Trochanteric Entry Nailing for Pediatric Femoral Shaft Fractures
Chapter 27
Trochanteric Entry Nailing for Pediatric Femoral Shaft Fractures
J. Eric Gordon June C. Smith
DEFINITION
Fractures of the femoral shaft are characterized by acute, nonpathologic fractures of the femur in which the primary portion of the fracture is at least 5 cm distal to the lesser trochanter and at least as far proximal to the distal femoral physis as the width of the physis.
ANATOMY
Understanding of the bony and vascular anatomy of the proximal femur is essential to the successful insertion of lateral trochanteric entry nails.
The proximal femur originates from a single proximal femoral epiphysis that develops two separate ossification centers that lead to the femoral head and greater trochanter.
Although the bony portion of the epiphysis is separate at age 8 years, a remnant of the proximal femoral epiphysis lies along the lateral aspect of the femoral neck allowing the femoral neck to increase in diameter (FIG 1).15
After age 8 years, injury to the lateral aspect of the greater trochanteric physis has no effect on the ultimate
shape of the femoral neck.3 Injury to the medial aspect of this physis can lead to proximal femoral valgus and femoral neck narrowing ( FIG 2A).
The medial femoral circumflex artery originates from the profunda femoris artery and courses medially to the femoral neck, passing adjacent to the piriformis fossa and forming the extracapsular arterial ring which lies at the base of the femoral neck, then anastomosing with branches of the lateral femoral circumflex artery.12, 16
Branches of the extracapsular ring give off the ascending cervical branches, which lie along the lateral femoral neck and enter the posterolateral epiphysis of the femoral head (see FIG 1).
Injury to the medial circumflex artery or the external ring can produce avascular necrosis (AVN) of the femoral head (FIG 2B).
PATHOGENESIS
Fracture of the femoral shaft can result from a direct blow, which can produce a transverse or oblique fracture with or without comminution.
Fracture of the femoral shaft can also result from rotational stresses or a twisting injury, often seen during sports injuries, leading to a spiral-type fracture.
NATURAL HISTORY
Muscle forces following fracture of the femoral shaft produce flexion and external rotation of the proximal fragment.
Muscle forces on the distal fragment produce shortening of the fracture with varus alignment.
These muscle forces produce shortening, procurvatum, varus, and an internal rotation deformity in the untreated fracture.
PATIENT HISTORY AND PHYSICAL FINDINGS
Fractures of the femoral shaft in adolescents can be produced by either sporting activities or more commonly high-energy trauma.
Examination usually reveals tenderness at the midthigh area with swelling present. The limb may have obvious deformity and shortening and may show ecchymosis or open wounds in the case of an open fracture.
A careful neurovascular examination should also be performed—palpating distal pulses and evaluating both motor and sensory neurologic function.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Good-quality anteroposterior and lateral radiographs of the femur should be obtained that allow visualization of the entire femur including the hip and knee.
If any question of a potential femoral neck fracture arises, anteroposterior and lateral views of the hip should be performed.
Patients with femoral shaft fractures secondary to high-energy trauma should have a separate anteroposterior radiograph of the pelvis to rule out concomitant injury.
DIFFERENTIAL DIAGNOSIS
Pathologic femoral shaft fracture due to benign or malignant tumor
NONOPERATIVE MANAGEMENT
Nonoperative management of older children with femur fractures consists of skeletal traction for 2 to 3 weeks followed by application of either a spica cast or a cast brace for an additional 6 to 8 weeks.
Nonoperative management of adolescents with femur fractures historically has consisted of skeletal traction for 3 to 4 weeks followed by application of a spica cast or cast brace for an additional 8 to 12 weeks.
SURGICAL MANAGEMENT
Children younger than the age of 12 years and up to 50 kg with femoral shaft fractures can be surgically treated by flexible intramedullary nailing.2
Children older than the age of 8 years can be treated by lateral trochanteric nailing using either reamed or unreamed rigid nails.5, 6
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FIG 1 • A. Anteroposterior view of the bony and vascular anatomy of the proximal femur. B. Superoinferior view of the bony and vascular anatomy of the proximal femur.
