Displaced phalangeal neck fractures should be reduced. Closed reduction usually is successful in acute fractures (fewer than 7 to 10 days after injury). Open reduction is sometimes required, but is associated with a risk of extensor tendon injury and avascular necrosis of the condyles.31 Percutaneous reduction using a K-wire as a joystick in the fracture site decreases the risk of these complications and can be used for subacute fractures (1-3 weeks after injury) when closed reduction is unsuccessful and impending malunion is a concern.34 Al-Qattan examined a series of 67 phalangeal neck fractures in 66 children and assessed the outcome of these fractures based on the amount of displacement. Nondisplaced fractures were almost all treated with splinting and had excellent results in nearly all cases. Displaced fractures, including those that were only minimally displaced, in general had better outcomes if treated with K-wire fixation than if simply closed reduced, including decreased risk of malunion and nonunion.3 Most displaced fractures, therefore, need percutaneous pinning for adequate fixation (Fig 3). Pins are usually left in place for 4 weeks to allow for complete healing of the fracture. The hand and involved finger(s) are immobilized in a cast while the pins are in place. Adjacent joint stiffness is common after fracture healing, but is easier to overcome in children than in adults. Failure to protect the pins in a cast until fracture healing, conversely, could allow redisplacement and malunion of the fracture, which is much more difficult to address than stiffness in the pediatric population.
Phalangeal neck fractures are generally thought to have little remodeling potential because of their distance from the physis.3,6,14,17,19,23 However, remodeling of a phalangeal neck malunion has been shown to occur in the flexion-extension plane in several case reports.11,22,25 In certain circumstances, surgical reconstruction may be delayed to allow for fracture remodeling in a child presenting with a malunion. The following conditions must be met before taking the remodeling approach: malunion in the sagittal plane with no rotational or coronal malalignment, congruent adjacent interphalangeal joint, bony union of the fracture, substantial growth potential, toleration of the limited adjacent joint motion during remodeling by the child and family, and patience by the child and family to allow remodeling to occur.11
Corrective osteotomy of a malunited phalangeal neck fracture can be technically challenging and poses a potential risk of avascular necrosis to the condyles.30,34 Although there are no reports of increased risk of avascular necrosis in performing intraarticular or extraarticular osteotomy of the phalanx in children, avascular necrosis of the condyles has been reported in open reduction of pediatric phalangeal neck fractures. Topouchian et al31 noted four of 13 pediatric phalangeal neck fractures treated with open reduction and internal fixation went on to avascular necrosis of the phalangeal head. Techniques have, therefore, been developed to operatively address incipient malunions and established malunions of phalangeal neck fractures while avoiding late open reduction or corrective osteotomy. Waters et al34 reported percutaneous reduction using a K-wire as a joystick in the fracture site to reduce partially healed malunions successfully without the complication of loss of motion or avascular necrosis. All patients had restoration of the subchondylar fossa with this technique. Simmons and Peters30 suggested subcondylar fossa reconstruction for treating hyperextended phalangeal neck fracture malunions with a block to adjacent joint flexion. This technique removes the volar spike from the proximal fragment, recreating the volar concavity of the subcondylar fossa and improving flexion of the adjacent interphalangeal joint.
Phalangeal Condyle Fractures
Fractures of the phalangeal condyles are intraarticular fractures that can involve one or both condyles. Fracture patterns include lateral avulsion fractures, unicondylar or intracondylar fractures, bicondylar or transcondylar fractures, and a shearing fracture that separates the articular surface and subchondral bone from the remaining phalanx. These fractures may be associated with joint subluxation or dislocation.18
Condyle fractures may be difficult to identify and hard to treat. Recognition of the true extent of this injury on the original radiographs is important for long-term outcome because articular congruity is essential. The anteroposterior (AP) view may look apparently normal, but lateral radiographs can often show the double density sign, representing the offset of a displaced, fractured condyle (Fig 4). Oblique views are also helpful. Most of the fractures are displaced and an anatomic reduction is needed to restore proper joint alignment. Closed or percutaneous reduction using a towel clip or pin is often successful in acute fractures, but open reduction may be required. During open reduction, it is important to check that the subcondylar fossa is cleared of bone, because failure to do this step may result in a block to flexion despite anatomic reduction. In addition, excessive soft tissue stripping from the condyle fragment should be avoided to minimize the potential risk of avascular necrosis, which has been reported in open reduction of phalangeal neck fractures.31 Fixation is obtained using mini screws or pins. Pin or screw placement through the collateral ligaments should be avoided to prevent tethering on these structures that may limit motion.18 Cast protection is important during healing, especially when pins are used for fixation because stiffness is easier to correct than a loss of fixation leading to malunion.
