In an analysis from the accident research unit of the Hannover Medical School (MHH), Germany, a total of 22,500 traffic accidents between 1985 and 2003 were analyzed and 447 femoral shaft fractures documented. This corresponds to a percentage of less than 2 % of all accidents. From these fractures, 90 % were unilateral, and 10 % were bilateral. In more than half of the cases car passengers were involved. Up to 15 % motorized two-wheel drivers and in more than 9 % of cyclists were concerned. 17 % of the femoral shaft fractures referred to the group of the pedestrians [9]. In a recent study from the US about pediatric femoral shaft fractures, the incidence was 19 per 100,000 inhabitants and year. There were more boys than girls [10].
One third of all patients with a femoral shaft fracture after traffic accidents have accompanying injuries in the area of chest, head, pelvis and ipsilateral leg. With falls from heights resulting in femoral shaft fractures, accompanying injuries appear in only 3 % of the cases. The mortality is about 6 % and is caused mainly by lung contusion, pneumonia, fat embolism, ARDS and myocardial failure [1]. High speed trauma and open fractures lead to an increased morbidity with healing disturbances (delayed and non-union), restrictions in range of motion and leg length differences [1]. More than one third of the cases with femoral shaft fractures require blood transfusions in the early phase of hospitalization [11]. The average hospitalization time in the USA during 60s till the 80s was 25 days [12]. Current information from 2000 to 2002 from Germany for patients with a femoral shaft fracture shows an average hospital stay of 15 days for men and 21.5 days for women [7].
Economic analyses made by employer’s liability insurance coverage for the period from 2000 to 2003 show that more than half of the accident victims with the main diagnosis femoral fracture below the trochanter required a pension, i.e. at least temporarily a decrease of the capacity to work of 20 % or more [13]. In one quarter of all accident victims a decrease of the capacity to work was given between 20 and 30 %. Only 10 % of the affected patients were addressed with a decrease of 40 % or above [13].
Femoral shaft fractures are often described in terms of the level at which they occur (proximal, middle, distal third) (Fig. 19.2) and configuration (spiral, transverse, oblique, segmental, comminuted) (Fig. 19.3) [14, 15]. In 1980, Winquist proposed a classification based on fracture comminution (Fig. 19.4) [16].
Fig. 19.2
Definition of femoral fracture zones. Definition of proximal femur (AO.31), femoral shaft (AO.32) and distal femur (AO.33) according the AO/OTA classification (Reprinted with permission from Gösling and Krettek [9])
Fig. 19.3
AO classification groups and subgroups. (a) Groups: A simple fractures: A1 spiral, A2 oblique (≥30°), A3 transverse (<30°). B Wedge fractures: B1 torsion wedge, B2 bending wedge, B3 multifragmentary. C complex fractures: C1 comminuted spiral fracture, C2 segmental fracture, C3 Irregular comminuted fracture (b) Subgroups of the C fractures: C1 spiral fracture, C1.1 2 intermediate fragments, C1.2 3 intermediate fragments, C1.3 more than 3 intermediate fragments, C2 segment fracture, C2.1 1 segment, C2.2 1 segment + wedge fracture, C2.3 2 segments, C3 irregular comminuted fracture, C3.1 2 or 3 fragments, C3.2 < 5 cm of comminution, C3.3 ≥ 5 cm of comminution (Reprinted with permission from Gösling and Krettek [9]). Without image: For the groups A and B the following subgroups are defined: 32-XY.1: subtrochanteric zone, 32-XY.2: middle zone, 32. XY.3: distal zone
Fig. 19.4
Winquist classification. Grade 0: no comminution, Grade I: small wedge fragment or comminutions, at least 50 % of intact cortical contact, Grade II: large wedge or comminution segment, at least 50 % of intact cortical contact, Grade III: large wedge or comminution segment, less than 50 % of intact cortical contact, Grade IV: comminution zone without direct contact between the main fragments (Reprinted with permission from [9, 16])
19.2 Pathophysiology of Femoral Fractures
19.2.1 Isolated Femoral Fracture
Compared to other long bone fractures, femoral shaft fractures are associated with a higher risk for post-traumatic complications. This is due to the fact that the femoral bone requires a huge amount of energy to break, resulting not only in a bony lesion, but also significant soft tissue damage and considerable blood loss [17]. Of all long bones, the femur has the thickest layer of soft tissues around the bone, which might result in additional negative effects in case of massive soft tissue injury.
Femoral fractures and the associated soft tissue injuries of the surrounding tissue envelope initiate a physiological, local inflammation reaction, which is normal and important for the healing process. These inflammatory processes control the course of wound healing with specific mediators and represent a specific initiator for the cell replication [18]. Under all mediators, the cytokines seem to play a special role, because a blocked or decreased expression of these mediators caused healing disturbances in an animal model [19].
The cytokine concentrations (Tumor-Necrosis-Factor-α (TNF-α), Interleukin (IL)-1, IL-β, IL-6, IL-8, IL-10) in the wound area are increased as a function of the injury severity and the kind of the disrupted tissue (bone, muscle) [17, 20, 21]. Initially after trauma, these local cytokine levels are much higher compared to systemic levels, indicating a local production and later a systemic release [17, 21, 22]. Therefore a local injury always has systemic impact caused by a systemic inflammation (systemic inflammatory response syndrome (SIRS)) [23].
19.2.2 Femoral Fracture in Polytrauma Patients
The femoral shaft fracture is also a significant injury within the scope of a polytrauma patient. In polytrauma patients, the incidence of femoral fractures is higher than those of other long bone fractures. In addition, bilateral femoral fractures show a higher mortality rate than patients with a unilateral injury (16 % versus 4 % with isolated femoral injuries) [24]. This phenomenon could not be shown for fractures of other long bones.
Besides, the inflammation reaction induced by a multiple trauma is determined not only by bony or soft tissue injuries, although these two tissues represent 87 % of the body mass [25]. Also injuries of other body regions contribute significantly to the local production and systemic release of inflammatory mediators. In a clinical study it could be shown, that the lungs are one of the most significant sources for systemically released IL-8 [21]. From this it becomes obvious, that the risk for the development of SIRS in a polytraumatized patient is significantly higher compared to a patient with an isolated femoral fracture. Neutrophile granulocytes release toxic substances (proteases and others) resulting in raised capillary permeability and interstitial edema [26]. All these factors are involved in the development of an adult-respiratory-distress-syndrome (ARDS) and a multi-organ-dysfunction-Syndrome (MODS) which might be aggravated under certain circumstances by the reaming process and the debris associated with the reaming procedure (Fig. 19.5).
Fig. 19.5
Reaming debris. (a) Reaming debris in a human cadaver bone. In the left quarter of the image, the femoral bone has a closed cross section, in the right three quarters, the anterior part of the femur is resected to give visual access to the reamer shaft (Synthes, Oberdorf, Switzerland). (b) Reamer debris is pressed out of the medullary cavity
19.3 Decision Making
19.3.1 Limb Salvage
A great difficulty in the treatment of patients with femur fractures with severe soft tissue damage and/or other multiple injuries (polytrauma) exists in the decision whether to salvage or to amputate the limb. In this specific setting, an amputation can be a life-saving surgery. There exist several scores which are designed to support the surgeon in the decision making process.
MESS
One of them is the ‘mangled extremity severity score’ (MESS) (Table 19.1) [27]. The MESS was developed by retrospectively reviewing 25 trauma victims with 26 severe lower-extremity open fractures with vascular compromise. The four significant criteria (with increasing points for worsening prognosis) were skeletal/soft-tissue injury, limb ischemia, shock, and patient age. The scoring system was then prospectively evaluated in 26 lower-extremity open fractures with vascular injury over a 12-month period at two trauma centers. There was a significant difference in the mean MESS; 4.00 for the 14 salvaged limbs and 8.83 for the 12 amputated limbs (p < 0.01). In both the prospective and retrospective studies, a MESS of greater than or equal to 7 had a 100 % predictable value for amputation. This relatively simple, readily available scoring system of objective criteria was highly accurate in acutely discriminating between limbs that were salvageable and those that were unsalvageable and better managed by primary amputation [27].
