Despite the decreasing trends, in comparison with previous decades, of the incidence of proximal femoral fractures,1–3 the actual numbers of these fractures on an annual basis are daunting; in 2013, they approached 268,000 in the United States2,4 and 61,500 in the United Kingdom.5 Their high incidence, high mortality, and subsequent heavy financial burden make them a constant challenge and a subject of continuous clinical research.6–8
Many classification systems have been used to describe them, none has gained universal acceptance, although in clinical practice they are generally divided into intracapsular and extracapsular fractures. The intertrochanteric hip fractures represent a large subgroup (33%–50%) of these injuries, with their higher incidence between the elderly population.9 The AO/OTA classification system defines them as proximal femoral fractures type 33.A1, which are considered stable intertrochanteric fractures; type 33.A2, which are intertrochanteric fractures with unstable medial buttress; and type 33.A3, which are unstable fracture patterns because of either fracture extension below the vastus ridge or a reverse obliquity of the main fracture line.10
A large number of implants have been developed for intertrochanteric fracture fixation. Since the 50s, when the compression/sliding hip screw—side plate concept (SHS) was introduced, it represents the gold standard of extramedullary devices. Intramedullary devices were introduced in the 80s and are typically represented from short or long nails entering from the area of the greater trochanter, with various diameters, anteversion angles, and proximal configuration as far as the size, shape, and number of lag screws. The shaft and the distal end of these nails vary significantly as far as the radius of curvature, width, shape of the nail tip and also the number, location, and method of insertion/guidance of distal locking screws. It is universally accepted that type 33.A3 or unstable fractures are best treated with an intramedullary device, whereas an SHS has been shown to have fewer complication rates and no worse functional outcomes compared with intramedullary devices for more stable fracture patterns.11 Clinical study results do not match biomechanical data suggesting the superiority of a long distally locked cephalomedullary nail over the SHS for the management of “stable” intertrochanteric fractures.12,13 At the same time, a striking increase of the use of cephalomedullary nails, from 3% to 67% over the last 15 years, has been recorded in the United States and in Europe.14 This shift of practice is even more impressive between the younger generation of surgeons, has interesting geographic variations, and in large follows the introduction of third- and fourth-generation nails from most of the implant industries.4
A recent Cochrane Systematic Review detected limited high-quality evidence with mainly inconclusive results pertaining to the use of intramedullary nailing for the management of extracapsular hip fractures.15 Moreover, no conclusive evidence exists on the specific characteristics of intramedullary fixation of these fractures.
However, contemporary understanding of the advantages of intramedullary nailing of extracapsular hip fractures dictates their use for the unstable fractures,16,17 that is, those with reverse obliquity,15,18 with posteromedial comminution, compromised or fractured lateral wall,19,20 and clearly those with subtrochanteric extension.15
This article attempts to summarize the contemporary understanding of the existing biomechanical and clinical evidence on intramedullary nailing of intertrochanteric fractures, as to whether they should be short or long nails spanning the whole length of the femur, and the use or not of distal locking screws.
Short Versus Long
Intertrochanteric intramedullary nailing, in general, refers to an antegrade insertion of a femoral nail with a wider proximal part and proximal slots that allow a single or a couple of lag screws/or a blade to be inserted from the lateral cortex of the femur, passing through the nail slot/s, across the femoral neck, finishing at the subchondral area of the femoral head. The length of such a nail initially was short finishing above the level of the femoral isthmus. However, soon after its introduction in the late 80s, a long version of these nails was produced spanning the whole length of the femoral shaft, ending at the supracondylar region of the femur.21
There is relatively paucity of high-quality evidence to support the use of a long over a short nail for the management of these fractures. Table 1 summarizes the most recent relevant comparative studies. A recent Cochrane Systematic Review detected only 1 randomized trial comparing short versus long nails for the management of type 31.A3 reverse oblique fractures.
A number of authors suggest that long nails may be less likely to refracture than short nails and thus provide a more stable construct. In the review study of Norris et al,22 of 13,568 intertrochanteric fractures from 89 different studies, this advantage of long nails did not reach statistical significance (1.1% vs. 1.7%, P = 0.28); however, they described a clear improvement on the performance of modern long nails versus previous designs.
