Chapter 15: Evaluation of Pediatric Distal Humeral Fractures

James H. Beaty, James R. Kasser

Chapter Outline

Introduction to Evaluation of Pediatric Distal Humeral Fractures

At the end of the 19th century, Sir Robert Jones echoed the opinion of that era about elbow injuries: “The difficulties experienced by surgeons in making an accurate diagnosis; the facility with which serious blunders can be made in prognosis and treatment; and the fear shared by so many of the subsequent limitation of function, serve to render injuries in the neighborhood of the elbow less attractive than they might otherwise have proved.”37 These concerns are applicable even today. The importance of correct diagnosis was recently emphasized in a study of litigation against the National Health Service in England: over half of the cases involved missed or incorrectly diagnosed injuries, most of which were fractures about the elbow.4 The difficulty in correctly diagnosing elbow injuries in children was shown by Shrader et al.,55 who found that emergency room physicians accurately diagnosed elbow fractures in children only 53% of the time. 
In other bones, good results can often be obtained with minimal treatment, but in the elbow, more aggressive treatment is often required to avoid complications. An understanding of the basic anatomy and radiographic landmarks of the elbow is essential in choosing appropriate treatment. 

Epidemiology of Pediatric Distal Humeral Fractures

Because children tend to protect themselves with their outstretched arms when they fall, upper-extremity fractures account for 65% to 75% of all fractures in children. The most common area of the upper extremity injured is the distal forearm8,41; 7% to 9% of upper-extremity fractures involve the elbow. 
The distal humerus accounts for approximately 86% of fractures about the elbow region. Supracondylar fractures are the most frequent elbow injuries in children, reported to occur in 55% to 75% of patients with elbow fractures. Lateral condylar fractures are the second most common, followed by medial epicondylar fractures. Fractures of the olecranon, radial head, and neck and medial condyle and T-condylar fractures are much less common. 
Elbow injuries are much more common in children and adolescents than in adults.14,63 The peak age for fractures of the distal humerus is between 5 and 10 years old.32 Houshian et al.34 reported that the average age of 355 children with elbow fractures was 7.9 years (7.2 years in boys and 8.5 years in girls). Contrary to most reports, these investigators found elbow fractures more frequent in girls (54%) than in boys. In a study of 450 supracondylar humeral fractures, Cheng et al.17 found a median age of 6 years (6.6 years in boys and 5 years in girls) and a predominance of injuries (63%) in boys. In a series of 1,297 consecutive supracondylar humeral fractures, including 873 type III fractures, Fletcher et al.24 found that 18% occurred in children older than 8 years; these children had more open fractures from high-energy mechanisms than younger children. Stoneback et al.61 reported that elbow dislocations were most frequent in those aged 10 to 19 years; 44% were sustained in sports. 
Physeal injuries in most parts of the body occur in older children between the ages of 10 and 13; however, the peak age for injuries to the distal humeral physes is 4 to 5 years in girls and 5 to 8 years in boys. In most physeal injuries, the increased incidence with advanced age is believed to be due to weakening of the perichondrial ring as it matures (see Chapter 5). Thus, some different biomechanical forces and conditions must exist about the elbow to make the physis more vulnerable to injuries at an earlier age. (For more data on the relationship of fractures about the elbow to all types of fractures, see Chapter 1.) 

Anatomy of Pediatric Distal Humeral Fractures

The elbow is a complex joint composed of three individual joints contained within a common articular cavity. Several anatomic concepts are unique to the growing elbow. 

The Ossification Process of Pediatric Distal Humeral Fractures

The process of differentiation and maturation begins at the center of the long bones and progresses distally. The ossification process begins in the diaphyses of the humerus, radius, and ulna at the same time. By term, ossification of the humerus has extended distally to the condyles. In the ulna, it extends to more than half the distance between the coronoid process and the tip of the olecranon. The radius is ossified proximally to the level of the neck. The bicipital tuberosity remains largely unossified (Table 15-1).26 Brodeur et al.12 compiled a complete atlas of ossification of the structures about the elbow, and their work is an excellent reference source for finer details of the ossification process about the elbow. 
 
Table 15-1
Sequence and Timing of Ossification in the Elbow
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Table 15-1
Sequence and Timing of Ossification in the Elbow
Girls (y) Boys (y)
Capitellum 1 1
Radial head 5 6
Medial epicondyle 5 7.5
Olecranon 8.7 10.5
Trochlea 9 10.7
Lateral epicondyle 10 12
 

Data from Cheng JC, Wing-Man K, Shen WY, et al. A new look at the sequential development of elbow-ossification centers in children. J Pediatr Orthop. 1998; 18:161–167.

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Distal Humerus

Ossification of the distal humerus proceeds at a predictable rate. In general, the rate of ossification in girls exceeds that of boys.23,26,30 In some areas, such as the olecranon and lateral epicondyle, the difference between boys and girls in ossification age may be as great as 2 years.26 During the first 6 months, the ossification border of the distal humerus is symmetric (Fig. 15-1). 
Figure 15-1
During the first 6 months, the advancing ossifying border of the distal humerus is symmetric.
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Lateral Condyle

On average, the ossification center of the lateral condyle appears just before 1 year of age but may be delayed as late as 18 to 24 months.14 When the nucleus of the lateral condyle first appears, the distal humeral metaphyseal border becomes asymmetric. The lateral border slants and becomes straight to conform with the ossification center of the lateral condyle (Fig. 15-2). By the end of the second year, this border becomes well defined, possibly even slightly concave. The capitellar ossification center is usually spherical when it first appears. It becomes more hemispherical as the distal humerus matures,13 and the ossific nucleus extends into the lateral ridge of the trochlea (Fig. 15-3). On the lateral view, the physis of the capitellum is wider posteriorly. This is a normal variation and should not be confused with a fracture.13 
Figure 15-2
Ossification at 12 months.
 
As the ossification center of the lateral condyle develops (arrow), the lateral border of the metaphysis becomes straighter.
As the ossification center of the lateral condyle develops (arrow), the lateral border of the metaphysis becomes straighter.
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Figure 15-2
Ossification at 12 months.
As the ossification center of the lateral condyle develops (arrow), the lateral border of the metaphysis becomes straighter.
As the ossification center of the lateral condyle develops (arrow), the lateral border of the metaphysis becomes straighter.
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Figure 15-3
At 24 months, the oval-shaped secondary ossification center of the lateral condyle extends into the lateral crista of the trochlea.
 