Table 19.1
Mangled extremity severity score (MESS)
Type | Characteristics | Injuries | Points |
|---|---|---|---|
Skeletal/soft-tissue group | |||
1 | Low energy | Stab wounds, simple closed fractures, small-caliber gunshot wounds | 1 |
2 | Medium energy | Open or multiple-level fractures, dislocations, moderate crush injuries | 2 |
3 | High energy | Shotgun blast (close range) high-velocity gunshot wounds | 3 |
4 | Massive crush | Logging, railroad, oil rig accidents | 4 |
Shock group | |||
1 | Normotensive hemodynamics | BP stable in field and in OR | 0 |
2 | Transiently hypotensive | BP unstable in field but responsive to intravenous fluids | 1 |
3 | Prolonged hypotension | Systolic BP less than 90 mmHg in field and responsive to intravenous fluid only in OR | 2 |
Ischemia group | |||
1 | None | A pulsatile limb without signs of ischemia | 0a |
2 | Mild | Diminished pulses without signs of ischemia | 1a |
3 | Moderate | No pulse by Doppler, sluggish capillary refill, paresthesia, diminished motor activity | 2a |
4 | Advanced | Pulseless, cool, paralyzed and numb without capillary refill | 3a |
Age group | |||
1 | <30 years | 0 | |
2 | >30 <50 years | 1 | |
3 | >50 years | 2 | |
NISSSA
The MESS was extended by McNamara by including the nervous damage and a more differentiated judgment of the bone and soft tissues in the NISSSA score (nerve injury, ischemia, soft-tissue injury, skeletal injury, shock and age) [28].
PSI/LSI
HFS/HFS-98
LEAP Study
All these scores have been validated within the LEAP-Study (Lower Extremity Assessment Project). This study showed, that a low sensitivity is given for the decision for an amputation [32]. The authors point out to the fact that the scores seem suitable to indicate a limb salvage, but that scores in the range of cut-off should be used with great care. They also focus on the point, that decisions should never be based on the scores alone. The principle ‘Life before Limb’ is still valid. But it should also be considered, that amputations above knee lead to a functionally worse result, compared to below knee amputations [33].
19.3.2 Surgical Therapy
Femoral shaft fractures are a clear indication for surgical fixation. Numerous studies have proven the advantages (morbidity, mortality and functional result) of the surgical therapy when compared to conservative treatment. Only very rare circumstances like the refusal of surgery by the patient justifies from our point of view a non-surgical therapeutic procedure. The femoral shaft fracture is an emergency indication and should be surgically stabilized immediately. A delayed fracture stabilization of femoral shaft fractures is complicated with an increased morbidity and longer hospitalization [34–37].
19.4 Intramedullary Fixation Concepts
Today intramedullary locking nailing is the treatment of choice and gold standard for the stabilization of femoral shaft fractures of the adult because of the high healing and low complication rate. Intramedullary fixation technologies take advantage of a central load sharing concept. The insertion point is far away from the fracture site, and reduction is usually done closed and with indirect techniques, avoiding additional soft tissue damage at the fracture site.
The classical nailing concept in engineering or in a handcraft environment consists of a rigid un-elastic nail (i.e. steel), which is inserted in a relatively soft and elastic material (i.e. wood). However, this is not the only way to achieve fixation. Various principles and fixation concepts, depending on the type of intramedullary fixation in the medullary canal, have been developed over the years.
19.4.1 Intramedullary Splinting with Wires
Intramedullary splinting with wires (‘Markdrahtung’) must be distinguished from intramedullary nailing, where there is either jamming between nail and bone (slotted nails) or interlocking using screws. Intramedullary splinting with wires is not a load bearing fixation and hence, should be restricted to children with A and B type fractures only [38]. The wires have a low diameter and a much higher flexibility compared to a nail. In the literature, a variety of implants have been described (Lottes nail, Rush-Pin, Ender nail, Morote nail, Nancy nail or bundle nail) [39–44].
The stabilization depends on a 3 or 4 point contact. The friction from elastic spanning of the wires in the bone provides fixation. The stability of the fixation is dependent on the stiffness of the wire, which is given by the wire material, the diameter and the working length. Nevertheless, the wires should not be too stiff to allow an easy insertion and should not be too elastic, to provide sufficient elastic 3 or 4 point spanning. The principle of the bundle nailing described by Hackethal is different and based on dense ‘packing’ of the medullary cavity with wires in the isthmic zone [45].
19.4.2 Rigid Intramedullary Nailing
The stabilization of fractures by the classical (no interlocking screws) Küntscher nail is based on two different mechanical principles.
Internal Mounting/Sheathing
When the nail is connecting two tubes, the nail prevents dislocation by symmetrical internal mounting (‘Innenschäftung’) against bending moments and shear. If there is no elastic jamming, there is no resistance against torque and in comminuted fractures against shortening. The stiffness of the nail-bone construct towards bending moments is mainly determined by the stiffness of the nail (Fig. 19.6a, b).
Fig. 19.6
Fixation principle in the ‘hour glass shape’ of the femoral canal. (a, b) The loose fitting nail prevents larger bending deviations, but cannot prevent torsion or shortening in case of fracture comminution. (c) If the nail gets in tight contact with the inner cortex on the narrowest segment of the femoral diaphysis, bending and torsion can be prevented, because of the friction between nail and bone. However, the tight contact between nail and bone must be realized in both fragments. The tight contact and friction can be improved by the realization of elasticity (cloverleaf profile). (d) If the tight contact is realized only in one fragment, bending, torsion, and in comminuted fractures shortening cannot be prevented. (e) Interlocking screws prevent bending, torsion, and shortening, but in loose fitting, still small movements (f) are possible
Elastic Jamming
The other stabilization principle of the classical Küntscher nail is the elastic jamming. A carpenter’s nail is fixed by elastic radial oriented forces from the deformation of the wood. Driving the nail into the wood generates tension. This tension causes a radiate working force. The resultant strength is proportionally of the contact surface between the wood and the nail.
In contrast to the carpenter’s nail the classical Küntscher nail is the part which deforms when inserted in the bone. But the stabilization principle is the same. To raise the elasticity of a hollow nail, a cloverleaf-shaped cross section has been developed. Besides that, a longitudinal slit was added. This does not lead to a significant reduction of the bending strength, but eases nail insertion. However, it does significantly reduce torsional stiffness [46, 47]. The internal mounting as well as the elastic jamming is dependent on the contact of the nail with the bone. Hence, in a native medullary canal a Küntscher nail would stabilize only the area of the isthmus (Fig. 19.6c, d).
Reaming
The diameter of the shaft can be adapted by reaming out. For the intramedullary nailing this has two essential mechanical effects. On the one hand the contact surface between nail and bone increases. This increases the indications for intramedullary fixation, because also fractures above and below the isthmus can be stabilized. Another effect is, that nails with larger diameter and therefore raised stiffness can be implanted. The classical non-locked Küntscher nail neutralizes by its long lever arm bending forces very effectively. However axial and torsional displacement are only prevented by friction between bone and nail.
Interlocking Screws
This is solved with the introduction of interlocked nailing. The principle of the elastic jamming becomes less important, but the importance of internal mounting as a stabilizing principle remains. Now the stability towards torsion and axial forces is mainly dependent on the stability of the screws and the connection of the screws with the bone. Now fractures with long comminution zones can be safely stabilized (Fig. 19.10e, f). Nevertheless, in osteoporotic bone the osseous bolt connection is the weak point of the locking nailing. Now special efforts go for raising the stability of the bolts by surface enlargement [48, 49]. Some nails offer the possibility to introduce a spiral blade instead of the locking bolt [50]. Investigations in osteoporotic distal femoral bone have shown that the application of a surface-increasing blade rises stiffness by 41 % and strength of about 20 % when compared with conventional bolts [51].
It could be shown that a breakage of the locking screws is associated with a higher rate of malalignment [52]. Mechanical tests show that the bolt diameter has significant influence on the fatigue strength of the bone-screw-construct. A 20 % enlargement of the nail diameter led to an increase of the fatigue strength of more than 70 % [53].
