➢ Seymour fractures are open juxta-physeal fractures of the distal phalanx. A true lateral radiograph should be obtained for diagnosis, and treatment should include removal of the nail, irrigation and debridement of the fracture, and percutaneous Kirschner wire stabilization.
➢ Mallet fractures are more common in children than adults, and treatment is generally nonoperative for nondisplaced or minimally displaced fractures without volar subluxation of the distal phalanx; however, splinting compliance should be carefully assessed in younger populations.
➢ Phalangeal neck fractures have a limited potential to remodel and a propensity to redisplace. A true lateral radiograph will show displacement best; treatment is generally with percutaneous pinning. Open reduction should be avoided when possible because of the risk of osteonecrosis of the phalangeal condyles.
➢ The epidemiology of scaphoid fractures in children is changing, with waist fractures now the most common type. This may be due to an increase in body mass index (BMI) as well as high-level sports participation in today’s pediatric population. Although the vast majority of acute scaphoid fractures can be treated successfully with cast immobilization, children who present with established nonunions should be offered open reduction and internal fixation as the primary treatment.
Hand fractures are very common in children of all ages, comprising a quarter of all fractures from birth to eighteen years1. Fortunately, the vast majority of these can be treated nonoperatively with full return of function and aesthetics. However, there are several fractures with unique characteristics in the pediatric population. This article will detail these more troublesome fractures, including Seymour fractures, mallet fractures, phalangeal neck fractures, and scaphoid fractures.
The annual incidence of phalangeal fractures is 207 per 100,000 individuals from birth to four years of age, which is the highest incidence for any age group except for the age group of more than eighty-five years2. For children who are five to fourteen years of age, the incidence of phalangeal fractures drops slightly, to 185 per 100,000 individuals, but it is still more common than metacarpal fractures, with an incidence of 100 per 100,000 individuals, and carpal fractures, with an incidence of 133 per 100,000 individuals. For comparison, the same study found the incidence of forearm fractures to be 271 per 100,000 children from birth to four years of age and 557 per 100,000 children who are five to fourteen years of age. In an epidemiologic review of all pediatric fractures, hand fractures were among the five most common fracture types throughout childhood3.
Radiographic interpretation of pediatric hand fractures can be challenging, especially in young children in whom ossification is not complete. It is helpful to first understand the normal radiographic progression of ossification, which in the hand begins in the capitate between one and three months of age and progresses, sometimes simultaneously, to the hamate. The scaphoid then begins to ossify at the age of five years and the trapezoid and trapezium begin to ossify at the age of six years4,5. The epiphyseal ossification centers of the phalanges and metacarpals become apparent from one to three years of age, earlier in girls than boys. The physes of the phalanges begin to fuse in girls between thirteen and fifteen years of age and in boys between fourteen and sixteen years of age6.
Poor outcomes and complications can be associated with Seymour fractures, mallet fractures, phalangeal neck fractures, and fractures of the scaphoid when the potential for complications is underestimated by families and/or providers. Prompt identification and treatment of these fractures can lead to excellent functional and cosmetic outcomes.
A Seymour fracture is a juxta-physeal fracture of the distal phalanx that occurs in conjunction with a nail bed laceration7. These are actually open fractures, with the fracture open through the nail bed, and must be treated as such to reduce the risk of subsequent osteomyelitis. These can be fractures of the epiphysis (Salter-Harris types I and II) or metaphyseal fractures just distal to the physis8 (Fig. 1). These fractures are often a result of finger entrapment in doors and crushing with a heavy object8,9. The majority of cases presented in the literature are in patients younger than twelve years of age8-10. Seymour fractures in all digits have been documented, with middle fingers and thumbs most commonly affected8,9.
Seymour fractures can be misdiagnosed as mallet injuries if proper lateral radiographs of the distal interphalangeal joint are not reviewed before treatment planning. Both types of fractures can result in a flexion deformity of the distal phalanx; however, the underlying mechanics of this displacement are different11. Because the terminal extensor tendon inserts onto the epiphysis of the distal phalanx and the flexor tendon inserts onto the metaphysis volarly, the energy of a Seymour fracture dissipates through the physis, with resulting dorsal displacement of the proximal fragment and volar displacement of the distal fragment. Another key finding is that the nail plate in a Seymour fracture can be dorsally displaced beyond the dorsal nail fold. Mallet injuries, discussed later, are associated with flexion deformities because of either an osseous avulsion or a disruption of the terminal extensor tendon.
