Subtrochanteric Fractures of the Femur




Subtrochanteric femoral fractures are challenging to manage and differ significantly from both femoral shaft fractures and more proximal femoral injuries in their mechanism, treatment, and complications. The combination of strong muscle forces, high axial and bending loads with normal activities, and complex fracture patterns make treatment difficult.


The subtrochanteric zone of the femur is usually defined as the area extending from the lesser trochanter to a point 5 cm distally. Fractures whose primary component is thought to occur within this region are usually reported as subtrochanteric fractures, even if fracture lines extend proximal to the lesser trochanter or distally into the diaphysis. The exact definition of the subtrochanteric femur fracture is further confused by the tendency for surgeons to consider elderly patients’ fractures as a subclass of hip fracture while including young patients’ subtrochanteric fractures as a variation of a dia­physeal femur fracture.


Pathology


Anatomy


The adult femoral shaft has an asymmetrical anterior bow with an average radius of curvature between 109 and 120 cm. The average proximal neck-shaft angle is 129 degrees in men and 133 degrees in women, although significant variability exists. The femoral neck and head are anteverted approximately 13 degrees and offset anteriorly relative to the central axis of the femoral shaft. The linea aspera represents the posterior cortical thickening of the femoral diaphysis, which acts as a muscular attachment site and buttresses the concavity of the femoral shaft. The linea aspera divides proximally to the lesser and greater trochanters. The calcar femorale is the osseous thickening deep to the lesser trochanter and posterior to the neural axis of the femoral neck. The lesser trochanter is the attachment for the iliacus and psoas major; therefore, its integrity is important for predicting deformity and stability. The lesser trochanteric profile viewed on anterior-posterior (AP) imaging is a sensitive indicator of proximal segment rotation. The greater trochanter is the primary attachment for the gluteus medius, gluteus minimus (anteriorly), piriformis, and short external rotators of the hip.


The subtrochanteric region of the femoral shaft is almost completely encased in a muscular envelope ( Figs. 57-1 and 57-2 ). Knowledge of the muscular attachments and their nerve supply allows for an atraumatic surgical dissection along the length of the femur. The proximal femoral shaft is most easily exposed through a lateral exposure with careful dissection of the vastus lateralis from the lateral intermuscular septum and ligation (or protection) of any perforating vessels. Depending on the anatomic requirements, the proximal dissection can be extended by splitting the gluteus maximus or by using the intervals between the gluteus medius and the tensor fasciae latae or between the tensor fasciae latae and the sartorius.




Figure 57-1


Anterior anatomy of the hip and thigh.

(Copyright Elsevier, Inc. From The Netter Collection of Medical Illustrations, www.netterimages.com .)



Figure 57-2


Lateral anatomy of the hip and thigh.

(Copyright Elsevier, Inc. From The Netter Collection of Medical Illustrations, www.netterimages.com .)


These same muscular attachments that surround the proximal femur are primarily responsible for the commonly observed deformity patterns following fracture in the subtrochanteric region ( Fig. 57-3 ). Because of these strong deforming forces, reduction is difficult, especially in young patients. Femoral shortening is due to the resting or spastic tone of the major muscle groups spanning the proximal femur, including the quadriceps and hamstrings. The integrity of the trochanters influences the deformities observed. For fractures below the lesser trochanter, the proximal segment is typically flexed, abducted, and externally rotated by the hip abductors, external rotators, and iliopsoas muscles. The adductors typically medialize the distal shaft component. For subtrochanteric fractures with an associated fracture of the lesser trochanter, the deformity pattern of the proximal segment may actually be less severe because the flexion and external rotation of the psoas will be neutralized. Given these multiple and large muscular forces, reduction with pure axial traction is frequently unsuccessful. Similarly, the usual maneuver of trying to align the distal segment to the misaligned proximal segment is impractical. As a result, a combination of positioning, bumps, externally applied forces, and simultaneous control of both the proximal and distal fracture segments is necessary to reduce subtrochanteric fractures.




Figure 57-3


Superficial and deep anatomy of the posterior hip and thigh.

(Copyright Elsevier, Inc. From The Netter Collection of Medical Illustrations, www.netterimages.com .)


The relevant blood supply to the femoral shaft is from the primary nutrient vessel(s) combined with contributions from the multiple periosteal vessels. The nutrient artery enters in the region of the linea aspera in the proximal half or third of the femur. Therefore, the linea aspera should not be exposed or stripped of its muscular attachments to preserve the remaining femoral shaft blood supply. The femoral head blood supply has been well described by Gautier and colleagues. The location of the medial femoral circumflex vessel is most relevant for surgical exposures to the hip but becomes significant when considering its proximity to nail insertion locations. Interestingly, although branches from the medial femoral circumflex vessel are in close proximity to the piriformis fossa entry portal and injury can occur with nail entry preparation, avascular necrosis of the femoral head after antegrade piriformis entry nailing in adults is an almost nonexistent complication. However, an appreciation for the location of the predominant femoral head blood supply is important for limiting the potential and devastating complication. Damage to the femoral head blood supply and avascular necrosis is a known complication of antegrade piriformis entry nailing in skeletally immature patients.


Biomechanics


The femur is subjected to high compressive, tensile, and torsional forces with normal activities. Paul measured hip joint forces in adults which ranged from about four times body weight for slow walking to nearly seven times in rapid walking with the highest forces just after heel strike. The subtrochanteric region is subjected to high mechanical stresses as a result of a combination of body weight and the multiple muscles that exert a deforming force on the proximal femur. Because the angle of the applied force was nearly perpendicular to the axis of the femoral neck, there is considerable bending induced in the subtrochanteric region of the femur.


Koch is credited with first performing a detailed mechanical analysis of the stresses on the femur during weight bearing. He modeled a femur as a curved beam with a 100-lb force applied at the femoral head. The highest stresses in compression occurred just at the base of the medial subtrochanteric region (≈1253 lb/in 2 , 8.6 × 10 6 N/m 2 ), and in tension, just below the greater trochanter (≈921 lb/in 2 , 6.3 × 10 6 N/m 2 ). In 1969, Toridis reported a detailed analysis of the mechanical stresses in the femur under loading conditions. He presented an interesting model of the femur as a three-dimensional model, emphasizing that the ability of the femur to adjust itself in response to its mechanical environment differentiates it from a beam or other geometric approximations that have fixed mechanical properties. The primary forces acting on the femur are produced by the weight of the body and the force of the surrounding and spanning muscles. A series of complex calculations was used to demonstrate the maximum and minimum stress locations of the femur. In support of Koch’s original work, he demonstrated the relationship between the trabecular pattern of the femur and the pattern of the normal stress trajectories. However, Koch’s original mathematical beam model required further expansion to understand the further contributions of muscle forces with activities. Rybicki and colleagues produced a more detailed model of the one-legged stance during walking using the finite element analysis method and including the load of the hip abductor muscles and the tensor fasciae latae. They compared their results with those of Koch and Toridis. Although the highest stresses remained in the same regions as those predicted by Koch with compressive stress highest at the base of the femoral neck and subtrochanteric region, the tensor fasciae latae significantly reduces the overall load on the shaft of the femur that is induced by joint loading and the abductor muscles. Both the joint load and abductor muscles apply bending moments that effectively cause the femur to want to bow laterally while the tensor fasciae latae counteracts these moments. However, the subtrochanteric region stresses remain nearly the same for all the conditions (joint load alone; joint and abductor load; and joint, abductor, and fascia load).