The lateral border of the neck (metaphysis) of the radius is normally angulated both anteriorly and laterally.
The lateral border of the neck (metaphysis) of the radius is normally angulated both anteriorly and laterally.
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Figure 15-3
At 24 months, the oval-shaped secondary ossification center of the lateral condyle extends into the lateral crista of the trochlea.
The lateral border of the neck (metaphysis) of the radius is normally angulated both anteriorly and laterally.
The lateral border of the neck (metaphysis) of the radius is normally angulated both anteriorly and laterally.
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Medial Epicondyle

At about 5 to 6 years of age, a small concavity develops on the medial aspect of the metaphyseal ossification border. In this area, a medial epicondyle begins to ossify (Fig. 15-4). 
Figure 15-4
At about 5 or 6 years of age, a secondary center develops in the medial epicondylar apophysis (white arrows).
 
At this same time, the ossification center of the radial head also develops (open arrow). Note that the physis of the proximal radius is widened laterally (curved arrow).
At this same time, the ossification center of the radial head also develops (open arrow). Note that the physis of the proximal radius is widened laterally (curved arrow).
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Figure 15-4
At about 5 or 6 years of age, a secondary center develops in the medial epicondylar apophysis (white arrows).
At this same time, the ossification center of the radial head also develops (open arrow). Note that the physis of the proximal radius is widened laterally (curved arrow).
At this same time, the ossification center of the radial head also develops (open arrow). Note that the physis of the proximal radius is widened laterally (curved arrow).
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Trochlea

At about 9 to 10 years of age, the trochlea begins to ossify. Initially, it may be irregular with multiple centers (Fig. 15-5). 
These multiple centers can give the trochlea a fragmented appearance.
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Figure 15-5
At about 9 years of age, the ossification of the medial crista of the trochlea may begin as two well-defined centers (arrows).
These multiple centers can give the trochlea a fragmented appearance.
These multiple centers can give the trochlea a fragmented appearance.
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Lateral Epicondyle

The lateral epicondyle is last to ossify and is not always visible (Fig. 15-6). At about 10 years of age, it may begin as a small, separate oblong center, rapidly fusing with the lateral condyle.13 
Figure 15-6
The apophysis of the lateral epicondyle ossifies as either an oblong or a triangular center (arrows).
 
The wide separation of this center from the metaphyseal and epiphyseal borders of the lateral condyle is normal.
The wide separation of this center from the metaphyseal and epiphyseal borders of the lateral condyle is normal.
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Figure 15-6
The apophysis of the lateral epicondyle ossifies as either an oblong or a triangular center (arrows).
The wide separation of this center from the metaphyseal and epiphyseal borders of the lateral condyle is normal.
The wide separation of this center from the metaphyseal and epiphyseal borders of the lateral condyle is normal.
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The Fusion Process in Pediatric Distal Humeral Fractures

Just before completion of growth, the capitellum, lateral epicondyle, and trochlea fuse to form one epiphyseal center. Metaphyseal bone separates the extra-articular medial epicondyle from this common humeral epiphyseal center (Fig. 15-7). The common epiphyseal center ultimately fuses with the distal humeral metaphysis. The medial epicondyle may not fuse with the metaphysis until the late teens. 
Figure 15-7
The secondary ossification centers of the lateral condyle, trochlea, and lateral epicondylar apophysis fuse to form one center (white arrows).
 
This common center is separated from the medial epicondylar apophysis by advancing metaphyseal bone (black arrows).
This common center is separated from the medial epicondylar apophysis by advancing metaphyseal bone (black arrows).
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Figure 15-7
The secondary ossification centers of the lateral condyle, trochlea, and lateral epicondylar apophysis fuse to form one center (white arrows).
This common center is separated from the medial epicondylar apophysis by advancing metaphyseal bone (black arrows).
This common center is separated from the medial epicondylar apophysis by advancing metaphyseal bone (black arrows).
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Proximal Radius

The head of the radius begins to ossify at about the same time as the medial epicondyle (Fig. 15-4). The ossification center is present in at least 50% of girls by 3.8 years of age but may not be present in the same proportion of boys until around 4.5 years.23 Initially, the ossification center is elliptical, and the physis is widened laterally because of the obliquity of the proximal metaphysis. The ossification center flattens as it matures. At about age 12, it develops a concavity opposite the capitellum.13 
Ossification of the radial head may be bipartite or may produce an irregularity of the second center. These secondary or irregular ossification centers should not be interpreted as fracture fragments. 

Olecranon

There is a gradual proximal progression of the proximal ulnar metaphysis. At birth, the ossification margin lies halfway between the coronoid process and the tip of the olecranon. By about 6 or 7 years of age, it appears to envelop about 66% to 75% of the capitellar surface. The final portion of the olecranon ossifies from a secondary ossification center that appears around 6.8 years of age in girls and 8.8 years in boys (Fig. 15-8A). Peterson and Peterson49 described two separate centers: one articular and the other a traction type (Fig. 15-8B). This secondary ossification center of the olecranon may persist late into adult life.47 
Figure 15-8
Ossification of the olecranon.
 
A: Secondary ossification begins as an oblique oblong center at about 6 to 8 years of age. B: It may progress as two separate ossification centers: Articular (open arrow) and traction (closed arrows).
A: Secondary ossification begins as an oblique oblong center at about 6 to 8 years of age. B: It may progress as two separate ossification centers: Articular (open arrow) and traction (closed arrows).
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Figure 15-8
Ossification of the olecranon.
A: Secondary ossification begins as an oblique oblong center at about 6 to 8 years of age. B: It may progress as two separate ossification centers: Articular (open arrow) and traction (closed arrows).
A: Secondary ossification begins as an oblique oblong center at about 6 to 8 years of age. B: It may progress as two separate ossification centers: Articular (open arrow) and traction (closed arrows).
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Fusion of the Ossification Centers

The epiphyseal ossification centers of the distal humerus fuse as one unit and then fuse later to the metaphysis. The medial epicondyle is the last to fuse to the metaphysis. The ranges of onset of the ossification of various centers and their fusion to other centers or the metaphysis are summarized in Figure 15-9. Each center contributes to the overall architecture of the distal humerus (Fig. 15-9C). 
Figure 15-9
Ossification and fusion of the secondary centers of the distal humerus.
 
