13 Subtrochanteric Fractures

Intramedullary Fixation

Boyd and Griffin 190

Fielding and Magliato 190

Zickel 190

Seinsheimer 190

Waddell 191

Russell and Taylor 192

AO/OTA 192

Preoperative Planning and Choice of Implant 192

Follow-up Care and Physical Therapy 200

Subtrochanteric fractures are a heterogeneous and imprecisely defined category of fractures in the area of the lesser trochanter. These fractures can be divided into two basic groups.

Figure 13-1 A to D, Intertrochanteric fractures, type 31A3 according to the AO/OTA classification.

In the second group, the term subtrochanteric fracture is used by most investigators for fractures occurring between the lesser trochanter and the isthmus of the femoral shaft (i.e., approximately 5 cm distally from the lesser trochanter)¹³^–¹⁵ (Fig. 13–2). Moreover, there is a continuum between these two groups. This situation has resulted in terminologic and morphologic confusion that may lead to discrepancies in the comparison of treatment type and outcome of these fractures.^11,¹⁶^–²⁴

Figure 13-2 A to C, Fractures occurring between the lesser trochanter and the isthmus of the femoral shaft.

In both intertrochanteric and subtrochanteric fractures, the proximal fragment is formed by the femoral head, the femoral neck, and the greater trochanter, including its base with the vastus ridge (tuberculum vastoadductorium or innominate tubercle) (Fig. 13–3). The gluteus medius muscle (proximally) and the origin of the vastus lateralis muscle (distally) are attached on this tubercle. Tension in these muscles may cause displacement of the proximal fragment and complicate fracture reduction. This situation applies particularly to certain types of subtrochanteric fractures, in which a portion of the iliopsoas tendon is also attached to the medial cortex of the proximal fragment and pulls the fragment into flexion. The femoral shaft is the distal fragment, and another fragment can be formed as a result of avulsion of the lesser trochanter with the medial cortex. Secondary fracture lines may be present in the area of the greater trochanter or the femoral shaft. The subtrochanteric area of the proximal femur is composed mainly of cortical bone. This type of bone is less vascular and the fracture surface available for healing is smaller than in cancellous bone in pertrochanteric fractures.

Figure 13-3 The proximal fragment is formed by the femoral head, the femoral neck, and the greater trochanter including its base with the vastus ridge (tuberculum vastoadductorium or innominate tubercle). The femoral shaft constitutes the distal fragment, and another fragment can be formed as a result of avulsion of the lesser trochanter with the medial cortex.

The mechanism of injury is usually direct trauma, and it varies with age. In younger patients, these fractures are more commonly caused by high-energy trauma such as motor vehicle accidents, vehicle-pedestrian accidents, falls from significant heights, and penetrating injuries. Fractures from high-energy trauma are often associated with comminution involving large areas of the proximal end of the femur and frequently resulting in significant soft tissue damage.

In older patients, fractures result from low-energy trauma, as in a simple fall. Fractures from low-energy trauma usually have minimal comminution and are transverse, short oblique, or spiral (Fig. 13–4).

Figure 13-4 The difference between fractures resulting from low-energy trauma (A) and those caused by high-energy trauma (B).

Subtrochanteric fractures have usually been considered a homogenous group of injuries resulting from low-energy trauma in older patients with osteoporosis or high-energy trauma in younger patients with normal bone. For this reason, recommendations for the most successful method of treating subtrochanteric fractures are confusing.

Intramedullary nailing has become increasingly common in the treatment of subtrochanteric fractures and currently represents the best available implant technique for proximal femoral fractures. In addition, locking plates constructed specifically for the proximal femur are becoming more popular thanks to the indirect reduction technique, which preserves the integrity of the blood supply around the fracture. General experience with the indirect reduction technique is still limited, however, and intramedullary nailing will likely remain the preferred technique for most surgeons treating this type of fracture for some time.

History

In the last 30 years, intramedullary nailing techniques underwent a process of rapid innovation, although the cornerstones of this process were set in 1940. For better understanding of the present state of intramedullary nailing, it is crucial to know when and how the individual construction principles were developed.²⁵

Essentially, the development of this approach took two directions. First, the nail was introduced from the area of the proximal femur (fossa piriformis, greater trochanter) into the medullary canal. Next, various types of implants were inserted through the nail and into the femoral neck and head.