The fracture pattern is determined by the magnitude of the applied load, the rate of load application, and the local strength of the femur. In the subtrochanteric region, osseous failure caused by pure torsion or a combination of torsion and bending produces the commonly observed patterns. Given the eccentric location of the mechanical axis medial to the anatomic axis of the femur in the subtrochanteric region, axial loading injuries are expected to produce compressive fracture patterns medially and tensile patterns laterally. The presence of medial comminution and segmental wedge fractures confirms this.


Fixation of subtrochanteric fractures requires an understanding of the biomechanical impact of the commonly used implants and their relationship to stable and unstable fracture patterns. Intramedullary implants are mechanically well suited for femoral fractures given their central location. Early nail designs were slotted and did not have interlocking options. As a result, these implants resisted bending forces but poorly counteracted torsional and axial loads. Current nail designs have multiple interlocking options that have improved resistance to deformation in response to axial and torsional loads. The impact of the different moduli of elasticity of stainless steel and titanium implants on healing in subtrochanteric femoral fractures is unknown.


Axial stability after intramedullary nailing of a subtrochanteric femur fracture is primarily determined by the strength of the proximal and distal interlocking screws, osseous contact at the fracture site, and the interface between the interlocking fixation points and bone. Torsional rigidity is similarly related to the proximal and distal fixation but also is dependent on certain nail design characteristics. Specifically, smaller diameter implants, the presence of a slot or an open section, and a thin-wall design significantly decrease torsional rigidity. Bending stiffness is primarily determined by the outer diameter of the nail and the type of metal (stainless steel vs. titanium). Titanium has a modulus of elasticity that is approximately half that of 316-L stainless steel and an ultimate strength that is approximately 1.6 times that of steel. Therefore, final construct stiffness is related to a number of factors, including implant material, nail design, interlocking fixation, and fracture reduction.


The age-independent average radius of curvature of an adult femur has been estimated to range between 109 and 120 cm. In virtually all nails manufactured, there is a mismatch between the radius of curvature of the nail and femur. Most femoral nails are significantly straighter than the average femur and have an average radius of curvature ranging from 150 to 300 cm. This can affect final sagittal plane alignment, entry portal location, and entry bursting strains. A more posterior starting point in the posterior third of the greater trochanter is associated with anterior cortical impingement or perforation of the nail at the distal tip of the nail in the distal femur. Nail perforation and impingement of the nail on the endosteum of the distal femoral cortex have been decreased substantially with newer nail designs using a smaller radius of curvature. During antegrade piriformis entry femoral nailing, Tencer and colleagues and Johnson and colleagues demonstrated that anterior misplacement of the nail entry site, increased nail flexural rigidity, and mismatch in radius of curvature all affect the potential for femoral bursting during nail insertion. Similarly, the starting point for trochanteric nails also appears to have a potential effect on proximal femoral strain. The entry point location for trochanteric nails was reviewed in 21 cadavers in an attempt to identify the optimal universal starting point. The authors used three different starting points relative to the greater trochanteric tip and five different nails with varying proximal lateral bends (4–10 degrees) and radii of curvature (150–350 cm). A starting point lateral to the tip of the greater trochanter was associated with lateral cortical gapping and varus in the subtrochanteric region. The authors concluded that the starting point should be at the tip or slightly medial to the tip to prevent these common deformities.


Proximal femoral plates, applied laterally, are eccentric relative to the mechanical axis of the femur compared with nails and are therefore associated with decreased bending stiffness after fixation. Implant design characteristics have a significant influence on the mechanical stability after fixation. Implants with a proximal fixed angle are thought to offer a mechanical and fixation advantage, although few biomechanical studies have failed to demonstrate this. The 95-degree angled blade plate has been shown to produce superior torsional stability compared with other plate constructs, including locking plates. Newer locking plates and various locking screw configurations have been compared with conventional locking plates and the 95-degree angled blade plate in a subtrochanteric gap model. The authors found that the newer locking implants that use an additional angled locked screw into the femoral head resulted in the highest stiffness in axial bending and had the least irreversible deformation. Tencer and colleagues evaluated multiple implants in a cadaver subtrochanteric fracture model with and without osseous contact to determine final construct stiffness. Plates were found to be stiffer in torsion than antegrade interlocking nails but similar in bending stiffness. However, nails were found to be stronger in combined compression and bending to failure. Whereas nails were found to support between 300% and 400% of body weight, plates failed between 100% and 200% percent of body weight. More recently, the biomechanical stiffness of a trochanteric entry nail was compared with a 95-degree condylar blade plate in a synthetic femur model that simulated both stable and unstable patterns. Although there was no difference in combined axial, bending, and torsional construct stiffness between the plate and nail constructs, greater displacement magnitudes in shear were identified in models stabilized with a cephalomedullary nail. The biomechanical performance of a cephalomedullary nail, a proximal femoral locking plate, and a 95-degree angled blade plate was compared in a subtrochanteric fracture model. Using incrementally increasing cyclic load testing, the cephalomedullary nail was found to withstand more cycles and failed at higher loads compared with the plate constructs. Finally, Lundy and coauthors directly compared an angled blade plate, a dynamic condylar screw, and a sliding hip screw in a composite unstable subtrochanteric fracture model. The condylar screw was found to be stiffer and stronger than the angled blade plate. The sliding hip screw was found to be the stiffest and strongest implant, but this was postulated to be due to design flaws in the study that did allow cephalad hip screw perforation, the usual mode of failure. Newer plate designs that allow locking screw fixation proximally and distally may offer fixation advantages in patients with osteoporotic bone.


There is significant support in biomechanical studies for the use of second-generation cephalomedullary nails. A second-generation nail was found to offer enhanced mechanical stiffness and a larger load to failure in a synthetic subtrochanteric femur fracture model. In one cadaver study comparing a reconstruction nail with short and long trochanteric entry nails, final construct strength was highest with the reconstruction nail. In a larger study directly comparing three different second-generation nails, Wheeler and colleagues determined construct stiffness in a cadaver model with a subtrochanteric osteotomy. Whereas two of the implants with similar design characteristics demonstrated a final construct stiffness of 40% of the intact femur, the cephalomedullary nail with a spiral blade was more than 50% less stiff than the other two devices. The screw configuration into the femoral head in a cephalomedullary nail has been specifically evaluated. In one biomechanical study, a crossed screw configuration (with one screw placed into the femoral head and one placed with a caudal direction) was found to have a higher load to failure than two screws placed up the femoral neck. Finally, cephalomedullary nails from four manufacturers (three reconstruction nails, one trochanteric entry nail) were compared in four different proximal femur fracture patterns of varying complexity. For well-reduced fractures, the implants used were found to be similar. However, for unstable patterns, the trochanteric nail with its larger proximal diameter had decreased fracture site motion. The steel reconstruction nail also demonstrated decreased fracture site motion that was hypothesized to be due to material differences of the steel implant compared with the two titanium reconstruction nails.


One of the design characteristics of cephalomedullary nails that differentiates them from conventional antegrade interlocking nails is the presence of dynamic fixation into the femoral head. Initiation of sliding of the proximal screws in three different cephalomedullary nails and a sliding hip screw were reviewed and compared in a biomechanical study. The sliding hip screw demonstrated sliding superior (i.e., lower force necessary to initiate sliding) to that of any of the cephalomedullary nails. Force to initiate sliding in the cephalomedullary nails was positively related to the screw length. Finally, two small proximal screws required less force to initiate sliding than did a single large lag screw in the specific designs tested.