Expandable Nails
In recent years expandable nails were propagated for the stabilization of femoral shaft fractures. The mechanical properties of expandable nails are similar to the classical Küntscher nail. The axial stability and torsion stability is based on friction between the nail and the bone. In contrast to the classic Küntscher nail, the unexpanded implant does not jam between bone and nail. Only after activation of the expanding mechanism, the nail jams bone and implant. A variety of expanding mechanisms have been developed (mechanically driven/claws [54], or fluid activated) (Fig. 19.7a–i). Mechanical tests show a lower torsion and axial stiffness and strength compared with the locking nail [54, 55]. In clinical trials, it could be shown that especially comminuted fractures could not be stabilized sufficiently, and that implant removal can be difficult and complicated [56, 57].
Fig. 19.7
Painful non-union after stabilization with a statically locked unreamed femur nail. (a–f) Simple oblique midshaft femur fracture, stabilized with an unreamed femur nail. Despite callus formation no fracture healing within the next 6 months (g, h) Treatment with reaming and large diameter expandable femur nail (Fixion®) without correction of the genuine varus deformity. (i) Uneventful healing after closed intramedullary nailing. Arrows indication a ‘Poller wire’ blocking the initial relatively lateral nail entry portal. This was removed later
Working Length
An important mechanical parameter of an intramedullary nail is its working length. In unlocked nails, the bone is fixed since the elastic nail jams in the medullary cavity proximal and distal the fracture. The working length is the distance between the first stabilization point (proximal jamming area) proximal to the fracture to the first stabilization point distal to the fracture (distal jamming area). According to fracture length and jamming length the working length can vary with unlocked nails considerably.
In locked nailing the working length is the distance between the locking bolts closest to the fracture. The working length influences the stiffness of the system with special regard to bend and torque. The flexural stiffness is inversely proportional to the square of the working length. The torque stiffness is simply inversely proportional to the working length [46]. The flexural stiffness is depending on the external diameter of the nail. Slotted and un-slotted do not differ much concerning their flexural stiffness. Nevertheless, un-slotted nails show a significantly higher torsional stiffness [58].
Nail Deformation During Insertion
During the insertion, the nail is exposed to various bending moments and reacts with bending. Insertion related nail bending can be up to 20 mm, no matter if it’s a slotted or un-slotted nail. However slotted nails show significant insertion related torsion, which was not observed in un-slotted and solid nails [59].
Most important mechanical facts of intramedullary nailing are summarized in Table 19.2.
Table 19.2
Mechanical facts of intramedullary nailing
Bone nails act as internal splints. |
Slotted hollow nails have weak torsional stiffness compared to solid nails |
The flexural stiffness of the nail depends primarily on the external diameter |
Quality of fixation between bone and nail is based on friction/jamming (weak) or locking (strong) |
Friction/jamming of unlocked nails provide weak resistance against the moments of torque and axial forces. |
The locking bolts of the nail counteract against the moments of torque and axial forces. |
Dynamic or Static Locking
Locking nails can be either locked statically or dynamically. In the early times of locking nailing, dynamic locking was performed by leaving the nail either proximally or distally unlocked [60, 61]. Later, the nails showed a longitudinal hole or slot in the proximal part which allowed limited axial migration (shortening) but retained torsional stability [62, 63].
Transverse, short oblique and some wedge fractures with a significant remaining part of the bone tube are suitable for dynamic locking. The dynamic locking is assumed to stimulate fracture healing [64]. For this reason in the early years of interlocking nailing dynamization was carried out quite routinely 6−8 weeks after static locking [61, 65]. However, experimental and clinical studies could show no evidence for routine dynamization [66–68]. That’s why one should be reserved with the routine dynamization, especially if there is good fragment contact obtained by backslap technique (see below). But in fractures which are locked in distraction, in cases with resorption at the fracture fragments, and/or delayed fracture healing, dynamization is still a valid option.
19.5 Techniques of Intramedullary Nailing
19.5.1 Antegrade Nailing
The antegrade insertion is still today the standard in locking nailing. Any femoral shaft fracture can be fixed with the antegrade technique. Distal metaphyseal fractures are less easy and more ‘tricky’ to stabilize with antegrade techniques and frequently need additional support like Poller screws [69, 70]. The primary stabilization of the femoral shaft is an emergency. But even in an emergency situation, pre-surgical planning is essential.
19.5.1.1 Preoperative Planning
Preoperative planning includes exact analysis of the fracture. Techniques for preoperative planning include traditional overlay techniques using a transparent paper sheet, non-calibrated imaging programs (Fig. 19.8) or calibrated planning programs with implant databases (Fig. 19.9).
Fig. 19.8
Preoperative planning (2D overlay technique) using a transparent paper sheet. (a) Radiograph of a segmental shaft fracture (AO.32-C2.2). (b) All major fragments are traced on separate pieces of transparent paper. (c) In this example 4 pieces have been drawn. (d) The axis of the femoral shaft is drawn as a straight line and the 4 fragments are virtually ‘reduced’. (e) Femoral nail and static interlocking screws are added on an additional sheet (From Gösling and Krettek [9])
Fig. 19.9
Preoperative planning with a 2D overlay technique using a digital planning tool. The contralateral side is used as a reference. (a) Radiographs of a multi-fragmentary intertrochanteric fracture in an 18y old female patient. The image is uploaded and calibrated. (b) Each of the main fragments is traced on the computer screen. (c) The fragments get ‘mirrored’ and adapted/‘reduced’ to the shape of the contralateral femur. (d) The fragments are then connected to a single fragment, again ‘mirrored’ and shifted back to the fractured side. Now different implants can be overlayed and analyzed (Reprinted with permission from Gösling and Krettek [9])
Imaging
Radiographs of the whole femur in two planes are essential. They allow the classification and exact localization of the fracture. Fracture type and localization are crucial for implant selection and fixation strategy. Imaging with a C-arm cannot substitute conventional radiographs because of limitations in resolution, distortion, and field of view. If adjacent knee or hip joint is not displayed on the plain films, additional x-rays of the adjacent joints are necessary. Femoral neck and/or condylar (AO.33B) fractures are easily missed and have significant impact on fixation strategy. Un-displaced femoral neck fractures are difficult to see on C-arm images. Nowadays, most patients with femoral fractures have routine CT scans of the trunk, including the pelvis and femoral neck. It is wise to have pre-operatively a critical look to the femoral neck to rule out an un-displaced femoral fracture.
Nail Length
Radiographs of the femoral shaft allow a first guess of the implant length and diameter. Precise measurements are only possible with calibrated images (CT, radiographs with calibration). Studies could show that the use of calibrated rulers with plain radiographs of the femur in 100 cases did not fit the true magnification [71]. Intraoperative measurement of the nail length is unavoidable, except there are CT data. A too short nail cannot stabilize the fracture properly. A proximally too long nail can lead to soft tissue irritation, pain, and heterotopic ossifications. A distally too long nail can penetrate the anterior cortex and irritate the femoro-patellar track, or cause condylar fractures.
Nail Diameter
Especially in unreamed nailing, the choice of the correct nail diameter is essential. A too thick nail can jam or split the femur. A too thin nail does not provide sufficient stability, can cause pain, toggling, malalignment, and healing problems.
Consent
The conscious patient needs to consent beside the general risks of the fracture the specific risks of the antegrade nailing procedure. Among these are an iatrogenic femoral neck fracture, malalignment (length, torsional difference, varus-valgus, ante-recurvatum deformity), nerve and vascular damage, delayed healing, non-union, infection, positioning related risks (nerve damage, pressure sores), pain (hip, knee), gluteal insufficiency, range of motion restrictions of the hip or knee joint, heterotopic ossifications and others (see below).
Antibiotic Therapy
The effectiveness of the preoperative antibiotic prophylaxis has been proven in a recent Cochrane analysis [72]. In closed fractures (patients without additional risk factors) a single shot second generation Cephalosporin is sufficient. The management of open fractures is different (see below).
Positioning: Supine – Lateral – Traction Table
Proper positioning is essential in antegrade nailing. Compromises in positioning can prevent proper approach, starting point, reduction, and nail insertion. Mainly, four different positioning techniques are used: supine without traction table, supine with traction table, lateral without traction table, and lateral with traction table. The supine position without traction table represents the easiest and fastest positioning. It allows the most options for the management of additional injuries in polytrauma patients (parallel surgeries with additional teams).
Traction Table
The traction table was introduced by Gerhard Küntscher and used for intramedullary nailing of the femur. Advantages are (1) the not fatiguing continuous traction, (2) potentially eased reduction procedures, and (3) that the operation can be performed without an assistant.