Küntscher Y-Nail, Detensor

The beginnings of intramedullary nailing of proximal femoral fractures are connected with the names of G. Küntscher and R. Maatz. In 1940, just after successfully introducing intramedullary nailing of femoral shaft fractures, Küntscher developed a conical nail for treatment of high subtrochanteric fractures. This nail was inserted from the apex of the greater trochanter. Shortly afterward, this advance was followed by the so-called Y-nail, a precursor to the reconstruction nails in present use (Fig. 13–5). From the apex of the greater trochanter, a U-shaped intramedullary nail 32 cm long was introduced into the medullary cavity of the femoral shaft. At a distance of 8 cm from proximal end, this nail had a hole for introducing a shorter (11.5-cm) transverse nail, with a double-T profile. This transverse nail was introduced into the femoral neck and head at an angle of 135 degrees with the help of a targeting device attached to the diaphyseal nail.²⁶ The instruments Küntscher used were very advanced for the time. Küntscher later reported that he had successfully treated more than 150 pertrochanteric fractures with this technique.²⁷

Figure 13-5 Küntscher Y-nail and nail insertion set.

(Redrawn from Küntscher G, Maatz R. Technik der Marknagelung. Leipzig: Thieme; 1945; and Küntscher G. Die Marknagelung. Berlin: Saenger; 1950.)

The Y-nail method had its advocates as well as its critics. In 1983, almost 40 years after its introduction, this technique was described in detail in a monograph by Maatz et al.²⁸ This publication includes quotations from surgeons who had used the technique.

In 1962, Küntscher ²⁹ modified his approach. Indeed, he reversed it by introducing the transverse nail to the femoral neck first and then, through the opening in the transverse nail’s lateral widened part, inserting the intramedullary nail from the tip of the greater trochanter into the medullary canal.

Zickel Nail

In 1967, another intramedullary nail was described by Zickel.³⁰ This device was intended for subtrochanteric fractures and resembled the Küntscher Y-nail in shape. The form of the Zickel nail followed the shape of the femoral medullary cavity, with its proximal portion curved in valgus as well as in anteversion. After reaming, a tri-fin nail was inserted into the femoral head at an angle of 125 degrees with the help of a targeting device and a guidewire. This nail was locked into position by a locking bolt inserted from the apex of the widened proximal part of the intramedullary nail (Fig. 13–6).

Figure 13-6 Zickel nail.

(Redrawn from Zickel RE. A new fixation device for subtrochanteric fractures of the femur: a preliminary report. Clin Orthop Relat Res 1967;54:140-5.)

Russell-Taylor Nail

As a result of a combination of advantages of intramedullary nail and a principle of gliding screw of femoral neck, reconstruction nails (second-generation nails) were created. Reconstruction nails are antegrade femoral intramedullary nails designed to provide locking into the femoral head. They were originally designed for subtrochanteric femoral fractures, pathologic femoral fractures, and selected ipsilateral femoral neck and shaft fractures. The original reconstruction nail was the Russell-Taylor reconstruction nail introduced in 1986.³¹ It was a closed-section implant for piriformis fossa entry. A pair of cancellous bone screws is directed into the femoral head at an angle of 135 degrees through the proximal widened part of the nail. This device is a long reamed nail with distal locking.

Gamma Nail

In an effort to minimize fracture deformity and loss of reduction or fixation, third-generation reconstruction nails for use with a trochanteric entry portal were designed. In the early 1980s, Grosse and Taglang were developing a nail designed for treatment of proximal femoral fractures. The first prototype appeared in 1980, but it was only in 1986 that the nail was implanted for the first time. This device was a 200 mm-long massive nail, through which one lag screw was inserted into the femoral neck. In 1988, an incident of diaphyseal split under the nail occurred, and therefore a long version (360 to 420 mm in length) of the nail was designed and implanted.

The Gamma nail (Stryker, Kiel, Germany) has been in use for many years. It has gone through many stages of development and many versions. Common to all versions of the Gamma nail is the type of screw for the femoral neck. This screw cannot rotate in the nail because of a locking bolt, but it can move mediolaterally in specially integrated grooves.

