Fig. 8.1
AO Classification system for intertrochanteric fractures. Adapted from “Tscherne Unfallchirurgie.” N.P. Haas, C. Krettek; [Per- and sub-trochanteric fractures]; Copyright Springer: Berlin, Heidelberg 2012
Several studies have shown superior intra- and inter-observer reliability for the AO classification system, when compared to all other, major classification systems, especially in experienced surgeons. This is based on classification for intertrochanteric fracture main types 31-A1 through 31-A3 (mean kappa value 0.82) that allow sufficient prediction of fracture stability and required implant type. AO sub-classification is less reliable, and reaches kappa values comparable to the other classification systems (mean kappa value 0.54) [13]. No classification system with sub-groups can be used reliably to distinguish between stable and unstable fractures. The AO classification system without sub-groups should be used in preference to all other systems.
Relevant Anatomy and Biomechanics
The intertrochanteric femur region is one of the four distinct regions of the proximal femur (femoral head, neck, intertrochanteric, and sub-trochanteric regions). The greater trochanter is an apophysis and insertion point for several important muscles: the piriformis muscle inserts on its tip, and the gluteus medius and minimus fan around the dorsolateral and ventrolateral side, while the intertrochanteric fossa is the insertion point for the short external rotators (Mm. gemelli, obturatorius internus and obturatorius externus). The lesser trochanter is the insertion point for the iliopsoas muscle and an important cortical stabilizer (Calcar). In intertrochanteric fractures requiring intramedullary nail fixation, four main fragments are commonly found: head-neck, greater trochanter, lesser trochanter, and shaft, corresponding to AO fracture types A2 and A3. As a mechanical axis runs medial to the lesser trochanter, the fracture typically displaces in a varus direction. In intertrochanteric fractures, the gluteal musculature and the iliotibial band cannot neutralize this force. After an intertrochanteric fracture, the resulting muscle forces lead to a typical displacement pattern. The gluteal muscles abduct the proximal main fragment. If the lesser trochanter is intact, the adherent main fragment is further flexed and externally rotated. The distal main fragment is commonly adducted through the adductor and hamstring muscles and externally rotated. Understanding the resulting muscle forces is a key prerequisite for assuring correct intra-operative reduction (Fig. 8.2). To counteract the displacement forces, the typical reduction maneuver thus requires traction, internal rotation, and abduction. To allow axial placement of the nail, however, adduction prior to nail insertion is necessary, depending on the entry point and patient body habitus. Intertrochanteric fractures are extracapsular fractures by definition and thus rarely compromise the femoral head perfusion [14]. However, if the piriformis fossa approach is used as an entry point for the intramedullary nail, injuries to the anterior branch of the medial femoral artery have been described [15].
Fig. 8.2
Typical reduction maneuver based on the common dislocation pattern encountered in intertrochanteric femur fractures requiring intramedullary nailing. Adapted from Tscherne Unfallchirurgie. N.P. Haas, C. Krettek; [Per- and sub-trochanteric fractures]; Copyright Springer: Berlin, Heidelberg 2012
Initial Management
Diagnostics
Standard anterior-posterior (ap) and lateral views of the fracture are usually enough to adequately diagnose and classify; however, due to severe pain, sometimes only one view can be achieved (Fig. 8.3). An additional ap pelvic view is advantageous for guiding intra-operative reduction based on the contralateral side, especially in severely displaced and comminuted fractures. To adequately assess whether intramedullary nailing is necessary, the medial calcar region of the proximal femur should be clearly visible on at least one plane. Traction-internal rotation radiographs may further delineate the calcar region and hint at ease of fracture reduction. Furthermore, the femur should be visualized distally to assess the inner diameter of the intramedullary canal and antecurvation of the femur. Computed tomography is rarely necessary, but should be considered if adequate classification and stability assessment of the fracture are not possible on plain radiographs, or in cases of suspected non-displaced fractures. In cases of occult fractures, magnetic resonance imaging (MRI) has superior diagnostic accuracy compared to both scintigraphy and thin layer radiography [16]. Overall careful pre-operative fracture visualization is the key to a reliable classification and implant choice [14].
Fig. 8.3
Standard ap view of an intertrochanteric fracture with insufficient medial and calcar support, typically considered for intramedullary fixation
Timing of Surgery
Several large-scale studies and meta-analyses have investigated the effect of early definitive stabilization on treatment outcome. A recent meta-analysis that included more than 190,000 individuals showed significantly higher overall survival for patients operated within the first 48 h [14]. Surgery within 24 h has been shown to be associated also with a reduced risk for secondary complications, such as in-hospital pneumonia and pressure sores [17]. In general, any delay to operate significantly prolongs the hospital stay and thus increases the likelihood of hospital-related complications [18]. Preliminary studies from 2014 suggest that decreasing the time to surgery from 24 to 6 h further decreases the risk for major peri-operative complications and shortens the time to first mobilization [19].