As with phalangeal neck fractures, phalangeal condyle fractures must be treated promptly; delaying reduction and fixation even into the second week post-fracture can create great difficulty in achieving an anatomic reduction. Remodeling does not occur with these fractures and malunion may result in clinical deformity. Attempted osteotomy of a condyle malunion, as with a phalangeal neck malunion, raises concern for avascular necrosis and should not be attempted.
The so-called Seymour fracture is a Salter I or II fracture of the distal phalanx physis, with avulsion of the proximal edge of the nail from the eponychial fold (Fig 5). This is an open fracture because the nail is avulsed and the germinal matrix is torn. Some have suggested this fracture can also occur in a juxtaepiphyseal position, 1 to 2 mm distal to the physis in the metaphysis. This position was noted by Seymour in his original description,28 and also by Barton6 and Al-Qattan,2 who found the majority (15 of 18) of fractures in his series were in a juxtaepiphyseal location. Al-Qattan also reported seven cases of Seymour fractures in adults, where the fracture line was just distal to the extensor tendon insertion.2
Physical examination findings in the Seymour fracture include a mallet posture of the involved finger with an exposed proximal nail plate. These fractures, as well as juxtaepiphyseal fractures of the distal phalanx, mimic true mallet injuries in children because of the insertion of the extensor and flexor tendons.1,2 The terminal extensor tendon inserts into the epiphysis, while the flexor digitorum profundus tendon inserts onto the metaphysis-diaphysis.18 Although the nail bed laceration usually is not visible, the proximal edge of the nail sits atop of the eponychial fold, and thus, the visible nail appears too long. In some cases, the nail is not actually avulsed from the eponychial fold, but the nail bed underneath is torn and the cuticle seal is broken, creating an open fracture (Fig 6). A tell-tale sign in this apparently closed Seymour fracture with minimal displacement is evidence of trace bleeding around the nail bed, typically confirming the fracture is actually open.21
Radiographs should be examined closely for physeal injury. Dorsal physeal widening is common, as is flexion of the distal segment. When in doubt, nail removal will reveal the open physis (Fig 5).
This is a problem fracture that can lead to substantial complications if missed. Incomplete fracture reduction because of interposition of the proximal edge of the torn nail matrix or nail fold in the open physis has been reported in the literature.2,5 Complete reduction is possible only after removal of this tissue. Fracture instability tends to occur if the nail plate is completely removed and not replaced,28,37 and therefore, the avulsed nail should always be replaced. Malunion with residual pseudomallet or flexion deformity can occur in fractures treated without fixation. In two studies, three of 182 and three of four6 Seymour fractures treated with closed reduction and splinting healed with mild residual flexion deformity. This may be secondary to incomplete initial reduction, redisplacement after reduction, or poor patient compliance with splinting. Weekly lateral radiographs should be performed during the first 2 weeks to monitor fracture stability. In addition, when there is a concern for fracture instability or patient compliance, K-wire fixation of the fracture is recommended.2,10 Seymour fractures are open injuries, and infection is a concern if the injury is not treated as such (Fig 6). Thorough irrigation, débridement, and antibiotic therapy are necessary acutely to avoid possible fracture site infection and/or osteomyelitis.2,15,16,26,28,39 Premature growth plate closure can occur because of direct physeal injury, but may also be secondary to infection.2,15 Dorsal rotation of the epiphysis can occur in Salter I Seymour fractures.33 This is a rare complication, but if unrecognized, can lead to extensor mechanism dysfunction, distal phalanx deformity, and articular surface deformity. Finally, nail bed deformity or absence may result from the associated nail bed injury in these fractures.