Disadvantages of the traction table are longer setup time, longer operation room time, longer anesthesia time, and higher rate of postoperative torsional malalignment [73, 74]. There is number of papers describing pressure sores or pudendus nerve damage which can result in erectile dysfunction [75–79] (see below). Table 19.3 is giving an overview of pros and cons of the use of a traction table.
Table 19.3
Pros and cons of the use of a traction table
Advantage | Disadvantage | |
|---|---|---|
No traction table | Easy and quick positioning | Assistant needed |
No extra setup time for traction table | Manual traction | |
Lower rate of postoperative torsional malalignment | ||
Traction table | Continuous, non fatiguing traction | Longer setup time, |
Operation without assistant | Longer OR time, | |
Longer anaesthesia time, and | ||
Higher rate of postoperative torsional malalignment |
Supine Position
In supine position, the contralateral leg is often positioned in an obstetric leg holder to clear the lateral ‘view’ for the image intensifier (Fig. 19.10). Careful positioning of the contralateral leg is essential to avoid positioning related problems (peroneal nerve damage, compartment syndrome) [80–82].
Fig. 19.10
Positioning for antegrade nailing without traction table. Patient is in supine position. In order to make the approach to the proximal femur easier, the pelvis will later be elevated centrally with towels (8–10 cm). In order to stabilize the trunk, the contralateral pelvis and trunk are stabilized with table supporters. This allows elevating the ipsilateral side and gives good access to the proximal femur. The contralateral leg is positioned on an obstetric leg holder in hip flexion, external rotation and abduction. A positioning check with the C-arm is necessary in order to make sure, that anteroposterior and axial views of the proximal femur are possible. These views are crucial for the correct starting point. The lateral view of the entire femur is usually easy to obtain with this setup (Reprinted with permission from Gösling and Krettek [9])
Tan et al. showed a correlation between positioning the leg and increase of the compartment pressure [83]. The compartment pressures were higher in patients with obesity. For this reason, it is advisable in lengthy operations to check from time to time the contralateral side for clinical signs of increased compartment pressures, to move the knee from time to time underneath the draping, and eventually modify and release a bit the position of the leg holder.
Contralateral Leg
Flexible draping of the contralateral leg can serve as an alternative to the positioning in an obstetric leg holder. This has also the advantage to use the contralateral leg as a reference for length and torsion. The disadvantage is, that this contralateral leg needs to be lifted for lateral C-arm views [84].
Lateral Position
The main advantage of lateral positioning is an easier access to the starting point in the piriformis fossa and easier sterile draping. A major disadvantage of the lateral position is limited possibility for clinical examination for torsional differences between the femora. The lateral position is suitable for isolated femur fractures only. For polytrauma patients with spine, chest, brain or other extremity injuries, the lateral position might be an additional risk and might prevent from or hinder additional parallel surgery (Table 19.4).
Table 19.4
Pros and cons of supine and lateral patient positioning
We prefer the supine as the most universal position |
Be aware that positioning the healthy contralateral leg on an obstetric leg holder has a risk for compartment syndrome |
The lateral decubitus is suitable especially for the mono trauma or revision surgery |
The lateral decubitus allows an easier access to the piriformis fossa. |
The supine position without traction table offers the best clinical torsional control. |
19.5.1.2 Entry Point
With the introduction of unslotted nails, the piriformis fossa became the recommended starting point. The piriformis fossa is named after the insertion of the tendon of the piriformis muscle in the medial border of the major trochanter (Figs. 19.11 and 19.12).
Fig. 19.11
Topographic anatomy of the structures relevant for the fossa piriformis approach. Representation of the trochanter major, the piriformis fossa (arrow), the gluteus medius and the piriformis muscles (Reprinted with permission from Gösling and Krettek [9])
Fig. 19.12
Definition of the piriformis fossa starting point. (a–d) The starting point in the piriformis fossa is defined by the intersection point of the axes in the center of the medullary cavity in anteroposterior (yellow) and lateral (red) view. The true lateral image of the femoral shaft demonstrates a quite posterior starting point due to the curvature of the femoral shaft. If starting points are incorrect, they are mostly too far lateral and too far anterior (Adapted with permission from Gösling and Krettek [9])
Definition
However it is important to know, that the entry point of a straight unslotted nail is not defined by the insertion of the piriformis tendon, but by the extension of the center of the femoral canal into the trochanteric region. Is to be noted on this occasion, that (1) the femoral canal shows an antecurvation and (2) the extension of the center of the femoral canal in the trochanteric region is posterior of the piriformis fossa (Fig. 19.12). The stiffer the nail, the less the nail can adapt to the anatomy and the more crucial is the correct insertion point. Proximal femur fractures can compensate less good a suboptimal entry point when compared with fractures in the midshaft region (Fig. 19.13).
Fig. 19.13
Problems with wrong piriformis fossa starting point. (a) With the selection of a starting point which is too far lateral, there is (b, c) a risk of fracturing, or asymmetrically reaming the medial cortex. (d) Due to the pull of the gluteus muscles, this will result in varus deformity, when the nail enters the distal main fragment (Reprinted with permission from Gosling et al. [85])
Risks of a Suboptimal Starting Point
With a too medial entry, there is a risk of an iatrogenic fracture of the femoral neck. A too lateral entry point can lead to a blast out of the medial cortex (Fig. 19.13c). As already mentioned, the correct entry point is essential especially with fractures of the proximal shaft. A too lateral entry point leads here to a varus deformity (Fig. 19.13d) with unfavorable biomechanical conditions for fracture healing.
Adduction Problem
The intraoperative identification of the correct entry point faces several difficulties. With the hip joint in neutral position, the opening wire gets in conflict with the iliac bone (Fig. 19.14). The access to the piriformis fossa is eased with adduction and flexion of the thigh (Fig. 19.15). Adduction however causes considerable tension of the iliotibial tract, causing shortening of the fracture and making reduction more difficult (Table 19.5). Therefore, we recommend after elaboration of the entry point and nail insertion in the proximal fragment a neutral frontal plane position and abduction of the distal main fragment. This releases the ilio-tibial tract and makes the reduction much easier.
Fig. 19.14
Topographic relation between femoral shaft and iliac wing. In a situation of a patient with extended hip joint and neutral ab-adduction, it is impossible to insert a femoral nail through the piriformis fossa into the femoral canal. In females and patients with obesity, the situation is even more difficult (Reprinted with permission from Gösling and Krettek [9])
Fig. 19.15
Positioning for the piriformis starting point in supine position. Flexion and ad-duction enables access in line with the medullary cavity of the proximal main fragment. (a) Fracture temporarily bridged with the large distractor. This allows manipulation into flexion and ad-duction. (b) After skin incision ‘in line’ access to the medullary cavity with the opening wire
Table 19.5
Influence of fragment position for ease of finding starting point and of reduction
1. Starting point and nail insertion | 2. Reduction | ||
|---|---|---|---|
Proximal fragment position | Accessibility to the proximal femur | Distal fragment position | Reducibility (tension of iliotibial tract/shortening) |
Ad-duction | Good | Ad-duction | Not good |
Neutral | |||
Ab-duction | |||
Neutral | Not good | Ad-duction | Not good |
Neutral | Ok | ||
Ab-duction | Good | ||
Muscle Damage
To reach to the desired entry spot, a splitting of the medial gluteus muscle is necessary causing additional muscle trauma, usually contaminated with debris from the medullary cavity. This can result in heterotopic ossifications. In an own retrospective study on 147 patients, 60 % showed heterotopic ossifications, mainly Brooker 1 and 2 [85]. Also a decreased abduction strength of the affected side could be found [86].
Overhang Problem
Another difficulty is that the anatomy of the entry point varies between individuals. In a cadaver study on 100 femoral bones, in more than 50 % of the cases there was a trochanteric ‘overhang’ of the medial aspect of the major trochanter [87].