From a clinical point of view, however, operating within the first 24 h remains a challenge. In the majority of institutions worldwide, femur fracture patients are operated with a delay of more than 24 h [20]. Statistics from the U.K. and France have shown that almost 50% of femur fracture patients are operated after more than 48 h [21]. One of the main reasons for this delay is the necessary management of comorbidities, which is especially complicated by older patients’ intertrochanteric hip fractures that require intramedullary nailing, as they present with more and more severe comorbidities. However, in most of the cases, the delay is caused by organizational reasons, rather than medical [21]. Overall measures need to be established to enable surgery as quickly as possible without compromising patient safety by neglecting manageable medical comorbidities.
Pre-operative Assessment, Managing Comorbidities
The outcome of femoral fractures requiring intramedullary nailing in elderly patients is directly influenced by the associated comorbidities . More than 75% of the intertrochanteric hip fracture patients are over 70 years old, and more than 95% of them present with at least one major comorbidity. A common rating scale to assess patient comorbidities that is directly associated with long-term mortality is the Cumulative Illness Rating Scale [22]. However, the need for medical optimization has to be weighed against a possible delay of surgery that could be required for further consultations. Medical reasons account for over 40% of surgical delays in femur fractures [21]. In many cases, there is no adequate alternative to surgery, and the risk of delaying surgery outweighs a specialist’s consultation if the comorbidity cannot be correct in a timely fashion. Particularly in patients with coronary artery disease, additional investigations are not necessary, as long as a manifest acute coronary syndrome is not present. Likewise, chronic, stable congestive heart failure does not benefit from additional echocardiography [22]. A chest radiograph should be performed to recognize uncompensated heart failure in all patients over 65.
Despite the need for an expedited schedule to surgery, a reasonable preoperative delay to optimize a patient’s electrolyte and volume status should be allowed. The intra-operative period , and also post-operative one (ICU vs. intermediate ICU), are periods in which the patient is closely monitored and, if necessary, urgent medical interventions can be provided immediately. To evaluate the necessity for further evaluation, the American College of Cardiology and American Heart Association have provided a flow-chart on peri-operative cardiovascular evaluation necessity (Fig. 8.4) [23]. As pulmonary complications are as prevalent as cardiac complications, predictive risk factors need to be assessed. Especially important are chronic obstructive pulmonary disease, congestive heart failure, prolonged surgery, advanced age, and low serum albumin (<30 g/L) [24]. Chest radiographs and spirometry have limited evidence as risk stratification tools. Careful post-operative management is necessary if pulmonary complication risks are identified,and serum albumin levels can be corrected peri-operatively.
Fig. 8.4
ACC/AHA flowchart to determine necessity for preoperative management of cardiovascular related comorbidities. Adapted from Orthopedic Traumatology, M.K. Sethi, A.A. Jahangir, W.T. Obremsky; Copyright Springer Science + Business Media: New York 2013
Another common problem is that many patients with intertrochanteric fractures require anticoagulants for either coronary artery disease-related interventions, or atrial fibrillation. Aspirin does not need to be put on hold, as the risk of peri-operative bleeding is clinically irrelevant [25]. Also, the commonly given clopidogrel has been shown to have no significant effect on bleeding, transfusions, length of surgery, or hospital stay [26]. Vitamin K antagonists , however, need to be interrupted and replaced by either unfractionated heparin, or low molecular weight heparin. In cases with an INR over 1.5, the administration of Vitamin K cannot timely correct the bleeding increase, but the administration of prothrombin complex concentrates allows an immediate correction without delaying surgery [27]. Newer oral anticoagulants , such as dabigatran, apixaban and rivaroxaban, might delay surgery for more than 48 h, as there is still no antidote available. Surgical intervention should be timed according to the respective antifactor Xa values for each drug, and in cooperation with the hematology department if available.
Operative vs. Non-operative
Randomized studies comparing the difference between operative and non-operative treatment in intertrochanteric femur fractures are few. The goal to allow an early functional aftercare in patients with oftentimes severe comorbidities cannot be reached by non-operative treatment. Non-operative treatment is associated with significantly longer hospital stays and greater loss of independency [28]. Non-operative therapy of intertrochanteric femur fractures should thus only be considered in moribund patients or patients with severe comorbidities, placing them at an unacceptable risk for surgery and anesthesia [29]. Fracture union is rare, and even if it is achieved, severe rotational and longitudinal malalignment has to be expected [30]. The resulting muscle forces will cause the proximal main fragment to be in an abducted, flexed, and externally rotated position. Extension treatment will correct only longitudinal malalignment, so conservative treatment of femoral fractures is thus considered virtually obsolete [31].
