Intramedullary Fixation of Radial and Ulnar Shaft Fractures in Skeletally Immature Patients

Maya E. Pring, MD

Hilton P. Gottschalk, MD

Henry G. Chambers, MD

Dr. Pring or an immediate family member serves as a board member, owner, officer, or committee member of the American Academy for Cerebral Palsy and Developmental Medicine and the Pediatric Orthopaedic Society of North America. Dr. Chambers or an immediate family member serves as a paid consultant to or is an employee of Allergen and OrthoPediatrics and serves as a board member, owner, officer, or committee member of the American Academy of Orthopaedic Surgeons, the American Academy for Cerebral Palsy and Developmental Medicine, and the Pediatric Orthopaedic Society of North America. Neither Dr. Gottschalk nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter.

PATIENT SELECTION

The vast majority of pediatric forearm fractures can be treated nonoperatively. Pediatric fractures heal much more quickly and have remodeling potential so when the physes are open, anatomic alignment of the fracture is not always necessary (see Table 1);¹ furthermore, because children rarely have difficulty with stiffness, early mobilization is not as important as it is with adults.² The small percentage (˜10%) of pediatric forearm fractures that require surgical fixation are treated differently than similar fractures in adults. Adult forearm fractures are commonly fixed with plates and screws to maintain alignment and allow early mobilization to prevent stiffness. Although it is an option, plates and screws are not as commonly used in the skeletally immature patient for the following reasons: they disrupt the periosteal blood supply and fracture hematoma, which may alter the healing potential, and they create a stress riser both while the plate is in place and once it is removed, which leads to increased risk of repeat fracture as children return to regular activities. Intramedullary (IM) fixation is a minimally invasive and relatively safe method of fixing pediatric forearm fractures that are not amenable to routine casting. This technique minimizes soft-tissue disruption and scarring and allows for easy implant removal. However, the reported rate of complication with this procedure is between 14 and 21%.³^,⁴ The complication rate increases with increasing age of the patient.⁵ No significant difference has been found in complication rates of intramedullary nails (IMN) when compared with plates and screws.⁶

TABLE 1 General Guidelines for Acceptable Values in Both-Bone Forearm Fractures

Age	Acceptable Angulation	Acceptable Translation	Acceptable Rotation
Younger than 9 yr	≤15°	Bayonet	≤45°
9 yr or older with >2 yr of growth remaining	≤10° for proximal fractures, ≤15° for distal fractures	100%	≤30°
Data from Noonan KJ, Price CT: Forearm and distal radius fractures in children. J Am Acad Orthop Surg 1998;6(3):146-156.

Indications

Radial and ulnar shaft fractures are very common injuries in children and adolescents (comprising 3% to 10% of all pediatric fractures).⁴^,⁷ Both-bone forearm fractures can be sustained through a variety of mechanisms, from simple falls onto the outstretched arm to higher energy falls sustained in contact sports or wheeled activities such as skateboarding, motorcycle riding, and all-terrain vehicle riding. If the fracture is open (Figure 1) or if an adequate closed reduction cannot be obtained or maintained in a cast, IM fixation can stabilize and maintain reduction with minimal soft-tissue disruption and scarring.³^,⁵^,⁸ The implants are easily removed with minimal downtime once the fracture is healed. Fractures with associated compartment syndrome that require fasciotomies can also be stabilized with IM implants to avoid the need for a cast or anything that may increase compartment pressures. A patient with multiple fractures who would be significantly disabled if not able to use the arm may also benefit from IM stabilization of the forearm fracture.

Acceptable reduction is different at different ages. In young children, fractures have a high potential for remodeling; the closer children get to skeletal maturity, the less likely the fractures are to remodel. Distal fractures also have significantly more remodeling potential than proximal fractures.¹ Fractures are more likely
to remodel when closer to the physis and in the plane of motion (dorsal or volar angulation at the wrist). Rotational deformity is unlikely to remodel, so a loss of pronation and supination, even in young children, can create a long-term functional deficit.² Even though angulation and displacement are described on AP and lateral views, the actual fracture angulation and displacement may be out of plane, and the magnitude of the deformity is at least as great as that seen on each view.¹ Guidelines for acceptable values in treating radial and ulnar shaft fractures are presented in Table 1; however, all of the factors described previously need to be considered when making the decision to proceed with surgery versus allowing the fracture to heal with slight malunion and the expectation that remodeling will occur and function will be normal.

