving displaced and rotated fragments
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Type IV - Fractures involving comminuted fracture fragments
The Arbeitsgemeinschaft für Osteosynthesefragen (AO)-Orthopaedic Trauma Association (OTA) classification is the most commonly used system for clinical research and treatment. [21] The OTA and the International Society for Fracture Repair expanded the AO-ASIF classification to provide a more detailed system for reproducibility. It contains 28 different fractures of the distal humerus and separates the patterns into groups and subgroups according to the specific fracture propagation and involvement.
The AO-OTA group classification is as follows [21] :
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Group A - Extra-articular fractures
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Group B - Partial articular fractures
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Group C - Complete articular fractures
The subgroup classification is as follows [21] :
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Subgroup A1 - Avulsion fracture
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Subgroup A2 - Simple fracture
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Subgroup A3 - Wedge or multifragmentary fracture
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Subgroup B1 - Lateral sagittal fracture
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Subgroup B2 - Medial sagittal fracture
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Subgroup B3 - Frontal/coronal plane fracture
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Subgroup C1 - Simple articular, simple metaphyseal fracture
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Subgroup C2 - Simple articular, wedge or multifragmentary metaphyseal fracture
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Subgroup C3 - Multifragmentary articular fracture, wedge or multifragmentary metaphyseal fracture
The classification system most commonly used for pediatric supracondylar humerus fractures is the Gartland classification, which is based on the degree of displacement. Skaggs et al found a high interobserver reliability with this classification system and an overall κ value of 0.74. [22] The Gartland classification system is as follows:
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Type I - Nondisplaced fractures
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Type II - Minimally displaced fractures with an intact posterior cortex
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Type III - Completely displaced fractures with complete cortical disruption
Pediatric supracondylar humerus fractures can also be classified as extension-type and flexion-type fractures, depending on the angulation of the distal fragment.
Lateral condylar physeal fractures can be differentiated on the basis of either the anatomic location of the fracture or the amount of displacement. The Milch classification is as follows:
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Type I (Salter-Harris type IV) - Describes the fracture extending lateral to the trochlea through the capitulotrochlear groove
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Type II (Salter-Harris type II) - Describes the fracture line penetrating to the trochlea, producing elbow instability
Medial condylar physeal fractures also are classified according to the Milch classification, as follows:
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Type I - Salter-Harris type II fracture
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Type II - Salter-Harris type IV fracture
Fracture separation of the distal humeral epiphysis also has been described. (In some cases, separation of the epiphysis with an attached portion of the metaphysis may occur.) DeLee et al classified this type of fracture into the following three groups [23] :
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Group A - These fractures involve patients aged 1 year or younger with Salter-Harris type I physeal injuries
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Group B - These fractures involve children aged 1-3 years in whom ossification of the lateral condyle epiphysis is evident
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Group C - These fractures occur in children aged 3-7 years and produce a metaphyseal flag with the distal fragment
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Radiograph of a supracondylar-intracondylar distal humerus fracture. Note the posteromedial and posterolateral column plate placement used for reconstruction with the chevron osteotomy.
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Lateral radiograph of a supracondylar-intracondylar distal humerus fracture. Note the distal extent of the contoured plate placed extra-articularly.
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Radiograph of a supracondylar-intracondylar humerus fracture. Note the ipsilateral radial head fracture fixed through a posterior incision.
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Lateral radiograph of a supracondylar-intracondylar distal humerus fracture with an ipsilateral radial head fracture.
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Anteroposterior radiograph of a pediatric type III supracondylar humerus fracture. Note the lateral pinning.
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Lateral and medial pinning of a type III extension-type supracondylar humerus fracture.
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Lateral radiograph after open reduction and pinning of a type III supracondylar humerus fracture.
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Lateral radiograph of a distal humerus fracture of the left elbow. Only the intra-articular portion of the lateral condyle is involved.
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Anteroposterior radiograph following a distal humerus fracture of the right elbow.