The Gamma nail is a prototype cephalomedullary nail with serious implant-related complications, such as fractured shaft of the femur (17%),³²^–³⁵ failure of fixation (7%),^33,^34,³⁶ and complications of distal locking (10%),^19,³⁷ requiring reoperation. The shape of the proximal fragment in subtrochanteric fractures offers three areas for nail fixation: the subchondral bone of the femoral head, the lateral cortex below the vastus ridge for lag screws, and the apex of the greater trochanter for the proximal part of the nail. This firm fixation in the proximal fragment results in increased bending forces acting on the nail and in some cases also in its breakage.^20,^33,³⁷^–⁴⁰ Excessive bending stress acting on the implant in subtrochanteric fractures was confirmed by biomechanical studies carried out by Mahomed et al⁴¹ and Rosenblum et al.⁴²

Most the technical failures consist of collapse of the fracture area and cutting out of the neck screw as a result of the rotation potential of the femoral head-neck fragment. Nevertheless, the initially high incidence of complications was caused not by the design of the implant but rather by the lack of experience in the treatment of reverse intertrochanteric fractures with intramedullary hip nails. Therefore, the prevalence of complications decreased significantly with the number of nails implanted.³⁷ Moreover, further progress in design gradually gave rise to the third generation of Gamma nail, which was associated with reduced prevalence and types of complications.³⁷

Gliding Nail, Proximal Femoral Nail, Proximal Femoral Nail Antirotation, Targon-PF

Subsequently, newer generations of reconstruction nail were introduced by various manufacturers. These nails differ in their proximal geometric features, diameter, and cross-sectional design. The developers of next-generation implants learned a lesson from the drawbacks of the Gamma nail design.

In 1997, the AO/OTA developed the proximal femoral nail (PFN), which has two proximal screws, the lower load-bearing neck screw and an additional antirotation hip screw. Among the main benefits of the PFN is the possibility for dynamic locking, a longer nail (PFN, 240 mm; Gamma nail, 200 mm), and a shaped distal part of the nail. This shape distributes the bending forces over a longer part of the femoral shaft and, together with the position of the locking holes, significantly reduces the risk of femoral shaft fracture in the region of the nail tip.^22,⁴³ In addition, the PFN eliminates the necessity for distal reaming and thereby reduces the duration of the surgical procedure. The data published so far confirm the PFN to be a reliable implant with results comparable to other nails results in unstable proximal femoral fractures.^18,^24,⁴⁴^–⁴⁷ However, various investigators have reported screw cutout of the femoral head-neck fragment.^18,^19,^24,⁴⁶

Wang et al ⁴⁸ conducted an experimental study comparing the efficacy of using a single femoral neck screw versus two femoral neck screws along with the intramedullary nail. These investigators concluded that two lag screw configurations should be avoided in patients who have a high risk of osteoporotic cutout. The recommendation of these investigators for intertrochanteric fractures in elderly patients with poor bone quality was to use the single screw nail design. In 2004, the AO/OTA developed the proximal femoral nail antirotation (PFNA), to improve rotational and angular stability with one single element. The PFN-A (Synthes, Solothurn, Switzerland) is based on a similar concept, whereby the load carrier for the femoral neck is a helical blade providing rigid rotational stability. This nail proved its value mainly in treating elderly patients with osteoporotic bone.

The special feature of the Gliding nail (Plus Orthopedics, Rotkreuz, Switzerland) lies in the geometric profile of the femoral head stabilizer, which is designed as a double-T blade.¹⁹

Targon-PF (Aesculap, Tuttlingen, Germany) is an implant with a femoral neck screw to carry the load and a smaller unthreaded bolt cranial to this screw to prevent rotation of the main proximal fragment.

Most reconstruction nails are now available in two versions: a short one, with a length between 200 and 240 mm; and a long one, with a length between 340 and 500 mm. The long nails are right-sided and left-sided, to compensate for femoral anterior bow and anteversion of the femoral neck in relation to the shaft axis.

Entry openings for proximal screws are in anteversion of 8 to 15 degrees in relation to the plane of insertion of distal screws. Nail femoral neck-shaft angles vary between 125 and 135 degrees.⁴⁹ One or two screws, or in some cases a helical blade (PFN-A) or double-T blade (Gliding nail), are introduced to the femoral neck and head to provide rigid rotational stability. The lag screws vary between 5 and 12 mm. Reconstruction nails are typically enlarged proximally to compensate for the higher stress in the subtrochanteric region. This feature must be taken into account during preoperative planning because additional reaming of the proximal fragment will be necessary.⁴⁹ Distal interlocking screws vary from 4.5 to 6.4 mm in diameter. Especially when using the short version of the nail, a surgeon has a choice between static and dynamic distal locking.

