Chapter 25

Flexible Intramedullary Nailing of Femoral Shaft Fractures

 

Christine M. Goodbody John M. Flynn

 

DEFINITION

Femoral shaft fractures in children occur with an incidence of 20 per 100,000.3, 9, 14 They constitute 2% of all pediatric fractures.11

In a very young child who presents with a femoral shaft fracture, child abuse must be considered,

especially if the child is not yet walking.2 In the young child who has a history of multiple fractures or fracture after minimal trauma, osteogenesis imperfecta might be the underlying cause and is often mistaken for child abuse.

In children who sustain multiple traumatic injuries, the nature and severity of each injury must be considered in order to prioritize and optimize treatment.

 

 

ANATOMY

 

During childhood, the femur is initially composed of weaker woven bone, which is gradually replaced with lamellar bone.

 

The profunda femoris artery gives rise to four perforating arteries, which enter the femur posteromedially. The majority of the blood is supplied by the endosteal circulation. During fracture healing, however, the majority of the blood is supplied by the periosteal circulation.

 

The femoral shaft flares distally, forming the supracondylar area of the femur. This area serves as the entry point for retrograde nailing with flexible intramedullary nails. Surgeons should maintain an awareness of the nearby distal femoral physis, which can be injured during nail insertion.

 

PATHOGENESIS

 

Age is an important factor to consider in terms of the pathogenesis of the injury. The degree of trauma required to cause injury increases exponentially, as the character of the bone changes and gradually becomes stronger and larger from infancy to adolescence. Low-energy injuries resulting in fractures may point to a pathologic nature of the condition.

 

The radiographic appearance of the fracture usually reflects the mechanism of injury and the force applied. High-velocity injuries usually present with more complex, comminuted patterns.

 

The position of the fracture fragments after the injury depends on the level of the fracture and reflects the soft tissue and muscle forces acting on the femur.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

In most cases, there is a history of a traumatic event.

 

In an isolated femur fracture, the thigh appears swollen, with minor bruises and abrasions. Shortening may also be present.

 

The affected extremity should be checked to ensure that no vascular or neurologic injury is present.

 

In cases of high-energy trauma, concomitant injuries to the skin and soft tissue as well as other organ systems are usually present.

 

An examination of the knee should be performed to ensure that no ligamentous injury is present. This may be performed under anesthesia.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Standard high-quality anteroposterior (AP) and lateral radiographs of the femur are usually all that is needed to define the extent and severity of the injury (FIG 1).

 

Radiographs should include the joints above and below the fracture site to avoid missing any concomitant injuries.

 

 

DIFFERENTIAL DIAGNOSIS

Acute traumatic fracture in normal bone Stress fracture

Pathologic fracture

 

 

SURGICAL MANAGEMENT

 

Elastic nailing of the femoral shaft is the optimal treatment for most femur fractures in children 5 to 12 years old.

 

In rare cases in the 5- to 12-year-old age group, children with very length-unstable fractures, or older children who are very

 

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heavy, are best treated with another method (submuscular plating, external fixation, or trochanteric entry nailing, described in other chapters).

 

 

 

FIG 1 • Preoperative AP (A) and lateral (B) radiographs of a 6-year-old girl who sustained a spiral diaphyseal femoral shaft fracture while playing soccer. This injury was treated with titanium elastic nails.

 

 

Elastic nailing can be used in skeletally immature adolescents, especially for length stable fractures in children less than 50 kg, although there is a slightly higher rate of loss of alignment, delayed healing, and poor results than in younger children.

 

In very rare circumstances, elastic nailing can be used in children 3 to 5 years old. Possible indications include very high energy injury, soft tissue injury that makes casting risky, very obese preschool children, or polytrauma.

 

Preoperative Planning

 

The diameter of the nails is predetermined by measuring the isthmus of the femoral shaft. The nail size to be used is usually 40% of the narrowest diameter. For instance, if the isthmus measures 1 cm, two 4-mm nails are used.

 

The presence of concomitant injuries should be considered as well as factors that may hinder or complicate treatment.