A: The average ages for the onset of ossification of the various ossification centers are shown for both boys and girls. B: The ages at which these centers fuse with each other are shown for both boys and girls. (Modified and reprinted with permission from Haraldsson S. On osteochondrosis deformans juvenilis capituli humeri including investigation of intraosseous vasculature in distal humerus. Acta Orthop Scand. 1959;38:1–232.) C: The contribution of each secondary center to the overall architecture of the distal humerus is represented by the stippled areas.
A: The average ages for the onset of ossification of the various ossification centers are shown for both boys and girls. B: The ages at which these centers fuse with each other are shown for both boys and girls. (Modified and reprinted with permission from Haraldsson S. On osteochondrosis deformans juvenilis capituli humeri including investigation of intraosseous vasculature in distal humerus. Acta Orthop Scand. 1959;38:1–232.) C: The contribution of each secondary center to the overall architecture of the distal humerus is represented by the stippled areas.
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Figure 15-9
Ossification and fusion of the secondary centers of the distal humerus.
A: The average ages for the onset of ossification of the various ossification centers are shown for both boys and girls. B: The ages at which these centers fuse with each other are shown for both boys and girls. (Modified and reprinted with permission from Haraldsson S. On osteochondrosis deformans juvenilis capituli humeri including investigation of intraosseous vasculature in distal humerus. Acta Orthop Scand. 1959;38:1–232.) C: The contribution of each secondary center to the overall architecture of the distal humerus is represented by the stippled areas.
A: The average ages for the onset of ossification of the various ossification centers are shown for both boys and girls. B: The ages at which these centers fuse with each other are shown for both boys and girls. (Modified and reprinted with permission from Haraldsson S. On osteochondrosis deformans juvenilis capituli humeri including investigation of intraosseous vasculature in distal humerus. Acta Orthop Scand. 1959;38:1–232.) C: The contribution of each secondary center to the overall architecture of the distal humerus is represented by the stippled areas.
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Fusion of the proximal radial and olecranon epiphyseal centers with their respective metaphyses occurs at around the same time that the common distal humeral epiphysis fuses with its metaphysis (i.e., between 14 and 16 years of age).9,12,53 
Noting that the pattern and ossification sequence of the six secondary ossification centers around the elbow were mainly derived from studies conducted more than 30 years ago, Cheng et al.17 evaluated elbow radiographs of 1,577 Chinese children. They found that the sequence of ossification was the same in boys and girls—capitellum, radial head, medial epicondyle, olecranon, trochlea, and lateral epicondyle—but ossification was delayed by about 2 years in boys in all ossification centers except the capitellum (Table 15-1). 

Blood Supply to Pediatric Distal Humerus

Extraosseous

There is a rich arterial network around the elbow (Fig. 15-10).65 The major arterial trunk, the brachial artery, lies anteriorly in the antecubital fossa. Most of the intraosseous blood supply of the distal humerus comes from the anastomotic vessels that course posteriorly. 
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Figure 15-10
The major arteries about the anterior elbow.
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Three structural components govern the location of the entrance of the vessels into the developing epiphysis. First, there is no communication between the intraosseous metaphyseal vasculature and the ossification centers. Second, vessels do not penetrate the articular surfaces. The lateral condyle is nonarticular only at the origin of the muscles and collateral ligaments. Third, the vessels do not penetrate the articular capsule except at the interface with the surface of the bone. Thus, only a small portion of the lateral pondyle posteriorly is both nonarticular and extracapsular (Fig. 15-11).31 
Figure 15-11
The vessels supplying the lateral condylar epiphysis enter the posterior aspect of the condyle, which is extra-articular.
 
(Modified and reprinted with permission from Haraldsson S. On osteochondrosis deformans juvenilis capituli humeri including investigation of intraosseous vasculature in distal humerus. Acta Orthop Scand. 1959; 38:1–232.)
(Modified and reprinted with permission from 


Haraldsson S
.
On osteochondrosis deformans juvenilis capituli humeri including investigation of intraosseous vasculature in distal humerus.
Acta Orthop Scand.
1959;
38:1–232.)
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Figure 15-11
The vessels supplying the lateral condylar epiphysis enter the posterior aspect of the condyle, which is extra-articular.
(Modified and reprinted with permission from Haraldsson S. On osteochondrosis deformans juvenilis capituli humeri including investigation of intraosseous vasculature in distal humerus. Acta Orthop Scand. 1959; 38:1–232.)
(Modified and reprinted with permission from 


Haraldsson S
.
On osteochondrosis deformans juvenilis capituli humeri including investigation of intraosseous vasculature in distal humerus.
Acta Orthop Scand.
1959;
38:1–232.)
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Intraosseous

The most extensive study of the intraosseous blood supply of the developing distal humerus was conducted by Haraldsson30,31 (Fig. 15-12A), who demonstrated that there are two types of vessels in the developing lateral condyle. These vessels enter the posterior portion of the condyle just lateral to the origin of the capsule and proximal to the articular cartilage near the origin of the anconeus muscle. They penetrate the nonossified cartilage and traverse it to the developing ossific nucleus. In a young child, this is a relatively long course (Fig. 15-12A). These vessels communicate with one another within the ossific nucleus but do not communicate with vessels in either the metaphysis or nonossified chondroepiphysis. Thus, for practical purposes, they are end vessels. 
Figure 15-12
Intraosseous blood supply of the distal humerus.
 
A: The vessels supplying the lateral condylar epiphysis enter on the posterior aspect and course for a considerable distance before reaching the ossific nucleus. B: Two definite vessels supply the ossification center of the medial crista of the trochlea. The lateral vessel enters by crossing the physis. The medial one enters by way of the nonarticular edge of the medial crista.
 