Synthesizing the available biomechanical studies is difficult. The entry point is critical for both reconstruction and trochanteric nails. Plates are optimal in torsion but weaker in combined bending and axial loading compared with nails. Cephalomedullary nail design characteristics influence a variety of biomechanical measures, including stiffness, strength, and fracture site motion after fixation. Stainless steel and large-diameter implants in the proximal segment may offer some enhanced characteristics.


Incidence and Mechanism of Injury


Subtrochanteric fractures occur across all age groups and are attributable to a number of mechanisms. There is an asymmetric age- and gender-related bimodal distribution of fractures with high-energy injuries occurring in young men and low-energy injuries occurring in elderly women. The majority of these fractures occur in elderly patients. Subtrochanteric injuries occur in approximately 25% of hip fractures and 7% to 34% of all femur fractures. The exact incidence is hard to determine given the inconsistency of defining these injuries in published studies. Bergman and colleagues elucidated the distribution of these injuries in a retrospective review of 131 patients with subtrochanteric femur fractures. They found that almost half of the patients were elderly and sustained injuries from low-energy falls, approximately 25% were young patients with high-energy mechanisms, and approximately 25% were pathologic fractures. The vast majority of the nonpathological fractures were unstable patterns with associated posteromedial comminution. The average age of patients with high-energy mechanisms was 40.6 years compared with 76.2 years in the patients with low-energy mechanisms. Young patients tended to sustain comminuted patterns from motor vehicle crashes, falls from height, penetrating trauma, and other high-energy mechanisms. Elderly patients sustained patterns of variable complexity that ranged from simple spiral fractures to comminuted subtrochanteric fractures with proximal extensions.


More recently, a form of “atypical” insufficiency fracture in the subtrochanteric region or femoral shaft has been described. This fracture has been associated with the use of alendronate caused by the prolonged suppression of bone remodeling with the mechanism. Alendronate, a bisphosphonate medication, inhibits bone resorption by osteoclast suppression, thereby decreasing bone turnover. Although this medication has been shown to decrease the incidence of insufficiency fractures in elderly patients with osteoporosis, the decreased bone turnover is associated with impaired repair of microscopic damage in the subtrochanteric region leading to fractures. These fractures have several characteristics that are commonly observed, including cortical thickening on the lateral side of the femur in the subtrochanteric region, a transverse or short oblique fracture pattern, and a medial cortical spike. The majority of patients have reported prodromal pain, and bilateral involvement is common. Understanding the exact incidence of these atypical fractures and proving this association with bisphosphonates has proven difficult. In a review of 3515 patients with a fracture of the proximal femur at two large academic referral hospitals in the United Kingdom, 7% of the 156 subtrochanteric femur fractures were “atypical” fractures; the vast majority of these patients were receiving bisphosphonates for a mean of 4.6 years. Dell and colleagues used an extensive database of 188,814 patients taking bisphosphonates to better understand the incidence of these injuries. The incidence of atypical fractures was 1.79 per 100,000 per year in patients with shorter term bisphosphonate treatment (0.1–1.9 years), but this incidence increased to 113.1 per 100,000 per year with exposure of 8 to 9.9 years. This certainly suggests that there is a time relationship between bisphosphonate use and the occurrence of these atypical fractures, especially in patients on treatment beyond 5 years. This existence of a relationship between bisphosphonate use and atypical femoral fractures was further confirmed in a review by Abrahamsen and Einhorn.


Associated injuries are more common in young patients with high-energy mechanisms. Ipsilateral noncontiguous femur fractures, femoral neck fractures, acetabular and pelvic injuries, and other ipsilateral fractures are seen. Associated abdominal, thoracic, and head trauma related to the mechanism of injury requires a careful evaluation by a specialized team of physicians. In Bergman and colleagues’ review of 31 subtrochanteric fractures caused by high-energy mechanisms, 16 had injuries to other long bones, the pelvis, or the spine, and five were open.


Fracture in the subtrochanteric region can also occur as a complication of screw fixation for femoral neck fracture ( Fig. 57-4 ). Placement of screws weakens the tension side cortex of the proximal femur. Because these stresses are highest at and below the level of the inferior edge of the lesser trochanter, it is recommended that the screw entry site be situated above this level. This mechanical observation is supported by a review of four patients with subtrochanteric fracture after femoral neck fracture fixation. The actual screw configuration may also influence the incidence of subtrochanteric fracture after cannulated screw fixation. In a biomechanical study of human cadaveric femora, Oakey and colleagues found that the ultimate load to failure was significantly reduced if an apex-proximal configuration of the three screws was used. This led to the conclusion that if a triangular screw configuration is planned for stabilization of a femoral neck fracture, an apex-distal configuration may minimize this risk.




Figure 57-4


A 58-year-old woman sustained a femoral neck fracture that was treated with open reduction and internal fixation using three cannulated screws with an apex superior orientation. The patient sustained a fall 4 weeks after surgery, resulting in a secondary fracture at the screw entry at the level of the lesser trochanter ( A ). This was treated with removal of one of the cannulated screws, open reduction of the fracture, and placement of a reconstruction nail with additional fixation into the femoral head ( B and C ).


Similarly, subtrochanteric fractures may occur after other prior proximal femoral surgeries that violate the lateral cortex of the femur. Core decompression for avascular necrosis and free fibular grafting have both been complicated by infrequent subtrochanteric fracture. Current recommendations to prevent this include keeping the lateral cortical defect above the level of the inferior edge of the lesser trochanter.




Diagnosis


History


A complete history is important and can be obtained from the patient, family members, and emergency medical personnel. The relevant portions of the history include the patient’s age, the mechanism of injury, the time from injury to presentation, the need for extrication, and any comorbid conditions. The time from injury to evaluation can give valuable information regarding ongoing blood loss in the thigh, dehydration, the overall condition of the patient, and the progression of associated myonecrosis in higher energy mechanisms. In young patients with high-energy mechanisms, a detailed search should ensue for other sites of discomfort that may be masked by the pain of the proximal femoral fracture. Young patients with fractures caused by low-energy mechanisms or falls should undergo evaluation for pathologic bone conditions. Similarly, elderly patients who sustain their injury secondary to a fall should be questioned regarding antecedent discomfort or known metastatic disease.


Physical Examination


In a conscious patient, the diagnosis of femoral injury is usually obvious. However, a comprehensive and methodical examination of all extremities and the pelvis should be performed to ensure that associated injuries are not missed. The patient usually has pain localized to the proximal thigh. Typically, the limb is shortened. Loss of rotational control is consistent with femoral discontinuity. A careful visual inspection of the entire circumference of the hip and thigh should be performed to look for open wounds and closed degloving injuries. Any skin disruption should be considered a potential open fracture and further evaluated. The knee should be examined for any associated ligamentous injury. The vascular examination of the extremity is determined with palpation of the distal pulses and confirmed with Doppler examination in high-energy injuries. An ankle-brachial index of less than 0.90 is sensitive and specific for arterial injury of the lower extremity. A careful neurologic examination in an awake and cooperative patient includes evaluation of the femoral and sciatic nerve distributions distally. Because of the proximity of the sciatic nerve to the femur in the subtrochanteric region, documentation of the motor and sensory function of the tibial and peroneal branches is recommended.


Radiographic Studies


The radiographic evaluation begins with full-length AP and lateral radiographs of the entire femur from the hip to the knee. Additionally, biplanar hip radiographs and an AP pelvis radiograph are necessary to fully evaluate the extent of injury. Traction radiographs are extremely helpful for delineating subtle fracture lines, for understanding the fracture pattern, and for preoperative planning. The radiographs should be evaluated to determine the fracture pattern, associated comminution, bone quality, and the presence of bone loss. Contralateral hip and femur radiographs may be helpful for preoperative planning and can help determine the femoral length, canal diameter, femoral bow, and femoral neck anteversion. Radiographs should be scrutinized for the presence of osteopenia, metastases, and cortical irregularities in the femur or at the site of fracture.