 

Positioning

 

The patient is positioned in the supine position. We prefer using a fracture table (FIG 2), although a radiolucent table may be used as well.

 

The groin area is adequately padded before application of the post.

 

The affected extremity is abducted 15 to 30 degrees to allow room for nail placement. The uninjured leg can be held by the ankle (the well-foot holder) and “scissored” with extension of the hip so that it does not block the lateral radiographic view.

 

We generally avoid the well-leg holder that places the hip and knee flexed high above the rest of the patient. Compartment syndrome has been associated with this positioning for femoral shaft fracture treatment.

 

A distraction force is applied to the affected extremity through the foot using a foot holder. If there is significant soft tissue injury to the leg, the distraction force may be applied through a traction pin. However, this is rarely necessary in children.

 

Ideally, the fracture should be brought out to length and reduced to as near an anatomic position as possible before prepping and draping. Time spent optimizing alignment in the unprepped patient generally pays large dividends in time saved struggling with the fracture reduction just before the nail is passed across the fracture site.

 

The extremity is then prepared and draped.

 

 

 

 

FIG 2 • The patient is properly positioned in the fracture table, the landmarks are identified fluoroscopically, and the proper incision sites are marked.

 

TECHNIQUES

• Retrograde Flexible Intramedullary Nailing

Nail Introduction and Fracture Reduction

The nail entry sites, which are located on the medial and lateral aspects of the distal femoral metaphysis, are identified using an image intensifier.

The distal femoral physis is identified, and this position is marked on the skin to remind the surgical team to avoid the dissection in this area.

A 2-cm incision is made beginning at the level where the nail will enter the femoral metaphysis and extending distally. Incisions proximal to the entry site in the distal femur do not aid in nail placement.

The incision is made and carried through the fascia and quadriceps muscle; spreading with a hemostat can facilitate exposure down to bone.

A drill is placed (with a soft tissue protector) through the incision site against the distal femoral

 

metaphysis. The starting point is the midpoint of the femoral shaft in the AP plane (TECH FIG 1A).

 

The size of the drill bit used is largely dependent on the size of the nail; the drill bit should be slightly larger than the nail (eg, a 4.5-mm drill bit is used when using a 4.0-mm nail).

 

The drill is inserted, and once the femoral cortex has been breached, the drill is angled to a very oblique orientation to facilitate nail passage (TECH FIG 1B).

 

The nails are prebent into a gentle C shape before insertion (TECH FIG 1C).

 

The first nail is inserted into the entry site and gently tapped into the femur. The position of the nail is checked under fluoroscopy in both the AP and lateral views to ensure proper nail placement (TECH FIG 1D).

 

Once the tip of the nail has reached the fracture site, the fracture reduction is perfected and documented in both the AP and lateral planes. The “F” tool can be used to maintain alignment if necessary. The tool was constructed from radiolucent fiberglass bars that are available on most sets.

 

Once the reduction is ensured, the first nail is passed across the fracture site, advancing 1 or 2 cm into the proximal fragment (just enough so that it will hold the reduction but not so much that it will begin to alter the alignment between the two fragments at the fracture site).

 

Once the first nail has crossed the fracture line, the same steps for insertion are followed for introduction of the second nail (TECH FIG 1E).

 

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TECH FIG 1 • A. Once the incision has been made, the entry point for the nail is identified 2 cm superior to the growth plate at the midpoint of the femur anteroposteriorly. A 4.5-mm drill bit is used to make the starting point. B. Once the cortex has been entered, the drill is angled obliquely to fashion a tract. C. The nail is prebent in a gentle C shape before insertion. D. The first nail is inserted until it reaches the fracture line. E.

Once the first nail has reached the fracture line, the second nail is inserted in the same fashion.

 

Final Nail Placement

 

When reduction has been confirmed and both nails have sufficiently crossed the fracture line (TECH FIG 2A-C), both nails are advanced a few millimeters and their position is checked with the image intensifier in both the AP and lateral planes (TECH FIG 2D).

 

Once the position of both nails has been confirmed, they are gradually advanced to their final proximal point (TECH FIG 2E).