The treatment of Seymour fractures requires special attention with respect to debridement because components of the germinal matrix can become incorporated into the growth plate, leading to infection, chronic osteomyelitis, growth arrest, and nail-plate deformities12 (Fig. 2). The nail plate should be removed to allow for thorough debridement of the fracture and complete visualization of fracture reduction. Fracture fixation is generally performed with smooth Kirschner wires placed retrograde through the fracture and the distal interphalangeal joint. Given the proximal location of this injury, special care should be taken with the nail-bed repair, with absorbable sutures methodically applied and placed underneath the eponychial fold. Longitudinal incisions on either side of the proximal eponychial fold may be necessary to completely visualize and to repair the injury. Following fixation, the nail plate can be cleaned and can be replaced for added stability to the fracture reduction12.
When treated appropriately with open debridement and internal fixation, outcomes after Seymour fractures are generally good. In a series of six Seymour fractures that were operatively treated, Ganayem and Edelson reported no infections, flexion deformities, or nail dystrophies at a mean follow-up time of eighteen months9. Al-Qattan demonstrated similar findings in a series of five Seymour fractures treated with open debridement and Kirschner wire fixation; no complications were noted8. In a larger series of fifteen Seymour fractures treated with debridement, open reduction, and either splinting or Kirschner wire fixation, all but one patient had a full recovery of range of motion after treatment10; six patients had a residual nail dystrophy and three patients who were operatively treated had minor growth disturbance of the involved phalanx and nail.
Closed management of Seymour fractures has a much higher rate of complications than operative intervention. In a series of eighteen patients treated with closed reduction and splinting, there were three mild flexion deformities and a single infection8. A more recent series of nine patients treated with closed reduction and splinting had four nail deformities and one growth arrest of the distal phalanx and nail10.
Mallet injuries occur when a flexion force is placed on a fully extended fingertip. In children (in whom tendinous attachments are strong), these tend to be osseous avulsions (Salter-Harris type III or IV) of the epiphysis, rather than the tendinous injuries more common in adults. The presentation and mechanism of injury of a mallet fracture are similar to Seymour fractures; however, the mallet has a fracture line that involves the distal interphalangeal joint, whereas a Seymour fracture is an injury along the physeal line.
For mallet fractures that are diagnosed acutely, extension splinting is an effective treatment for most fractures, with excellent return of function and osseous remodeling13 (Fig. 3). For younger patients, splinting compliance may be a concern, and so frequent checks may be warranted. If the child is unable to comply with splinting, the splint can be applied and then covered with a long arm club cast. However, there is the potential for skin breakdown using this technique, so the cast should be removed weekly during treatment and skin checks should be conducted. Alternatively, percutaneous pinning across the distal interphalangeal joint can be performed, with an age-appropriate cast (long arm club cast for a child less than five years or short arm club cast for older children) applied to cover the pin.
The primary operative indications for mallet fractures include open fractures, distal interphalangeal joint subluxation that is not correctable in an extension splint, and fractures that are not amenable to closed reduction because of physeal-epiphyseal injury. For fractures that present with distal interphalangeal subluxation initially, radiographs taken in the extension splint can demonstrate whether the splint is sufficient to reduce the joint. Many surgeons will also consider avulsion fractures of ≥30% of the articular surface to be a relative indication for operative treatment, as these larger fragments are more likely to lead to distal interphalangeal joint subluxation if not reduced anatomically. Operative management of these fractures consists of first reducing the fracture and then placing a retrograde Kirschner wire across the distal interphalangeal joint with the fingertip extended, followed by casting. Once reduction is obtained, a single longitudinal pin is generally sufficient. Extension block pinning can be used in cases of difficult fracture reductions. To use this method, the finger is first flexed at the distal interphalangeal joint, and the Kirschner wire is inserted dorsally through the extensor tendon at a 45° angle into the distal aspect of the middle phalanx. The distal interphalangeal joint is then extended, and the Kirschner wire blocks the mallet fragment from displacing, thus reducing the fracture. Once reduced, a standard longitudinal Kirschner wire is then placed with the distal interphalangeal joint in extension14 (Fig. 4). Open reduction of mallet fractures, although not the first line of treatment, may be required if a stable reduction cannot be attained by closed reduction and/or extension block splinting. In this case, a standard S-shaped dorsal approach to the distal interphalangeal joint is used, generally followed by Kirschner wire fixation. Kirschner wires appropriate to the size of the patient are used, usually 0.7 to 1.1-mm (0.028 to 0.045-inch) wires. For those children at or near skeletal maturity, screw fixation, tension bands, or pull-out wires can be considered.
