ASSESSMENT OF FRACTURES INVOLVING THE ENTIRE DISTAL HUMERUS
Mechanisms of Injury for Fractures Involving the Entire Distal Humerus
The exact mechanism of this injury is unknown and probably varies with the age group involved. A few consistent factors are evident. First, many fractures of the entire distal humeral physis have occurred as birth injuries associated with difficult deliveries.2,4,6,19,69 Siffert69 noted that the clinical appearance of these injured elbows at the time of delivery was not especially impressive. There was only moderate swelling and some crepitus.
Second, DeLee et al.17 noted a high incidence of confirmed or suspected child abuse in their very young patients. Other reports2,16,49,56,79 have confirmed the frequency of child abuse in infants and young children with these fractures, and up to 50% of these fractures in children under the age of 2 may be the result of abuse.
Bright9 showed that a physis is more likely to fail with rotary shear forces than with pure bending or tension forces. Young infants have some residual flexion contractures of the elbow from intrauterine positioning; this prevents the hyperextension injury that results in supracondylar elbow fractures in older children. Rotary or shear forces on the elbow, which can be caused by child abuse or birth trauma in young infants, are probably more responsible for this injury in young children. In older children, a hyperextension force on an outstretched arm may cause the injury. Abe et al.1 reported 21 children, ranging in age from 1 to 11 years (average: 5 years), with fracture separations of the distal humeral epiphysis, all of which were sustained in falls.
Associated Injuries with Fractures Involving the Entire Distal Humerus
Child abuse should always be considered in children with this injury, especially a type A fracture pattern (see classification below), unless it occurs at birth. A young infant is unlikely to incur this type of injury spontaneously from the usual falls that occur during the first year of life. Of the 16 fractures reported by DeLee et al.,17 six resulted from documented or highly suspected child abuse, all in children younger than 2 years of age. Therefore, other injuries commonly found in cases of child abuse should be considered. If child abuse is suspected, a bone scan and a skeletal survey are warranted, to look for metaphyseal corner fractures, rib fractures, or fractures at various stages of healing, and the possibility of head trauma should not be ignored.
Signs and Symptoms of Fractures Involving the Entire Distal Humerus
In an infant less than 18 months of age, whose elbow is swollen secondary to trauma or suspected trauma, a fracture involving the entire distal humeral physis should be considered. In a young infant or newborn, swelling may be minimal with little crepitus. Poland64 described the crepitus as “muffled” crepitus because the fracture ends are covered with softer cartilage than the firm osseous tissue in other fractures about the elbow. Because of the large, wide fracture surfaces, there are fewer tendencies for tilting with distal fragment rotation, and the angular deformity is less severe than that with supracondylar fractures. In older children, the elbow is often so swollen that a clinical assessment of the bony landmarks is impossible, and only radiographic evaluation can provide confirmation of the diagnosis.
Imaging and Other Diagnostic Studies for Fractures Involving the Entire Distal Humerus
Confirming radiographic evidence of a distal humeral physeal separation can be difficult, especially if the ossification center of the lateral condyle is not visible in an infant. The only relationship that can be determined is that of the primary ossification centers of the distal humerus to the proximal radius and ulna. The proximal radius and ulna maintain an anatomic relationship to each other but are displaced posteriorly and medially in relation to the distal humerus. This posteromedial relationship is diagnostic. Although theoretically, the distal fragment can be displaced in any direction, with rare exceptions,6 most fractures reported have been displaced posteromedially. Comparison views of the opposite uninjured elbow may be helpful to determine the presence of posteromedial displacement (Fig. 20-1A, B).
Distinguishing the injury from an elbow dislocation may be challenging. It should be remembered that elbow dislocations are rare in the peak age group for fractures of the entire distal humeral physis. With elbow dislocations, the displacement of the proximal radius and ulna is almost always posterolateral, and the relationship between the proximal radius and lateral condylar epiphysis is disrupted. Unfortunately, this can be especially difficult to assess in young children when the capitellum is not ossified. In contrast, the anatomic relationship of the lateral condylar epiphysis with the radial head is maintained with a transphyseal separation, even though the distal humeral epiphysis is displaced posterior and medial in relation to the metaphysis of the humerus. Once the lateral condylar epiphysis becomes ossified, displacement of the entire distal epiphysis is much more obvious.