(Modified and reprinted with permission from Haraldsson S. On osteochondrosis deformans juvenilis capituli humeri including investigation of intraosseous vasculature in distal humerus. Acta Orthop Scand. 1959; 38:1–232.)
A: The vessels supplying the lateral condylar epiphysis enter on the posterior aspect and course for a considerable distance before reaching the ossific nucleus. B: Two definite vessels supply the ossification center of the medial crista of the trochlea. The lateral vessel enters by crossing the physis. The medial one enters by way of the nonarticular edge of the medial crista.
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Figure 15-12
Intraosseous blood supply of the distal humerus.
A: The vessels supplying the lateral condylar epiphysis enter on the posterior aspect and course for a considerable distance before reaching the ossific nucleus. B: Two definite vessels supply the ossification center of the medial crista of the trochlea. The lateral vessel enters by crossing the physis. The medial one enters by way of the nonarticular edge of the medial crista.
(Modified and reprinted with permission from Haraldsson S. On osteochondrosis deformans juvenilis capituli humeri including investigation of intraosseous vasculature in distal humerus. Acta Orthop Scand. 1959; 38:1–232.)
A: The vessels supplying the lateral condylar epiphysis enter on the posterior aspect and course for a considerable distance before reaching the ossific nucleus. B: Two definite vessels supply the ossification center of the medial crista of the trochlea. The lateral vessel enters by crossing the physis. The medial one enters by way of the nonarticular edge of the medial crista.
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The ossification center of the lateral condyle extends into the lateral portion of the trochlea. Thus, the lateral crista or ridge of the trochlea derives its blood supply from these condylar vessels. The medial ridge or crista remains unossified for a longer period of time. The trochlea is covered entirely by articular cartilage and lies totally within the confines of the articular capsule. The vessels that supply the nucleus of the ossific centers of the trochlea must therefore traverse the periphery of the physis to enter the epiphysis. 
Haraldsson's31 studies have shown two sources of blood supply to the ossific nucleus of the medial portion of the trochlea (Fig. 15-12B). The lateral vessel, on the posterior surface of the distal humeral metaphysis, penetrates the periphery of the physis and terminates in the trochlear nucleus. Because this vessel supplying the trochlea is an end vessel, it is especially vulnerable to injury by a fracture that courses through either the physis or the very distal portion of the humeral metaphysis. Injury to this vessel can markedly decrease the nourishment to the developing lateral ossific nucleus of the trochlea. The medial vessel penetrates the nonarticulating portion of the medial crista of the trochlea. This multiple vascular source may account for the development of multiple ossification centers in the maturing trochlea, giving it a fragmented appearance (Fig. 15-5). When growth is complete, metaphyseal and epiphyseal vessels anastomose freely. The blood supply from the central nutrient vessel of the shaft reaches the epicondylar regions in the skeletally mature distal humerus.39 

Intra-articular Structures of the Pediatric Distal Humerus

The articular surface lies within the confines of the capsule, but nonarticulating areas involving the coronoid and radial fossae anteriorly and the olecranon fossa posteriorly are also within the confines of the articular cavity.64 The capsule attaches just distal to the coronoid and olecranon processes. Thus, these processes are intra-articular.36 The entire radial head is intra-articular, with a recess or diverticulum of the elbow's articular cavity extending distally under the margin of the orbicular ligament. The medial and lateral epicondyles are extra-articular. 
The anterior capsule is thickened anteriorly. These longitudinally directed fibers are very strong and become taut with the elbow in extension. In hyperextension, the tight anterior bands of the capsule force the ulna firmly into contact with the humerus. Thus, the fulcrum of rotation becomes transmitted proximally into the tip of the olecranon in the supracondylar area. This is an important factor in the etiology of supracondylar fractures. 

Fat Pads

At the proximal portion of the capsule, between it and the synovial layer, are two large fat pads (Fig. 15-13). The posterior fat pad lies totally within the depths of the olecranon fossa when the elbow is flexed. The anterior fat pad extends anteriorly out of the margins of the coronoid fossa. The significance of these fat pads in the interpretation of radiographs of the elbow is discussed later. 
Figure 15-13
The elbow fat pads.
 
Some of the coronoid fat pad lies anterior to the shallow coronoid fossa. The olecranon fat pad lies totally within the deeper olecranon fossa.
Some of the coronoid fat pad lies anterior to the shallow coronoid fossa. The olecranon fat pad lies totally within the deeper olecranon fossa.
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Figure 15-13
The elbow fat pads.
Some of the coronoid fat pad lies anterior to the shallow coronoid fossa. The olecranon fat pad lies totally within the deeper olecranon fossa.
Some of the coronoid fat pad lies anterior to the shallow coronoid fossa. The olecranon fat pad lies totally within the deeper olecranon fossa.
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Ligaments

The pertinent ligamentous anatomy involving the orbicular and collateral ligaments is discussed in the sections on the specific injuries involving the radial neck, medial epicondyle, and elbow dislocations. 

Radiographic Findings in Pediatric Distal Humeral Fractures

Because of the ever-changing ossification pattern, identification and delineation of fractures about the elbow in the immature skeleton may be subject to misinterpretation. The variables of ossification of the epiphyses should be well known to the orthopedic surgeon who treats these injuries. 
Several studies have suggested that children with a normal range of elbow motion after elbow trauma do not require immediate radiographic evaluation. In a large multicenter prospective study, Appelboam et al.3 found that of 780 children evaluated for elbow trauma, 289 were able to fully extend their elbow; among these, 12 (4%) fractures were identified, all at their first evaluation. Among the 491 children who could not fully extend their injured elbow, 210 (43%) had confirmed fractures. These authors suggested that an elbow extension test can be used to rule out the need for radiographs, provided the physician is confident that an olecranon fracture is not present and that the patient can return for reevaluation if symptoms have not resolved in 7 to 10 days. Lennon et al.,42 in a study involving 407 patients ranging in age from 2 to 96 years, proposed that patients aged no more than 16 years with a range of motion equal to the unaffected side do not require radiographic evaluation. Darracq et al.19 found that limitation of active range of motion was 100% sensitive for fracture or effusion, whereas preservation of active range of motion was 97% specific for the absence of fracture. Other studies20,40 have confirmed a high sensitivity (91% to 97%) of an inability to extend the elbow as a predictor of elbow fracture in both children and adults. More recently, however, Baker and Borland warned that in children with blunt trauma a normal range of motion does not rule out significant injury and should not be used as a screening tool. In their 177 patients, an abnormal range of motion had a negative predictive value of only 77%.5 
Waters et al. described a subset of serious injuries to the pediatric elbow that they termed TRASH (The Radiographic Appearance Seemed Harmless) lesions (Table 15-2). These lesions represent predominantly osteochondral injuries in children younger than 10 years of age who have sustained high-energy trauma; the lesions are often associated with unrecognized, spontaneously reduced elbow dislocations (Fig. 15-14). Any elbow dislocation in a child younger than 10 years of age should raise concern about a displaced, intra-articular osteochondral fracture, especially with a high-energy mechanism of injury and more swelling than the seemingly benign radiograph demonstrates. A high index of suspicion and early additional imaging (ultrasound, arthrogram, or magnetic resonance imaging [MRI]) usually contribute to a more accurate diagnosis of these injuries.62 
 