Lateral trochanteric nails are particularly indicated in children 12 years of age or older or who weigh 50 kg or more up to skeletal maturity.7, 8
Lateral trochanteric nailing is also indicated in children age 8 years or older who have length-unstable fractures.
Preoperative Planning
Measurement of the femur from the greater trochanter to the distal femoral physis as well as measurement of the diameter of the medullary canal of the femur at the isthmus should be performed preoperatively in order to ensure that appropriately sized implants are available.
Positioning and Prepping
The patient is positioned supine on a fracture table.
The contralateral limb is flexed and abducted away from the injured limb.
The ipsilateral upper extremity should be positioned across the chest and padded and secured. The perineal post should be padded well.
Traction is applied through a well-padded boot placed on the injured limb.
Prior to draping, the image intensifier should be used to ensure that the hip and entire femur can be visualized and that adequate traction has been applied through the boot to bring the fracture out to length (FIG 3A).
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FIG 2 • A. Anteroposterior view of the left hip in a patient with proximal femoral valgus and neck narrowing following nailing through the tip of the trochanter. B. Anteroposterior view of the left hip in an adolescent with AVN of the femoral head following intramedullary nailing through the piriformis fossa.
The patient's skin should be prepared from above the hip at least 10 cm proximal to the tip of the greater trochanter to the midtibia circumferentially.
Sterile split sheets should be used to drape the patient allowing access to the femur in order to reduce the fracture via manual manipulation or open reduction if necessary.
The image intensifier should be draped sterilely as well (FIG 3B).
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FIG 3 • A. Supine positioning of a patient on a fracture table prior to intramedullary nailing of the femur. B. Supine positioning of the patient after draping.
Approach
The preferred approach is percutaneously to the lateral aspect of the greater trochanter.
Insertion of the nail can also be performed through a lateral open approach.
TECHNIQUES
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Guide Pin Placement
The image intensifier should be used to visualize the hip. Because the proximal fragment usually externally rotates, the image intensifier may need to be arced past perpendicular (overrotated) to obtain a good anteroposterior image of the proximal femur (TECH FIG 1A,B).
The guide pin should be placed on the skin proximal to the greater trochanter and the image intensifier used to align the pin
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so that the entry point allows placement onto the midportion of the lateral aspect of the greater trochanter and allows the pin to be driven in an angle that allows the trajectory of the pin to impact the medial cortex 1 to 2 cm distal to the lower edge of the lesser trochanter (TECH FIG 1C,D).
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TECH FIG 1 • A. Draped patient with image intensifier oriented to obtain a clear anteroposterior view of the proximal femur. B. Anteroposterior image of the proximal femur obtained by the image intensifier. C. Marking the entry site of the guide pin. (continued)
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TECH FIG 1 • (continued) D. Image of the proximal femur showing the guide pin on the skin oriented to push onto the lateral aspect of the proximal femur. E. AP view showing the guide pin placed in the appropriate entry point oriented to a point 1 to 2 cm distal to the inferior edge of the lesser trochanter. F. AP view showing the guide pin placed in the appropriate entry point driven to a point 1 to 2 cm distal to the lesser trochanter. G. Photograph of the image intensifier oriented to obtain a lateral of the guide pin after placement into the proximal femur. H. Lateral view of the proximal femur showing the guide pin placed in the appropriate entry point oriented and placed centered in the femoral canal. I. Incising the skin at the site of the guide pin.
The pin is then pushed down onto the greater trochanter and aligned (TECH FIG 1E).
After the pin is driven into the proximal femur (TECH FIG 1F), a lateral image is obtained by arcing the image intensifier back to obtain an image perpendicular to the anteroposterior image (TECH FIG 1G,H).
Following this, the skin is incised approximately 15 mm proximally from the guide pin, and the scalpel is passed down along the wire through the fascia (TECH FIG 1I).
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Reaming and Guidewire Placement
A soft tissue protector is placed, and a rigid cannulated reamer is then used to enter the greater trochanter (TECH FIG 2A-C) and is driven down into the medullary canal beyond the greater trochanteric physis.