Trochanteric Versus Piriformis Entry Point Nails
Difficulties with the centric fossa piriformis entry point have directed the attention to an easier accessible lateral eccentric entry point lateral to the tip of the major trochanter. As already mentioned, the use of a relatively rigid straight nail with an eccentric starting point can be dangerous. In 2005 Ricci published details on a so-called antegrade trochanteric nail [88]. The special bend of the proximal nail allowed a more lateral entrance in the major trochanter. Experimental investigations showed a lower soft tissue damage (in particular of the gluteus medius muscle) in comparison to the conventional entry point [89]. Today various models from different manufacturers exist (Fig. 19.16) rising a new problem. The conventional centric entry point with straight nails is independent from the manufacturer. For the lateral entry point nails there are different entry points [90] according to the nail and the proximal bend. In lateral entry point nails, deviations from the exact entry point lead to the same problems as straight nails, and iatrogenic fractures have been reported [91]. Especially with proximal fractures, in doubt a slightly more medial starting point is more forgiving than a too lateral starting point, in order to avoid varus deformity [90]. In a prospective cohort study it could be shown that using the trochanteric entry point nail results in a lower screening time as well as in a trend towards shorter surgery time with the same clinical and radiological results [92] (Table 19.6).
Fig. 19.16
Starting point for Lateral Femur Nail (LFN, Synthes, Oberdorf, CH). (a) In the anteroposterior image, the entry point turned laterally for a certain angle (here 10°) against the femoral shaft axis. The exact distance from the tip of the trochanter depends on the bend of the nail, which varies between the different producers. (b) The entry point in the lateral view is defined by the cross section between middle and posterior third of the trochanter. The anterior cortex is situated on the left, the posterior cortex on the right side of this picture. (c, d) Example of a proximal femoral shaft fracture, which is healed in the meantime. The LFN has the option of inserting two neck screws (Reprinted with permission from Gösling and Krettek [9])
Table 19.6
The key role of the entry point in antegrade nailing
A wrong entry point can lead to alignment problems. This problem increases, the more proximal the fracture is. |
The conventional entry point in the piriformis fossa is defined by the longitudinal axis of the center of the medullary cavity (in anteroposterior and lateral views). |
Lateral femoral nails seem to be easier to insert. Their exact entry point is defined not by anatomical circumstances, but by the given bend of the nail. |
19.5.1.3 Surgical Technique Step-by-Step: Supine Positioning Without Fracture Table
Various techniques exist for antegrade locked nailing. Every surgeon has a favorite technique, depending on the facilities, staff available, and his personal history and experience. The following technique is developed and used in the author’s institution since 1996 [93, 94] and accessible at VuMedi [84].
Positioning
The patient is slightly elevated in the area of the sacrum with an approx. 3−5 cm high upholstering (for example towels). This elevates the pelvis and gives better access from postero-lateral.
Femoral Torsion – Range of Motion of the Contralateral Side
First a clinical rotation check of the uninjured contralateral hip joint with hip and knee in 90° of flexion is done. The values of external/0/internal rotation are noted/stored in the charts and later used for comparison to the fractured side after fixation (Fig. 19.17).
Fig. 19.17
Clinical differences in femoral torsion after a fracture of the left femur. The right leg shows 15° internal rotation and 35° external rotation. The left leg shows −5° internal rotation and 55° external rotation. Therefore this corresponds to a 20° external torsion of the left femur. This examination is done preoperatively on the healthy contralateral side, and then after fixation on the side with the broken femur (Reprinted with permission from Gösling and Krettek [9])
More femoral neck antetorsion leads to internal torsional deformity, less femoral neck antetorsion results in more external torsional deformity of the femur. Femoral antetorsion per se is difficult to measure intraoperatively. Especially in patients with severe comminution in which fracture inter-digitation is not available to help guide rotational alignment, methods are needed to obtain information about the correct femoral torsion.
Femoral Torsion – Lesser Trochanter Shape Sign
In 1998 Krettek et al have described the so called lesser trochanter shape sign. It uses the C-arm image shape of the lesser trochanter of the contralateral side which is stored in the image intensifier’s memory on the non-active screen of the dual display C-arm. This shape is used as a reference for the ipsilateral fractured side [95, 96], (Fig. 19.18).
Fig. 19.18
Lesser trochanter shape sign. Intraoperative fluoroscopic assessment of torsional alignment by comparison of the shape of the lesser trochanter on the ipsilateral and contralateral sides. (a) Preoperatively, before the patient is positioned, the shape of the lesser trochanter on the contralateral side is stored in the image intensifier’s memory while the position of the patella is controlled and oriented strictly in an anterior direction. (b) Before the second main fragment is locked, the patella is oriented in a strictly anterior direction while the proximal fragment is rotated until the shape of the lesser trochanter on the ipsilateral side matches the contralateral shape. (c) In the event of an external rotation deformity, the shape of the lesser trochanter is diminished. With the patella pointing in a strictly anterior direction, the lesser trochanter is partially hidden by the proximal femoral shaft. (d) In the case of an internal rotation deformity, the shape of the lesser trochanter is enlarged. With the patella pointing in a strictly anterior direction, the lesser trochanter is less hidden by the proximal femoral shaft (Reprinted with permission from [95, 97])
Femoral Torsion – Diameter Difference and Cortical Step Sign
Less sensitive and ‘qualitative’ hints for a torsional deformity are differences in the bone diameter and differences in the cortical thickness. The basis for these signs is that the femoral bone is not a complete symmetric structure, but has irregularities. The “cortical step sign” and “diameter difference sign” are qualitative, not quantitative indicators for torsional deformity. The absence of a “cortical step sign” or “diameter difference sign” does not exclude a torsional deformity [95, 96], (Fig. 19.19).
Fig. 19.19
Diameter difference and cortical step sign as indicators for torsional malalignment. The “cortical step sign” and “diameter difference sign” are qualitative, not quantitative indicators for torsional deformity. The absence of a “cortical step sign” or “diameter difference sign” does not exclude a torsional deformity. (a) Radiograph of a femoral shaft fracture with torsional deformity and positive cortical step sign and positive diameter difference sign. (b) Schematic drawing of a femoral shaft fracture with torsional deformity and positive cortical step sign and (c) Positive diameter difference sign. (d) Short segment of a femoral midshaft area arranged in 20° rotation increments representing differences in cortical thickness and diameter difference. In the presence of torsional deformity, the cortical structures of the proximal and distal main fragments have non-matching thicknesses and non-matching diameters. This results in the different diameters and cortical thicknesses proximal and distal the main fracture line (Reprinted with permission from Krettek et al. [95])
Femoral Torsion – C-arm Based Techniques
Other methods are based on femoral neck anteversion measurements. One of these methods is using the C-arm intraoperatively to measure the patients’ normal femoral anteversion angle, and then adapt the fractured side before locking to this accordingly [98], (Fig. 19.20).
Fig. 19.20
Intraoperative femoral neck anteversion measurement. The technique is based on intraoperative C-arm images [98]. (a) Anteversion unbroken side (α): In a first step and before draping the patient, a ‘true lateral’ image of the contralateral normal hip is obtained with the C-arm. In the next step, the C-arm is moved distally and rotated, until the posterior contour of the femoral condyles are ‘in line’. The angular difference between the two positions of the C-arm is the anteversion α of the unbroken side. (b) Anteversion broken side (β): The C-arm is moved to the broken side at knee level. The insertion handle is rotated until it is completely horizontal to the floor. The C-arm is rotated, until the posterior contours of the femoral condyles are in line. Then the C-arm is moved proximally and rotated, until a complete ‘true lateral’ image of the proximal femur can be obtained. The angular difference between the two positions of the C-arm is the anteversion β of the broken side. (c) Adapting the anteversion of the broken side to the unbroken side: There are two ways having manipulative control over the distal and proximal fragment, depending on which fragment is locked first. Both have advantages and disadvantages. Distal locking first: The insertion handle is kept in a strict horizontal position when the C-arm image with the posterior ‘in line contour’ of the femoral condyles is obtained. Then the C-arm is moved proximal and rotated for the amount of angle α (anteversion angle of the unbroken side). If the image is not ‘true lateral, the proximal fragment is rotated around the nail with a Schanz screw until a ‘true lateral’ image of the hip is obtained. During this manipulation, the insertion handle is kept strictly horizontal to the floor. Important, before we do the locking of the proximal main fragment, we adapt the distal main fragment to the proximal main fragment by gentle ‘backslapping’ with the insertion hammer to correct the nail insertion induced diastasis. Pro’s and Cons: This is the author’s preferred modification for standard nails (nails without femoral neck screws like proximal femur nail, gamma nail etc.). It is preferred, because it allows distal locking first. Distal locking first helps to avoid diastasis by the ‘backslapping’ technique. In nailing situations, where a femoral neck screw is needed, the original ‘proximal-locking-first’ technique must be used (see below). 2) Proximal locking first: First, a true lateral image of the hip is obtained. The C-arm is then moved distally and rotated to match the contralateral anteversion angle α. The surgeon stabilizes the proximal fragment by holding the proximal locking jig, while an assistant rotates the distal fragment via the traction pin or foot plate. The distal fragment is rotated until the posterior condyles line up on the C-arm image. The patient’s normal anteversion has now been restored. Then distal locking is performed. Pro’s and Cons: This is the original method [98], which can be used in standard and nails with femoral neck screws (proximal femur nail, gamma nail etc.). However, there is a problem with this technique. In unreamed or single pass reaming situations, the nail tends to ‘push’ the distal main fragment away from the proximal main fragment, which frequently results in diastasis. This lack of contact can result in more load transfer over the bolts rather than the bone and can result in delayed or non-union. With proximal locking first, ‘backslapping’ with the insertion instruments is not possible
Leg Length
In simple fracture patterns, restoration of the preoperative length is determined by the fracture itself. In comminuted fractures, estimation of the correct length can be difficult. In these cases, the correct femoral length can be taken from the contralateral side, either from CT data which might be available or intraoperatively with C-arm based measurements. With the C-arm, the leg length can be measured on the contralateral side radiographically using a radio-dense meter-stick. The upper limit of the femoral head serves as the proximal reference, distally, the distal contour of the medial condyle is used. It is important that the measuring point is positioned in the centre of the C-arm image, because otherwise, projection errors could occur [97, 99], (Fig. 19.21).
