Stuart M. Myers and John M. Flynn
DEFINITION
Femoral shaft fractures occur in children with a bimodal age distribution peaking at ages 2 and 12.
The peak in age distribution at age 2 is due to relative weakness of primarily woven bone at a time when ambulation increases the risk of fall-related trauma.
ANATOMY
Muscular deforming forces, if severe, increase the need for surgical fixation. In proximal and midshaft femoral shaft fractures, the proximal fragment tends to be forced into abduction and external rotation. This is more significant in proximal fractures than in midshaft fractures.
Fractures of the distal third of the femoral shaft tend not to deform greatly, while supracondylar femoral fractures are often forced into apex posterior angulation.
PATHOGENESIS
In toddlers, these injuries tend to be low energy and occur during normal activity. In adolescents, they tend to be higherenergy injuries that may result from motor vehicle, biking, or high-speed sporting accidents.
Abuse should be considered in the infant or toddler with a femur fracture, especially if the child is nonambulatory.
PATIENT HISTORY AND PHYSICAL FINDINGS
In an unconscious patient or a patient with an insensate lower extremity, deformity, erythema, crepitance, and swelling might indicate the presence of a femoral fracture.
If child abuse is suspected, a skeletal survey should be obtained and Child Protective Services should be notified. Infants are more likely than toddlers to be the victims of child abuse in the setting of a femoral fracture.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Anteroposterior (AP) and lateral radiographs of pelvis and femur are obtained. The hip and knee should be visualized on the femur radiograph or separately to evaluate possible associated injuries (FIG 1).
Radiographs should be evaluated for fracture pattern, location, displacement, angulation, and shortening.
DIFFERENTIAL DIAGNOSIS
In a child with an insensate extremity, the swelling and erythema caused by a femur fracture may resemble an infection.
NONOPERATIVE MANAGEMENT
Nonoperative management (casting) is appropriate for an isolated femur fracture in a child younger than 6 years. Most children older than 6 years are now treated with some form of operative fracture stabilization.
Nonoperative options include Pavlik harness or splints for children younger than 6 months and a spica cast for those older than 6 months.
SURGICAL MANAGEMENT
Operative management of femoral shaft fractures should be considered in any femur fracture in a child older than 6 years. In younger children, polytrauma, head injury, high-energy trauma, an open fracture, severe comminution, or body habitus incompatible with spica cast care are relative indications for operative management.
Surgical options include flexible nailing, plating, rigid intramedullary nailing, and external fixation.
Indications for external fixation include polytrauma, concomitant head injury, open fracture with severe soft tissue damage or contamination, severe comminution, and very proximal subtrochanteric or distal diaphyseal–metaphyseal junction fracture.
Midshaft transverse fractures are at a higher risk of refracture when treated with external fixation compared to other methods of stabilization.
FIG 1 • Preoperative radiograph of a 12-year-old boy who sustained a distal femoral shaft fracture.
Preoperative Planning
The surgeon should determine where pins will be placed before surgery.
In each fragment there must be at least 2 cm of intervening bone between the physis and the outermost pin and at least 2 cm between the fracture and the innermost pin.
The appropriate pin size varies according to the device. The AO/Synthes device guide recommends 4.0-mm Schanz screws be used, while the EBI device guide recommends screws not larger than one third of the bone diameter.
Positioning
The patient should be placed on either a radiolucent operating table or a fracture table. The latter is useful if preoperative reduction is desired.
TECHNIQUES
EBI DFS XS FIXATOR TECHNIQUE
Pin and Screw Placement
The first pin inserted should be one into the shorter or more difficult bone fragment.
After making a stab incision over the first pin site, the surgeon dissects bluntly to the near cortex.
The trocar is inserted into the soft tissue guide and seated onto the femur perpendicular to its long axis. The trocar is removed and the soft tissue guide is impacted gently to prevent slippage.
The appropriate drill guide (based on the chosen screw size) is inserted into the soft tissue guide.
After attaching a drill stop onto the appropriate bit, the surgeon drills through the near cortex, using the drill guide to keep the pilot hole perpendicular to the long axis of the bone. Drilling should stop once the near cortex is penetrated.
