Fixation and treatment of the young femoral neck fracture continues to be associated with anxiety among orthopaedic providers. This is due in large part to the potentially high complication rate of avascular necrosis (AVN) and nonunion, as well as the need for reoperation, which has been cited at nearly 20% in this patient population.1 There is a lack of general consensus and quality literature on most key controversies surrounding the care of these potentially devastating injuries including, but not limited to, open versus closed reduction and the ideal/preferred implant for fixation and treatment. Indeed, of 540 respondents in a recent survey of both academic and community-based physicians, no clear consensus to the type of implant or open versus closed reduction was noted.2 The obvious goal in treating these fractures is the same as all fracture care: minimization of complications with return to maximal function. Although there are several opinions on the “optimum” treatment strategy for this injury, there is very little quality supportive evidence to help define the “gold standard” treatment, as is the case with many other fracture patterns. As reviewed elsewhere, the distinction between “young” and “old” is important and each carries a set of treatment ideology, strategy, and differing outcomes. The goal of this section is to help provide the treating surgeon with a basis for tackling the young femoral neck fracture in treatment modalities, reduction strategies, and clinical decision making of implant choice when faced with these difficult fractures.
INITIAL ASSESSMENT AND PLANNING
It is important that the patient be optimized from a trauma perspective and from any other associated injuries before beginning the endeavor of operative fixation for a femoral neck fracture. These can often be long cases and, although certainly a surgical urgency and a priority within the fracture fixation triage injury list, the surgeon must look at the whole patient and ascertain whether they are able to withstand such a procedure.In addition, it is the author's view that having an experienced and qualified team (nursing, anesthesia, and radiology) and surgeon is paramount to obtaining the best functional results. Current evidence suggests no benefit to emergent fixation and no increased rates of complication with delay in fixation.3–6 Therefore, these cases are often not performed in the middle of the night but put on as a start case for the following day when the patient is optimized, an experienced surgeon is available, and a team of nurses and anesthesia is readily available that routinely does cases such as this. Essential also to obtaining optimal outcomes is a good preoperative plan. Careful scrutinization and time studying both plain radiography, as well as computed tomography, can pay dividends in the operating room. These fractures most often result in an apex anterior deformity, with possible posterior comminution and varus—something the treating surgeon must take into consideration when considering reduction. Radiographs of the contralateral hip can also be valuable in determining native version and overall varus/valgus alignment. In addition, the combination of femoral neck/femoral shaft highlights specific treatment and implant logistics and necessitates a good preoperative plan.
After adequate induction of anesthesia and antibiotics, positioning of the patient ensues. A fracture table may be used in some fracture patterns. This is especially true of the valgus impacted femoral neck fracture in which the surgeon does not wish to destabilize the biomechanically ““friendly” stable fracture (Fig. 1). The fracture table is also preferred when a closed reduction is going to be attempted. This may be in situations where the fracture is nondisplaced on radiographs and computed tomography, is deemed so comminuted that a primary open reduction is unfeasible, or in cases where the surgeon wishes to attempt a closed reduction. In attempting fracture table manipulation and reduction, the surgeon must be ready to perform an open reduction on the fracture table, should a closed reduction be unsuccessful. Understanding that reduction is a surgeon-controlled variable directly related to outcome, it is critical to achieve anatomic reduction in these fractures if possible. Both the anterior-posterior (AP) and lateral radiographs are scrutinized for varus/valgus alignment, femoral neck shortening, and posterior roll off. Should any of these variables not align while on the fracture table with closed manipulation, conversion to open reduction should be considered. Wang et al examined 150 patients over a 2-year period, all treated with a closed reduction and percutaneous screw fixation for femoral neck fracture. The rate of AVN was found to be 18% with correlation to worsening Garden classification and residual displacement after internal fixation. The authors conclude that quality reduction is key to help avoid AVN.7 Min et al8 came to the same conclusion that quality of reduction and initial displacement are primary predictive variables for AVN in their review of 163 patients. Haidukewych et al9 in their series of 82 patients demonstrated fracture reduction and fracture displacement as primary predictors of native hip survivorship free of conversion to total hip arthroplasty at 10 years. Yang et al10 evaluated 202 patients comparing a triangular versus inverted triangular configuration for femoral neck fixation and found that nonunion is associated with both fracture displacement and poor reduction.