Fig. 19.21
Intra-operative femoral length measurement and potential sources of error. In comminuted fractures the judgment of femoral length can be very difficult. Femoral length can be measured with a meter stick and fluoroscopy. It is important, that (1) the target structure (upper end of femoral head, distal end of the medial femoral condyle) are always in the center of the image and (2) the meter stick is held in a consistent way (parallel to the femur). (a) Correct position of meter stick and image intensifier. (b) Oblique position of the meter stick results in a false (too long) measurement. (c) Eccentric display can also result in a false (too short) measurement (Reprinted with permission from Krettek et al. [97, 99])
Management of Contralateral Leg
The contralateral leg is positioned on an obstetric leg holder (Fig. 19.10). The alterative positioning would be with both legs draped. If a lateral view of the fractured leg is needed, the contralateral leg will have to be elevated. The image intensifier is positioned on the contralateral side. Before draping, all necessary C-arm positions are checked.
Draping
The drapes are fixed to the skin in proper ad-duction of the leg in order to be very posterior (Figs. 19.15 and 19.22). This is a crucial step. Sticky drapes do not resist the mechanical stress during intramedullary nailing very well, at least not at the proximal femur. We have changed our protocol some years ago and fix the drapes with sutures or staples (Fig. 19.23a–c).
Fig. 19.22
Positioning, draping, and skin incision. (a) the dotted line on the skin represents the femoral shaft axis in lateral projection. Notice that there is enough space proximal to the trochanter. (b) The skin incision proximal and lightly posterior to the trochanter is adapted to the femoral antecurvation (Reprinted with permission from Gösling and Krettek [9])
Fig. 19.23
Sticky drapes do not hold well. Fixation with sutures or skin staples resists better the mechanical stress during the procedure. (a) Suturing the drapes to the proximal femur. (b) After suturing. (c) After nailing the drapes are still in place
Nail Selection
Nail length and nail diameter can be chosen with the help of metallic rulers with marks for length and diameter. For the nail length and diameter estimation, the surgeon should keep in mind the magnification phenomena, if the ruler is placed between bone and C-arm receiver. In such a setup, the bone is more magnified than the ruler. Choosing the right nail diameter is more difficult and crucial in un-reamed compared to reamed nailing. If the nail is too thick, the nail can get stuck and jammed, or in rare cases split the fracture. A too thin nail has ‘play’ in the medullary cavity, potentially causing instability, malalignment, pain, and healing problems. In doubt, it is more safe to select the next smaller nail diameter that the next larger diameter.
Skin Incision
It is advisable to draw the major trochanter and the axis of the shaft on the skin. The axis of the shaft is continued proximal with the given antecurvation of the femoral shaft. For a piriformis fossa entry point, the leg should be brought in the greatest possible adduction. Depending on the tissue thickness, the skin incision is placed approx. 8 cm proximal of the trochanter in extension of the axis of the femoral shaft. The skin incision should allow the insertion of the nail together with the index finger of the surgeon (approx. 3 cm) (Figs. 19.15, 19.22, and 19.23).
Bone Entry Point (Piriformis Fossa)
The subcutaneous tissue and the fascia are split with the knife, then dissection is continued toward the piriformis fossa. The palpating finger feels the tip of the greater trochanter and stays medial of it. Sometimes the greater trochanter is curved, and the bone starting point is relatively posterior in order to fit the femoral antecurvation. The index finger guides the opening guide wire into the piriformis fossa. In the anticipated correct spot, the guide wire or opening drill is inserted in the bone with a few hammer blows in the longitudinal axis of the proximal femur. The position of the guide wire is checked with the C-arm in anteroposterior an lateral view (Figs. 19.12 and 19.14). Frequently, the first try for the osseous starting point is not perfect. In such a situation, do not remove the wire and try again. Leave the wire and use it as a reference for your second attempt and check again with the C-arm for position and direction of the guide wire (Fig. 19.24).
Fig. 19.24
Piriformis fossa entry point. Entering the medullary cavity with the 3.2 mm guide wire and T-handle. The position of the guide wire is assessed in two planes with the image intensifier. If the position is not accurate, it must be corrected. The first guide wire is left in place as a reference to insert the second wire in a better position [97, 99]
Some producers offer mechanical guides with defined offset options, for the insertion of the opening guide wire (Fig. 19.25).
Fig. 19.25
Mechanical aiming guide with offset options demonstrated on a bone model. (a) Mechanical aiming guide with a spike for fixation into the bone and several options for the placement of the guide wire for the drill for the femoral opening. (b) The device is inserted through the approach and temporarily fixed to the trochanter by inserting the spike into the bone. (c) The device is fixed with one pin, which allows rotation of the device around this pin axis. This allows modification of a more anterior or posterior position. (d) Once the anterior-posterior position is optimized, a pin is inserted. (e) The different device holes can be used to optimize the medio-lateral position. This pin is inserted only superficially, the direction is optimized after the mechanical aiming guide is removed
Opening of the Medullary Cavity
In the early decades of intramedullary nailing, the medullary cavity was opened with an awl. Today, most systems use a guide wire supported reamer with a diameter, slightly above the diameter of the proximal nail end. If position and direction of the guide wire are correct, the large cannulated drill is put over the guide wire and the proximal femur is opened. The cannulated drill is usually forwarded to the level of the upper end of the lesser trochanter (Fig. 19.26).
Fig. 19.26
Opening the medullary cavity over the opening guide wire. Left sided femoral fracture. Reduction was achieved with a femoral distractor. (a) The opening guide wire is in place. The protective sleeve is placed over the guide wire and pushed down to the bone. (b) The cannulated 13 mm drill if brought through the protective sleeve down to the bone. (c) The proximal femur is opened and drilled until the upper level of the lesser trochanter (Reprinted with permission from Krettek et al. [97])
Bone Entry Point (Lateral Entry Point)
With lateral entry point the skin incision is performed approximately 2 cm above the trochanter tip. Subcutaneous tissues are split, usually not much adduction is necessary. The entry point can be identified directly with C-arm control with a guide wire. Some nail manufacturers offer aiming tools for easier identification of the correct starting point (Fig. 19.16).
Nail Insertion
The nail is inserted in the proximal fragment and forwarded to the fracture line.
Fracture Reduction
Reduction is usually one of the more difficult maneuvers during interlocking nailing. The advantages of closed nailing should not be endangered or compromised by opening the fracture for the purpose of reduction. However, the concomitant wound of open fractures can be used for reduction after thorough debridement. Due to the thick layer of muscles around the femur, almost every dislocated femoral shaft fracture is shortened. During the reduction maneuver this shortening needs to be corrected by longitudinal traction. Own intraoperative reduction force measurements have shown, that the force needed to gain original length is more than 400 N [100].