Table 15-2
Elbow “TRASH” Lesions
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Table 15-2
Elbow “TRASH” Lesions
  •  
    Unossified medial condylar humeral fractures
  •  
    Unossified transphyseal distal humeral fractures
  •  
    Entrapped medial epicondylar fractures
  •  
    Complex osteochondral elbow fracture-dislocation in a child younger than 10 years of age
  •  
    Osteochondral fractures with joint incongruity
  •  
    Radial head anterior compression fractures with progressive radiocapitellar subluxation
  •  
    Monteggia fracture-dislocations
  •  
    Lateral condylar avulsion shear fractures
 

Modified from Waters PM, Beaty J, Kasser J. Elbow “TRASH” (the radiographic appearance seemed harmless) lesions. J Pediatr Orthop. 2010; 30(suppl 2):S77–S81.

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Figure 15-14
 
A: Anteroposterior, lateral, and oblique views of an osteochondral fracture of the lateral condyle. If unrecognized, this can lead to painful nonunion and intra-articular incongruity. B: Magnetic resonance imaging scan documenting displacement and operative indications. C: Percutaneous reduction and screw fixation were done based on MRI findings.
 
(From Waters PM, Beaty J, Kasser J. Elbow “TRASH” (the radiographic appearance seemed harmless) lesions. J Pediatr Orthop. 2010; 30(suppl 2):S77–S81.)
A: Anteroposterior, lateral, and oblique views of an osteochondral fracture of the lateral condyle. If unrecognized, this can lead to painful nonunion and intra-articular incongruity. B: Magnetic resonance imaging scan documenting displacement and operative indications. C: Percutaneous reduction and screw fixation were done based on MRI findings.
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Figure 15-14
A: Anteroposterior, lateral, and oblique views of an osteochondral fracture of the lateral condyle. If unrecognized, this can lead to painful nonunion and intra-articular incongruity. B: Magnetic resonance imaging scan documenting displacement and operative indications. C: Percutaneous reduction and screw fixation were done based on MRI findings.
(From Waters PM, Beaty J, Kasser J. Elbow “TRASH” (the radiographic appearance seemed harmless) lesions. J Pediatr Orthop. 2010; 30(suppl 2):S77–S81.)
A: Anteroposterior, lateral, and oblique views of an osteochondral fracture of the lateral condyle. If unrecognized, this can lead to painful nonunion and intra-articular incongruity. B: Magnetic resonance imaging scan documenting displacement and operative indications. C: Percutaneous reduction and screw fixation were done based on MRI findings.
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When radiographs are indicated, a number of anatomic landmarks and angles should be evaluated and measured, including any displacement of the fat pads about the elbow. It is important to be familiar with these landmarks and angles and to be aware of the significance of any deviation from normal. 

Standard Views

The standard radiographs of the elbow include an anteroposterior (AP) view with the elbow extended and a lateral view with the elbow flexed to 90 degrees and the forearm neutral. 

Jones View

It is often difficult for a child to extend the injured elbow, and an axial view of the elbow, the Jones view, may be helpful (Fig. 15-15). The distal humerus is normally difficult to interpret because of the superimposed proximal radius and ulna. There is often a high index of suspicion for a fracture, but none is visible on routine AP and lateral radiographs. In this case, internal and external oblique views may be helpful. This is especially true in identifying fractures of the radial head and coronoid process and judging displacement in lateral condylar fractures. 
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Figure 15-15
Jones axial radiographic view of the elbow.
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Measurement of Displacement of Pediatric Distal Humeral Fractures

The determination of the amount of fracture displacement is critical to the choice of treatment of medial epicondylar fractures. The general consensus among pediatric orthopedic surgeons seems to be that fractures with less than 2 mm of displacement can be treated nonoperatively, whereas those with more than 5 mm of displacement should be treated operatively. A difference of 1 or 2 mm in the measurement of displacement can change the management of these fractures. To determine the reliability of displacement measurements, Pappas et al.48 had radiographs of 38 children with fractures of the medial humeral epicondyle evaluated by five reviewers with different levels of orthopedic training. Pappas et al. found that the reviewers disagreed an average of 87% of the time about measurements on the lateral view, 64% of the time about measurements on the oblique view, and 54% about measurements on the AP view. The findings cast doubt on whether the amount of perceived displacement should be used as a criterion for choosing operative or nonoperative treatment of fractures of the medial epicondyle. Proposed methods for improving displacement measurement were (1) measuring displacement on AP views and (2) measuring displacement as the maximal distance between the fragment and the bone location from which it came (Fig. 15-16). In contrast, Edmonds22 suggested that internal oblique views appear to best approximate the true anterior displacement. Comparison of measurements of displacement on radiographs to those on three-dimensional computed tomography (CT) scans demonstrated that fractures that appear to be minimally displaced or nondisplaced on radiographs, especially AP and lateral views, may have more than 1 cm of anterior displacement by CT scan. 
Figure 15-16
On anteroposterior radiograph of a left elbow with a medial epicondylar fracture, there are three different places where displacement could be measured.
 
The red line represents 2 mm of displacement; the green line, 3 mm; and the blue line, 5 mm.
 