In addition, fluoroscopy can be extremely deceiving in confirming adequate reduction. When performing open reduction, a significant amount of displacement under direct visualization can look quite good on intraoperative fluoroscopy. Therefore, direct visualization of the fracture remains the gold standard if an anatomic reduction is the ultimate goal. The author currently uses the fracture table only for femoral neck fractures deemed too comminuted for anatomic open reduction or nondisplaced fractures (confirmed on preoperative imaging and intraoperatively). With the use of the fracture table, 2 intraoperative fluoroscopy machines can be used, with 1 machine positioned in an AP radiograph and the other in a lateral radiograph to allow ease of provisional and final hardware placement and to avoid having to “swing through” back and forth from AP to lateral views. Although this takes more time for set-up, once done, the benefit intraoperatively can be very satisfying for hardware placement. If a closed reduction is performed, cannulated screws are often used and will be described below in greater detail because the methodology is the same as with an open reduction and use of cannulated screws. Consideration can be given with closed reduction to an anterior percutaneous capsulotomy to decrease intracapsular pressure and decompress the hematoma in hopes of decreasing the rate of AVN. A small laterally based incision can be made, followed by sliding a knife along the anterior femoral neck under fluoroscopy guidance to perform capsulotomy and release the intracapsular hematoma.11
In most scenarios, when treating femoral neck fractures, the author prefers to drape the leg free in a supine position with a bump under the hips on a radiolucent operative table. Preprep and drape radiography is used to confirm that adequate imaging can be obtained intraoperatively, and a rotating operating table is always used to allow adjustments intraoperatively as needed with imaging. Draping the leg free allows for complete degrees of freedom and manipulation of the leg to aid in reduction without the limitation and constraints of the fracture table.
OPEN SURGICAL APPROACHES AND REDUCTION TOOLS
An open approach to the femoral neck is achieved either through a Watson-Jones or via Smith-Peterson incision. In addition, a modified Smith-Peterson incision has been explained and is typically the approach used by the author.12 This approach is between the tensor fascia lata and gluteus medius laterally and the sartorius and rectus femoris muscles medially. A radiolucent triangle or towel bump under the knee to flex the hip can relax the hip flexors and make exposure easier. If greater exposure is needed, a rectus femoris tenotomy can be performed of the anterior inferior iliac spine with a cuff of tendon for later repair. If this is performed, heterotopic ossification prophylaxis is sometimes given in the form of indomethacin. The thick and robust anterior capsule of the hip is now exposed, and a T-shaped capsulotomy can be performed with the transverse limb of the “T” along the femoral head (care taken not to damage the labrum) so as not to endanger the blood supply. This open capsulotomy both visualizes the fracture but also decompresses the underlying hematoma. The drawback to this anterior approach is that instrumentation must then be placed through a second, laterally based incision. A benefit of the Watson-Jones approach is that instrumentation can be placed via the same incision as the reduction. This approach is especially useful for basicervical and femoral neck fractures, which are more laterally based. However, for most femoral neck fractures, the author prefers to use the Smith-Peterson or modified Smith-Peterson approach. In doing so, once the capsule is open, the surgeon will be looking directly at the fracture as opposed to “up and over” via the Watson-Jones approach. This also aids in the placement of provisional reduction tools/aids and ensuring anatomic fracture reduction.
As alluded to in the above, it is the author's preferred method to open reduce “all” femoral neck fractures for achievement of an anatomic reduction, understanding that reduction is the most important surgeon-controlled variable affecting outcome. Interestingly, Ghayuomi et al13 found no difference in the rate of nonunion or AVN in their meta-analysis of the literature when comparing open versus closed reduction techniques, although the authors admit that the quality of evidence was lacking. However, because reduction is one of the few variables which consistently has demonstrated a key to successful outcome, and with malreduction predicting failure, an anatomic reduction is obviously preferred and therefore an open reduction is performed in the vast majority of cases.6,14 Commonly, the anterior femoral cortex and calcar are simpler fractures, with most comminution posterior and superior. Therefore, with the leg draped free, the leg can be brought to the head/neck segment and rotated as needed to aid in reduction. Multiple k-wires or guide pins can be placed to the level of the fracture in preparation for reduction. Once the fracture is reduced, the wires can be driven across the fracture for ease of maintenance of reduction and not having to worry about pin trajectory while holding a potential tenuous reduction. It has been postulated that the presence of bleeding of the femoral head, either via a separate drill hole into the head at the time of reduction or via the drill tracts from cannulated screws, may help predict vascularity of the femoral head and hence predict AVN.15 Although controversial and not universally accepted as a practice, the author will typically document the presence or absence of bleeding within the femoral head during open reduction.