Fracture Displacement
Frequently, longitudinal traction alone is not sufficient to achieve reduction. Inserting muscles with a great variety of force vectors result in various dislocation patterns, depending on the fracture location. These dislocation patterns and force vectors should be kept in mind when planning and executing the reduction maneuvers (Fig. 19.27).
Fig. 19.27
Femur fracture displacement varies depending on fracture level. (a, b) Proximal fractures: the proximal fragment is abducted (gluteal muscles), flexed (iliopsoas muscle) and externally rotated (piriformis, gemelli and obturator internus muscles). The distal main fragment is medial to the proximal main fragment (adductor muscles) and shortened. (c, d) Distal fractures: the proximal fragment is adducted (adductor muscles). Flexion forces (iliopsoas muscle) are neutralized by gluteal and hamstring muscles. The distal fragment is in recurvatum position (gastrocnemii muscles) and shortened (hamstring muscles)
Fracture Deformity in Proximal One Third Fractures
The typical deformity of the proximal fragment is: hip flexion (iliopsoas muscle), hip ab-duction (gluteus medius/maximus muscles), hip external rotation (gluteus minimus, piriformis, gemelli and obturator internus muscles). Slight elevation of the patient’s trunk can neutralize the activity of the hip flexors (Fig. 19.27a, b).
Fracture Deformity in Distal One Third Fractures
The distal main fragment is pulled by the activity of the gastrocnemii muscles, resulting in recurvatum deformity. This can be neutralized by slight knee flexion (bean bag etc.) (Fig. 19.27c, d).
Priority Conflict in Femoral Nailing
Many times surgeons try to get good access to the proximal main fragment by ad-ducting the proximal main fragment. Then they bring the distal main fragment in ad-duction as well in order to get the fracture reduced (Fig. 19.28). However, this last step, the distal main fragment ad-duction maneuver tightens the iliotibial tract, shortens the fracture and this makes fracture reduction very difficult, especially in simple fracture patterns and/or delayed surgery.
Fig. 19.28
Setup on a fracture table with the fractured left leg ad-ducted. Patient positioning on a fracture table. A transverse traction pin is in the proximal tibia. The fractured left leg is adducted. This gives good access to the starting point, but the iliotibial tract is tensioned due to the adduction. This causes shortening which is frequently difficult to overcome during the reduction maneuver (Image with courtesy of Dr. Amir Matityahu, San Francisco, USA)
Our Recommendation: 2 Positions for Access and Reduction
At all levels, the activity of the tensor fasciae lata muscle and the ilio-tibial tract is frequently underestimated and needs to be considered [84].
We suggest the following for fracture reduction: (1) optimize leg position for access to the proximal femur by ad-duction and flexion of the proximal main fragment, not caring about the distal main fragment. And then in step (2) once the femoral starting point is made and the guide wire or nail is inserted into the proximal main fragment and forwarded to the fracture line only then do step 2 and optimize the leg position for reduction process. Let the proximal fragment with the nail inserted swing back in neutral position and then ab-duct the distal main fragment. This significantly reduces the tension in the ilio-tibial tract and allows fine tuning at the fracture level. The fracture manipulation is supported by Schanz screws, one each in the proximal and distal main fragment. This gives good tactile feedback and is used to get tactile information which fragment is anterior and which is posterior. The other plane (anteroposterior or posteroanterior) is controlled by fluoroscopy [84].
Additional Tools for Reduction – Schanz Screws/Joy Sticks
The thigh is usually very thick and because of the thick soft tissue layer it is difficult to get direct control on the bone. The Schanz screws are either already in place from the damage control fixation before. They can then be turned back to clear the medullary canal in the proximal main fragment, but distally stay in place until the guide wire/nail is inserted in the distal main fragment. Another option is to place them posterior to the medullary cavity (the femoral crista thickens the femur posterior). In nailing with not cannulated nails it might be easier to place the Schanz screw in the proximal main fragment when the nail is already inserted in the proximal main fragment. Jamming is then easily recognized at an early stage (Fig. 19.29) [62, 84, 93, 97, 101].
Fig. 19.29
Reduction Tool: Schanz screw as joystick. (a) Schematic drawing illustrating how joysticks allow direct manipulation of the bone. In the proximal fragment the Schanz screw is placed in the posterior quarter in a way, that is does not obstruct the medullary canal. In the distal fragment this is not necessary if the Schanz screw is placed several centimeters distal from the fracture line. In case of non cannulated nail, this allows the nail during the reduction maneuver to enter the distal main fragment. Once it has securely entered the proximal part of the distal main fragment, this Schanz screw can be removed. (b) C-arm images demonstrating the use of a joystick in the distal main fragment in a surgery with a cannulated nail. The joysticks allows good control over the distal main fragment and is easily passed by the guide wire. Later, when the nail is entering the distal main fragment, it can be partially or completely removed (Reprinted with permission from Gosling et al. [85])
Additional Tools for Reduction – Distractor
The large femoral distractor can be also very helpful for manipulation. The flexibility of the system is sometimes a problem. Again, exact placement of the Schanz screws is necessary (Fig. 19.30), [102].
Fig. 19.30
Femoral distractor and Schanz screw placement. (a) Standard arrangement with the proximal screw in anteroposterior direction. (b) Alternative arrangement with both screws from lateral (proximal screw anterior to the femoral canal. The proximal Schanz screw should not interfere with the passage of the nail. The proximal screw is easier to place in anteroposterior than in lateral direction [99]
Additional Tools for Reduction – Reduction Finger
The so called finger allows manipulation of the proximal main fragment and simultaneous manipulation of the guide wire (Fig. 19.31). A hollow manipulation nail with slightly stooped point is introduced in the proximal fragment and can be manipulated with a handle. With the stooped point the surgeon gets tactile feedback and ‘feels’ the bone or the medullary canal of the distal fragment. Then over this hollow ‘finger’ the guide wire can be forwarded into the distal main fragment.
Fig. 19.31
Reduction tool (‘finger’). (a) Demonstration of the so called ‘finger’ (Smith and Nephew, Memphis, TN, USA). It consists of a tube, which is slightly curved and flattened at the tip. The flattened tip should ease catching the other main fragment. A handle is available, which eases the manipulation of the tube. (b) Demonstration of the tube just before entering the other main fragment. (c) After correct placement of the finger, a guide wire for reaming or insertion of a cannulated nail is placed. (d) With the help of the finger and rotation of a slightly curved guide wire, the guide wire can be exactly placed (Images with courtesy from R. Sanders and T. Russell)
Additional Tools for Reduction – Towel Slings
A towel sling can be used as an aid to the manipulation of the distal fragment. The sling can be tightened by a stick, which is placed between the leg and the sling and rotated.
Additional Tools for Reduction – Awl
Also an awl can be used to push main fragments in a desired direction. However, they slip off easy from the hard round bone. An incomplete uni-cortical drill hole might improve the situation.
Exact anatomical reduction is not necessary, especially in fractures with additional fragments. In the diaphysis, the nail is a self-aligning implant. This is not the case in the metaphysis.
Reaming/Over-Reaming
After secure placement of the guide wire in the distal main fragment and fluoroscopic confirmation of correct positioning, the reaming can begin. Some manufacturers allow reading the nail length directly from the guide wire. We recommend always starting with the smallest reamer head, usually a diameter of 9 mm. Due to the irregular shape of the femoral canal even after reaming and due to the not existing ‘transverse elasticity’ of a solid nail it is necessary to ream larger than the planned nail diameter, usually 1–2 mm. The amount of over-reaming depends on various factors like femoral shape, fracture location, nail diameter, nail material and others. A femur with a significant antecurvation needs more over-reaming compared to a situation when the nail shape (bend) fits the anatomy. A thicker nail has less capacity to deform longitudinally and needs more over-reaming than a thin one. The less flexible the nail material is (steel is less flexible than titanium), the more over-reaming is necessary.
Nail Selection
Some manufacturers allow reading the nail length directly from the guide wire, others require the calculation of the nail length from the amount of length of the guide wire outside the bone. Nail diameter is estimated either with the help of fluoroscopy (ruler), from the diameter of the last reamer, or with a sound probe. As mentioned above, a canal size 1–2 mm larger than the nail diameter is recommended.