(From Pappas N, Lawrence JT, Donegan D, et al. Intraobserver and interobserver agreement in the measurement of displaced humeral medial epicondyle fractures in children. J Bone Joint Surg Am. 2010; 92:322–327.)
The red line represents 2 mm of displacement; the green line, 3 mm; and the blue line, 5 mm.
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Figure 15-16
On anteroposterior radiograph of a left elbow with a medial epicondylar fracture, there are three different places where displacement could be measured.
The red line represents 2 mm of displacement; the green line, 3 mm; and the blue line, 5 mm.
(From Pappas N, Lawrence JT, Donegan D, et al. Intraobserver and interobserver agreement in the measurement of displaced humeral medial epicondyle fractures in children. J Bone Joint Surg Am. 2010; 92:322–327.)
The red line represents 2 mm of displacement; the green line, 3 mm; and the blue line, 5 mm.
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Anteroposterior Landmarks in Pediatric Distal Humerus Fractures

Baumann's Angle

In the standard AP view, the major landmark is the angulation of the physeal line between the lateral condyle and the distal humeral metaphysis. The ossification center of the lateral condyle extends into the radial or lateral crista of the trochlea (Fig. 15-9C). This physeal line forms an angle with the long axis of the humerus. The angle formed by this physeal line and the long axis of the humerus is the Baumann's angle (Fig. 15-17A).6 The Baumann's angle is not equal to the carrying angle of the elbow in older children.13 This is a consistent angle when both sides are compared, and the x-ray beam is directed perpendicular to the long axis of the humerus. Acton and McNally1 reviewed the descriptions of the Baumann's angle in a number of commonly used textbooks and discovered three variations of measurement technique. They recommended that the angle should always be measured between the long axis of the humerus and the inclination of the capitellar physis, as Baumann described, and that it should be called the “shaft-physeal” angle to avoid confusion. 
Figure 15-17
AP radiographic angles of the elbow.
 
A: Baumann's angle. B: The humeral–ulnar angle. C: The metaphyseal–diaphyseal angle.
 
(Reprinted with permission from O'Brien WR, Eilert RE, Chang FM, et al. The metaphyseal–diaphyseal angle as a guide to treating supracondylar fractures of the humerus in children. Presented at: 54th Annual Meeting of AAOS; 1987; San Francisco, CA.)
A: Baumann's angle. B: The humeral–ulnar angle. C: The metaphyseal–diaphyseal angle.
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Figure 15-17
AP radiographic angles of the elbow.
A: Baumann's angle. B: The humeral–ulnar angle. C: The metaphyseal–diaphyseal angle.
(Reprinted with permission from O'Brien WR, Eilert RE, Chang FM, et al. The metaphyseal–diaphyseal angle as a guide to treating supracondylar fractures of the humerus in children. Presented at: 54th Annual Meeting of AAOS; 1987; San Francisco, CA.)
A: Baumann's angle. B: The humeral–ulnar angle. C: The metaphyseal–diaphyseal angle.
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Caudad–cephalad angulation of the x-ray tube or right or left angulation of the tube by as much as 30 degrees changes the Baumann's angle by less than 5 degrees. If, however, the tube becomes angulated in a cephalad–caudad direction by more than 20 degrees, the angle is changed significantly and the measurement is inaccurate. In their cadaver studies, Camp et al.15 found that rotation of the distal fragment or the entire reduced humerus can also alter the projection of the Baumann's angle. They found that to be accurate, the humerus must be parallel to the x-ray plate, with the beam directed perpendicular to the film as well. Thus, in the routine AP radiographs of the distal humerus, including the Jones view, the Baumann's angle is a good measurement of any deviation of the angulation of the distal humerus.18,54,56,57 

Other Angles

Two other angles measured on AP radiographs are commonly used to determine the proper alignment of the distal humerus or carrying angle. The humeral–ulnar angle is determined by lines longitudinally bisecting the shaft of the humerus with the shaft of the ulna on an AP view (Fig. 15-17B).7,35,48 The metaphyseal–diaphyseal angle is determined by a line that longitudinally bisects the shaft of the humerus with a line that connects the widest points of the metaphysis of the distal humerus (Fig. 15-17C).46 The humeral–ulnar angle is the most accurate in determining the true carrying angle of the elbow. The Baumann's angle also has a good correlation with the clinical carrying angle, but it may be difficult to measure in adolescents in whom the ossification center of the lateral condyle is beginning to fuse with other centers. The metaphyseal–diaphyseal angle is the least accurate of the three.60 

Lateral Landmarks in Pediatric Distal Humerus Fractures

Teardrop

The lateral projection of the distal humerus presents a teardrop-like shadow above the capitellum.53 The anterior dense line making up the teardrop represents the posterior margin of the coronoid fossa. The posterior dense line represents the anterior margin of the olecranon fossa. The inferior portion of the teardrop is the ossification center of the capitellum. On a true lateral projection, this teardrop should be well defined (Fig. 15-18A). 
Figure 15-18
Lateral radiograph lines of the distal humerus.
 
A: The teardrop of the distal humerus. B: The angulation of the lateral condyle with the shaft of the humerus. C: The anterior humeral line. D: The coronoid line.
A: The teardrop of the distal humerus. B: The angulation of the lateral condyle with the shaft of the humerus. C: The anterior humeral line. D: The coronoid line.
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Figure 15-18
Lateral radiograph lines of the distal humerus.
A: The teardrop of the distal humerus. B: The angulation of the lateral condyle with the shaft of the humerus. C: The anterior humeral line. D: The coronoid line.
A: The teardrop of the distal humerus. B: The angulation of the lateral condyle with the shaft of the humerus. C: The anterior humeral line. D: The coronoid line.
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Shaft-condylar Angle

On the lateral radiograph, there is an angulation of 40 degrees between the long axis of the humerus and the long axis of the lateral condyle (Fig. 15-18B). This can also be measured by the flexion angle of the distal humerus, which is calculated by measuring the angle of the lateral condylar physeal line with the long axis of the shaft of the humerus.51 

Anterior Humeral Line

If a line is drawn along the anterior border of the distal humeral shaft, it should pass through the middle third of the ossification center of the capitellum. This is referred to as the anterior humeral line (Fig. 15-18C). Passage of the anterior humeral line through the anterior portion of the lateral condylar ossification center or anterior to it indicates the presence of posterior angulation of the distal humerus. In a large study of minimally displaced supracondylar fractures, Rogers et al.51 found that this anterior humeral line was the most reliable factor in detecting the presence or absence of occult fractures. Herman et al.,33 however, found that the location of the anterior humeral line varied according to age: in almost half of children younger than 4 years of age the line passed through the anterior third of the capitellum, whereas in older children the anterior humeral line more consistently passed through the middle third. 