Computed tomography (CT) can be valuable in complex fracture patterns, fractures with proximal extension, and fractures with significant rotation of the proximal segment such that visualization is poor. Often, a CT of the abdomen or pelvis is obtained for other reasons and is available for review. Additionally, the CT can be extended distally to include the proximal femur. Valuable information revealed by CT scanning includes proximal extension into the piriformis fossa, the presence of an associated femoral neck or intertrochanteric fracture, and the presence of nondisplaced fracture lines that may influence the surgical approach or implant selection. Additional radiographic studies for evaluation of the osseous injury are unnecessary. However, additional radionucleotide studies or magnetic resonance imaging (MRI) may be indicated if a pathologic fracture is suspected.


Classification


Subtrochanteric femoral fractures have been classified by the anatomic location, fracture morphology, number of fragments, degree of comminution, and combinations thereof. Early classification systems did little to influence treatment but did identify fracture patterns of particular difficulty. In 1949, Boyd and Griffin included the subtrochanteric fracture pattern in their classification of pertrochanteric injuries and noted a higher incidence of unsatisfactory results after treatment of this subgroup. In 1966, Fielding and Magliato introduced a classification system based on the location of the major fracture line relative to the lesser trochanter and proposed three types. In 1976, Zickel reported his results with treatment of proximal femoral fractures using a cephalomedullary implant. He introduced a six-part classification system that included medial and lateral comminution, long spiral patterns, and trochanteric extension. Shortly thereafter, Seinsheimer grouped fractures based on the commonly observed fragmentations and fracture configurations. The fractures were grouped based on the number of segments and included identification of the lesser and greater trochanter as separate fragments. The Arbeitsgemeinschaft für Osteosynthesefragen (AO) introduced its comprehensive classification, which included description of the fracture morphology and the degree of comminution but did not include a means of describing fractures with extension into the trochanteric region.


The Russell-Taylor classification was introduced primarily as a guide to treatment based on their experience with managing these injuries ( Fig. 57-5 ). The important con­siderations in this system are the integrity of the lesser trochanter and proximal extension into the region of the greater trochanter and the piriformis fossa. The integrity of the lesser trochanter is perceived to be a reasonable surrogate for posteromedial support of the subtrochanteric region. Given the common late deformities of varus and extension, combined with the known biomechanical data on forces in the subtrochanteric region, the presence or absence of involvement of the posteromedial proximal femur is important when considering implant and fixation stability. Additionally, fracture extension into the region of the starting point for traditional medullary implants (first-generation and cephalomedullary nails) complicates treatment, changes the surgical strategy, and may impact the implant selection.




Figure 57-5


Russell-Taylor classification of subtrochanteric fractures. Fracture lines within red zones determine the type. In type I fractures, the piriformis fossa remains intact. Involvement of the piriformis fossa intramedullary nail entry site is the hallmark of type II fractures. Subtype A fractures do not involve the lesser trochanter, but in subtype B, the lesser trochanter is a separate fragment. A, Type IA subtrochanteric fracture, suitable for first-generation locking nail. B, Type IB subtrochanteric fracture, which requires a cephalomedullary nail. C, Type IIA subtrochanteric fracture. The piriformis entry site is involved, but the lesser trochanter is intact. D, Type IIB subtrochanteric fracture. The nail entry site is involved, and lesser trochanteric comminution increases instability. See text.

(Modified from Tencer AF, et al. Orthop Biomech Lab Report 002, Memphis, TN, 1985, Richards Medical Co.)


The Russell-Taylor classification system involves two major groups each with two subgroups. Group I fractures do not have extension into the piriformis fossa and the posterior greater trochanter and can be treated with antegrade piriformis entry interlocking nails. The subgroup may influence the recommended proximal interlocking options. Group IA fractures are characterized by an intact lesser trochanter. Group IB fractures are characterized by involvement of the lesser trochanter and the posteromedial buttress. This fracture extension into the posteromedial femur and the lesser trochanter complicates interlocking options with most conventional antegrade nails. Typically, an intact medial cortex is necessary for engagement of the proximal interlocking bolts. Cephalomedullary implants with proximal locking into the femoral head are indicated in these patterns. Reverse obliquity intertrochanteric fractures, because of their behavior when treated with sliding hip screws, are sometimes classified as group IB fractures.


The group II fractures have proximal extension into the greater trochanter and piriformis fossa, which makes closed techniques of piriformis entry intramedullary nailing unpredictable. As a result, trochanteric nails, fixed angled plated devices, or a careful open reduction with a piriformis start cephalomedullary nail is recommended in most of these injury patterns. Trochanteric nails, although avoiding the piriformis fossa as an entry portal, do not reduce the proximal fracture extensions and guarantee an accurate restoration of the relationship between the femoral head and shaft. An open reduction may still be required. Additionally, piriformis entry cephalomedullary nails are still possible in these injury patterns if the fracture is first accurately reduced by whatever means necessary.




Management


The decision for operative management requires a thorough understanding of the associated injuries, the condition of the patient, the fracture pattern, and the relevant biomechanics of the subtrochanteric region of the femur. Although nonoperative treatment has had a role in these fractures in the past, operative stabilization of these injuries takes the same priorities as fractures of the femoral shaft and proximal femur; that is, operative treatment is advocated to allow for patient mobilization, restoration of anatomy, and maximization of function.


Evolution of Treatment and Implants


The complexity of these injuries and the difficulty with treatment are reflected in the large number of implants and techniques that have been attempted in the past and are now of historical interest only. Broadly categorized, most implants are variations of intramedullary nails or lateral side plates, and reduction techniques have evolved over time for each. Currently used reduction techniques involve the use of indirect reduction techniques, preservation of the local biology, avoidance of primary bone grafting, and the use of relative stability for most fracture patterns. An improved understanding of the fracture patterns, observed secondary deformities, and modes of failure have similarly influenced implant design and techniques.


The use of a cephalomedullary implant for the operative treatment of subtrochanteric fractures dates back to Kuntscher. In addition to the conventional slotted antegrade nails for femoral shaft fractures, he used a medullary implant that allowed fixation into the femoral head, extending the indications for treatment of proximal femoral fractures. Design improvements to the concept of combined medullary and femoral head fixation ultimately led to the Zickel nail. Zickel reported his 9-year experience with the use of his medullary implant in 1976. This nail was designed to avoid previously encountered plate problems, especially screw loosening, implant breakage, and inadequate proximal fixation. This implant consisted of a trochanteric entry nail combined with a triflanged fixation blade, which passed through the nail and into the femoral head. In his series of 84 patients with subtrochanteric fractures, the authors reported successful healing and low complication rates. This device minimized subsequent varus, shaft displacement, and nonunion. The Zickel nail had the advantages of a large proximal medullary implant, controlled impaction of the proximal segment, and some rotational control of the femoral neck. Multiple subsequent studies supported its use for subtrochanteric fractures and demonstrated improved results compared with previously designed nail-plate devices. In a large review of 131 patients with subtrochanteric fractures, Bergman and colleagues reported a low rate of nonunion (5%). Although the majority of patients were treated with adjunctive cerclage wiring, supplemental bone grafting was rarely used. They found less favorable results in young patients with high-energy fractures. These results represented a significant improvement over previous implants. However, subsequent reports of high failure rates limited its use.


