Reducing Subtrochanteric Femur Fractures

Tips and Tricks, Do's and Don'ts

Abstract

Summary: 

Treatment of subtrochanteric fracture remains a challenge, but evolution of strategy has allowed for reliable results with low complications. Although several fixation options exist, reamed, antegrade intramedullary nailing (IMN) has evolved as the standard of care. Cognizant effort to achieve anatomic reduction before IMN passage allows for desired outcomes. Several reduction techniques can be used to overcome the deforming forces present in the proximal femur to allow for proper IMN placement. The purpose of this article is to review the tips, tricks, and pitfalls to avoid in the treatment of subtrochanteric femur fractures with IMN.

INTRODUCTION

The treatment strategy for subtrochanteric femur fractures has evolved significantly over the past 2 decades. Although early fixation options led to implant failure and high rates of nonunion, advances in implant technology in addition to an improved understanding of the proximal femoral anatomy have led to a successful modern treatment paradigm.^1–4 Although several methods of treatment options have been reported in the recent literature, our preference is to use reamed, antegrade intramedullary nailing (IMN).^1,3,5–7

Arguably the standard of care in treating subtrochanteric femur fractures, IMN can lead to reliable reproducible results.^2,3,5,8,9 Furthermore, combining intimate knowledge of the surrounding anatomy with a few technical tricks, desired outcomes can be achieved while avoiding pitfalls and known complications. The goals of this article are to highlight specific strategies and provide a concise technical guide in achieving reliable, efficient, and desired outcomes when using IMN for subtrochanteric fractures.

Implant Selection: Why Choose an Intramedullary Nail?

Comparatively, screw and side plates, condylar blade plates, proximal femoral locking plates, and IMN have all been used to treat subtrochanteric fractures. However, implant selection for definitive fixation ends up as a choice between using a blade-plate, locking-plate, or an IMN construct. Overall, one should avoid the use of screw- and side-plate constructs, because outcomes and high rates of cutout have caused it to fall out of favor (Fig. 1).¹⁰ A recent meta-analysis compared reported outcomes between screw- and side-plate constructs to blade plates and IMN.¹⁰ The authors could not advocate for the use of screw- and side-plate constructs because of a high rate of reduction loss, fixation failure, and need for reoperation.¹⁰ Blade plates, despite inferior results to IMN, still warranted some favor from the authors with satisfactory outcomes.¹⁰ Also, the other types of fixation, using the varying types of proximal, femoral locking-plate technology, have also been described. However, despite theses favorable results, there are several advantages to the use of an IMN.^{2,5,7,9,11,12}

FIGURE 1: Screw and side-plate constructs have a high rate of failure in the treatment of subtrochanteric femur fractures.

Biomechanically, IMN fixation is superior for several reasons. First, its increased rigidity, stiffness, and shorter moment arm allows for a biomechanically stronger construct with decreased strain placed on the implant. Spanning the entire length of the femur, IMN allows for a more efficient and shared load transfer and resists greatly, the deforming forces that occur, primarily, by preventing excessive medialization of the femoral shaft caused by the pull of the adductors.^13–15 Superior stiffness is inherent in IMN, because of its closed-section design, which yields bending stiffness similar to that of an intact femur.¹⁶

These biomechanical advantages translate into the clinical realm, with primary benefits, including less soft-tissue dissection, potentially less blood loss, restoration of the mechanical axis, and arguably, most importantly, allowance for immediate weight bearing after fixation as per surgeon's recommendations.¹⁶ However, to yield reliable desired results, IMN utilization requires understanding the difference between specific nail types, its application to proximal femoral anatomy, and the implementation and use of reduction aids and techniques to achieve and maintain appropriate bony reduction.^1,2,11,17

Anatomic Considerations: Importance of the Start Point

Some of the highest tensile and compressive mechanical forces in the human body occur across the proximal femur.^4,18,19 Specifically regarding subtrochanteric fractures, powerful deforming forces created by the abductors, external rotators, and the iliopsoas muscles result in a characteristic varus, externally rotated, and flexed deformity of the proximal fragment, whereas the pull of the adductors causes medialization of the distal fragment (Figs. 2A, B).