With these potential complications in mind, acute treatment of Seymour fractures should consist of removal of the nail, thorough irrigation and débridement of the fracture, gentle removal of the incarcerated nail bed from the fracture site, reduction of the fracture with or without pinning, repair of the nail bed if a substantial proximal flap exists, replacement of the nail underneath the eponychial fold, and splinting or casting. Adequate observation of the nail bed injury and the fracture site may require incising and reflecting the eponychial fold. Postoperative antibiotics should be given for these open injuries.
Bony Mallet Fractures
Although a Salter I or II fracture of the distal phalanx mimics the appearance of an adult mallet finger on clinical exam, it does not involve the distal interphalangeal joint surface as in adults. Salter III and/or Salter IV fractures of the distal phalanx, representing avulsion injuries of the terminal extensor tendon, are more appropriate pediatric equivalents of the adult mallet finger. These injuries are intraarticular fractures and are most commonly seen in teenagers. Mallet fractures result from an axial load or flexion force applied to an extended fingertip.18 These fractures generally can be treated with closed reduction and splinting, but occasionally surgery is indicated. In a large review of adult and pediatric mallet finger injuries and mallet fractures, Wehbe and Schneider35 suggested the results were uniformly good, with surgical treatment offering no advantage over nonoperative treatment. They recommended splinting of mallet fractures in nearly all cases, with surgery indicated only for irreducible epiphyseal-physeal injuries seen in the pediatric population. Although studies such as the one done by Wehbe and Schneider35 have included some pediatric and/or adolescent patients in their study population, to our knowledge, no study examines the results of nonsurgical treatment of mallet fractures exclusively in the pediatric and/or adolescent population.
A major issue with nonoperative treatment of mallet fractures that is unique to children is patient compliance with splinting. In older children, where compliance seems to improve, Stack splints can be well tolerated if fitted appropriately. If splinting is chosen for treatment of a pediatric mallet fracture, compliance should be checked early in the treatment course, and regularly from then on, to ensure proper fit and position of the splint. Often young children are not able to maintain the splint, either for behavioral reasons or for improper fit on a short, plump digit. In these situations, we do not hesitate to place a transarticular K-wire through the DIP joint and cast the hand to protect the pin from breakage.
Indications for surgical treatment of mallet fractures include the presence of a large dorsal fracture fragment greater than or equal to 50% of the joint surface or evidence of substantial DIP joint subluxation.18,29 Reduction of the fracture fragment or DIP subluxation is typically performed with percutaneous K-wire fixation and may involve multiple pins to reduce the fracture and the DIP joint in extension.10 Extension block pinning can be used to percutaneously reduce and stabilize the fracture and DIP joint (Fig 7). If the patient is near skeletal maturity, a screw, tension band, pullout wire, or suture anchor may be used for fixation.
Irreducible Proximal Phalanx Base Fractures
Fractures of the base of the proximal phalanx are very common. Most occur in the small finger and are termed the extra-octave fracture because of the typical abduction deformity related to ulnar angulation. While most of these fractures are felt to be Salter II injuries, some have suggested the fracture line may actually be entirely metaphyseal, 1 to 2 mm distal to the physis, and are more appropriately termed juxtaepiphyseal fractures.4,6-8 Substantial remodeling can occur with these fractures, due to the proximity to the physis and the multiplanar motion of the metacarpophalangeal (MCP) joints. Growth arrest is rare.