Multiple instruments are at the disposal of the treating surgeon to help affect reduction and should be readily available if undertaking fracture fixation of a young femoral neck. A femoral distractor with pin placement in the pelvis and femur can help provide the needed traction in some cases (Fig. 2). A ball spike pusher can help reduce the apex anterior deformity of the fracture, whereas a 3.5-mm tap, a schanz pin, or k-wire in each fragment may allow for a “joystick” affect in helping rotate fragments into position (Fig. 3). Small drill holes can be used as docking sites for weber or pointed reduction clamps (Fig. 4). In addition, a collinear clamp can be used to hold reduction and gain compression (Fig. 5). A jungbluth clamp can be used to gain compression and can be quite useful as both a joystick and an aid for compression in simple 2-part fractures (Fig. 6). Once fracture reduction is achieved, provisional to definitive stabilization occurs. Screw fixation is common and is the preferred method of fixation by surgeons with evidence supporting increased torsional stability, minimally invasive insertion, and preservation of blood supply.16–21 Screws should not be placed below the level of the lesser trochanter to decrease stress riser and minimize risk of iatrogenic subtrochanteric femur fracture. In the common inverted triangle configuration, the author will often use the calcar screw to help resist shear/varus collapse and the superior-posterior screw to help augment the common posterior comminution to prevent apex anterior deformity. Initial guide pins used for fracture reduction/provisional stabilization, if placed appropriately, can be “swapped” for cannulated screws. In addition, because many young femoral neck fractures are high Pauwel angle fractures prone to shear force, the addition of a screw perpendicular to the fracture can be used (Fig. 7). This allows for improved compression at the fracture site because it is directed perpendicular to the main fracture line but also helps resist the shear forces and varus collapse of higher angle femoral neck fractures.22 As such, this is often the first screw to be placed and is partially threaded to provide a lag screw by design to the fracture in high Pauwel angle fractures. The choice of fully threaded versus partially threaded screws can also help the surgeon with fracture reduction, partially threaded screws being able to “pull” the fracture while simultaneously increasing compression. For example, a fracture which is in slight varus or valgus or with slight gapping may be able to be pulled into a more anatomic position by placement of a well-positioned partially threaded screw first as compression occurs inevitably, pulling the head into a more varus or valgus position. It should be noted that this is typically done for minor correction and will certainly not help the surgeon with overall reduction, which should be done with direct visualization (Fig. 8). Along with the addition of compression, there is at least some consideration that a partially threaded screw will allow “slide” of the fracture as fracture resorption occurs along the femoral neck. This will allow continued compression at the fracture site to assist in healing. The use of fully threaded screws can be used in cases where the surgeon wishes to prevent this “collapse” and keep reduction length because the threads on either side of the fracture, in theory, do not allow sliding and should maintain length.
The author's preferred treatment for more vertical femoral neck fractures is a fixed angle construct (such as a sliding hip screw or dynamic blade). Maintenance of an anatomic reduction to keep the abductor moment and hip biomechanics aligned is an important functional factor and outcome measure.23–25 Placement of the fixed angle construct necessitates a lateral incision for introduction of hardware in addition to the anterior reductive portal. Optimal position of the sliding hip screw/cephalomedullary device is centered within the femoral head on both the AP and lateral views, although it can also be used as a “calcar screw” of an inverted triangle with the addition of screws above along the anterior superior and posterior superior femoral neck. When driving the guide pin into the femoral head, it is important to ensure that the correct angle guide is used based on preoperative planning to fit the patient's native varus/valgus orientation and the guide maintains direct contact onto the femur. If this is not done, placement of the final plate will induce either a varus or valgus deformity and malreduce the fracture as the plate is brought into contact with the bone. Care must be taken for insertion of the screw, especially in left-sided femoral neck fractures because the insertion of the screw may induce an apex anterior (rotational) deformity on final tightening. Tapping of the screw tract is advised, especially in young bone, before screw insertion to help avoid this complication. Robust provisional stabilization can also be helpful.
However, a quick direct visual confirmation of maintenance of reduction should be done after the screw is inserted because rotational deformity is common even with what is deemed “adequate” provisional stabilization. If a rotational deformity occurs, the surgeon may be able to reduce this by over-tightening the screw and then “turning the screw” back to allow the deformity to settle. This maneuver, however, should be used with caution because it may damage what remaining vasculature there is to the femoral head.