FIGURE 2: Characteristic appearance of a subtrochanteric femur fracture with (A) varus and external rotation deformity of the proximal fragment because of the pull of the abductors and external rotators; the distal fragment is pulled medially because of the adductors, and (B) flexion is caused by the pull of the iliopsoas.

Excessive deforming forces are what that make achieving initial reduction so difficult and why fixation failure is a common occurrence with improper implant selection. Ignoring the inherent forces about the proximal femur can also lead to malreduction and implant failure, even when using IMN as your treatment modality. However, one can combat the deforming forces and use them to your advantage in maintaining the ideal reduction, especially when using IMN. And this process begins with the most important technical aspect of the operation, obtaining the ideal start point.

Early IMN designs used a piriformis entry starting point. Originally designed to treat femoral shaft fractures, piriformis entry nails allowed for a “straight-shot” down the femur with minimal hoop stresses and less change of iatrogenic femoral bursting.¹³ However, although the first femoral nails proved consistent, reliable, and reproducible for femoral shaft fractures, results were less forgiving for more proximal femur fractures. An improper piriformis start point will lead to malalignment, possible increased comminution at the fracture site, and if the start point is too anterior, increased hoop stresses will cause femoral bursting at the site of entry.¹³ A closer look at the anatomy of the greater trochanter revealed a very small window for proper entry in the piriformis fossa.²⁰ Grechenig et al²⁰ conducted a cadaveric study analyzing 100 specimens, noting that only 63% had an unobstructed ideal entry point, whereas the remaining 37% all had some degree of obscuring of the entry portal.

In an effort to avoid the complications seen with piriformis entry nails, trochanteric entry nails were designed. With a built-in proximal bend to help prevent varus malignment, and a significantly smaller proximal body to reduce damage to the tendonous insertions, the trochanteric entry nails were also designed for an easier mode of entry, by targeting a more subcutaneous anatomic landmark. However, much like the piriformis entry IMN, obtaining the perfect start point is just as important for trochanteric entry nails.^21,22

Using a trochanteric entry nail has inherent advantages and disadvantages. We prefer to use a trochanteric start nail because it removes the guesswork of any fracture extension into the piriformis fossa, and its more subcutaneous placement makes the anatomic landmark easier to locate and instrument. However, because it is not colinear with the long axis, there is a risk of inducing iatrogenic comminution on entry. Avoiding iatrogenically induced comminution can be done by rotating the nail 90 degrees with the bow pointed at apex medial. After advancing it across the fracture and slowly derotating it back to the desired position, can reproducibly avoid causing excess fracture comminution.

A critical analysis of trochanteric entry nails conducted by Ostrum et al²¹ noted that varus malalignment of the proximal fragment occurred with too lateral of a start point. Interestingly, using the ideal entry point recommended by the manufacturers also lead to slight varus deformity. Slight medialization of the starting point, however, lead to slight valgus alignment, which is desired when nailing subtrochanteric fractures. In a separate study by Perez et al,²³ a slightly more medial start point also protected the abductors and caused no damage. However, although obtaining the correct start point is arguably the most important part of the case, the canal must be prepped with the fracture reduced. No matter the starting point, without achieving a good reduction, normal anatomy will not be restored.

Reduction Tools, Aids, and Techniques

Before Incision

The first step to achieving anatomic reduction starts with positioning of the patient. Although there is no literature to support for or against any 1 specific position, surgeon preference and familiarity should dictate desired patient positioning, as each has its inherent advantages and disadvantages.^24–26 Being placed supine on a radiolucent flat table can allow access to other extremities in the setting of polytrauma. For more obese patients, the lateral decubitus position can allow for adduction of the ipsilateral leg to allow for a more prominent greater trochanter, and thus the ability to obtain the starting point a little easier. We prefer the patient to be positioned supine on a fracture table for the allowance of sustained longitudinal traction and circumferential access to the injured extremity for both surgeon and imaging.