Techniques
Intramedullary Nail vs. Sliding Hip Screw
The most recent Cochrane Review comparing intramedullary nails with the sliding hip screw design has reached the conclusion that there is no significant difference in the outcome between both devices for intertrochanteric femur fractures [32]. The reported outcome measures that do not differ between both fixation devices were cut-out, non-union, infections, mortality, length of surgery, pain, and return to previous residence. In light of the reported complication rates for intramedullary devices, namely intra-operative and late fractures around the intramedullary nail system, the review favors extramedullary fixation devices, especially in stable fracture situations. In contrast, other studies reported fewer complications, decreased intra-operative blood loss, earlier mobilization, and faster return home for intramedullary systems [33, 34]. Economic considerations warrant the use of extramedullary fixation devices in stable fracture AO type A1 situations. For potentially unstable fracture situations (AO types A2 and A3), in which the medial support of the calcar is missing, intramedullary fixation devices have an advantage over sliding hip screw systems. The developmental principle behind the intramedullary systems was in part to shorten the lever arm of force affecting the medial calcar region (Fig. 8.5). Biomechanical studies have shown that the load to failure resistance is almost doubled for intramedullary systems compared to extramedullary ones [35].
Fig. 8.5
The concept of the shorter lever arm for intramedullary fixation compared to extramedullary plating is shown (D > d). Adapted from Leung 1992; Copyright The British Editorial Society of Bone and Joint Surgery, London 1992
Intramedullary Nail vs. Arthroplasty
There have been only a few studies on primary arthroplasty for unstable intertrochanteric proximal femur fractures. A Cochrane Review from 2006 concluded that there was no clear evidence for the advantage of one method over another. In the clinical practice, primary hip arthroplasty is not an appropriate treatment option for intertrochanteric fractures, as it is difficult to achieve sufficient primary stability of standard stems in the femur. One study, comparing cephalomedullary nailing in unstable fractures with long-stem, uncemented hemiarthroplasty, showed significantly higher surgical time, and more blood loss and mortality for the arthroplasty group [36]. Arthroplasty is thus mainly considered to be revision surgery for failed intramedullary treatment. One study comparing secondary arthroplasty after intramedullary nailing and extramedullary sliding hip screw surgery showed an increased complication rate for revision after intramedullary nailing [37]. No difference in functional results was seen.
Differences between Intramedullary Nail Designs
There is a variety of intramedullary fixation devices, all of which have structural advantages and disadvantages (Fig. 8.6). The most common designs include either a femoral neck screw or blade. The blade offers the advantage of increased stability in lower-quality bone due to the impaction of the cancellous bone during implantation, and an increased load-carrying surface [38]. There are other design differences in the implementation of rotational stability, such as systems with additional anti-rotational screws placed in the femoral neck, as well as locking mechanisms for the femoral neck screw. Biomechanical studies and simulations have shown less cut-out risk for the locked one-screw designs [39], and the newest nail designs offer additional guidance systems for screw fixation of the lesser trochanter region. A recent Cochrane Review could not find any differences in the outcomes among the available nail systems [40]. Furthermore, in isolated intertrochanteric fractures, no difference was seen between failure rates of long and short cephalomedullary nails [41]. Biomechanical and limited clinical studies have shown increased cut-out resistance of cement-augmented intramedullary nails [42]. A careful operative technique is needed to avoid perforation of the femoral head with the guidewire, as this would lead to cement leakage into the hip joint. The risk of such leakage into the fracture, and thermal necrosis of the trabecular bone, can be avoided by applying only small amounts of cement.
Fig. 8.6
Different, current intramedullary nail designs are shown from left to right: a system with a femoral neck screw and additional anti-rotational femoral neck screw (Targon® PFT; B Braun AG Melsungen, Germany); a system with a femoral neck blade (PFNA; Synthes GmbH Umkirch, Germany); and a system with a femoral neck screw and anti-rotational locking inside the nail itself (Gamma3 Nail; Stryker GmbH & Co. KG: Duisburg, Germany)
Piriformis vs. Trochanteric Entry Point
The piriformis fossa (Fig. 8.7) was introduced as an entry point that is in line with the longitudinal axis of the femur , to reduce the risk of varus malalignment at a time when rigid straight nails were used. Studies showed a high union and low infection rate [43]. A disadvantage of this entry point is its lower tolerance for incorrect portal placement. If the entry point deviates anterior to the piriformis fossa by as little as 6 mm, the resulting circumferential stresses can cause anterior cortical “blow-out” [44]. Establishing the entry point can be challenging in obese patients, due to the higher medialization needed, compared to the trochanteric entry point [45] especially in minimally invasive exposures. Cadaveric studies have shown that the piriformis entry point can damage the anterior branches of the medial femoral circumflex artery, compromising the femoral heads’ blood supply [15].