Because they have a large metaphyseal fragment, type C fractures may be confused with either a low supracondylar fracture or a fracture of the lateral condylar physis. The key diagnostic point is the smooth outline of the distal metaphysis in fractures involving the total distal physis. With supracondylar fractures, the distal portion of the distal fragment has a more irregular border.
Differentiation from a fracture of the lateral condylar physis in an infant can be made on radiograph. With a displaced fracture of the lateral condylar physis, the relationship between the lateral condylar epiphysis and the proximal radius can be disrupted but may remain normal (Fig. 20-2). If the lateral crista of the trochlea is involved, the proximal radius and ulna may be displaced posterolaterally. Oblique radiographs or other advanced imaging may be needed to distinguish these injuries.
If differentiation of this injury from an intra-articular fracture is uncertain, arthrography or MRI may be helpful (Fig. 20-3).56 In neonates and infants in whom ossification has not begun, ultrasonography can be used to identify the displaced epiphysis of the humerus (Fig. 20-4).18
If the diagnosis is delayed, new periosteal bone forms around the distal humerus, and the whole epiphysis may remain displaced posteriorly and medially (Fig. 20-5).
Classification of Fractures Involving the Entire Distal Humerus
DeLee et al.17 classified fractures of the entire distal humeral physis into three groups based on the degree of ossification of the lateral condylar epiphysis (Fig. 20-1). Group A fractures occur in infants up to 12 months of age, before the secondary ossification center of the lateral condylar epiphysis appears (Fig. 20-1A). They are usually Salter–Harris type I physeal injuries. This injury may be missed because of the lack of an ossification center in the lateral condylar epiphysis. Group B fractures occur most often in children of 12 months to 3 years of age in whom there is definite ossification of the lateral condylar epiphysis (Fig. 20-1C). Although there may be a small flake of metaphyseal bone, this is also essentially a type I Salter–Harris physeal injury. Group C fractures occur in older children, from 3 to 7 years of age and result in a large metaphyseal fragment that is most commonly lateral but can be medial or posterior (Fig. 20-1 D, E).
These fractures are almost always extension-type injuries with the distal epiphyseal fragment displacing posterior to the metaphysis. A rare flexion type of injury can occur in which the epiphyseal fragment is displaced anteriorly.6 Stricker et al.72 reported a coronal plane transcondylar (Salter–Harris type IV) fracture in a 3-year-old child that was initially diagnosed as a fracture of the lateral humeral condyle. No growth disturbance was evident 3 years after open reduction and pin fixation.
PATHOANATOMY AND APPLIED ANATOMY RELATING TO FRACTURES INVOLVING THE ENTIRE DISTAL HUMERUS
Distal humeral physeal injuries have similar anatomic considerations as supracondylar humerus fractures. However, because the patients who suffer this injury are often very young, diagnosis and treatment can be more challenging.
Because fractures coursing along the distal humeral physis traverse the anatomic centers of the condyles, they are the pediatric counterparts of the adult bicondylar fracture. Because the fracture is distal, the fracture surfaces are broader than those proximally through the supracondylar fractures. This broader surface area of the fracture line may help prevent tilting of the distal fragment. Because the fracture lines do not involve the articular surface, development of joint incongruity with resultant loss of elbow motion is unlikely if malunion occurs.
The distal humeral epiphysis extends across to include the secondary ossification of the medial epicondyle until about 6 to 7 years of age in girls and 8 to 9 years in boys. Thus, fractures involving the entire physeal line include the medial epicondyle up to this age. In older children, only the lateral and medial condylar physeal lines are included.
Finally, part of the blood supply to the medial crista of the trochlea courses directly through the physis. The blood supply to this area is vulnerable to injury, which may cause osteonecrosis in this part of the trochlea.
Because the physeal line is more proximal in young infants, it is nearer the center of the olecranon fossa (Fig. 20-6). A hyperextension injury in this age group is more likely to result in a physeal separation than a bony supracondylar fracture.14
TREATMENT OPTIONS FOR FRACTURES INVOLVING THE ENTIRE DISTAL HUMERUS
Treatment is first directed toward prompt injury recognition. Because this damage may be associated with child abuse, the parents may delay seeking treatment. The goal of treatment is to obtain acceptable alignment until the fracture heals over 2 to 3 weeks.