In another technique for trochanteric fracture nailing, the nails are introduced from the medial side of the femur, under the fracture level, and inserted into the femoral neck and head. This approach has largely been abandoned.

Letzius Nail

In 1950, Letzius ⁵⁰ described treatment of pertrochanteric and subtrochanteric fractures using a curved nail that was introduced into openings in the diaphyseal medial cortex and trepanned 10 to 12 cm under the level of the lesser trochanter (Fig. 13–7). The author reported a group of 22 patients treated with this method.

Figure 13-7 Letzius nail.

(Redrawn from Letzius A. Intramedullary nailing of intertrochanteric and subtrochanteric fractures with curved nail. J Int Coll Surg 1950;13:569-72.)

Küntscher Condylocephalic Nail

In 1966, Küntscher ⁵¹ described osteosynthesis of pertrochanteric fractures with a long, curved nail, 9 mm thick, that was inserted from medial femoral condyle with help of a guidewire. Küntscher noted that he elaborated the ideas of Letzius and Herzer.

Ender Nailing

Based on the principle of condylocephalic nailing and the ideas proposed by Hackethal, another method of intramedullary nailing was introduced into practice in 1969 by Ender and Simon-Weidner.⁵² This method was received with much enthusiasm, and in the 1970s and 1980s, many proximal femoral fractures (mostly pertrochanteric and subtrochanteric) were treated with Ender nailing. However, the analysis of outcome revealed unsatisfactory results, mainly in patients with unstable fractures, and the technique was gradually abandoned.

Classification

Several classification systems of subtrochanteric fractures have been suggested.

Boyd and Griffin

Boyd and Griffin ⁵³ originally called attention to subtrochanteric fractures as a variant of pertrochanteric fractures and noted a higher incidence of unsatisfactory results after operative treatment. These investigators divided all trochanteric fractures into four types (I to IV). In this system, type III represents subtrochanteric fractures, and type IV comprises subtrochanteric fractures with intertrochanteric extensions.

Fielding and Magliato

In 1966, Fielding and Magliato ¹³ developed a classification especially for subtrochanteric fractures. This system recognized three types of fractures, based on the location of the primary fracture line in relation to the lesser trochanter. Type I includes fractures at the level of the lesser trochanter, type II signifies fractures within 1 inch (2.5 cm) below the lesser trochanter, and type III fractures are within 1 to 2 inches (2.5 to 5 cm) of the lesser trochanter. However, this classification does not address the problem of comminution, which is critical in fracture stability assessment.

Zickel

In 1976, Zickel suggested a six-part classification system that included long spiral fractures and trochanteric extension.³¹ He used his classification system to emphasize the need for adjunctive fixation with his cephalomedullary nail for prevention of rotational and length deformity.

Seinsheimer

In 1978, Seinsheimer ⁵⁴ proposed a complex but concise classification, based on the number of major fragments and the location and shape of fracture lines (Fig. 13–8). This classification involves eight subgroups:

• Type I: Nondisplaced fractures

• Type II: Two-part fractures with three subgroups (type IIA, a transverse fracture; type IIB, a spiral fracture with the lesser trochanter attached to the proximal fragment; and type IIC, a spiral fracture with the lesser trochanter attached to the distal fragment)

• Type III: Three-part fractures with two subgroups (type IIIA, spiral fractures in which the lesser trochanter is part of the third fragment, with an inferior spike cortex of varying length; and type IIIB, spiral fractures of the proximal one third of the femur, with the third part a butterfly fragment)

• Type IV: Comminuted fractures with four or more fragments

• Type V: Subtrochanteric-intertrochanteric fractures (this group includes any trochanteric fracture with extension through the greater trochanter)

Figure 13-8 Seinsheimer classification of subtrochanteric fractures (see text for description).

(Redrawn from Seinsheimer F. Subtrochanteric fractures of the femur. J Bone Joint Surg Am 1978;60:300-6.)

The significance of the Seinsheimer classification is in identification of fractures with loss of medial cortical stability, which can be expected to have a higher rate of implant failure. Seinsheimer noted that all implant failures and nonunions occurred in type IIIA and type IV fractures. Unfortunately, interobserver reproducibility is poor with this classification because the course of fracture lines described by Seinsheimer does not correspond to clinical findings.

Waddell

In 1979, Waddell ⁵⁵ recommended another classification with three major subgroups: transverse or short oblique fractures, long oblique fractures, and comminuted fractures with extension into the trochanteric mass (Fig. 13–9).