Fig. 8.7
Superior view of the proximal femur . The trochanteric and piriformis entry points are marked by a T and P, respectively
The trochanteric entry point was introduced by Kuentscher already in 1939. Almost all current nail designs accommodate for the trochanteric entry side by having a lateral, proximal bend between 4 and 6° to prevent varus malalignment. The entry point is easier to establish, more forgiving, and causes less soft tissue damage to the abductor complex and short external rotators [46]. Further studies have shown decreased operating and fluoroscopy time [47].
Tip Apex Distance
To reduce the risk of screw migration or cutout, the distance between the tip of the femoral neck screw and the border of the femoral neck is a useful measure. This distance is measured in both the ap and lateral view and summated (Fig. 8.8). The resulting tip apex distance (TAD) is predictive of the risk of screw cutout. Studies have shown that TADs below 20–25 mm have significantly less migration and cutout complications [48, 49].
Fig. 8.8
Calculation of the Tip Apex Distance . Adapted from “Tip-apex distance of intramedullary devices as a predictor of cut-out failure in the treatment of peritrochanteric elderly hip fractures” International Orthopedics, J.A. Geller; Copyright Springer: Berlin Heidelberg 2009
Surgical Technique
The patient is placed in the supine position on a fracture table, and the non-injured leg is abducted, flexed, and placed in a stirrup. A perineal post with sufficient padding is placed between the legs, and the injured leg is placed in a traction device (Fig. 8.9). The reduction is performed prior to the skin preparation and draping under fluoroscopic control, alternatingly in ap and lateral views. The lateral view plane has to be adjusted to account for the femoral neck anteversion. Commonly, the fracture displacement is improved with traction and internal rotation of the leg. The preoperative radiographs should be available in the operating room to guide the reduction based on the contralateral anatomy. After correct reduction, the patient is prepped and draped in a sterile fashion according to standards (Fig. 8.10). A 4 cm skin incision is performed just proximal to the greater trochanter with sharp dissection through the gluteal fascia. Soft tissue is spread on to the tip of the greater trochanter. By palpation and fluoroscopy, the entry point is visualized—either at the trochanter or the piriformis fossa, depending on the nail to be used.
Fig. 8.9
Preoperative patient positioning . The uninjured leg is abducted and flexed on a stirrup. A perineal post is placed to apply traction to the injured leg with a traction table setup. Adapted from Operations atlas für die orthopädisch-unfallchirurgische Weiterbildung. D. Kohn, T. Pohlemann; Copyright Springer, Berlin, Heidelberg 2010
Fig. 8.10
Prepped and draped patient for intramedullary nailing. The main skin incision is marked. Femoral neck and locking screw incisions are intra-operatively based on the aiming device. Fluoroscopy is placed for an ap view
An awl or guide pin is used to establish the entry point. If the more common trochanteric approach is chosen, the entry point should be placed just medial to the tip of the greater trochanter in the ap view and in the central portion of the femur in the lateral view. After correct reduction and positioning of the guide wire have been confirmed, an entry reamer is used to open the medullary cavity. In narrow medullary canals, reaming can be necessary, using a ball-tipped guidewire. The nail is then placed under fluoroscopic control. If the placement cannot be performed gently, further reduction or reaming might be required. Correct placement is fluoroscopically confirmed, and the guide pin for the femoral neck screw is placed through the nails’ aiming device. To prevent malrotation during screw placement, another pin can be placed into the femoral head. Newer nail designs have incorporated aiming devices for this purpose. The guide is checked in both ap and lateral views. A cannulated step drill (with depth stop set to the previously measured screw length) is used to establish the path for the screw. In good quality bone, tapping prior to screw implantation is often necessary. The lag screw is then placed under fluoroscopic control to recognize and prevent medial guide perforation. After correct screw placement, traction can be released and the fracture compressed with the nail-specific instrumentation. Depending on the implant, a set screw, or an anti-rotational screw is placed. The nail is locked distally with an aiming guide or fluoroscopically controlled for long nails. The wounds are closed after copious irrigation in a layered fashion and a spica dressing might be applied.
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