Common adverse outcomes associated with either operative or nonoperative treatment include deformities of the nail and/or dorsal skin, mild extensor lag, and a swan-neck deformity of the distal aspect of the finger15. As there is very little information on the outcomes of mallet injuries in children specifically, results must be extrapolated from the adult literature. In adults, although extensor lag is associated with both operative and nonoperative treatment of mallet fractures, this does not appear to negatively impact function or patient satisfaction16. Complications associated with nonoperative splinting include skin ulceration and nail deformities, with the former generally resolving after the splint is removed15. In a review of thirty-one adult patients with mallet fractures treated with splinting, nine patients (29%) developed a swan-neck deformity and eleven patients (35%) had a persistent extensor lag of >10° at five years after treatment16.
Phalangeal Neck Fractures
Fractures of the phalangeal neck, although uncommon, present several potential complications of which clinicians must be aware. First, these fractures can be difficult to recognize in the incompletely ossified skeleton. Second, there is limited potential to remodel because of the distance from the phalangeal neck to the physis. Lastly, natural history studies have shown high rates of malunion with displacement in multiple planes17. The potential complications associated with phalangeal neck fractures make them important clinical entities to diagnose acutely and manage promptly. Like other hand fractures in children, they can be missed when the severity of the injury is underestimated or when proper radiographs including a true lateral radiograph are not obtained.
Phalangeal neck fractures are much more common in the pediatric population, occurring ten times more frequently in children than in adults18. The mechanism of injury is commonly the finger being entrapped by a door in younger children or a crushing injury in older children. The fracture occurs when the child twists and withdraws the finger from a door or other heavy object. The fractures tend to be transverse and can involve either the proximal or middle phalanx.
A classification system of phalangeal neck fractures was proposed by Al-Qattan and Al-Qattan that is based on the degree of displacement in the distal fragment of the fracture19. Type-I fractures have no displacement of the distal fragment, Type-II fractures have displaced distal fragments that maintain osseous contact between the proximal and distal fragments, and Type-III fractures have no osseous contact between the proximal and distal fragments19. Phalangeal neck fracture Types II and III are further subclassified on the basis of the position, the location of the fracture line, and the rotation of the distal fragment19. Al-Qattan also created a classification for outcomes after phalangeal neck fractures; excellent is defined as fracture union with full range of motion at the distal interphalangeal or proximal interphalangeal joint and no residual deformity, and good is defined as fracture union with >50° of motion at the distal interphalangeal or proximal interphalangeal joint and no residual deformity18.
Phalangeal neck fractures are ideally treated when recognized at the time of injury. Nondisplaced (Type-I) fractures can be treated with cast immobilization. Type-II and III fractures tend to be rotationally unstable and are prone to redisplacement after closed reduction. Therefore, any child treated with closed reduction and casting should be cautiously observed with serial radiographs to confirm reduction17. Alternatively, the surgeon may choose to proceed directly to closed reduction and pinning for fractures with any amount of displacement to ensure maintenance of reduction.
Standard surgical treatment of acute phalangeal neck fractures generally consists of closed reduction and percutaneous pinning20 (Fig. 5). In a series of four cases of displaced neck fractures, Karl et al. used percutaneous pinning successfully on both middle and proximal phalangeal neck fractures, all of which were pain-free at the eighteen-week follow-up and had near full flexion and extension21. Matzon and Cornwall reported on a large series of sixty-one Type-II displaced phalangeal neck fractures where a progressive treatment algorithm was used to achieve reduction by means of closed reduction and percutaneous pinning, followed by percutaneous reduction and closed pinning, and finally open reduction and percutaneous pinning22 (Fig. 6). Percutaneous reduction maneuvers include using the Kirschner wire under fluoroscopy to disrupt any callus that is forming. In addition, the Kirschner wire can be inserted in a proximal to distal direction at the fracture site and used to lever the distal fragment back into alignment23. Matzon and Cornwall achieved alignment in all sixty-one cases (forty-nine by closed reduction and percutaneous pinning and twelve by percutaneous reduction and percutaneous pinning) using this algorithm without needing to advance to open reduction. However, all fractures treated more than thirteen days after the injury required percutaneous reduction. Ninety-two percent of those patients had good to excellent outcomes as defined by Al-Qattan and Al-Qattan.