Before starting, particularly for subtrochanteric fractures that extend distally into the shaft, or with excessive comminution, we recommend obtaining an estimate of the overall femoral version from the uninjured extremity. Noting the version preoperatively can be helpful in the setting of comminution with no cortical keys available to judge realignment.

Useful Reduction Tips and Tricks

Even with the longitudinal traction and rotation, it is rare to overcome the deforming forces of a subtrochanteric fracture with the table alone. Thus, one must have options for assisting in reduction before nail placement (Table 1). For simpler, two-part subtrochanteric fracture patterns, manipulation of the proximal and distal fragments can be achieved through the use of percutaneous joysticks.¹⁷ Placing Schanz pins with T-handles, the fragments can be aligned and held by an assistant while the guide wire is passed. Similarly, Schanz pins placed can be locked into place through a femoral distractor to hold the reduction to guide ideal wire passage. However, this technique is often a first resort and can be frustrating when attempting to maintain reduction.

TABLE 1: Tips and Tricks in Achieving Reduction Before IMN Placement

Another useful tool for two-part subtrochanteric fractures can be the finger reduction tool (Figs. 3A–C). Although most of the length can be restored with longitudinal traction, slight varus deformity often remains (Fig. 3A). Using a small open lateral technique and without any medial dissection, the finger can be passed down the canal, past the fracture site to hold the reduction and allow the passage of the guide wire down the desired path (Fig. 3B). Guide wire placement is crucial because it provides the correct path for the reamers, allowing for appropriate IMN implantation and maintained reduction (Fig. 3C).

FIGURE 3: A 22-year-old, 6′4″, 300-lb man sustained a left subtrochanteric femur fracture after a motorcycle crash. A, Longitudinal traction alone restored much of the length but left behind some varus deformity. B, The finger reduction tool helped to correct the deformity and allow for proper guide wire placement, leading to your (C) desired result.

For more comminuted fractures that span longer distances in the subtrochanteric region, your goals not only include obtaining a reduction, but also maintaining nail position to hold the reduction and avoid later cutout and failure (Figs. 4A, B). Similar to the strategy used for proximal third tibia fractures, blocking or Poller screws can be placed in the concavity of the deformity to hold the nail position and prevent undesired migration (Figs. 4C, D).

FIGURE 4: For fractures that extend more distally with multiple fragments (A and B), blocking screws (arrows, C and D) placed in the concavity of the deformity may help aid in maintaining nail position and prevent cutout.

Finally, for almost all subtrochanteric fractures, we have a very low threshold to use a small open incision to clamp the fracture fragments to maintain reduction. Described by Afsari et al,¹ using this technique can yield efficient and facile reduction to allow for ideal IMN placement (Figs. 5A–F).

FIGURE 5: In most subtrochanteric fractures (A), we have a very low threshold to use a (B) small open incision with minimal soft dissection to clamp (C and D) and maintain reduction to facilitate ideal IMN placement (E and F).

CONCLUSIONS

Treatment of subtrochanteric fracture remains a challenge, but with technological advancements, reliable results with low complications can be obtained. Although several fixation options exist, we prefer to use trochanteric-entry, reamed antegrade IMN for benefits of a shorter moment arm combined with a rigid stiff construct that allows for immediate weight bearing as per surgeon's recommendations. It is important to emphasize that technique is primary, where obtaining the reduction and using a slightly more medial starting point will help prevent implant failure, cutout, and malreduction. Several reduction techniques can aid in achieving reliable outcomes, including the use of percutaneous joysticks, blocking screws, and a femoral distractor. We have a low threshold to use a small open incision to reduce and clamp the fracture to allow for facile passage. These strategies, readily applied, can help aid in making IMN of subtrochanteric fractures an easier process.