FIGURE 1 Radiographs of a patient who sustained an open both-bone forearm fracture. Preoperative PA (A) and lateral (B) views. PA (C) and lateral (D) views obtained after intramedullary nail fixation.

Contraindications

IM fixation in children younger than 5 years has been reported,³ but given the high potential for remodeling in this population, there is very little role for IM fixation in this age group. On the other end of the pediatric age spectrum, in skeletally mature patients, the implants discussed in this chapter may not be rigid enough to maintain anatomic alignment, and as there is minimal remodeling potential, other methods of fixation, such as plates and screws, should be considered. It has been reported that the complication rate of IMN goes up with age of the patient, and there are significantly more complications after the age of 10 years.³ Some say that any fracture beyond the metaphyseal-diaphyseal junction is too proximal or too distal for IMN,⁹ but this boundary is often pushed. Contraindications to IM fixation include intra-articular fractures, significantly comminuted fractures, and fractures with gross contamination or extensive soft-tissue loss; in these cases, an external fixator may be a better or at least temporizing choice. If significant comminution is present, it is difficult to maintain the length of the bone with an IM implant. This can lead to shortening of one bone, which may disrupt the distal and/or proximal radioulnar joints. Also, it is difficult to get good fixation of distal/metaphyseal radius fractures with an IM implant.¹⁰ Proximal radius fractures (even radial neck fractures) can be reduced and stabilized with an appropriately contoured implant as long as the patient is close enough to skeletal maturity that crossing the physis with the implant is not a concern.¹¹^,¹²

PREOPERATIVE IMAGING

Diagnostic imaging includes AP and lateral radiographs of the forearm and dedicated views of the wrist and the elbow to ensure that the proximal radioulnar joint (PRUJ) and the distal radioulnar joint (DRUJ) are intact. A Monteggia fracture (ulnar fracture with dislocation of the radiocapitellar joint) (Figure 2) or a Galeazzi fracture (radial fracture with dislocation of the DRUJ) is easily missed if the joints above and below the fracture are not
carefully examined radiographically. The dislocation may occur far from the fracture and be missed by a radiograph centered on the deformity.

FIGURE 2 Radiographs demonstrate the importance of imaging adjacent joints. A, Lateral radiograph of forearm shows an ulnar shaft fracture and a distal radial buckle fracture. B, Dedicated lateral radiograph of the same patient’s elbow shows a Monteggia variant and a dislocation of the proximal radiocapitellar joint.

FIGURE 3 Illustration shows the operating room setup for intramedullary fixation of a forearm fracture.

VIDEO 111.1 Distal Forearm Fractures: Both-Bone Forearm Fracture Intramedullary Nailing: Step 1. Kelly D. Carmichael, MD; Chris English, MD (25 min)

View Quicktime Video

Video 111.1

PROCEDURE

Room Setup/Patient Positioning

When setting up the operating room (OR), it is important to arrange the room so that the C-arm can easily be brought in and out of the field without disrupting the surgery. The monitor should be positioned so that the surgeon does not have to turn his or her head to see the monitor. More surgeons are now using a mini C-arm to minimize radiation to the patient, surgeon, and OR staff. The arm is positioned on a radiolucent arm board or receiver of the mini C-arm perpendicular to the operating table (Figure 3).

Special Instruments/Equipment/Implants

A variety of commercially available flexible implants can be used, both titanium (more flexible) and stainless steel (more rigid); these come with a prebent tip to make passage down the IM canal easier. The surgeon will still need to contour the rod to maximize stability at the fracture site.³^,⁸ For younger children, Kirschner wires (K-wires) can be used in the same fashion, but more contouring is required. When planning which size implant or K-wire to use, the narrowest portion of the IM canal should be measured on the radiograph, and the surgeon should
plan to fill 40% to 80% of the canal diameter with the IM implant.⁷^,⁹^,¹³ No reaming is done, and the implant does not need to fill the canal.

Only gold members can continue reading. Log In or Register to continue