The capacity for bone remodeling with phalangeal neck fractures remains a subject of debate. The physiological principle is that remodeling potential is inversely related to the proximity to the physis, and therefore fractures of the phalangeal neck (which are as distant as possible from the phalangeal physis) will have limited ability to remodel, even in very young children. However, there are case reports of substantial remodeling of displaced phalangeal neck fractures over time24,25. Puckett et al. presented a retrospective analysis of eight cases of phalangeal neck fracture malunions and incipient malunions that were treated nonoperatively17. They found that all eight fractures remodeled completely in the sagittal plane with no residual deformity, but that they remodeled to a much lesser extent in the coronal plane. Cornwall and Waters presented a set of remodeling criteria used to determine if nonoperative strategies should be employed23. Their remodeling criteria are as follows: there is no rotational or coronal malalignment, the adjacent interphalangeal joint is congruent, osseous union of the fracture is achieved, substantial growth potential exists, the child and family can tolerate the limitation of adjacent-joint motion during remodeling, and the patient and family are willing to be patient23.
The limited potential for phalangeal neck fractures to remodel is important, as patients with these fractures often do not present to the hand surgeon until weeks after the initial injury. For late-presenting displaced fractures, it is important to note on examination whether the child still has tenderness over the fracture site, as this is a sign that the fragment is still likely to be mobile. Treatment of incipient malunions should consist of the stepwise algorithm described by Matzon and Cornwall of closed reduction and pinning, followed by percutaneous reduction and pinning, with open reduction as a last resort18,22 (Fig. 6). Because the blood supply to the phalangeal condyles enters through the collateral ligaments, open reduction has the potential to disrupt this blood supply and to cause osteonecrosis of the phalangeal condyle22. Residual malunion in the sagittal plane will compromise the concavity of the subcondylar fossa, which is essential to achieving full proximal interphalangeal or distal interphalangeal joint flexion. This obliteration of the subcondylar fossa can occur by either volar displacement of a bone fragment or the formation of new bone in a malunion19. For patients who present with healed malunions and limited joint flexion, subcondylar fossa reconstruction, via an open palmar approach, has been described to restore flexion as an alternative to corrective osteotomy26.
Although percutaneous pinning offers the best chance at restoring function after a phalangeal neck fracture, complications can still occur. Complications from the Matzon and Cornwall series were a flexion contracture, nonunion secondary to pin infection, osteonecrosis following a crush injury in the closed reduction and percutaneous pinning group, and a flexion contracture after percutaneous reduction and closed pinning22. In another large series of sixty-six neck fractures, Al-Qattan noted that closed reduction without pinning in Type-II fractures was associated with malunions or nonunions and that Type-I fractures could be successfully treated with splint immobilization27. Open reductions of late-presenting malunions should be avoided because of the limited vascularity of the distal fragment, as described above19.
Scaphoid fractures account for 2.9% of hand and wrist fractures in the skeletally immature patient, peaking in incidence at fifteen years of age28. The mechanism of injury that produces these fractures tends to be a fall on an outstretched hand, with the wrist in a position of extreme dorsiflexion. The classic presentation of scaphoid fractures in the skeletally immature patient is a distal pole fracture; however, newer studies indicate that injury patterns may be shifting to be more similar to those of adults, with the majority of fractures occurring at the waist of the scaphoid29.
In their 2011 series, Gholson et al. analyzed 351 confirmed scaphoid fractures in children and found the anatomic distribution to be eighty-one (23%) at the distal pole, 248 (71%) at the waist, and twenty-two (6%) at the proximal pole. The mean age at the time of injury in that study was 14.6 years. Waist and proximal pole injuries were associated with male sex, a high-energy mechanism of injury, closed physes, and a higher BMI. The convergence of pediatric and adult injury patterns may be explained by an increase in pediatric BMI and involvement in high-energy sports and activities29. A smaller series of fifty-six patients, with a mean age of 12.2 years for boys and 10.3 years for girls, had a fracture site distribution of forty-five (80%) at the distal pole, ten (18%) at the waist, and a single fracture (2%) at the proximal pole30. The discrepancies between these studies are likely due to the age ranges of the subjects; the age range in the study by Ahmed et al. only included children up to thirteen years of age, but the study by Gholson et al. included subjects up to eighteen years of age. It is likely that the younger cohort had fewer of the risk factors that Gholson et al. found to be associated with waist fractures.
