Pediatric forearm fractures occur very commonly, occurring in approximately 1 in 100 children per year.1 Among these injuries, diaphyseal forearm fractures are the third most common long-bone fracture in children. The peak incidence of these injuries is from 12 to 14 years of age. In addition, this type of fracture is the most common anatomic area for refracture in the upper extremity, and also the most common area for open fractures.1
When confronted with a pediatric diaphyseal forearm fracture, the treating physician must be aware of the guidelines for acceptable fracture alignment for fracture healing to allow for optimal functional results. As with most pediatric fractures, there is a greater remodeling potential in younger patients, designated as younger than 8 years of age, and less potential in older patients, those older than 11 years of age.2 When assessing fracture alignment, rotation must also be assessed; rotational malalignment has less potential for remodeling. Fractures that are displaced or angled within the plane of motion have a significantly higher potential for remodeling, especially in younger children. In total, 15 to 20 degrees of angulation in children younger than 8 years of age and 10 degrees of angulation in older children is generally considered acceptable1,2 and can be treated with immobilization and without additional reduction.
When it has been determined that a pediatric diaphyseal forearm fracture is not appropriately aligned, or that the alignment cannot be maintained, intramedullary flexible nailing is often utilized. Intramedullary flexible nails are an effective treatment method for unstable or malaligned forearm fractures. It is ideal for midshaft fractures because the intramedullary flexible nail provides a 3-point bending moment when placed internally into the canal of the radius and the ulna. This increases the longitudinal and angular stability of the fracture. Unfortunately, flexible intramedullary nails do not provide perfect rotational control. Therefore, some surgeons recommend supplementing with cast or splint immobilization.
PRINCIPLES OF MANAGEMENT
When utilizing flexible intramedullary nails, a few technical pointers may be helpful to be more effective at fracture fixation, to ease placement of the nails, and thus to improve patient outcomes. First, before beginning the surgical procedure, it is recommended to measure the narrowest point on the canal on the preoperative radiographs. One should note that the isthmus of the ulna can be very narrow and should be measured on both the anterior-posterior and lateral radiograph to ensure identification of the narrowest diameter of the canal. It can be quite problematic and frustrating to place a nail that is too large for the isthmus of the bone. Not only can it become incarcerated, it can lead to an iatrogenic fracture if too much force is applied. The prebent tip of the flexible intramedullary nail can effectively increase the nail diameter, making advancement of the nail difficult or impossible. The bent tip can be cutoff to facilitate nail passage.
We recommend that nail insertion into the radius be performed over the dorsal radial aspect of the wrist, proximal to the physis. Intraoperative fluoroscopy should be used to identify the distal radial physis location and the insertion hole should be made 2 cm proximal to the physis. A small incision is made to effectively retract the extensor tendons and also the superficial branch of the radial nerve to prevent iatrogenic injury or laceration. When a drill is used, it should be somewhat larger in diameter than the planned nail size to allow a smooth entry upon nail insertion. A soft tissue guide should be used to protect the soft tissues, while the drill is being used. Once the cortex is penetrated, the drill should be lowered to nearly align the drill bit with the shaft of the radius so that the drill itself ovalizes the entry hole (Fig. 1). One must take care not to drill completely across the bone bicortically, as this will cause weakness and possible iatrogenic fracture either at the time of nail placement or postoperatively.
There are 3 entry points that can be used for the ulna. A very easy entry point is the tip of the olecranon. Unfortunately, this entry point can lead to painful hardware and an irritated olecranon bursa (Fig. 2). We recommend using a lateral entry point on the ulna, approximately 1 to 2 cm from the tip of the olecranon. It has also been described to use a distal insertion for the ulnar nail, though care must be take to avoid the distal ulnar physis and the dorsal sensory branch of the ulnar nerve. Of note, we do recommend leaving a segment of the flexible nails exterior to the surface of the bone to facilitate later planned removal after the fracture has healed.
To ease nail passage across the fracture site at the time of reduction, we recommended reducing the radius first. Begin by passing the flexible nails to the level of the fracture of both bones. Then proceed with reduction of the radius and dock the flexible nail across the fracture site into the proximal radial shaft piece before nailing the ulna. If the ulna is nailed and stabilized first, it becomes more difficult to reduce the radius.
Another important principle for intramedullary nailing of diaphyseal forearm fractures is to limit the number of attempts passing the nail across the fracture site. Increasing number of attempts passing the nail, proximally or distally, can increase the risk of compartment syndrome by traumatizing the soft tissues.3,4 Compartment syndrome of the forearm should be at the forefront of the surgeon’s mind when treating these injuries. We recommend attempting to pass the nail only 3 times across the fracture site. When reduction cannot be obtained in this timeframe, a small open incision should be made to directly guide the nail across the fracture. The surgeon should have a very low threshold for making a small, mini-open approach to both the radius and the ulna if there is difficulty in obtaining the reduction and passing the flexible nail across the fracture site. A small, mini-open incision has minimal morbidity and allows for removing any interposed soft tissues, such as periosteum or muscle, which could be preventing reduction.
Finally, as with all forearm fractures, it is strongly recommended to be aware of either a Monteggia or a Galeazzi fracture-dislocation.5 If a single radius or ulna fracture is identified, the treating surgeon must be diligent and check the proximal and distal joints to ensure radial capitellar reduction and distal radioulnar joint reduction.
COMPLICATIONS OF FLEXIBLE NAILS
As with any surgical procedure, there are potential complications that can arise from flexible nailing of the forearm. Painful hardware can result when the nails are left prominent, causing irritation of the skin at the nail insertion locations. We recommend cutting the nails close to the bone at the metaphyseal flare to minimize irritation, but leaving enough remaining nail to allow for removal if so desired. Some surgeons also utilize caps on the ends of the nails to minimize sharp prominence and potential irritation, these can be seen in Figure 2A. We do recommend removal of hardware once there is complete healing of the fracture, typically not earlier than 6 months from injury. There is potential for refracture after nail removal. While a low risk we do recommend bracing or splinting for an additional 6 to 8 weeks to minimize refracture risk. Irritation of the extensor tendons and/or radial sensory nerve can occur as another complication; to minimize this, we recommend making a small incision, as discussed above, and retracting these structures to avoid injury. Lastly, also as discussed above, compartment syndrome can occur with numerous attempted passes.
Pediatric diaphyseal forearm fractures are common injuries often seen by the pediatric orthopaedist. When operative reduction is indicated to obtain optimal fracture reduction and alignment, flexible intramedullary nailing should be considered to assist in maintaining alignment. The technical pointers discussed above can improve efficiency in surgical treatment and thus improve outcomes.
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