Nail Insertion
The nail is inserted in the distal main fragment under fluoroscopic guidance. Proximal and distal nail end positions are checked with the C-arm. Frequently, the proximal nail end is difficult to identify on the C-arm image. Some nailing systems allow to mark the level of the proximal nail end with a K-wire through the insertion handle [97].
Sequence of Locking
Especially when an unreamed nail is inserted or when limited reaming is used, the nail tends to push the distal main fragment forward and usually distracts the fracture. It is strongly recommended, after distal locking is performed to slap back on the insertion handle in order to minimize the fracture gap and get the main fragments in contact [84, 97].
Distal Locking with Free Hand Technique
Distal locking can be done with standard power drills. For almost all image based distal interlocking aids it is crucial to have perfectly round locking holes in the center of the image intensifier screen. It is helpful to have as much space between femur and image intensifier as possible. The use of the shortest possible drill also helps for the drilling process. It is helpful to make a starting hole first using an awl or a 3.5 mm K-wire to open the bone first. This diminishes the risk for drill slipping or drill migration on the hard and skewed bone surface. Several tools are available to support this targeting and bone opening process [60, 103, 104].
Distal Locking with Radiolucent Drill Guides
The placement of distal locking holes is made easier with the help of the radiolucent drill guide [105]. The advantage is that the surgeon sees the drill bit and nail hole position and orientation whenever it is needed under image intensification without having the hands in the x-ray beam. But also with this device, it is crucial to have perfectly round locking holes in the center of the image intensifier screen.
Distal Locking with Fixed Aiming Arms
Usually the nail gets deformed (mainly bent) along the longitudinal axis during the insertion procedure. The deformity can reach up to 20 mm [59]. For this reason simple aiming arms fixed to the proximal nail end do not work reliably.
Distal Locking with Deformity Adapted Distal Aiming Device (DAD)
Based on deformity investigations, Krettek et al have developed a Distal Aiming Device (DAD) for tibial and femoral fractures (Synthes) (see Chap. 4) [106, 107]. The system requires contact (anterior contact hole) between the aiming arm and the distal nail end. This allows the aiming arm to compensate the nail deformation.
Number of Locking Bolts
There is a controversy discussion about the number of distal locking screws to be inserted. Some authors recommend the use of a single locking screw [108, 109]. In our protocol, at least two locking screws should be used. This reduces the risk of screw deformation when back slapping and adapting the fracture. It also reduces the risk of locking screw breakage.
Locking Screw Length
Too long locking screws in the metaphysis can irritate the soft tissues and can cause knee pain in up to 10 % [90, 110]. Pure anteroposterior image intensifier views cannot rule out too long screws, since the distal femur has a trapezoid shape. Therefore it is important, to display the distal femur in internal rotation (Fig. 19.32).
Fig. 19.32
The trapezoid shape of the distal femur can hide too long locking screws. (a) Difficult to see in neutral anteroposterior position. (b) In internal rotation the screw over-length becomes visible
Intraoperative Testing for Length
This is required in comminuted fractures and situations, where length cannot be estimated from the reduced fracture situation. The meter stick is placed over the previously defined landmarks under fluoroscopic control. Length is measured and compared to the contralateral side (Fig. 19.21).
Intraoperative Correction of Length
If the femur is shortened, which is usually the case in comminuted fractures, length correction follows by tapping on the insertion handle with hammer blows. In simple A and B type fractures it is advisable to correct even small amounts of sometimes invisible distraction by slapping back with hammer blows on the insertion handle. This adapts the fracture, brings the fragments in load sharing mode, and reduces the risk of bolt breakage (Fig. 19.33).
Fig. 19.33
Backslap technique for fragment adaptation or length correction. Backslap technique for avoiding fragment diastasis. (a) Schematic drawing of a mid-shaft fracture with bending wedge. (b) Friction between nail and the narrow part of the medullary cavity (red lines), especially when inserted in unreamed technique and dense cancellous bone in the distal epiphyseal area (red dots) cause frequently diastasis of the main fragments. This diastasis cannot be prevented or corrected by ‘holding or pushing against it’. (c) This problem is easily addressed by the backslap technique. This includes distal locking first using (preferable) all distal locking options. (d) Then gentle backslapping under fluoroscopic control until the main fragments are adapted or desired length is achieved. (e) Proximal locking according to fracture pattern and localization. In this, case dynamic locking would be sufficient [97]
Intraoperative Testing for Torsional Deformity (C-Arm)
After placement of the distal locking screw(s) the bone-implant construct should be checked intra-operatively for differences in femoral torsion compared to the intact contralateral side. Rough qualitative signs or hints for the presence of torsional deformity can be a difference in the femoral diameter proximal and distal of the fracture and/or a difference in cortical thickness proximal and distal of the fracture. However these indicators are only positive in severe rotational deformities (Fig. 19.19). The analysis with more sensitivity is the lesser trochanter shape sign (Fig. 19.18). In case of relevant intra-individual torsional differences (>15°) corrections should be done. The earlier torsional differences are corrected, the easier it is.
Intraoperative control of torsional alignment can also be done with intraoperative anteversion angle measurement [98], which can be done in two technical modifications.
Proximal Locking
Proximal locking is done using the targeting options of the insertion handle in either static or dynamic mode.
Final Checks
Once proximal and distal locking is complete, details (nail and screw length, position) without instrumentation are fluoroscopically checked in anteroposterior and lateral views. Special attention is put to the femoral neck region in order to look for a potential femoral neck fracture.
19.5.2 Retrograde Nailing
Retrograde intramedullary stabilization has been performed for decades, mainly for intertrochanteric/subtrochanteric fractures with the use of several small diameter nails (Ender-nails, Hackethal nails, Zickel-nails) which were inserted through the condylar region [111, 112].
In 1984, Swiontkowski et al. reported the retrograde implantation of a Küntscher nail through the medial condyle for a combined femoral neck and shaft fracture [113]. Sanders et al. published 9 years later a series of 29 retrograde nailing cases through the medial condyle for patients who were unsuitable for antegrade nailing [114]. They used a slotted, AO universal femoral and later AO universal tibia nails with a bend for a better adaptation in the medial condyle.
In 1991 Henry and in 1993 Lucas et al. published a series of supracondylar femoral fractures stabilized with nails which were inserted through the femoral notch [115, 116]. Later the nails were modified to allow the fixation of supracondylar femoral fractures and femoral shaft fractures. Today, retrograde intramedullary nailing is an established treatment option for femoral shaft fractures [110, 117–120]. All shaft or distal femoral fractures (A32, A33-A) can be stabilized with retrograde nailing. Subtrochanteric fractures are no routine indication for retrograde nails because of the short working length of the nail above the fracture and the limited cortical ‘guidance’.
19.5.2.1 Preoperative Planning
The preoperative planning does not differ from antegrade nailing (see above). The specific risks of retrograde nailing are knee joint infection, postoperative knee pain, retro-patellar arthritis, and knee contracture. The conscious patient needs to consent beside the general risks of the fracture the specific risks of the retrograde nailing procedure.
Positioning
Positioning is less crucial compared to antegrade intramedullary nailing. Supine is the standard position with the most easy access to the knee joint, but in general, retrograde nailing would also be possible in lateral decubitus. The anterior and/or lateral part of the thigh must be accessible for proximal locking. In our view, traction using a fracture table is not necessary. However, there are data describing that tibia traction can save an assistant [121].
There are several options to keep the contralateral leg out of the C-arm view. (1) The contralateral leg can be on an obstetric leg holder (flexion and abduction in the contralateral hip joint) (Fig. 19.10). (2) Alternatively, flexible draping of the contralateral leg and temporary flexion in knee and hip joint allow lateral view fluoroscopy. (3) The contralateral leg can be positioned slightly elevated with some foam cushions, but kept ‘unsterile’ below the sterile drapes. (4) Some operating tables have the option to lower the contralateral leg below the table level.
19.5.2.2 Entry Point
The correct starting point in the trans-articular technique is the intercondylar area in the longitudinal axis of the shaft. This starting point is identified in anteroposterior and lateral C-arm views (Figs. 19.34 and 19.35) rather than relying on anatomic structures. Depending on the curvature of the implant, there are small differences between different implants [122].