The reamer is then withdrawn, leaving the guide pin in place. If necessary, the obturator is used to keep the guide pin in place.
Place the short exchange tube over the guide pin down into the medullary canal (TECH FIG 2D,E). Remove the guide pin, and place the ball-tipped guidewire down into the canal (TECH FIG 2F).
Orient the tip of the guidewire so that it passes distally down to the fracture site (TECH FIG 2G). Reduce the fracture fragments using direct pressure (TECH FIG 2H).
If necessary, a guide pin can be placed from anterior to posterior through the quadriceps muscle down onto the anterior aspect of the proximal fragment in order to aid reduction.
When the fragments are aligned, pass the guidewire across the fracture site into the distal fragment (TECH FIG 2H,I).
Occasionally, it is helpful to put a small bend in the tip of the ball-tipped guidewire to facilitate nail passage across the fracture site.
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TECH FIG 2 • A. Insertion of the rigid reamer over the guide pin. B. Intraoperative image showing rigid reamer insertion onto the greater trochanter. C. Intraoperative image of the rigid reamer after entering the medullary canal. D. Placing of the rigid exchange tube over the guide pin. E. Intraoperative image showing rigid exchange tube in canal with the guide pin. F. Intraoperative image obtained after removal of the guide pin showing the ball-tipped guidewire being placed though the rigid exchange tube with the bend in the
wire oriented so that the wire is passing down the femoral canal. G. Intraoperative anteroposterior image showing guidewire at the fracture site. H. Intraoperative lateral image showing guidewire at the fracture site showing reduction of the fracture. I. Intraoperative anteroposterior image showing guidewire across the reduced fracture site. J. Intraoperative lateral image showing guidewire across the reduced fracture site. K. Intraoperative anteroposterior radiograph showing guidewire positioned in the lateral distal femur approximately 1 cm proximal to the distal femoral physis.
Position of the guidewire must be checked on both the anteroposterior and lateral views to confirm (TECH FIG 2J).
The guidewire is then passed down into the distal femur and positioned in the lateral aspect of the metaphysis (if the nail has a distal bend at the tip to facilitate the lateral trochanteric entry).
The ball-tipped guidewire should be left approximately 1 cm proximal to the distal femoral physis (TECH FIG 2K).
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Measuring Nail Length and Diameter
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The measuring guide is then passed over the ball-tipped guidewire and into the incision down to the lateral aspect of the greater trochanter (TECH FIG 3A).
This position is confirmed using the image intensifier (TECH FIG 3B).
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TECH FIG 3 • A. Placing of the nail gauge over the guidewire. B. Intraoperative anteroposterior image showing the nail measuring guide advanced over the guidewire down to the lateral trochanteric entry site.
C. Reading of the nail measuring gauge.
The nail length is read from the end of the measuring guide (TECH FIG 3C). The nail length will allow placement of one to three potential nail diameters. The nail diameter is selected based on the patient weight and the clinical situation.
In a typical patient, an 8-mm diameter nail is planned. Very small patients use a 7-mm diameter nail. Larger patients or patients in which an abnormally long healing time is anticipated will often require a 9-mm nail. Ten millimeter nails are reserved for the largest patients.
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Canal Reaming
The canal is then reamed using a flexible reamer (TECH FIG 4A,B).
Except in situations where the canal is exceptionally small, the initial reamer should be 8.0 to 8.5 mm in diameter.
The reamer should be passed down over the guidewire but not beyond the bend in the distal tip of the guidewire.
Reamer diameter should be increased in 0.5 to 1.0 mm increments until a reamer diameter 1.5 to 2.0 mm larger than the proposed nail diameter is reached.
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TECH FIG 4 • A. Intraoperative image showing the flexible reamer advancing into the proximal femur. B. Intraoperative image showing the flexible reamer advancing to the bend in the guidewire. It is important that the reamer not be advanced beyond this bend as the reamer will bind up on the guidewire. C. Intraoperative image showing exchange tube in place after insertion of the smooth guidewire in the distal femur.