The introduction of the Gamma Nail by Kempf and Grosse represented a significant advance in the treatment of proximal femoral fractures with a cephalomedullary implant. Their nail was reportedly inspired by a combination of the interlocking nail and the Y-nail designed by Kuntscher. This was a large, trochanteric entry, medullary implant with a large proximal screw placed through the nail and into the femoral head. The authors reported acceptable reduction and surgical morbidity in their series of 121 cases of trochanteric fractures in elderly patients. Early reports of fracture at the tip of the short implant and difficulties with implant removal led to a number of design modifications that have improved the results and complications with this implant.


The reconstruction nail was introduced by Russell and Taylor and successfully used for proximal femoral fractures. Subsequent reports demonstrated successful treatment of many subtrochanteric fracture patterns. This implant addressed many of the issues that had limited successful surgical treatment for these injuries. Specifically, fixation into the head with two screws avoided the possibility of the head-neck segment rotating around a single screw and offered better control of more proximal fractures. Additionally, as they pointed out, screw fixation into the femoral head allows for fixation of fractures with lesser trochanteric involvement. Subsequent design modifications have included different fixation strategies into the femoral head and trochanteric entry portals.


Plate fixation of subtrochanteric fractures similarly evolved over time to implants with progressively higher success rates. The Jewett nail was introduced in 1941 as an improvement over previous fixation tactics. The authors introduced the combination of a Smith-Petersen nail combined with a flanged Hawley-type bone plate as a method for controlling rotation of the proximal fragment and stabilization of the distal segment. Although the implant is referred to as a nail, it is actually a side plate attached to a tri-fin nail (subsequently cannulated), which is driven into the femoral head. They reported good results in five patients with subtrochanteric and intertrochanteric fractures. Nail-plate devices became the standard treatment for a number of years and were modified with some success. However, varus deformities, implant failure, and nonunion continued to occur as complications.


The AO 95-degree condylar blade plate, developed for the distal femur, was soon identified as a potential solution for proximal femoral fractures and was used with increasing success. Initial recommendations for anatomic reconstruction and primary bone grafting led to problems with implant failure and nonunion. However, with indirect reduction and preservation of vascular soft tissue attachments, reliable fracture union was obtained along with maintenance of the anatomic axis of the femur. Because of difficulties with reduction encountered by surgeons using the angled blade plate, other plate designs have been used for complex subtrochanteric patterns. These include the dynamic hip screw and the dynamic condylar screw. Several patient series have reported good results with these implants in specific fracture patterns.


Current implants include multiple variations of the early designs. Plate possibilities include the sliding hip screw, the 95-degree condylar screw, the 95-degree angled blade plate, and locking implants for the proximal femur. Specifically designed locking implants for the proximal femur allow for submuscular applications and indirect reduction of fractures in the subtrochanteric region. These proximal femoral locking implants facilitate ease of plate placement and consistent screw positions. Nail designs include conventional interlocked nails with variable proximal interlocking screw configurations, piriformis entry cephalomedullary nails, and trochanteric entry cephalomedullary nails. Design modifications of these medullary implants and the associated instrumentation have simplified their use, expanded the indications, and solved many of the implant-related complications. The results of treatment with most of these implants are more related to surgical technique than to the implants themselves. That is, both plates and nails can be used with success for subtrochanteric fractures. However, in a systematic review of one level I and nine level IV studies of intramedullary and extramedullary fixation of subtrochanteric femur fractures, intramedullary implants were found to have decreased operative time and a reduction in fixation failure.


Current Algorithm


Treatment of subtrochanteric fractures depends on a number of factors, including the condition of the patient, the fracture pattern, any associated injuries, the available implants, and the available technologies. A comprehensive and systematic evaluation is essential for all patients with subtrochanteric fractures because multiple injuries are common. In general, nonoperative treatment is limited to the unusual circumstance in which the medical condition of the patient limits the possibility of surgical care. Open fractures require antibiotics, débridement, irrigation, and usually internal fixation as soon as the patient’s condition permits. Multiply injured patients and open subtrochanteric fractures are discussed later in this chapter.


Optimal fixation depends on an accurate assessment of the fracture pattern based on plane radiographs, CT, and traction radiographs in selected circumstances.


For injury patterns completely distal to the lesser trochanter, an antegrade, reamed, statically locked intramedullary nail is preferred. A closed nailing is performed if possible, but percutaneous reduction tools or a limited open reduction before nailing are preferred to attempting to nail a malreduced fracture. An angled blade plate, dynamic condylar screw, and locking implant are other possibilities that are effective if biologic techniques of implantation are used.


For injury patterns that have separation of the lesser trochanter, a cephalomedullary nail or angled blade plate is preferred. The angled blade plate requires precise placement into the proximal segment with subsequent indirect reduction to the femoral shaft. The temptation to reduce the posteromedial comminuted segments should be avoided. Similarly, for intramedullary nailing, indirect reduction techniques of any intercalary comminution are critical. However, an open reduction of the proximal and distal segments may be required to allow for an accurate nail placement. Fixation into the femoral head is important to maximize rotational control of the proximal segment and to prevent subsequent angulation. The entry portal and the type of fixation into the femoral head are probably less important than the reduction.


For injury patterns that have fracture extension into the piriformis fossa, the use of a cephalomedullary nail with a piriformis entry portal is difficult. However, this implant can still be used assuming a reduction of any proximal fracture extensions before entry portal preparation and canal reaming. A trochanteric entry nail avoids the potential secondary displacement of the proximal fracture extension into the piriformis fossa; however, the implant does not reduce these fracture extensions if they are displaced. For nondisplaced proximal extensions, a trochanteric nail may be advantageous. If the proximal extensions are displaced, an open reduction may be required before nail placement. Alternatively, a lateral plate implant can be used. After open reduction of the proximal fracture extensions, an angled blade plate, dynamic condylar screw, or locking proximal implant can be placed. A sliding hip screw can be used in certain patterns but is less predictable for maintaining length and reduction.




Description of Individual Procedures


Traction and Nonoperative Treatment


Nonoperative treatment is reserved primarily for patients with medical comorbidities that preclude operative treatment, some patients who are nonambulatory, or elderly patients in whom adequate fixation is thought to be impossible. However, these situations are rarely encountered. Even in patients who are nonambulatory (caused by either dementia or paralysis), operative stabilization is associated with improved pain control, nursing care, and mobilization. In elderly patients with severe osteopenia, medullary implants allow for reasonably secure fixation despite anticipated poor screw purchase. Furthermore, locking implants specifically designed for the proximal femur may allow for improved fixation in patients with severe osteopenia.