Simple splint or cast immobilization has been suggested by several authors.4,17,46,59 In some small children, this may be the only treatment option that is reasonable. However, some investigators have shown cubitus varus after nonoperative treatment of these fractures.1,16,17,34 The rate of varus was noted in 3/12,17 15/21,1 and 5/734 in these series. De Jager and Hoffman16 reported 12 fracture separations of the distal humeral epiphysis, three of which were initially diagnosed as fractures of the lateral condyle and one as an elbow dislocation. Because of the frequency of cubitus varus after this injury in young children, they recommended closed reduction and percutaneous pinning in children younger than 2 years of age so that the carrying angle can be evaluated immediately after reduction and corrected if necessary. Arthrography may be helpful for diagnostic reasons and to assess reduction after fixation.
Several investigators have reported open reduction, usually performed owing to misdiagnosis as a displaced fracture of the lateral humeral condyle.2,34,66,79 Mizuno et al.,53 however, recommended primary open reduction because of their poor results with closed reduction. They approached the fracture posteriorly by removing the triceps insertion from the olecranon with a small piece of cartilage. If the fracture is old (more than 5 to 6 days) and the epiphysis is no longer mobile, manipulation should not be attempted, and the elbow should be splinted for comfort. Many essentially untreated fractures remodel completely without any residual deformity if the distal fragment is only medially translocated and not tilted (Fig. 20-7). In the more displaced malunions, a later osteotomy may be indicated.
Nonoperative Treatment of Fractures Involving the Entire Distal Humerus
In neonates and very small infants in whom general anesthesia or percutaneous pin fixation may be difficult, splint or cast immobilization can be used to treat these fractures (Table 20-1).
TABLE 20-1 Nonoperative Treatment of Fractures Involving the Entire Distal Humerus
The arm is simply immobilized in up to 90 degrees of flexion with the forearm pronated. The extremity is then externally stabilized with a swathe or figure-of-eight splint.
Outcome and function is usually good, however some investigators have shown cubitus varus after nonoperative treatment of these fractures.1,16,17,34 The rate of varus was noted in 3/12,17 15/21,1 and 5/734 in these series.
Operative Treatment of Fractures Involving the Entire Distal Humerus
In most infants and young children with a displaced fracture, external immobilization is usually not dependable in maintaining the reduction, and therefore operative intervention is indicated.
Closed reduction and percutaneous pin fixation.
Preoperative Planning. Planning is similar to that of treating a supracondylar humerus fracture. In cases where the elbow is largely unossified, one must prepare for possible arthrography to help with diagnosis and to assess reduction (Table 20-2).
TABLE 20-2 ORIF of Fractures Involving the Entire Distal Humerus
Positioning. You can choose to position the patient in one of the two ways. You can position the patient on the edge of the table with the affected extremity free over the side of the table and use the base of the C-arm as the operative surface. Alternatively you can position the patient on a radiolucent table on the edge opposite of the affected extremity. The C-arm can be brought underneath the table so that you can use the radiolucent table as the operative surface rather than the C arm. In the very young, the head and body may also need to be on the radiolucent table.
Technique. Under general anesthesia, the elbow is initially manipulated while extension to correct the medial displacement, and then the fragment is stabilized by flexing the elbow and pronating the forearm. When the forearm is supinated with the elbow flexed, the distal fragment tends to displace medially. This displacement is usually a pure medial horizontal translocation without mediolateral coronal tilting. The fragment is secured with two lateral pins (Fig. 20-8). Because of the swelling and immaturity of the distal humerus, the medial epicondyle is difficult to define as a distinct landmark, making it risky to attempt the percutaneous placement of a medial pin. If a medial pin is necessary for stable fracture fixation, a small medial incision can be made to allow direct observation of the medial epicondyle and the ulnar nerve. Usually two or lateral small, smooth lateral pins are used. In small infants and young children with minimal ossification of the epiphyseal fragment, an intraoperative arthrogram may be obtained to help determine the quality of the reduction (Table 20-3).