If necessary, an exchange tube is then passed down over the ball-tipped guidewire beyond the fracture site to maintain the reduction (TECH FIG 4C).
The ball-tipped guidewire is removed, and a smooth guidewire is passed down the exchange tube into the distal femur.
The exchange tube is then removed, leaving the smooth guidewire in place.
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Nail Insertion
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The nail is mounted and secured on the inserter ensuring the proper orientation of the nail and checking that the appropriate nail laterality, diameter, and length has been mounted.
A final check is done to ensure proper mounting of the nail is to place a drill guide through the insertion guide to make sure that when placed, the drill guide aligns with the interlocking hole.
The nail is then passed down over the guidewire (TECH FIG 5A).
It is initially advanced by hand, leaving the inserter in a horizontal position. When the nail cannot be advanced further by hand, a mallet is used to advance the nail to the fracture site.
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TECH FIG 5 • A. Insertion of the nail. B. Intraoperative image showing nail across fracture site. C. Intraoperative image of the nail with the inserter still in place. Careful examination of the image reveals the junction of the nail and inserter to be just below the bony surface of the greater trochanter.
The alignment is then checked and the fracture realigned if necessary.
The nail is then driven across the fracture site down into the distal fragment (TECH FIG 5B).
When the fracture is stable, the guidewire is removed and the nail impacted into place.
The nail should be advanced to a position 1 to 2 cm proximal to the distal femoral physis, and the proximal tip of the nail should be placed just below the bony surface of the greater trochanter (TECH FIG 5C).
The screw securing the nail to the proximal interlocking guide is then tightened to ensure accurate targeting of the proximal interlocking screws.
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Placing Interlock Screws (Proximal and Distal)
The guide sleeves are placed together with the sharp trocar and are placed through the appropriate interlocking hole(s).
The sleeves are advanced to the skin, and a 1-cm incision is made through the skin and fascia.
The sleeves and trocar are then advanced down to bone and the lateral cortex scored by the trocar to prevent the drill bit from “skating” along the cortex.
The trocar is then removed and the drill advanced under image intensification through the lateral cortex, through the interlocking hole in the nail, and up to the medial cortex.
At this point, the gauge on the drill is used to estimate the screw length and the drill is then advanced through the medial cortex.
The drill is withdrawn along with the drill sleeve, leaving the outer sleeve in place.
The screw is then mounted on the screwdriver, and the screw is placed through the outer sleeve and is driven into the bone through the interlocking hole in the nail (TECH FIG 6A,B).
After proximal interlocking, the alignment of the limb is checked, and the fracture site configuration is evaluated to make sure that rotation is appropriate.
When examining the fracture site, the alignment of the fracture line on the proximal and distal fragments
is checked.
In addition, the relative diameter of the femur above and below the fracture can be used as clues to rotational alignment.
A decision is made by the surgeon as to how many distal interlocking screws are appropriate for the fracture distally.
Typically, a single interlocking screw is appropriate for stable isthmic or proximal fractures. Distal fractures or fractures that are length unstable often require two or three screws.
The distal interlocking hole is first visualized using the image intensifier.
The orientation of the intensifier is changed until a “perfect circle” is observed (TECH FIG 6C).
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TECH FIG 6 • A. Drilling for the proximal interlocking screw with the guide tubes in place. B. Intraoperative image showing the proximal interlocking screw being tightened into position. C. Anteroposterior image of the distal femur showing a perfect circle prior to insertion of an anteroposterior interlocking screw. D. The drill has been positioned with the tip directly over the distal interlocking hole prior to drilling. E. Anteroposterior view of the distal femur showing obscuration of the interlocking hole without extension outside the limits of the nail indicating placement of the screw through the distal interlocking hole. F. Lateral view of the distal femur showing good position of the distal interlocking screw with the tip engaging the posterior cortex.
The position of the intensifier is then locked, and a 1-cm incision is made over the hole.
If the screw is anterior to posterior, the incision should be carried down longitudinally though the quadriceps tendon.