Skeletal traction is the most commonly used method of nonoperative treatment. The predicted and observed deformity pattern of the proximal femur caused by the associated muscular attachments determines the method(s) of closed reduction and fracture reduction maintenance. The technique of traction for reduction has been described in detail by DeLee and coauthors. Traction is obtained with the use of a supracondylar pin placed at the distal femur. Direct application of force through the distal femur is preferable to pins placed at the proximal tibia in an effort to avoid pulling across the knee joint and the associated complications of knee stiffness and pain. Either a small-diameter (2 mm) Kirschner wire (K-wire) with a tensioned bow or a larger, centrally threaded pin with a standard bow can be used. The hip and knee are then flexed to 90 degrees to allow for correction of the primary flexion deformity observed (i.e., to allow the distal segment to “catch up” to the flexed proximal segment). Length, rotation, and abduction are adjusted primarily with the applied traction, often resulting in an imperfect overall reduction. The leg is suspended parallel to the floor and supported with a short leg cast or appropriate splinting to maintain the ankle at neutral. Traction of 30 to 40 lb is typically adequate to allow for restoration of length and alignment. AP and lateral radiographs, with both films parallel to the femur, are obtained to confirm a satisfactory reduction initially and to allow appropriate adjustment as the deforming muscles relax with time. Acceptable alignments include less than 5 degrees of varus or valgus angulation, shortening or lengthening of less than 1 cm, and 25% fracture apposition on both radiographic views. Weekly radiographic evaluations are obtained to allow for weight and alignment adjustments. The duration of traction is determined by the overall treatment strategy. After approximately 4 weeks of traction at 90 degrees, the amount of flexion may be decreased weekly assuming fracture callus formation and improved patient comfort. Decreasing flexion may be associated with varus, necessitating some leg abduction. For definitive treatment by traction, 12 to 16 weeks may be required. However, if fracture consolidation has progressed to the point that shortening and angulation due to the muscular forces is unlikely, a cast brace with a proximal mold and pelvic band can be applied to allow for some mobilization of the patient. Weight bearing is limited until adequate fracture consolidation is observed. As an alternative, a hip spica cast can be applied to allow for removal of the traction pin. However, this method of treatment is poorly tolerated in adult patients.


Temporary Stabilization Before Definitive Fixation


The initial stabilization is influenced by the age of the patient, the energy of the injury, and the amount of limb shortening. Temporary stabilization or some form of traction assists with aligning the limb, provides patient comfort, and limits additional soft tissue injury from the fracture segments. Options for temporary fixation before definitive fixation include hip joint spanning external fixation, fracture spanning external fixation applied to the femur, distal femoral skeletal traction, and skin traction. Timing of definitive surgical care can be unpredictable; therefore, a temporizing treatment plan should reflect anticipated delay to definitive treatment. Skin traction is ineffective for length reestablishment in young patients and may be only marginally effective in elderly patients with low-energy fractures after a fall from standing. If skeletal traction is used, application at the distal femur is preferable to the proximal tibia. A small-diameter K-wire (2 mm) with a tensioned bow averts the need for a larger, centrally threaded transfixion pin. Temporary hip joint or fracture spanning external fixation is rarely required but may be necessary in multiply injured patients.


Plate Fixation, Including Minimally Invasive Plating of Subtrochanteric Fractures


Background


The use of plates for subtrochanteric fractures has decreased with improvement in nail designs and nailing techniques for these injuries. This is especially true in fractures that are entirely below the lesser trochanter (type IA patterns). However, plate fixation is effective and may be particularly useful if fluoroscopic imaging is unavailable or suboptimal. For fractures with extension into the trochanteric region, especially into the region of the greater trochanter, the piriformis fossa, or along the intertrochanteric line, plates have a definite role and may be the optimal implant in some circumstances. Plating offers several advantages compared with medullary implants, including the ability to obtain an anatomic reduction in appropriate fracture patterns and the lack of additional surgical trauma to the proximal femur and trochanteric region. Proximal segment control is optimized with plating, allowing for an accurate restoration of the neck-shaft angle in all planes. The main disadvantages to plating are the larger surgical exposure, the increased blood loss in open techniques, and the potential for further insult to the vascular supply of the intervening bone segments. Furthermore, because the plate is largely a load-bearing implant, weight bearing is typically delayed until there is some evidence of healing. Minimally invasive plating techniques may help to minimize the additional vascular insult to the periosteal and endosteal blood supplies of the femur.


A number of different implants and techniques are applicable when considering plating a subtrochanteric fracture. The fracture pattern, the comfort of the surgeon, and the available technologies all contribute to the planned implant and technique. Commonly used plating implants include a standard large fragment plate, a sliding hip screw (with or without an additional trochanteric stabilizing plate), a dynamic condylar screw, a 95-degree angled blade plate, and newer proximal femoral locking plates. For subtrochanteric fracture patterns with an associated intertrochanteric fracture, a sliding hip screw and the dynamic condylar screw allow for compression across the more proximal fracture combined with stabilization of the subtrochanteric component of the fracture. Conventional large fragment plates are most applicable for distal subtrochanteric fractures that allow bicortical screw purchase in the diaphyseal portion of the distal aspect of the proximal fragment. A 95-degree angled blade plate is most useful in open plate applications in fracture patterns that do not require controlled compression along the femoral neck. Newer proximal femoral locking plates may be useful for both routine and complex patterns. These implants help to facilitate implant placement in a submuscular fashion and may help to minimize the necessary surgical dissection for lateral implant placement.


The primary plating techniques include open reduction and lateral plating and submuscular plating techniques using a smaller proximal surgical approach. The critical aspect of any plating technique is preservation of the osseous vascularity in the region of the fracture and of any intercalary, comminuted fragments. Traditional open techniques can be successfully performed if the temptation to dissect anteriorly, medially, and posteriorly is avoided. Submuscular plating techniques are probably most useful in forcing the surgeon to avoid unnecessary and potentially harmful soft tissue dissection in the region of the fracture.


Indications


Virtually all subtrochanteric fractures can be successfully plated. However, immediate weight bearing may not be possible in most fracture patterns treated with plating for fractures in the subtrochanteric region. Relative indications include patients with an extremely narrow medullary canal in whom nailing is impossible or difficult, fractures adjacent to a previous malunion, and fracture patterns with proximal extension into the trochanteric or neck region. Plates are desirable in complex proximal fragment fractures that may require open reduction regardless of the ultimate implant. In fracture patterns with extension into the planned starting location for a medullary implant, open reduction and plate fixation should be considered. In fractures with significant angular and rotational deformities of the proximal segment, nailing can be difficult, and plating may offer the solution of proximal segment control at the time of open reduction. Finally, for subtrochanteric fracture patterns with associated and displaced intertrochanteric or femoral neck fractures, plating may optimize the reduction and fixation of the more complex portion of the fracture(s).


Technique


The patient can be positioned supine or laterally on a radiolucent table to allow unimpeded fluoroscopic imaging of the entire femur from the hip to the knee. A fracture table can be used to facilitate intraoperative traction, but this may accentuate the primary observed deformities of the proximal segment and impede lower extremity manipulation at the time of fracture reduction. Lateral positioning facilitates the retraction of the vastus lateralis, allows hip flexion, and improves access to the proximal segment. However, intraoperative imaging may be more difficult, rotation is more difficult to judge, and lateral positioning may not be practical in a polytraumatized patient.


A small bump placed beneath the ipsilateral hip helps to internally rotate the proximal segment to neutral, simplifying the surgical approach and making the intraoperative assessment of rotation easier. A radiolucent ramp or folded blankets placed beneath the leg and distal thigh assists with intraoperative lateral imaging as well as reduction of the subtrochanteric portion of the fracture. The entire limb should be prepped in the surgical field. Several additional folded sterile towels placed beneath the distal segment can further assist with fracture reduction in the sagittal plane. Any additional deformities of the proximal segment can be addressed directly after exposure of the proximal segment.


The fracture pattern and the experience of the surgeon will determine the plating technique used. Open and submuscular reduction techniques are both applicable for the subtrochanteric portion of the fracture. The reduction of any proximal fracture extensions into the region of the greater trochanter should be addressed using the same principles described in Chapter 55 . For simple fracture patterns (e.g., transverse or short oblique) that allow an accurate cortical reduction of the majority of the subtrochanteric region, an open technique with compression plating using AO principles is advisable. In fracture patterns with significant comminution, bridge plating techniques with any of the previously listed implants are applicable. This can be accomplished with an open technique that leaves all the intercalary segments undisturbed or with submuscular implant placement. Regardless of the technique chosen, the soft tissue attachments and vascular supply of the femoral shaft, fracture segments, and lesser trochanter should be preserved.