TABLE 20-3 Closed Reduction and Pinning of Fractures Involving the Entire Distal Humerus
AUTHOR’S PREFERRED TREATMENT FOR FRACTURES INVOLVING THE ENTIRE DISTAL HUMERUS
In neonates and very small infants in whom general anesthesia or percutaneous pin fixation may be difficult, we typically simply immobilize the extremity in 90 degrees of flexion with the forearm pronated. The extremity is then externally stabilized with a figure-of-eight splint.
In most older infants and young children, external immobilization is usually not dependable in maintaining the reduction. As a rule, in these patients, we perform the manipulation with the patient under general anesthesia and the fragment is secured with two lateral pins (Fig. 20-8). If a medial pin is necessary for stable fracture fixation, a small medial incision should be made. An intraoperative arthrogram may be obtained to help determine the quality of the reduction in patients with limited ossification. We have done similar surgery in neonates and very young children who can tolerate anesthesia safely.
If treatment is delayed more than 3 to 5 days and if the epiphysis is not freely movable, the elbow is simply immobilized in a splint or cast. It is probably better to treat any resulting deformity later with a supracondylar osteotomy rather than to risk the complication of physeal injury or osteonecrosis of the epiphysis by performing a delayed manipulation or open reduction. Only occasionally does an untreated patient have a deformity severe enough to require surgical correction at a later date. Because the articular surface is intact, complete functional recovery can usually be expected.
A cast or splint is maintained for 3 weeks. At 3 weeks, the patient’s cast is removed, imaging is obtained, and the pins are removed in the office. The patient is discharged without immobilization and active elbow motion is resumed. The patient is then followed until full motion is regained and until there is radiographic evidence of normal physeal and epiphyseal growth.
Potential Pitfalls and Preventative Measures
Because of the swelling and immaturity of the distal humerus, the ulnar nerve is at risk with placement of a medial pin. Making a small incision and by pulling ulnar nerve out of the way helps prevent iatrogenic injury. Quality of reduction is difficult to assess in small infants and young children and an intraoperative arthrogram can ensure adequate reduction (Table 20-4).
TABLE 20-4 Fractures Involving the Entire Distal Humerus
MANAGEMENT OF EXPECTED ADVERSE OUTCOMES AND UNEXPECTED COMPLICATIONS IN FRACTURES INVOLVING THE ENTIRE DISTAL HUMERUS
Significant cubitus varus deformity can occur after this injury (Fig. 20-7C).46,50 Because the fracture surfaces are wider with this injury than with supracondylar fractures, the distal fragment tends to tilt less, which seems to account for the lower incidence of cubitus varus after this injury than after untreated supracondylar fractures; however, reduction and percutaneous pinning are recommended for acute fractures with displacement to prevent this complication. Late supracondylar humerus osteotomy may be indicated when there is insufficient remodeling. (See Chapter 16 for details of surgical techniques for osteotomies.)
Neurovascular injuries, either transient or permanent, are rare with this fracture. This is probably because the fracture fragments are covered with physeal cartilage and do not have sharp edges. In addition, the fracture fragments are usually not as markedly displaced as supracondylar humerus. Finally, the fracture displacement is usually posteromedial rather than posterolateral.
Only one nonunion after this fracture has been reported; it occurred in a patient seen 3 months after the initial injury.53 Because of the extreme vascularity and propensity for osteogenesis in this area, union is rapid even in patients who receive essentially no treatment.
Osteonecrosis of the epiphysis of the lateral condyle or the trochlear epiphysis has rarely been reported after fractures of the entire distal humeral physis. Yoo et al.81 reported eight patients with osteonecrosis of the trochlea after fracture separations of the distal end of the humerus. Six of the eight fractures were diagnosed initially as medial condylar fractures, lateral condylar fractures, or traumatic elbow dislocation. All eight patients had rapid dissolution of the trochlea within 3 to 6 weeks after injury, followed by the development of a medial or central condylar fishtail defect. Further discussion regarding the etiology of this complication is discussed in the section on osteonecrosis of the trochlea (Table 20-5).