The surgeon slides the bit up to the far cortex without drilling. The drill stop is adjusted so that the drill can be advanced no more than 5 mm (TECH FIG 1A). The surgeon then drills through the far cortex.
The drill bit and the drill guide are removed without unseating the soft tissue guide.
The appropriate screw is inserted into the pilot hole, and the screw is advanced using the T-wrench until it protrudes 2 mm beyond the far cortex. The screw cannot be backed out of bone without losing grip because of its conical shape.
Any tented skin is released.
The surgeon slides the telescoping arm of the assembled fixator onto the screw in the appropriate position. The clamp bolt is not tightened.
The soft tissue guide is inserted into another clamp position on the same telescoping arm. Again, the clamp bolt should be loose enough to allow translation of the soft tissue cover through the arm.
Once the soft tissue guide has been seated on the near cortex, the clamp bolt is tightened to prevent loss of alignment. Repeating the above steps, a second screw is inserted in the position now occupied by the soft tissue guide (TECH FIG 1B).
Once both screws have been placed in the first fragment, the above steps are repeated on the second fragment (TECH FIG 1C).
The telescoping arm clamp bolts are tightened before final reduction.
Final Reduction
The final reduction is made with a variety of adjustments.
Length can be adjusted on each telescoping arm by either loosening the telescoping set screw and adjusting length manually or by loosening the compression–distraction screw and using this feature to adjust length (TECH FIG 2A).
The locking connector bolts can be loosened for the correction of angular deformity (TECH FIG 2B).
TECH FIG 1 • A. Repositioning of drill stop about 5 mm from the base of the drill guide. B. Insertion of a second bone screw into the same bone screw cluster using the identical technique as previously described. C.Insertion of a second bone screw into the opposite bone screw cluster using the identical technique as previously described. (Courtesy of Biomet Trauma, Copyright 2009. All rights reserved.)
Each telescoping arm can also be rotated using the rotational set screw on the central body of the fixator (TECH FIG 2C). These can be loosened simultaneously to rotate the central body of the fixator to bring the central locking joints into the plane of correction (TECH FIG 2D).
Each telescoping arm is able to extend up to 2 cm. If more length is needed, a 4-cm arm may be used. This is especially useful when one arm is occupied by the Tclamp, which has no telescoping feature.
Alternative T-Clamp Technique
If desired, the T-clamp can be used when the fracture pattern precludes placement of screws longitudinally in one of the bone fragments.
The T-clamp is applied before the telescoping arm using the screw insertion technique described.
After the T-clamp is in place, the screws for the telescoping arm are placed in the other fragment as in the standard configuration described above.
TECH FIG 2 • A. Manual length adjustment. B. Each of the locking joints will provide angular adjustments in a plane relative to fixator position as applied to the bone. C. Rotation about the axis of the fixator may be achieved by releasing the rotational set screw on either end of the central body component. D. Translational adjustments are performed by releasing two locking joints in the same plane as the desired correction. (Courtesy of Biomet Trauma, Copyright 2009. All rights reserved.)
AO/SYNTHES TECHNIQUE USING PEDIATRIC FEMORAL SHAFT FRAME WITH COMBINATION CLAMPS
Construct Application
Note: All Schanz screws must be coplanar if double stacking (for increased rigidity) or dynamization is desired.
The most proximal screw and the most distal screw are inserted before inserting the inner pins. Screws should be placed with at least 2 cm of bone between the screw and the physis.
The screw is inserted in the following manner.
A stab incision is made.
The trocar with protective sleeve is seated onto the femur by passing it through the incision.
The trocar is removed, the screw is inserted into the protective sleeve, and the surgeon drills until the screw is embedded in the far cortex.
If preferred, a power drill is used until the near cortex is penetrated; then the surgeon can drill into the far cortex by hand.
After inserting the outermost (most distal and most proximal) Schanz screws, the surgeon attaches a medium combination clamp to each screw.
The carbon rod is attached to each clamp. The construct should now consist of two screws, two clamps, and one carbon rod.
The fracture is reduced and the clamp bolts are tightened.