An open plating technique can be used with any of the described plates that can be placed through an extensile lateral approach. The incision length should be adequate to allow placement of a long plate directly on the lateral aspect of the femur. The iliotibial band is sharply incised, and the vastus lateralis is atraumatically elevated from the lateral intermuscular septum from distal to proximal. Perforating vessels should be identified and ligated or preserved, depending on the preference and skill of the surgeon. The vastus lateralis can then be atraumatically elevated from the underlying periosteum, allowing access to the lateral femur. Additional dissection anteriorly and medially is unnecessary. Levering retractors placed medially are avoided.


Reduction techniques for proximal fracture extensions into the femoral neck and intertrochanteric regions are covered in detail in Chapters 54 and 55. Reduction of the subtrochanteric portion of the fracture can be difficult. One of two basic techniques can be used: complete reduction of the entire fracture with definitive plate application or use of the implant to control the proximal segment and facilitate reduction to the femoral shaft. Useful instruments for control of the proximal segment include Schanz pins, pointed bone-holding clamps, a femoral distractor, and a spiked pusher. For the rarely observed transverse subtrochanteric fracture, appropriate plate overcontouring and fracture compression should be performed. This can be accomplished with the articulated tensioning device, eccentric screw placement within “dynamic compression” plate holes, a pull screw (an independent screw is placed distal to the plate in the femoral shaft, and a Verbrugge clamp is hooked over the screw and placed into the last hole in the plate), or combinations thereof. For oblique fractures without comminution, compression can be obtained using standard techniques. For comminuted fractures, bridging is appropriate.


The size and length of the implant remain controversial. The choice of a broad or narrow plate depends of the femoral diameter and the patient size. As the fracture comminution increases, so should the plate length. As a general rule, at least five screw holes of plate length should extend distally relative to the fracture. The number of screws remains unknown, although eight cortices (four bicortical screws or more if unicortical) have been recommended. Three bicortical screws in the distal segment spread out over five or more screw holes are probably adequate. Proximal fixation is based on the implant chosen, generally using all available fixation elements, unless the proximal femoral segment is significantly longer than usual.


The technique of submuscular plating in subtrochanteric fractures is similar to that used in other long bones. The critical aspect of the procedure is minimization of the soft tissue dissection in the regions of the fracture and distally along the shaft of the femur. A small incision proximally can be used to manipulate, reduce, and stabilize the proximal segment. A plate of appropriate length that spans the fracture can be slid beneath the vastus lateralis and along the lateral femur. Distally, the plate can be secured to the femoral shaft using either a separate distal incision or multiple short incisions for screw placements. This technique is ideally suited for the dynamic condylar screw and the newer locking proximal femoral plates.


After plate stabilization of a subtrochanteric fracture, external supports such as casts or braces are unnecessary. Weight bearing should be limited to the weight of the leg until there is radiographic evidence of bridging callus, typically at 6 or 12 weeks.


Results


The results of plating in subtrochanteric fractures are favorable using an angled blade plate, a sliding hip screw, and the dynamic condylar screw. Additional studies have looked specifically at submuscular (minimally invasive) techniques with excellent results. In a review of 43 femoral fractures treated with indirect reduction and plating methods, Kesemenli and colleagues demonstrated union in 100% of 16 subtrochanteric fractures, although three patients healed with greater than 1 cm of shortening and two with greater than 8 degrees of varus. Bone grafting was not used in these patients. Furthermore, Vaidya and colleagues reported on 31 young patients with predominately high-energy subtrochanteric fractures treated with a dynamic condylar screw placed using biologic techniques. They obtained union in all patients at an average of 4.9 months, with malunions in 6%. Biologic plate fixation of comminuted subtrochanteric fractures was shown to be successful with multiple different implants including the angled blade plate, the dynamic condylar screw, and the dynamic hip screw.


95-Degree Angled Blade Plate


The 95-degree condylar blade plate has been used with success in the treatment of subtrochanteric femoral fractures. The distinct advantages of plating techniques for subtrochanteric fractures include improved control of the proximal segment and the ability to obtain an accurate restoration of the mechanical axis and femoral neck orientation in all planes. The major disadvantage is the difficulty of the surgical technique. Compared with a medullary implant, a lateral plate has the biomechanical disadvantage of a more eccentric location relative to the site of maximal compressive forces at the medial cortex of the proximal femur. As a result, immediate weight bearing is not recommended until there is evidence of sufficient fracture healing.


The primary indication for blade plate fixation of subtrochanteric fractures is patterns that involve proximal extensions into the trochanteric fossa or the greater trochanter (i.e., fracture extension into the region of the planned starting point for an intramedullary nail) ( Fig. 57-6 ). However, a fixed angled plate can be used for all subtrochanteric fractures. This may be especially important if intraoperative fluoroscopic imaging is unavailable because this technique can be accomplished with osseous landmarks alone.




Figure 57-6


A 38-year-old man sustained a comminuted subtrochanteric femur fracture after a motor vehicle crash. The injury anterior-posterior radiograph ( A ) demonstrates the lateral cortical comminution and extension into the greater trochanter and along the intertrochanteric line. Treatment consisted of open reduction and internal fixation with an angled blade plate with restoration of the proximal femoral anatomy. Healing progressed uneventfully ( B and C ).


The technique of implantation of a 95-degree angled blade plate has been reviewed in some detail. The essential aspects of the technique include avoidance of intercalary fragment devascularization, indirect reduction of the proximal (femoral head) segment to the shaft, reproduction of the anatomic neck-shaft angle, and avoidance of primary bone grafting ( Fig. 57-7 ). The technique is predicated on the ability of the surgeon to avoid the temptation to perform additional dissection (especially medially) in the subtrochanteric region. Indirect reduction is accomplished by securing the implant in the proper orientation to the proximal segment followed by reduction of the plate to the shaft. Femoral length is best accomplished using standard techniques, including push screws, the articulated distractor, or the femoral distractor. Orientation in varus/valgus, flexion/extension, and neck anteversion is determined by the proper placement of the implant in the proximal segment. Length and rotation are determined by fixation of the implant to the diaphysis and are confirmed using a combination of visual and radiographic clues.




Figure 57-7


Indirect reduction using an angled blade plate for a subtrochanteric femur fracture. After the blade is inserted into the proximal femoral segment, a femoral distractor or the articulated tensioning device can be used to regain length or to compress the fracture. The intercalary segments must be left undisturbed and bridged.

(Modified and redrawn from Kinast C, Bolhofner BR, Mast JW, et al. Results of treatment with the 95 degrees condylar blade-plate [see comments], Clin Orthop 238:122–130, 1989.)


Preoperative planning is critical in cases in which a 95-degree implant is planned. Contralateral proximal femoral radiographs in neutral rotation can be used to determine the patient’s normal neck-shaft angle and femoral neck anteversion. Templating to determine the proper blade entry location and angle is important and can be accomplished using the AP radiographs of both the injured and uninjured proximal femur. In comminuted fractures, assessment of length and rotation can be difficult. Length is best determined using the contralateral leg as a guide. Rotation can be assessed using techniques similar to those used in intramedullary nailing, including assessment of the lesser trochanteric contour (if intact) and lateral radiographic assessment of the femoral neck anteversion.


The patient can be positioned either supine or lateral on a radiolucent table. A fracture table can be used, but free-legged techniques have the advantage of allowing unimpeded intraoperative leg positioning. A rolled blanket or bump placed behind the injured hip and pelvis allows for lateral radiographic imaging of the femoral neck.