 

The lateral nail (nail entering through the lateral cortex of the femur) should end at the apophysis of the greater trochanter. The medial nail should come to rest at the medial end side of the calcar at the level of the hip.

 

The final position of the nails should be so that only about 1 to 2 cm of each nail is outside its cortical entry site (TECH FIG 2F,G). After their final position has been confirmed, the nails are backed out a few centimeters, cut to the proper length, and gently tapped back into their final position with the ends resting flush against the femur and just enough of the nail exposed in order to facilitate later removal. Bending the end of the nails will cause undue irritation of the skin and soft tissue.

 

The final fracture configuration is checked (TECH FIG 2H-J). If there is a significant gap between the fracture fragments, the distraction is released and the surgeon gently impacts the fracture fragments together.

 

A layered closure is performed.

 

Rotational alignment of the extremity is evaluated, and any malrotation is corrected before extubation.

 

 

 

TECH FIG 2 • A. Once both nails have reached the fracture line, reduction of the fracture is checked. The F tool can be used to aid in attaining and maintaining reduction. B. The reduction is checked fluoroscopically. C,D. Once the reduction is checked, the nails are passed across the fracture line and advanced until they reach their final end point. (continued)

 

 

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TECH FIG 2 • (continued) E. The lateral nail should end at the apophysis of the greater trochanter, whereas the medial nail at the calcar of the femoral neck. F. The distal ends of the nail should be flush with the femoral metaphysis. G. The final configuration of the nails should provide adequate three-point fixation. H-J. AP and lateral radiographs of the femur of the patient in FIG 1, showing adequate nail placement.

 

PEARLS AND PITFALLS

Indications

• The flexible nailing technique is most successful for children ages 5-12 years,

weighing less than 50 kg, with length-stable fractures. Skeletally immature adolescents and very proximal, distal, or length-unstable fractures can be treated with flexible nailing, but the complication rate is higher.

Preoperative ▪ Proper selection and preparation of the nails are crucial, as is proper patient

planning selection. The nail sizes and the entry points should be symmetric.

 

 

	Fracture ▪ Proper nail configuration must be achieved to obtain three-point fixation. The fixation nails should be gently curved before insertion to ensure maximum cortical contact. If insertion or nail passage proves difficult, or the entry site is complicated by soft tissue injury, an anterograde method of insertion through the greater trochanter may be used for one or both nails.     Difficulty in ▪ An instrument referred to as the F tool is a great aid to reduction. reduction     Skin ▪ To avoid skin irritation, the nails should be cut so that they lie flush with the irritation metaphysis of the distal femur, with only about 1-2 cm of the nail outside the cortical entry site.

 

 

POSTOPERATIVE CARE

 

We prefer a knee immobilizer in the immediate postoperative period to reduce the incidence of soft tissue irritation of the knee and to increase the child's comfort.

 

Weight bearing is instituted immediately after surgery as tolerated.

 

Postoperative analgesics are maintained for continued pain relief and to maximize the rehabilitation period.

 

 

OUTCOMES

Multiple studies have reported good to excellent outcomes in femoral shaft fractures treated with flexible intramedullary nails.1, 4, 5, 8, 10, 15

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Flynn and coworkers,6 in a multicenter trial, reported excellent results in 67% (39) of cases and satisfactory results in 31% (18); there was 1 poor result due to malrotation.

Mehlman and associates12 showed in a biomechanical study that if an acceptable starting point is

achieved, retrograde nailing, as opposed to antegrade nailing, is more stable for fractures of the distal third of the femoral diaphysis.

Flynn and associates7 reviewed their first 50 cases and found that insertion site irritation was the most common problem encountered (18% of cases). Very proximal fractures were more challenging to treat, and older, larger children were best managed with additional periods of adjunctive immobilization.

Moroz and colleagues,13 in a review of 234 femur fractures in 229 children, found excellent results in 150 (65%), satisfactory in 57 (25%), and poor in 23 (10%). The poor outcomes were secondary to leg length discrepancy in 5 cases, unacceptable angulation in 17, and failure of fixation in 1. They likewise reported a correlation with poor outcome in older children (older than 11 years) and in children who weighed more than 49 kg.