Two additional clamps are attached to the carbon rod. These will attach the inner screws to the carbon rod.
The two inner screws are inserted in the same fashion as the outer screws. There should be at least 2 cm of bone between the screw and the fracture. These screws are attached to the inner combination clamps and the bolts are tightened.
The construct now consists of four screws, four clamps, and one carbon rod (TECH FIG 3A).
A second carbon rod may be added if additional stiffness is desired and all screws are coplanar. The rod is secured to each screw with a combination clamp.
If this step is completed, the construct will consist of four screws, eight clamps, and two rods (TECH FIG 3B).
TECH FIG 3 • A. Completed construct with four combination clamps, four Schanz screws, and one carbon rod. B. A second rod is added to the frame to increase stiffness. The rod is attached to each Schanz screw using a Medium Combination Clamp. (© Synthes, Inc., or its affiliates. All rights reserved.)
Dynamization
Dynamization can be accomplished only in a doublestacked construct. To dynamize the fixator, the outer bolts on the proximal pins and the inner bolts on the distal pins will be adjusted as follows. The bolt is loosened, a dynamization clip is inserted between the rod vise plates, and the bolt is retightened. This procedure is repeated for all four appropriate bolts (TECH FIG 4A).
The dynamization clips can be used in the postoperative setting to increase axial loading across the fracture site or intraoperatively for compression or distraction of the fracture.
Intraoperative distraction or compression is achieved by dynamizing the fixator, attaching the distractor device adjacent to a dynamized clamp (TECH FIG 4B), turning the distractor adjustment ring to either distract or compress, removing the dynamization clips after dynamization or compression, and retightening the clamps.
TECH FIG 4 • A. Dynamization technique. Insertion of dynamization clips between rod vise plates. B. Distraction–compression technique. Placement of the distractor. (Copyright Synthes, Inc., or its affiliates. All rights reserved.)
AO/SYNTHES TECHNIQUE USING PEDIATRIC FEMORAL SHAFT FRAME WITH MULTIPIN CLAMPS
Assembly of this fixator requires screw insertion of one bone fragment to be completed before inserting screws in the other fragment. Therefore, Schanz screws will not be inserted in the outside-to-inside fashion used for the combination clamps.
The first Schanz screw should be an outer screw, inserted with at least 2 cm of bone between the screw and the physis. A multipin clamp is attached to this first screw and the screw is drilled into the femur. The clamp may be held parallel to the femoral shaft to ensure that the screw enters the femur perpendicularly.
The second Schanz screw is inserted through the opposite end of the clamp, with at least 2 cm of bone between the screw and the fracture site. This screw and all subsequent screws should be inserted as described above, with a stab incision, protective sleeve seating, and screw guidance with the sleeve (TECH FIG 5A).
TECH FIG 5 • A. Insertion of Schanz screws through multipin clamp. The screws must be perpendicular to the bone while the clamp is parallel to it. B. Completed construct with two multipin clamps with two Schanz screws each and one carbon rod. C. Completed construct with double-rod frame. (Copyright Synthes, Inc., or its affiliates. All rights reserved.)
Up to two additional Schanz screws may be inserted through the multipin clamp if necessary. This completes assembly of the hemifixator.
These steps are repeated for the other bone fragment.
The multipin clamp vise plate bolts are tightened on each hemifixator.
The carbon rod is attached to each multipin clamp.
The fracture is reduced and the rod clamping bolt and rod attachment bolt are tightened (TECH FIG 5B).
A second rod may be added to the construct to increase the stiffness of the fixator. This is accomplished with two rod attachment devices (TECH FIG 5C).
AO/SYNTHES TECHNIQUE USING MODULAR FRAME
Modular frame constructs may be created if the fracture pattern precludes coplanar insertion of Schanz screws. This is accomplished by sequential assembly of modules that are then connected by a spanning carbon rod.
The first screw, which should be an outer screw, is inserted with at least 2 cm of bone between the screw and the physis.