Closed reduction and casting or splinting is usually successful, but open reduction may be needed for displaced fractures with soft tissue interposition or unstable fractures. Al-Qattan reviewed a series of 34 juxtaepiphyseal fractures of the base of the proximal phalanx and found mildly displaced fractures all were treated successfully with closed reduction and splinting without complications whereas while several complications arose in attempting to obtain an adequate reduction in severely displaced fractures.4 Flexor tendon entrapment in the fracture site prevented closed reduction in one case, requiring open reduction and K-wire fixation. Five fractures required K-wire fixation to hold an adequate closed reduction, and two other cases developed a malunion with persistent pseudo-claw deformity from incomplete closed reduction.
Additional reports in the literature of irreducible juxtaepiphyseal fractures of the proximal phalanx include; two cases of entrapped flexor tendons,20,32 one case of fibrous tissue interposition at the fracture site,23 and two cases of extensor hood entrapment at the fracture site.12,38 We have treated a child with multiple proximal phalanx base fractures, two of which were irreducible because of interposition of volar periosteum. Open reduction and pin fixation were required. It is therefore important to recognize the possible need for open reduction in severely displaced proximal phalanx base fractures.
Pediatric Skier's Thumb
A skier's thumb injury in adults represents an acute rupture of the ulnar collateral ligament (UCL) of the thumb from forced abduction of the proximal phalanx. The UCL rarely ruptures in isolation in children, though cases have been reported in the literature.10,36 The more typical pediatric skier's thumb involves a fracture of the base of the proximal phalanx of the thumb. These are Salter III intraarticular fractures that avulse the UCL insertion at the base of the proximal phalanx of the thumb and destabilize the MCP joint. Displaced fractures should be treated with open reduction and internal fixation to restore joint congruity and UCL stability10 (Fig 8). Suture anchors can be used for fixation as long as injury to an open physis is avoided.
In younger children, Salter I and II fractures of the thumb are more common than Salter III fractures and may present as a pseudo skier's thumb injury because of apparent instability at the MCP joint on clinical examination caused by the displacement through the fractured physis while the UCL remains intact.9,13 There is a report in the literature, however, of a true skier's thumb injury in a 7 year-old girl with rupture of the UCL after sustaining a Salter II fracture of the proximal phalanx.13
Central Slip and Volar Plate Avulsion Fractures
The epiphysis of the middle phalanx is the site of insertion of the volar plate and extensor tendon central slip.18 Epiphyseal fractures of the base of the middle phalanx can therefore signify avulsions of these structures. It is important to distinguish between volar and dorsal avulsion fractures because treatment can differ considerably.
Volar plate avulsion fractures are secondary to hyperextension injuries and are common (Fig 9). They should be treated with early motion after a short period (up to 1 week) of splinting. Bony union is never achieved, but a fibrous nonunion confers adequate joint stability. The primary problem after this injury is joint stiffness and cast or prolonged splint treatment can lead to permanent joint contracture. Even with early motion, however, swelling and stiffness can persist for a long time with these injuries, and it is important to stress to the patient and parents that perfect motion is not guaranteed.
Central slip avulsion fractures are rare, but must be differentiated from volar plate avulsion fractures. Small flecks avulsed from the dorsal rim of the middle phalanx (Fig 10) can be treated like volar plate avulsion fractures as long as an Elson test indicates intact central slip function. Larger, nondisplaced fragments should be treated with splint or cast immobilization to keep the proximal interphalangeal joint extended, thus allowing bony healing and restoration of the central slip insertion. Displaced fractures or those associated with proximal interphalangeal joint subluxation require open reduction and internal fixation.
We have highlighted several fractures in a child's phalanges that deserve careful attention. Although the majority of fractures in the child's hand can be treated successfully with simple nonoperative methods, the fractures discussed here pose certain challenges and pitfalls that must be recognized.
Displaced phalanx neck fractures typically cause a block to flexion of the adjacent interphalangeal joint as well as clinical deformity that does not reliably remodel. Therefore, accurate assessment of displacement is critical in the initial evaluation. Pin fixation is required after reduction given the instability of the fracture. In addition, healing is rapid and late open reduction carries a risk of avascular necrosis of the condyles, necessitating prompt treatment. Similarly, displaced phalanx condyle fractures, as intra-articular fractures, cause joint dysfunction and deformity if not reduced and stabilized with pins or internal fixation. Again, rapid progression to a malunion can be avoided with prompt recognition and treatment.