The treatment of scaphoid fractures is dependent on fracture location and degree of displacement. In the study by Gholson et al., nondisplaced fractures treated with casting alone yielded unions in 181 (90%) of 201 cases. The type of casting for scaphoid fractures has been debated. Also in the study by Gholson et al., long arm thumb spica casts were used for three to six weeks, followed by short arm thumb spica casts until union. A recent randomized trial of sixty-two adults treated with casting for nondisplaced scaphoid fractures found actually higher union rates using a short arm cast with the thumb excluded compared with a short arm thumb spica cast31. When scaphoid fractures are treated with casting, families must be counseled that the duration of treatment can be as long as three months or more, especially for fractures of the proximal pole29. Factors associated with nonunion after cast treatment include displaced fractures, proximal pole fractures, and the casting of a chronic fracture nonunion. Open reduction and internal fixation is recommended for fractures that have a delayed presentation, are in the proximal pole, and/or are displaced (Fig. 7). Fortunately, scaphoid fractures in children managed surgically with open reduction and internal fixation followed by immobilization demonstrated an excellent union rate, with 109 (96.5%) achieving osseous union following the first operation29.
Scaphoid nonunions are relatively rare in acute fractures that receive appropriate and prompt immobilization, occurring in only 0.8% of cases in one study32. The likelihood of nonunion increases as the time to accurate diagnosis increases and is associated with fractures of the scaphoid waist and proximal pole33. Treatment of nonunion is generally surgical. In the study by Gholson et al., children who presented with nonunions had only a 2% rate of successful union with cast treatment alone29. The primary treatment for scaphoid nonunion in children is open reduction and internal fixation, with or without bone-grafting. Compression screw fixation is used whenever possible, although Kirschner wires may be needed in younger children or comminuted fractures. Bone-grafting from the distal part of the radius or the iliac crest is used for nonunions with cavitation and/or humpback deformities. High rates of union and functional outcomes have been achieved with surgical treatment of scaphoid nonunions34 (Fig. 7).
Scaphoid fractures are not always radiographically apparent during their acute presentation because of the complexity of viewing the three-dimensional scaphoid on a series of radiographs and the cartilaginous nature of the developing scaphoid. Estimates for misdiagnosis of scaphoid fractures in the pediatric population range from 12.5% to 37%35,36. The physical examination to diagnose a scaphoid fracture should include palpation of the dorsal aspect of the scaphoid via the anatomic snuffbox as well as the scaphoid tubercle volarly, along with axial compression of the thumb. Tenderness with all three of these maneuvers has both high sensitivity and high specificity at identifying scaphoid fractures, even when not radiographically apparent37. A high clinical suspicion of scaphoid fracture in a child with a negative initial radiograph should be treated with cast immobilization and repeated radiographs in one to two weeks38. Magnetic resonance imaging (MRI) has been shown to have a negative predictive value of 100% in occult scaphoid fractures39. In one study, immobilization was prevented in 58% of cases after undergoing MRI40. Although MRI is probably not appropriate for all children with suspected scaphoid fractures, it may be necessary to make the correct diagnosis in younger children, in whom the scaphoid is mostly cartilaginous. In addition, MRI should be kept in mind when the diagnosis is uncertain, especially when secondary radiographs and physical examination have not yielded satisfactory outcomes.
Long-term functional outcomes for patients with scaphoid fractures are generally good. One study found that sixty (95%) of sixty-three patients had good to excellent outcomes as measured by the Disabilities of the Arm, Shoulder and Hand (DASH) inventory and the modified Mayo Wrist Score34. The factors that increased the odds of poor outcomes were osteonecrosis of the scaphoid and chronic nonunion; however, these patients still had DASH scores and modified Mayo Wrist Scores within population norms. Twenty-six (41.3%) of the sixty-three patients were surgically managed and all had osseous unions, which supports the use of open reduction and internal fixation over casting in the case of a scaphoid fracture with poor prognostic features (i.e., displaced, at the proximal pole, or with a delayed presentation).
Hand fractures in children are quite common, and fortunately most can be managed successfully with closed treatment. However, treating physicians must be aware of the problematic fractures described here, including Seymour fractures, mallet fractures, phalangeal neck fractures, and scaphoid fractures. With appropriate diagnosis and prompt treatment, even these complex fractures can heal with excellent functional and cosmetic outcomes.
Source of Funding: No funding was received for this work.
Investigation performed at the UC Davis School of Medicine, Sacramento, California
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
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