If the hole is lateral to medial, the incision should be carried down through the iliotibial band laterally.
A drill is placed down onto the center of the hole as projected with the image intensifier (TECH FIG 6D) and advanced through the near cortex and through the interlocking hole.
The drill is removed from the drill bit, leaving the drill bit in the bone.
A check is made to ensure that the drill is through the interlocking hole.
The drill is reconnected to the drill bit and the drill passed through the far cortex.
The drill is withdrawn and either a depth gauge used to measure the screw length or the preoperative radiograph measured at the appropriate site to select a screw length.
Finally, the screw is placed and secured, with screw placement and length confirmed using the image intensifier (TECH FIG 6E,F).
This process is then repeated for any additional screws.
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Closure
Final radiographic images are then made to confirm appropriate nail placement and reduction of the fracture (TECH FIG 7A,B).
Wounds are closed in layers, closing fascia where appropriate with absorbable suture. The skin can be closed with absorbable monofilament suture, skin staples, or nonabsorbable suture at the surgeon's preference (TECH FIG 7C,D).
Sterile dressings are applied over each wound (TECH FIG 7E).
Drainage is often most significant at the incision for the nail entry site. Typically, minimal drainage is encountered at the interlocking screw sites.
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TECH FIG 7 • A. Final intraoperative radiographic AP of the hip to confirm correct position of the nail and proximal interlocking screw. B. Final intraoperative anteroposterior view of the fracture site showing near-anatomic reduction. C. Incisions prior to closure. D. Proximal incisions closed with absorbable suture. E. Dressed incisions.
PEARLS AND PITFALLS
Entry point of nail at lateral trochanter
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The guide pin must be inserted at the midportion of the lateral aspect of the greater trochanter.
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Insertion of the nail too close to the tip of the trochanter risks reaming into the blood supply to the proximal femur and producing AVN of the femoral head.
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Placement too laterally and too close to the greater trochanteric physis risks a difficult entry with subsequent reaming through the lateral cortex of the femur and subsequent lack of proximal femoral stability.
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The guide pin should be directed from the midportion of the lateral aspect of the greater trochanter to a point 1-2 cm distal to the lower edge of the lesser trochanter.
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If the guide pin is directed too transversely, at the lesser trochanter or more proximally, the ball-tipped guidewire will be curved significantly, leading to difficulty passing the reamer along the curved guidewire and potentially leading to cutting the guidewire with the reamer.
The ball-tipped guidewire should be placed into the lateral aspect of the femoral metaphysis or the center depending on the configuration of the nail.
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Lateral trochanteric nails can have either a straight tip or a bend in the tip to allow easier placement from a lateral trochanteric entry point, reducing the risk of comminuting the medial cortex of the proximal fragment.
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If the nail has a distal bend, the guidewire should be placed into the lateral aspect of the distal femoral metaphysis.
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If the guidewire is placed centrally when using one of these nails in a femur with a fracture distal to the isthmus, valgus alignment can potentially be produced.
Visualize the guidewire while reaming.
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If the guidewire is not visualized during reaming, migration can occur with the guidewire advancing distally across the physis leading to potential damage or the guidewire being pulled back across the fracture site with resultant loss of fracture reduction.
The nail diameter selected should be appropriate for the patient size.
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The tendency for the surgeon is to select the largest diameter nail possible to “fill” the canal.
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In pediatric and adolescent femur fractures, this is usually not necessary.
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In adult applications, intramedullary nails are placed, and the diameter selected when the reamer starts to ream the cortical bone as revealed by “chatter.”
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Pediatric fractures heal much more quickly, and there is no need to select very large-diameter nails to maintain stability during a 4-6 month period of healing.
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Selecting larger diameter nails has a drawback in that passage of an intramedullary nail from a lateral trochanteric entry point requires the nail to flex somewhat as the tip of the nail impacts the medial cortex of the proximal fragment as it passes down the canal.
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Larger nails have less ability to elastically deform and a greater likelihood of comminuting the medial cortex.
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POSTOPERATIVE CARE
Postoperatively, the patient is allowed weight bearing as tolerated in most situations.
