SURGICAL TECHNIQUES PEDIATRIC 2022, Dec, 22 | 12:00 am

Flexible Intramedullary Nailing of Femoral Shaft Fractures

 

Chapter 13

Flexible Intramedullary Nailing of Femoral Shaft Fractures

Gilbert Chan and John M. Flynn

 

DEFINITION

  • Femoral shaft fractures in children occur with an incidence of 20 per 100,000.2,8,12 They constitute 2% of all pediatric fractures.1,9

  • In the very young child who presents with a femoral shaft fracture, child abuse must be considered, especially if the child is not yet walking. In the child who has a history of multiple fractures, osteogenesis imperfecta might be the underlying cause and is often mistaken for child abuse in the young child.

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

    ANATOMY

  • The limb bud develops at about 4 weeks of gestation, with the femoral shaft serving as the primary ossification center. The proximal ossification center is seen by 6 months and the distal femoral ossification center appears at 7 months.

  • The femur is initially composed of weaker woven bone, which is gradually replaced with lamellar bone during childhood.

  • Both the endosteal circulation and the periosteal circulation supply the femur. The profunda femoris artery gives rise to four perforating arteries, which enter the femur posteromedi-ally. 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.

    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 is likewise 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.

  • Rarely, a CT scan may be helpful in assessing more complex injury patterns. It also helps in revealing subtle injuries that may not be apparent on radiographs, such as stress fractures, and aids in characterizing intra-articular injuries.

    DIFFERENTIAL DIAGNOSIS

  • Soft tissue trauma

  • Stress fracture

  • Tumor

  • Metabolic conditions

     

    A
    B

     

    FIG 1 • Preoperative radiographs of a 7-year-old boy who sustained a spiral diaphyseal femoral shaft fracture while playing football. This injury was treated with titanium elastic nails.

     

    1106

     

     

     

    NONOPERATIVE MANAGEMENT

    • Management of femoral shaft fractures depends on the age of the patient.

    • In infants, femoral shaft fractures can be treated with a Pavlik harness or a splint.

    • In children less than 6 years of age, nonoperative management is the treatment of choice. Nonoperative management usually consists of:

      • Closed reduction under sedation or anesthesia as needed

      • Placement of a hip spica cast to maintain reduction for 6 to 8 weeks

    • Correcting rotational and angular alignment is of the utmost importance in treatment. Shortening of up to 2 cm is acceptable.

      SURGICAL MANAGEMENT

    • In older children and adolescents, nonoperative management is not well tolerated.

    • General recommendations for titanium elastic nails are:

      • Children at least 5 years old (ideal for children 6 to 12 years of age)

      • Fractures of the middle 70% of the diaphysis

      • Length-stable fracture patterns. Some difficulty may be encountered in more complex and comminuted fracture patterns.

        Preoperative Planning

    • A detailed review of the clinical findings and all appropriate imaging studies is done before the procedure.

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

  • 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 well leg with 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 guide pin. However, a guide pin is rarely necessary in children.

  • 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

    • Once the patient is properly positioned in the fracture table, the best possible reduction of the fracture is obtained.

    • The patient is draped in the standard manner.

    • The nail entry site is identified using an image intensifier.

    • The distal femoral physis is identified and this position is marked on the skin to avoid dissection in this area.

    • A 2-cm incision is marked out both medially and laterally at the level of the distal femoral physis.

    • The incision is made and carried through the fascia and quadriceps muscle, observing meticulous hemostasis.

    • 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 obliquely (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 is reduced before further advancement of the nail. Reduction of the fragments is documented in both the AP and sagittal planes.

  • When reduction is obtained, the nail that is more difficult to pass is introduced through 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).

    • Alternatively, the second nail may be inserted immediately after the first nail to the level of the fracture site. Once proper reduction of the fracture is obtained, the nails are then advanced past the fracture site alternately as described in the technique above.

       

      A

       

       

      B

       

       

       

       

      TECHNIQUES

       

      C

       

      D

       

       

      E

       

       

      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 (TECH FIG 2F,G).

  • After the final position of the nails 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 of the nail resting flush against the femur. 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,I). 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 leaving the operating room.

     

     

     

     

     

     

     

     

     

     

    B C D

     

    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 endpoint. (continued)

    A

     

     

     

     

    G

     

     

     

     

     

     

     

     

    TECHNIQUES

     

    E F

     

     

    TECH FIG 2 • (continued) E. The lateral nail should end at the apophysis of the greater trochanter, 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,I. AP and lateral radiographs of the femur of the patient in Figure 1, showing adequate nail

    placement. H I

     

    PEARLS AND PITFALLS

    Indications ■ The flexible nailing technique is most successful for children ages 5 to 12, weighing less than 50 kg, with length-stable fractures. Very proximal, distal, or length-unstable fractures can be treated with flexible nailing, but the complication rate is higher and immobilization in a cast may be necessary as an adjunct to treatment.

    Preoperative planning ■ Proper selection and preparation of the nails are crucial. as well as proper patient selection. The nail sizes and the entry points should be symmetric.

    Fracture fixation ■ Proper nail configuration must be achieved to obtain three-point fixation. The nails should be gently curved before insertion to ensure maximum cortical contact. If insertion or nail passage may be 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 reduction ■ An instrument referred to as the “F tool” is a great aid to reduction.

    Skin irritation ■ To avoid skin irritation, the nails should be cut so that they lie flush with the metaphysis of the distal femur, with only about 1 to 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.3,4,7

    • Flynn and coworkers,5 in a multicenter trial, reported excellent results in 67% (39) of cases and satisfactory results in 31% (18); there was one poor result due to malrotation.

  • Mehlman and associates10 showed in a biomechanical study that if an acceptable starting point is achieved, retrograde nailing is more stable for fractures of the distal third of the femoral diaphysis.

  • Flynn and associates6 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,11 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.

 

COMPLICATIONS

  • Nonunion

  • Delayed union

  • Malunion (angular and rotational deformity)

  • Leg-length discrepancy (shortening and overgrowth)

  • Compartment syndrome

  • Neurovascular injury

  • Implant-related complications

     

    REFERENCES

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

    2. 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;86B:1152–1157.

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

    4. Cramer KE, Tornetta P 3rd, Spero CR, et al. Ender rod fixation of femoral shaft fractures in children. Clin Orthop Relat Res 2000; 376:119–123.

    5. 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;2:4–8.

    6. 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.

    7. 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.

    8. 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;81A:500–509.

    9. Landin LA. Epidemiology of children’s fractures. J Pediatr Orthop B 1997;6:79–83.

    10. 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.

    11. 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;88B:1361–1366.

    12. 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.