TABLE 20-5 Fractures Involving the Entire Distal Humerus
SUMMARY, CONTROVERSIES, AND FUTURE DIRECTIONS FOR FRACTURES INVOLVING THE ENTIRE DISTAL HUMERUS
Transphyseal injuries of the distal humerus are rare. In young children, child abuse should be suspected and the patient should be evaluated for associated injuries. The injury should be distinguished from an elbow dislocation, which may be difficult in the unossified elbow. In neonates or children in which anesthesia is difficult, simple immobilization can be used, but patients may heal in varus. In children who can tolerate anesthesia, closed reduction and pin fixation can improve alignment and minimize complications of cubitus varus. An arthrogram may be needed to assess reduction.
INTRODUCTION TO FRACTURES INVOLVING THE MEDIAL CONDYLE
Fractures of the medial condyle can be thought of as the mirror image of lateral condyle fractures, which are more commonly encountered (see Chapter 19). Fractures involving the medial condyle have two components. The intra-articular component involves, in some manner, the trochlear articular surface. The extra-articular portion includes the medial metaphysis and medial epicondyle. Because the fracture line extends into the articular surface of the trochlea, these often are called trochlear fractures. For purposes of description in this chapter, fractures of the trochlea are those that include only the articular surface.
Fractures involving the medial condyle are rare in skeletally immature children, accounting for less than 1% of fractures involving the distal humerus.35 Many of the large series of elbow fractures in the literature and early fracture texts do not mention these fractures as a separate entity. Blount8 described only one such fracture in his classic text. In Faysse and Marion’s21 review of more than 2,000 fractures of the distal humerus in children, only 10 fractures involved the medial condyle. Although it has been reported in a child as young as 2 years of age,3 this fracture pattern is generally considered to occur during later childhood. These rare injuries are very problematic as they can occur before the trochlear secondary center of ossification appears. A high index of suspicion is necessary to avoid missing a displaced, intra-articular fracture in the young (Fig. 20-9A, B) .
Most series21,60 show medial condylar fractures occurring somewhat later than lateral condylar fractures. A review of 38 patients in nine series3,12,13,20,21,24,28,60,65,78 in which the specific ages were given showed that 37 patients were in the age range of 8 to 14 years. Thus, this fracture seems to occur most often after the ossification centers of the medial condylar epiphysis begin to appear. As mentioned, a medial condylar fracture can occur as early as 6 months of age, however, before any ossification of the distal humerus has appeared,5,15 making the diagnosis extremely difficult and outcome poor if missed and not treated acutely.
ASSESSMENT OF FRACTURES INVOLVING THE MEDIAL CONDYLAR PHYSIS
Mechanisms of Injury for Fractures Involving the Medial Condylar Physis
Two separate mechanisms can produce physeal fractures of the medial condyle. Ashurst’s3 patients described falling directly on the point of the flexed elbow. This mechanism was also implicated in other reports.5,12,31,65 In this mechanism, it is speculated that the semilunar notch’s sharp edge of the olecranon splits the trochlea directly (Fig. 20-10A). This mechanism is also supported by a recent case report of a medial condyle fracture in the setting of a pre-existing fishtail deformity.55
In three more recent series,11,23,24 many patients sustained this injury when they fell on their outstretched arms. The theory is that this is an avulsion injury caused by a valgus strain at the elbow (Fig. 20-10B). Fowles and Kassab23 reported a patient with a concomitant valgus greenstick fracture of the olecranon associated with a fracture of the medial condyle. They believed this fracture provided further evidence that this was a valgus avulsion type of injury. Once the fragment becomes disassociated from the distal humerus, the forearm flexor muscles produce a sagittal anterior rotation of the fragment.
Associated Injuries with Fractures Involving the Medial Condylar Physis
As this fracture is rare, studies describing associated injuries are rare. Medial condylar physeal fractures have been reported in association with greenstick fractures of the olecranon and with true posterolateral elbow dislocations (Fig. 20-11).5,15,23 Some investigators5,15 found that child abuse was more common in their younger patients with these fractures than with other elbow fractures. Regardless, the extremity should be evaluated for concomitant injuries of forearm, wrist, or hand, and the radiographs should be inspected for additional fractures about the elbow.