A systematic review of the available literature on elastic nailing for pediatric femoral shaft fractures by

Baldwin and coworkers1 found that, although most complications were minor, some series reported complication rates upward of 50%. However, functional outcomes were excellent or satisfactory in greater than 88% of patients in each of four studies that reported them.

Symptomatic hardware was reported as a complication in 23.4% of all patients.

Although nonunion and refracture were uncommon, malunion and malalignment were. The latter occurred with an incidence of 15.1%.

Leg length discrepancy was also not unusual but generally not severe.

Noted benefits of elastic nailing included decreased length of hospital stay, early return to activity, and high rate of fracture union (99.5%).

 

 

COMPLICATIONS

Nail irritation at the nail entry site Nonunion or delayed union

Malunion (angular and rotational deformity)

Leg length discrepancy (shortening and overgrowth) Compartment syndrome

Neurovascular injury

Implant-related complications

 

 

REFERENCES

1. Baldwin K, Hsu JE, Wenger DR, et al. Treatment of femur fractures in school-aged children using elastic stable intramedullary nailing: a systematic review. J Pediatr Orthop B 2011;20(5):303-308.

    

    

2. Beaty JH. Femoral-shaft fractures in children and adolescents. J Am Acad Orthop Surg 1995;3:207-217.

    

    

3. Bridgman S, Wilson R. Epidemiology of femoral fractures in children in the West Midlands region of England 1991 to 2001. J Bone Joint Surg Br 2004;86(8):1152-1157.

    

    

4. Carey TP, Galpin RD. Flexible intramedullary nail fixation of pediatric femoral fractures. Clin Orthop Relat Res 1996;(332):110-118.

    

    

5. Cramer KE, Tornetta P III, Spero CR, et al. Ender rod fixation of femoral shaft fractures in children. Clin Orthop Relat Res 2000;(376): 119-123.

    

    

6. Flynn JM, Hresko T, Reynolds RA, et al. Titanium elastic nails for pediatric femur fractures: a multicenter study of early results with analysis of complications. J Pediatr Orthop 2001;21:4-8.

    

    

7. Flynn JM, Luedtke L, Ganley TJ, et al. Titanium elastic nails for pediatric femur fractures: lessons from the learning curve. Am J Orthop 2002;31:71-74.

    

    

8. Heinrich SD, Drvaric DM, Darr K, et al. The operative stabilization of pediatric diaphyseal femur fractures with flexible intramedullary nails: a prospective analysis. J Pediatr Orthop 1994;14:501-507.

    

    

9. Hinton RY, Lincoln A, Crockett MM, et al. Fractures of the femoral shaft in children. Incidence, mechanisms, and sociodemographic risk factors. J Bone Joint Surg Am 1999;81(4):500-509.

    

    

10. Ho CA, Skaggs DL, Tang CW, et al. Use of flexible intramedullary nails in pediatric femur fractures. J Pediatr Orthop 2006;26: 497-504.

     

     

11. Landin LA. Epidemiology of children's fractures. J Pediatr Orthop B 1997;6:79-83.

     

     

12. Mehlman CT, Nemeth NM, Glos DL. Antegrade versus retrograde titanium elastic nail fixation of pediatric distal-third femoral-shaft fractures: a mechanical study. J Orthop Trauma 2006;20:608-612.

     

     

13. Moroz LA, Launay F, Kocher MS, et al. Titanium elastic nailing of fractures of the femur in children: predictors of complications and poor outcome. J Bone Joint Surg Br 2006;88(10):1361-1366.

     

     

14. Rewers A, Hedegaard H, Lezotte D, et al. Childhood femur fractures, associated injuries, and sociodemographic risk factors: a population-based study. Pediatrics 2005;115:e543-e552.

     

     

15. Saikia K, Bhuyan S, Bhattacharya T, et al. Titanium elastic nailing in femoral diaphyseal fractures of children in 6-16 years of age. Indian J Orthop 2007;41:381-385.