Weight bearing can be limited in situations where healing will be slow, such as severely comminuted fractures or open fractures with bone loss.
The patient is mobilized postoperatively as soon as practical (usually postoperative day 1) on crutches.
Dressings are maintained 3 to 4 days postoperatively and then removed. If clean and dry, bathing and showering are then allowed.
Physical therapy can be instituted for knee and hip range of motion and strengthening beginning at the end of postoperative week 2.
Consolidation is usually observed within 6 weeks of surgery.
OUTCOMES
Union rate with good alignment has been reported in excess of 99%.7, 8
COMPLICATIONS
AVN of the femoral head has not been reported after lateral trochanteric nailing of the femur. The rate of AVN has been reported to be 1.4% after nailing through the tip of the trochanter and 2.0% following nailing through the piriformis fossa in children and adolescents.1, 9, 10, 11, 13
Femoral neck valgus and narrowing of the femoral neck can result from placement of an intramedullary nail through the piriformis fossa or tip of the trochanter, damaging the cartilaginous proximal femoral epiphysis that lies along the lateral aspect of the femoral neck in younger patients.4, 14
REFERENCES
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Astion DJ, Wilbe JH, Scole PV. Avascular necrosis of the capital femoral epiphysis after intramedullary nailing for a fracture of the femoral shaft. A case report. J Bone Joint Surg Am 1995;77(7):1092-1094.
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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(1):4-8.
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Gage JR, Cary JM. The effects of trochanteric epiphyseodesis on growth of the proximal end of the femur following necrosis of the capital femoral epiphysis. J Bone Joint Surg Am 1980;62(5): 785-794.
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González-Herranz P, Burgos-Flore J, Rapariz JM, et al. Intramedullary nailing of the femur in children. Effects on its proximal end. J Bone Joint Surg Br 1995;77(2):262-266.
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Gordon JE, Khanna N, Luhmann SJ, et al. Intramedullary nailing of femoral fractures in children through the
lateral aspect of the greater trochanter using a modified rigid humeral intramedullary nail: preliminary results of a new technique in 15 children. J Orthop Trauma 2004;18(7):416-422.
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Gordon JE, Swenning TA, Burd TA, et al. Proximal femoral changes after lateral transtrochanteric intramedullary nail placement in children: a radiographic analysis. J Bone Joint Surg Am 2003;85: 1295-1301.
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Jencikova-Celerin L, Phillips JH, Werk LN, et al. Flexible interlocked nailing of pediatric femoral fractures: experience with a new flexible interlocking intramedullary nail compared with other fixation procedures. J Pediatr Orthop 2008;28(8):864-873.
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Keeler KA, Dart B, Luhmann SJ, et al. Antegrade intramedullary nailing of pediatric femoral fractures using an interlocking pediatric femoral nail and a lateral trochanteric entry point. J Pediatr Orthop 2009;29(4):345-351.
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Macneil JA, Franci A, El-Hawary R. A systematic review of rigid, locked, intramedullary nail insertion sites and avascular necrosis of the femoral head in the skeletally immature. J Pediatr Orthop 2011;31(4):377-380.
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Mileski RA, Garvin KL, Huurman WW. Avascular necrosis of the femoral head after closed intramedullary shortening in an adolescent. J Pediatr Orthop 1995;15:24-26.
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Ogden JA. Changing patterns of proximal femoral vascularity. J Bone Joint Surg Am 1974;56(5):941-950.
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O'Malley DE, Mazur JM, Cummings RJ. Femoral head avascular necrosis associated with intramedullary nailing in an adolescent. J Pediatr Orthop 1995;15:21-23.
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Raney EM, Ogden JA, Grogan DP. Premature greater trochanteric epiphysiodesis secondary to intramedullary femoral rodding. J Pediatr Orthop 1993;13:516-520.
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Siffert RS. Patterns of deformity of the developing hip. Clin Orthop Relat Res 1981;(160):14-29.
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Trueta J. The normal vascular anatomy of the human femoral head during growth. J Bone Joint Surg Br 1957;39:358-394.