Coronoid Line

A line directed proximally along the anterior border of the coronoid process should barely touch the anterior portion of the lateral condyle (Fig. 15-18D). Posterior displacement of the lateral condyle projects the ossification center posterior to this coronoid line.51 

Lateral Humerocapitellar Angle

Shank et al.52 described measurement of the lateral humerocapitellar angle (LHCA) using digital measurement tools and digital radiographs (Fig. 15-19). This angle measures the angular relationship between the humeral shaft and the capitellum as seen on the lateral view. In normal elbows, the LHCA averaged 51 degrees and was not affected by age, sex, or side. Its reliability was found to be inferior to that of the Baumann's angle but improved with increasing patient age. The correlation between the LHCA and clinical outcome is unclear, with some studies finding no correlation44,45 and others reporting a strong correlation between the LHCA and loss of flexion at skeletal maturity.25,58 Although the exact relationship between the LHCA and clinical outcome is unclear, the authors suggested that an LHCA of more than three standard deviations from normal (more than 69 degrees) should be accepted with reservation, especially in older patients, because some studies have suggested unpredictable remodeling of angular deformity.25,27,58 
Figure 15-19
Lateral humerocapitellar angle (LHCA) on lateral radiograph of normal elbow.
 
(From Shank CF, Wiater BP, Pace JL, et al. The lateral capitellohumeral angle in normal children: Mean, variation, and reliability in comparison to Baumann's angle. J Pediatr Orthop. 2011; 31:266–271.)
(From 


Shank CF,

Wiater BP,

Pace JL
, et al.
The lateral capitellohumeral angle in normal children: Mean, variation, and reliability in comparison to Baumann's angle.
J Pediatr Orthop.
2011;
31:266–271.)
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Figure 15-19
Lateral humerocapitellar angle (LHCA) on lateral radiograph of normal elbow.
(From Shank CF, Wiater BP, Pace JL, et al. The lateral capitellohumeral angle in normal children: Mean, variation, and reliability in comparison to Baumann's angle. J Pediatr Orthop. 2011; 31:266–271.)
(From 


Shank CF,

Wiater BP,

Pace JL
, et al.
The lateral capitellohumeral angle in normal children: Mean, variation, and reliability in comparison to Baumann's angle.
J Pediatr Orthop.
2011;
31:266–271.)
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Pseudofracture

Some vagaries of the ossification process about the elbow may be interpreted as a fracture.53 For example, the ossification of the trochlea may be irregular, producing a fragmented appearance (Fig. 15-5). This fragmentation can be misinterpreted, especially if the distal humerus is slightly oblique or tilted. These secondary ossification centers may be mistaken for fracture fragments lying between the semilunar notch and lateral condyle (Fig. 15-20). 
Figure 15-20
Pseudofracture of the elbow.
 
The trochlea with its multiple ossification centers may be misinterpreted as fracture fragments lying between the joint surfaces (arrow).
The trochlea with its multiple ossification centers may be misinterpreted as fracture fragments lying between the joint surfaces (arrow).
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Figure 15-20
Pseudofracture of the elbow.
The trochlea with its multiple ossification centers may be misinterpreted as fracture fragments lying between the joint surfaces (arrow).
The trochlea with its multiple ossification centers may be misinterpreted as fracture fragments lying between the joint surfaces (arrow).
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On the lateral view, the physeal line between the lateral condyle and the distal humeral metaphysis is wider posteriorly. This appearance may give a misinterpretation that the lateral condyle is fractured and tilted.13 
On the AP view before the radial head ossifies, there is normally some lateral angulation to the radial border of the neck of the radius that may give the appearance of subluxation (Fig. 15-3). The true position of the radial head can be confirmed by noting the relationship of the proximal radius to the ossification center of the lateral condyle on the lateral projection.52 

Fat Pad Signs of the Elbow

There are three areas in which fat pads overlie the major structures of the elbow. Displacement of any of the fat pads can indicate an occult fracture. The first two areas are the fat pads that overlie the capsule in the coronoid fossa anteriorly and the olecranon fossa posteriorly. Displacement of either or both of these fat pads is usually referred to as the classic elbow fat pad sign. A third accumulation of fat overlies the supinator muscle as it wraps around the proximal radius. 
Olecranon (Posterior) Fat Pad
Because the olecranon fossa is deep, the fat pad here is totally contained within the fossa. It is not visible on a normal lateral radiograph of the elbow flexed to 90 degrees (Fig. 15-21A). 
Figure 15-21
Radiographic variations of the elbow fat pads.
 
A: Normal relationships of the two fat pads. B: Displacement of both fat pads (arrows) with an intra-articular effusion. C: In some cases, the effusion may displace only the anterior fat pad (arrows). D: In extension, the posterior fat pad is normally displaced by the olecranon. E: An extra-articular fracture may lift the distal periosteum and displace the proximal portion of the posterior fat pad. F: A radiograph showing displacement of both fat pads (arrows) from an intra-articular effusion.
 