A lateral approach to the femur should extend from the proximal greater trochanteric tip distally using a subvastus approach that respects the vastus lateralis by dissecting the entire muscle off the lateral intermuscular septum. Distally, the dissection can be limited in length to the proximal aspect of the femoral shaft if submuscular techniques are desired. However, the need for insertion of the angled blade plate into the proximal segment before attachment to the femoral shaft makes submuscular techniques more difficult. As a result, a lengthy incision is typically required because a long implant should be used. The deep dissection is the critical portion of the procedure. The lateral aspect of the greater trochanter must be exposed to allow for insertion of the blade plate and proper orientation of the implant. However, in the region of the fracture, the periosteum should be left intact on any intercalary fragments. Distally, only the lateral aspect of the femur requires exposure, and the periosteum can be left intact along the length of the plate.


The proper placement of the seating chisel in the proximal segment is the most important step of the procedure. Proximal fracture extensions along the intertrochanteric line or into the greater trochanter should be reduced and temporarily stabilized before placement of the seating chisel. These reductions can be held with clamps, temporary K-wires, strategic lag screws that avoid the ultimate blade path, or combinations thereof. The femoral neck anteversion can be determined by placing a smooth wire (2 or 2.4 mm in diameter) along the anterior neck of the femur and parallel to the long axis of the femoral neck. The location and orientation of this wire can be confirmed radiographically in two planes. The seating chisel entry site location and direction is determined primarily from the preoperative plan. A summation wire is first placed at a 95-degree angle relative to the anatomic axis of the proximal femur and centrally along the long axis of the femoral neck on the lateral view. This wire is parallel to the anteversion wire located in the anterior two-thirds of the greater trochanter and below the piriformis fossa. The wire location is confirmed radiographically. This is followed by placement of the seating chisel parallel to the wire and in the proper sagittal plane orientation. The angled blade plate is then selected based on the blade and plate lengths and implanted into the proximal segment.


After confirmation of the implant location, an additional point of fixation into the proximal segment is obtained with an appropriately placed screw through the plate. The proximal segment is controlled with the blade plate and reduced to the shaft, spanning any intercalary comminution of the subtrochanteric region ( Fig. 57-8 ). Length is established and determined as previously described. Rotation is confirmed visually and radiographically. The plate is then secured to the distal segment using multiple bicortical screws. A reasonable minimum length of the implant completely distal to the fracture is five holes with three screws placed. Longer implants may facilitate distal segment fixation but at the expense of additional distal atraumatic elevation of the vastus lateralis.




Figure 57-8


A comminuted subtrochanteric fracture in a 28-year-old man with hemophilia. The fracture pattern is characterized by proximal extension in the greater trochanter and separation of the lesser trochanter ( A ). Treatment consisted of fixation into the proximal segment with a 95-degree angled blade plate and bridging fixation to the femoral shaft distally ( B and C ). The intercalary segments were left undisturbed.


A number of technical aspects of the procedure require emphasis. The proper placement of the blade in the proximal segment determines the ultimate femoral neck anteversion, neck-shaft angle, and the sagittal plane rotation. Only length and rotation can be adjusted during the reduction of the proximal femoral segment to the shaft. An anatomic reduction of the intercalary bone segments, including the lesser trochanter if involved, is not necessary for successful healing. The benefit of maintaining the blood supply and local biology of these segments outweighs the benefits of accurately reducing them. In simple fracture patterns (spiral, transverse, or oblique without comminution), an anatomic reduction can be accomplished before placement of the blade plate ( Fig. 57-9 ). In these instances, dissection should be limited to the lateral femur. Only clamps that do not require additional stripping should be used.




Figure 57-9


A subtrochanteric fracture in a 24-year-old man after a motorcycle crash ( A ). This was treated with open reduction and internal fixation ( B and C ) with compression across the simple fracture pattern.


The results of treatment of subtrochanteric fractures with a 95-degree angled blade plate are favorable in experienced hands. This is best demonstrated in the retrospective longitudinal cohort study by Kinast and colleagues in which surgical treatment of subtrochanteric fractures changed with time. In the initial phase of the study, treatment consisted of anatomic reduction of all fractures after extensive surgical dissection combined with bone grafting as needed. This was followed by a period of treatment using indirect reduction techniques. The authors observed more rapid union, a decrease in the incidence of nonunion (from 16.6% to 0%), and avoidance of bone grafting by using these techniques. The success of indirect techniques using an angled blade plate was further supported at the same institution with a follow-up study of 15 additional patients. Only one nonunion occurred in a patient with a severe open injury that was complicated by infection. Further studies using these techniques demonstrate union rates of 97%.


Other authors have reported less favorable results with an angled blade plate in subtrochanteric fractures. In a series of 25 patients, Brien and colleagues reported higher blood loss, longer operative times, and increased complications compared with 33 patients treated with a locked medullary implant, including six malunions and two nonunions in the patients treated with plates. This led the authors to recommend closed interlocked nailing for subtrochanteric fractures in adults. Although intramedullary nailing is an effective method for these fractures, the angled blade still has a very useful role in acute fractures of the subtrochanteric region, especially comminuted fractures that make nailing difficult.


Dynamic Condylar Screw


The dynamic condylar screw has been used successfully for the treatment of subtrochanteric femoral fractures with and without proximal extensions. Its modularity allows for open reduction and implant placement into the proximal segment of the femur combined with submuscular plate placement for attachment of the shaft. Improved control of the proximal segment and precise restoration of the mechanical axis and femoral neck orientation in all planes is possible. However, similar to the blade plate, the correct, preplanned placement of the proximal screw is essential for restoration of normal frontal plane anatomy. Rotation about this screw does allow adjustment of sagittal plane alignment. The main disadvantages are the removal of a large quantity of bone from the proximal segment during implantation and the need for a second point of proximal fixation to prevent undesired rotation about the lag screw. The primary indications for the dynamic condylar screw include fractures with proximal extension, comminuted fracture patterns, and circumstances in which submuscular techniques are desired. Similar to other lateral plating techniques, postoperative weight bearing should be delayed until there is evidence of sufficient fracture healing.


The minimally invasive technique is similar to that used in other locations and has been described in some detail for the proximal femur by Krettek and colleagues Preoperative planning is necessary, and contralateral proximal femoral radiographs can be used to template the anticipated location of the condylar screw as well as the desired neck-shaft angle. With the patient positioned supine, a lateral approach to the proximal femur allows for exposure of the proximal segment. Any associated proximal fracture extensions into the greater trochanteric region or along the intertrochanteric line can be reduced and stabilized. An anteversion wire can be used to judge the proper femoral neck orientation. According to the preoperative plan, the condylar screw is placed parallel to the femoral neck on the lateral view and at a 95-degree angle on the AP view. The screw should be placed below the piriformis fossa and into the inferior femoral head. The ultimate sagittal plane orientation of the side plate is determined by the final rotation of the screw. This can be adjusted as needed and remains one of the advantages of this implant relative to the angled blade plate. The side plate is then placed along the midlateral aspect of the femoral shaft using either an open or submuscular technique as desired. As with all other plating techniques, it is important to avoid any additional intercalary dissection in the region of the fracture. Length and rotation of the limb are established using manual traction, the femoral distractor, or other techniques. The side plate is then secured to the condylar screw, and any adjustments to the sagittal plane orientation of the plate are made by advancing or retreating the screw. The plate is then secured to the distal femoral segment with multiple bicortical screws ( Fig. 57-10 ).


Jun 11, 2019 | Posted by in ORTHOPEDIC | Comments Off on Subtrochanteric Fractures of the Femur
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