The second screw, an inner screw, is inserted into the same fragment. There should be at least 2 cm of intervening bone between the screw and the fracture. This screw need not be coplanar with the first screw. This screw and subsequent screws should be inserted as described above, with a stab incision, protective sleeve seating, and screw guidance with the sleeve.
Combination clamps are attached to each screw and the bolts are tightened.
A carbon rod is connected to each combination clamp. This completes the assembly of the first module.
The second module is built in the same fashion as the first: the outer screw is inserted, then the inner screw; combination clamps are attached to the screws; and then the clamps are connected with a carbon rod. Each module should consist of two Schanz screws, two combination clamps, and a carbon rod.
Once each module has been constructed, a combination clamp is attached to each carbon rod. The placement of these clamps should be as follows:
The first clamp is placed on the proximal module distal to the most distal screw and the second clamp is placed proximal to the most proximal screw.
These combination clamps are connected to a third carbon rod.
If the spanning clamps are placed correctly, the fixator will have a Z conformation (TECH FIG 6A). If not, the fixator will have an I formation.
The fracture is reduced before tightening the spanning rod clamps.
The spanning rod combination clamps are tightened once adequate reduction is obtained.
To increase the stiffness of the fixator and add rotational stability, a second spanning rod is added. The placement of the second set of spanning clamps should be as follows:
The first clamp is placed on the proximal module proximal to the most proximal screw and the second clamp is placed on the distal rod distal to the most distal screw.
These combination clamps are connected to a fourth carbon rod.
If this second set of spanning clamps have been placed correctly, the modular rods and the spanning rods will have an hourglass configuration (TECH FIG 6B).
TECH FIG 6 • A. Basic modular frame with connected modules. B. Fourth bar is added to frame configuration to increase stiffness and rotational stability. The fourth bar should span the length of the frame, connecting the first and second modules. (Copyright Synthes, Inc., or its affiliates. All rights reserved.)
FIG 2 • Postoperative radiographs from the patient in Figure 1 on postoperative day 1 (A), before external fixator removal on postoperative day 63 (B), and at last follow-up on postoperative day 217 (C).
POSTOPERATIVE CARE
Pin care is essential in avoiding pin-track infection. This skill must be taught in the postoperative setting and reviewed at each office visit.
Antibiotics with adequate coverage of skin flora should be prescribed at the first sign of pin-track infection.
Some advocate removal of the external fixator as soon as bridging callus is seen, with subsequent casting if necessary. Others believe the fixator should be left in place until three of four cortices are bridged by callus.
A typical radiographic evolution of this injury when treated with external fixation is shown in FIGURE 2.
OUTCOMES
In one series of 37 femur fractures treated with external fixation, the average duration of fixation was 3 to 4 months (range 2 to 5 months). In all but one case, union was achieved at the time of fixator removal.4
Risk of refracture may be as high as 20% after fixator removal.2,4
Pin-track infections occur in about 65% of cases. These can almost always be managed successfully with oral antibiotics; fixator removal is rarely required.
While clinically insignificant malunion is often seen, malunion requiring surgical correction is rare.
COMPLICATIONS
Pin-track infection
Deep infection
Knee stiffness
Unsightly thigh scars
Delayed union
Refracture
Malunion
Leg-length discrepancy
REFERENCES
1. Flynn JM, Schwend RM. Management of pediatric femoral shaft fractures. J Am Acad Orthop Surg 2004;12:347–359.
2. Gregory P, Pevny T, Teague D. Early complications with external fixation of pediatric femoral shaft fractures. J Orthop Trauma 1996; 10:191–198.
3. Kasser JR, Beatty JH. Femoral shaft fractures. In: Beaty JH, Kasser, JR, eds. Rockwood and Wilkins Fractures in Children, ed 5. Philadelphia: Lippincott Williams & Wilkins, 2001:941–980.
4. Miner T, Carroll KL. Outcomes of external fixation of pediatric femoral shaft fractures. J Pediatr Orthop 2000;20:405–410.
5. Morrissey RT, Weinstein SL. Closed reduction and external fixation of femoral shaft fracture. In: Atlas of Pediatric Orthopaedic Surgery, ed 3. Philadelphia: Lippincott Williams & Wilkins, 2001: 525–530.