Fractures of the distal phalanx physis with any disruption of the nail bed should be considered open fractures. Therefore, a true lateral radiograph of the injured finger in isolation is of paramount importance in the assessment of any nail avulsion or mallet posturing of a digit in children. Principles of open fracture treatment should be followed, including urgent irrigation and débridement with fracture reduction and stabilization.
Proximal phalanx base fractures typically are reduced easily by closed means, but widely displaced fractures may be irreducible secondary to entrapment of periosteum, flexor tendons, or the extensor hood. Recognition of such potential difficulties will allow the surgeon to consider the possible need for open reduction of severely displaced fractures.
A variety of avulsion fractures occur in the child's phalanges. True mallet fractures that involve avulsion of the extensor tendon insertion can be treated nonoperatively while recognizing two important points. First, splint fitting and compliance are particularly unreliable in children, so pinning of the DIP joint should be considered whenever maintenance of DIP extension must be ensured. Second, few data exist regarding the long-term outcome of nonoperative treatment of displaced fractures and joint subluxations in the skeletally immature patient that are not reduced anatomically. Therefore, restoration of articular congruity should be considered a treatment goal unless outweighed by potential complications of operative treatment. Avulsion fractures of the thumb MCP ulnar collateral ligament insertion are typically displaced and will progress to nonunion and joint instability if not reduced anatomically and secured with internal fixation. Similarly, avulsions of the central slip insertion should be reduced and fixated if displaced. Conversely, volar plate avulsion fractures in the PIP joints should be treated with early mobilization, as they can cause profound joint stiffness if immobilized.
Central to the above recommendations are two important principles. First, each phalanx fracture described in this review poses a unique challenge relative to most pediatric fractures. Second, the treatment of these fractures in children differs substantially from that in adults.
The unique and complex anatomy of the finger necessitates special consideration of each type of fracture. While remodeling is reliable at the phalanx base, adjacent to the physis and the multiplanar MCP joint, remodeling is much more limited at the distal end of the phalanx, where sagittal remodeling is slow and unreliable and coronal remodeling does not occur. In addition, important differences must be recognized between seemingly similar fractures about the joints in the digits, such as between volar plate and central slip avulsion fractures. Finally, an understanding of the anatomy of the fingertip allows recognition that an open fracture can occur through the nail bed without disruption of the skin.
Second, important differences must be noted between children and adults in the treatment of these phalanx fractures. Children can heal fractures quite rapidly, and while this speed of healing is helpful in most cases, it can allow a late-presenting fracture to progress rapidly to a malunion. Therefore, prompt treatment of displaced fractures is required. Also, compliance with activity restriction and splint wear should not be relied on. Most well-meaning but active children will escape nearly any splint and play sports long before fracture healing if left to their own devices. Therefore, casts are preferable to splints when immobilization is truly important for maintenance of reduction or protection of pins. Finally, with few exceptions, the supple joints of children are not plagued with the problems of stiffness that challenge the hand surgeon treating the adult patient. For instance, the MCP joints can be immobilized in full extension for 4 weeks after a fracture, and full range of motion is typically achieved within 1 to 2 weeks of cast removal with no formal therapy.
Despite the common occurrence of phalanx fractures in children, the literature is devoid of prospective trials investigating treatments and outcomes of these injuries. Thus several questions remain unanswered. Can malunited phalanx neck and condyle fractures be safely corrected with osteotomy in the growing phalanx? Do displaced mallet fractures require restoration of articular and physeal alignment in children? What interventions can help to reduce the occurrence of missed or delayed diagnosis of a Seymour fracture? In the absence of evidence-based answers to these and other questions, the surgeon must apply the principles discussed above in the treatment of these fractures on an individualized basis. Nonetheless, recognition of the challenges posed by the fractures presented in this review is the first step toward improving evaluation and treatment through prospective research.
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