(Modified and reprinted with permission from Murphy WA, Siegel MJ. Elbow fat pads with new signs and extended differential diagnosis. Radiology. 1977; 124:656–659.)
A: Normal relationships of the two fat pads. B: Displacement of both fat pads (arrows) with an intra-articular effusion. C: In some cases, the effusion may displace only the anterior fat pad (arrows). D: In extension, the posterior fat pad is normally displaced by the olecranon. E: An extra-articular fracture may lift the distal periosteum and displace the proximal portion of the posterior fat pad. F: A radiograph showing displacement of both fat pads (arrows) from an intra-articular effusion.
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Figure 15-21
Radiographic variations of the elbow fat pads.
A: Normal relationships of the two fat pads. B: Displacement of both fat pads (arrows) with an intra-articular effusion. C: In some cases, the effusion may displace only the anterior fat pad (arrows). D: In extension, the posterior fat pad is normally displaced by the olecranon. E: An extra-articular fracture may lift the distal periosteum and displace the proximal portion of the posterior fat pad. F: A radiograph showing displacement of both fat pads (arrows) from an intra-articular effusion.
(Modified and reprinted with permission from Murphy WA, Siegel MJ. Elbow fat pads with new signs and extended differential diagnosis. Radiology. 1977; 124:656–659.)
A: Normal relationships of the two fat pads. B: Displacement of both fat pads (arrows) with an intra-articular effusion. C: In some cases, the effusion may displace only the anterior fat pad (arrows). D: In extension, the posterior fat pad is normally displaced by the olecranon. E: An extra-articular fracture may lift the distal periosteum and displace the proximal portion of the posterior fat pad. F: A radiograph showing displacement of both fat pads (arrows) from an intra-articular effusion.
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Distention of the capsule with an effusion, as occurs with an occult intra-articular fracture, a spontaneously reduced dislocation, or even an infection, can cause the dorsal or olecranon fat pad to be visible.66 
Coronoid (Anterior) Fat Pad
Likewise, the ventral or coronoid fat pad may be displaced anteriorly (Fig. 15-21B).11 Because the coronoid fossa is shallow, the fat pad in this area projects anterior to the bony margins and can be seen normally as a triangular radiolucency anterior to the distal humerus. Although displacement of the classic elbow fat pads is a reliable indication of an intra-articular effusion, there may be instances in which only one of the fat pads is displaced. Brodeur et al.13 and Kohn39 have shown that the coronoid fat pad is more sensitive to small effusions than the olecranon fat pad. The coronoid fat pad can be displaced without a coexistent displacement of the olecranon fat pad (Fig. 15-21C). Blumberg et al.10 analyzed the radiographs of 197 consecutive patients with elbow trauma and found that 113 (57%) had normal anterior fat pads; of these, only two had fractures, giving a 98% negative predictive value to the presence of a normal anterior fat pad. 
Supinator Fat Pad
A layer of fat on the anterior aspect of the supinator muscle wraps around the proximal radius. This layer of fat or fat pad may normally bow anteriorly to some degree. Brodeur et al.13 stated that displacement may indicate the presence of an occult fracture of the radial neck. Displacement of the fat line or pad is often difficult to interpret; in a review of fractures involving the proximal radius, Schunk et al.53 found it to be positive only 50% of the time. 
Fat Pad Variations
For the fat pads to be displaced, the capsule must be intact. This can explain why there may be no displacement of the fat pads with an elbow dislocation that has spontaneously reduced because of capsule rupture. Murphy and Siegel46 described other variations of classic fat pad displacement. If the elbow is extended, the fat pad is normally displaced from the olecranon fossa by the olecranon (Fig. 15-21D). Distal humeral fractures may cause subperiosteal bleeding and may lift the proximal portion of the olecranon fat pad without the presence of an effusion (Fig. 15-21E). These false-negative and false-positive determinations must be kept in mind when interpreting the presence or absence of a fat pad finding with an elbow injury. 
To date, fat pad studies draw disparate conclusions. Corbett's18 review of elbow injuries indicated that if a displacement of the posterior fat pad existed, a fracture was almost always present. Displacement of the anterior fat pad alone, however, could occur without a fracture. Corbett18 also determined that the degree of displacement bore no relation to the extent of the fracture. Skaggs and Mirzayan59 reported that 34 of 45 children (76%) with a history of elbow trauma and an elevated posterior fat pad had radiographic evidence of elbow fractures at an average of 3 weeks after injury, though AP, lateral, and oblique radiographs at the time of injury showed no other evidence of fracture. They recommended that a child with a history of elbow trauma and an elevated fat pad should be treated as if a nondisplaced elbow fracture were present. Donnelly et al.,21 however, found evidence of fracture in only 9 of 54 children (17%) who had a history of trauma and elbow joint effusion but no identifiable fracture on initial radiographs. Donnelly et al. concluded that joint effusion without a visible fracture on initial radiographs does not correlate with the presence of occult fracture in most patients (83%). Persistent effusion did correlate with occult fracture: 78% of those with occult fractures had persistent effusions, whereas effusions were noted in only 16% of those without fractures. More recently, in a prospective MRI study of 26 children with positive fat pad signs, Al-Aubaidi and Torfing2 concluded that the presence of a positive fat pad sign is not synonymous with an occult fracture. All 26 children had a positive fat pad sign on lateral radiographs, but MRI scans obtained an average of 7 days later found occult fractures in only 6 patients, none of whom had a change in fracture treatment. 

Comparison Radiographs of Pediatric Distal Humeral Fractures

Although it is often tempting to order comparison radiographs in a child with an injured elbow due to the difficulty evaluating the irregularity of the ossification process, the indications for ordering comparison radiographs are rare. Kissoon et al.38 found that using routine comparison radiographs in children with injured elbows did not significantly increase the accuracy of diagnosis, regardless of the interpreter's training. Petit et al.50 reviewed 3,128 radiographs of 2,470 children admitted to a pediatric emergency department for osteoarticular trauma and found that only 22% of the radiographs revealed abnormal findings; 33.3% of elbow radiographs revealed abnormalities. Fewer than half of clinically suspected fractures were confirmed by radiograph. 

Magnetic Resonance Imaging for Pediatric Distal Humeral Fractures

Major and Crawford43 used MRI to evaluate 7 children who had radiographs that showed effusion but no fractures; 4 of the children had fractures identified by MRI. These investigators suggested that an occult fracture is usually present when effusion occurs, even if a fracture is not visible on radiograph. Griffith et al.29 reviewed the radiographs and MRI scans of 50 children with elbow trauma. Radiographs identified effusions in 34% of the children and fractures in 52%; MRI identified effusions in 96% and fractures in 74%. Although MRI revealed a broad spectrum of bone and soft tissue injury beyond that shown on radiographs (bone bruising, muscle and ligament injuries, physeal injury, fracture), the additional information provided by MRI had little influence on patient treatment and no value in predicting clinical outcome. We have found MRI to be helpful in evaluating articular and osteochondral fractures to identify fracture pattern and extent, fragment position, and any interposed structure. 

Other Imaging Modalities for Pediatric Distal Humeral Fractures

Sonography and arthrography can be useful in examining children with posttraumatic elbow effusions, but these can be painful and invasive. The use of CT in the young can be limited by the need for sedation. In adolescent T-condylar humeral fractures, CT is extremely helpful for planning operative intervention. The development of multidetector CT (MDCT) technology allows examinations to be completed in seconds, eliminating the need for sedation in most cases. Studies using MDCT can also be reformatted and evaluated in multiple planes, reducing the manipulation necessary for a series of radiographs. Chapman et al.16 reported that, in a series of 31 children with posttraumatic elbow effusion and normal radiographs, MDCT depicted occult injuries in 52%. Besides the minimal manipulation required, making it relatively easy and pain free, and the speed with which the image is obtained, they cited as additional advantages of MDCT the lower radiation dose than conventional radiographs, its sensitivity (92%), specificity (79%), and high negative predictive value (92%). A limitation of this method may be its high cost compared to standard radiographic examination. 

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