In addition, the use of a derotation screw can be placed to help hold the reduction as, even with multiple k-wires, the power of the screw can often still cause deformity. This screw is often (but not always) a 6.5-mm partially threaded screw placed directly superior to the sliding hip screw to gain further compression at the fracture site. Care must be taken when placing the sliding hip screw to make sure there is enough room superiorly, should this derotation screw be necessary. Also, the screw should be parallel to the planned sliding hip device within the head/neck because any divergence or convergence of the derotation screw will negate the effect of sliding compression and controlled collapse at the fracture site. The surgeon may consider removal of this screw after insertion because no further stability in fixation is seen after the sliding hip screw is seated.23 Another technique to help avoid rotational deformities with placement of the screw is the use of a blade device instead of a screw. With this technique, the blade rifles into position via the barrel as opposed to a rotational/screw moment to rotate the femoral head. In young, hard bone, this is often advantageous to negate the possible induced rotational deformity while still allowing for the benefits of a fixed angle construct. However, as the blade is hammered into position, the surgeon risks gapping the fracture and distraction on final seating of the implant. Again, a direct visualization after final seating is important to ensure no loss of reduction has occurred.
ADJUNCTIVE REDUCTION TOOLS
A further reduction aid is the use of a calcar or anterior femoral neck plate. This can be placed in a buttress fashion along the calcar at the apex of the fracture. In doing so, this plate can help reduce the fracture via an antiglide effect but also help minimize and reduce the shear forces so dominant within this fracture pattern. The plate may also be placed along the anterior neck to help reduce and neutralize the apex anterior deformity of the fracture (Fig. 9). The plate is often placed after provisional reduction is achieved but before definitive placement of the sliding hip screw. In the author's experience, placement of the calcar plate is usually done last because significant flexion and external rotation of the leg is required to get this plate in the correct position. Ye et al24 demonstrated an 89% union rate with this technique in 27 patients with Pauwel 3 types of fractures.
Despite these techniques, failure rates including nonunion and malunion continue to exist at extremely high rates for these fracture types. New concepts of how to fix and hold these fractures sometimes do not work, as was demonstrated with the proximal femur locking plate technology applied to these fracture patterns.25 A new technology and system developed to help solve this difficult fracture pattern is the Conquest device developed by Smith and Nephew (Fig. 10). This device attempts to bring much of the theory behind other fixation constructs/technology together. This is also similar to the Targon FN system used within the European community. The Conquest uses an inverted triangle of partially threaded screws that are designed as compressible, telescoping/sliding screws, allowing for controlled collapse at the fracture site while fracture resorption occurs. In addition, the screws lock into a side plate, which give an “intact” lateral wall and buttress against collapse, providing both strength and preventing screw back out as the controlled fracture collapse occurs. As the screws are partially threaded, the use of the screw to help achieve minor corrections in reduction can be done similar to partially threaded cannulated screws as discussed previously, with additional benefit of compression along the tension side of the fracture if placed appropriately. Benefit also comes from the technique of insertion of the implant as, unlike current fixed angle constructs such as the sliding hip screw or helical blades, no deformity is imparted to the reduction on insertion, given the cannulated technology and predrilling before screw insertion. The device has a compression handle to gain intraoperative compression at each screw if this is desired. Although certainly further clinical study is needed on the effectiveness of this device and similar devices, the theory behind the technology helps tie together both biomechanics and reduction advantages of cannulated screws and fixed angle devices.
Reduction of young femoral neck fractures can be quite challenging. As reduction is a key determinant to patient outcome, all attempts at an anatomic reduction should be made. For nondisplaced or severely comminuted fractures that cannot be anatomically reduced, a closed reduction can be attempted. In most fracture patterns, an open reduction is preferred. Although either cannulated screws or a fixed angle construct has been shown effective and are used, there is some evidence that fixed angle constructs have biomechanical and clinical advantage to cannulated screws alone and are the author's preferred method of fixation for this difficult fracture. It is important to understand the fracture pattern before entering the operative room and to have an idea of potential reduction tools, aids, and maneuvers to ensure that all equipment is available and ready. The case of ipsilateral femur and neck fractures is difficult, but, if taken separately and as 2 distinct entities, good results and reduction can be obtained.
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Keywords:Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.
young femoral neck fracture; reduction techniques; fixation for a femoral neck fracture