In the pilot study of Okcu et al,23 the 2 versions of the proximal femoral nail antirotation (Synthes, Oberdorf, Switzerland) were compared in small series of 33 patients. There was no difference between the short and long nail groups in the length-of-surgery, reoperation, blade penetration, superficial/deep wound infection, malunion, length-of-hospital stay, mortality, Harris-hip-score, or Parker and Palmer mobility score. Longer operative and fluoroscopy time in the long nail group of patients was observed. Although the study was underpowered and had a short follow-up, the authors concluded that reverse oblique fractures can be treated effectively with either short or long nails.
Kleweno et al24 compared retrospectively four nail types used in 559 patients with all types of intertrochanteric fractures. Despite its limitations of being a retrospective study and the fact that 20% of patients were lost to follow-up, this study represents the largest series in the current orthopaedic literature comparing short versus long nails. The authors observed similar periprosthetic fractures (2.7% and 1.5% in short and long nails, respectively) and reoperation rates (3.2% and 3.5%) in the 2 groups. The main reason for reoperation in both groups was cutout of the head/neck component. The authors concluded that there is no difference of failure rates between short and long nails for the fixation of intertrochanteric fractures in patients older than 65 years.
Hou et al25 retrospectively reviewed the outcomes in patients treated with short or long cephalomedullary nails after excluding reverse oblique and fractures with subtrochanteric extension. Apart from blood loss and operative time, which were significantly increased in the long nails, all the other treatment-related variables were similar in both groups. No difference was observed in intraoperative complications, union rates, and postoperative complications. Of note is the observation that no difference of the above parameters was evident, even when stable (31A.1) fractures were compared with unstable ones (31A.2). The authors concluded that no clear benefit to the elderly patients is offered by using a long nail in simple and multifragmentary intertrochanteric fractures.
Boone et al26 reviewed 201 patients with type 31A.1 and 31A.2 fractures. The cohort of patients with long nail fixation had statistically significant longer operative time and transfusion requirements. No difference was observed in intraoperative and postoperative complications. Based on the low periprosthetic fracture rate (0.5%), the authors suggested an individualized approach to the management of these injuries based on the patient's anatomy and surgeon's expertise.
Finally, the retrospective series of Vaughn et al27 reported on 256 intertrochanteric fractures of all types and concluded that similar results in catastrophic failures (ie, periprosthetic fractures, proximal fixation failure, and avascular necrosis of the femoral head), should be anticipated from the use of either short or long nails. Significant more minor complications (ie, prominent lag or interlocking screws) were reported for the long nails.
In general, and until any future contradicting evidence, long nails are preferable when longer working length is needed, that is, in comminuted fractures with extension to the subtrochanteric region, or when protection of the whole femoral shaft is necessary, that is, severe osteoporosis, known metastatic lesions, or suspected femoral pathology.
Locked Versus Unlocked
The use of long or even short cephalomedullary nails with and without distal interlocking fixation has been recommended for both stable and unstable intertrochanteric femoral fractures. Intramedullary nails function as internal splints that allow, or even promote, secondary bone healing.28 Intramedullary nails are designed to bear most of the load initially, and then gradually transfer it to the bone, as fracture healing progresses. The load bearing of any intramedullary nailing is largely dependent on the fracture pattern and the achieved reduction. Reaming of the canal and distal interlocking allow the transmission of physiologic loads to the proximal and distal ends of the nail through the screws. In the absence of interlocking screws, the implant transfers axial compaction motion along the longitudinal axis of the nail to the bone. If significant cortical contact can be attained, compressive loads will be supported in large by the bone cortices; however, without cortical contact, all compressive loads will be transferred distally through the nail to the distal interlocking screws, which will resist fracture collapse and length loss until their fatigue failure or fracture healing.28
Distal locking screws for axial and/or rotationally unstable fracture patterns have been found to maintain fracture length, prevent limb shortening, and subsequently increase fracture stability and allow early postoperative ambulation.29–31 Nevertheless, there is a good number of clinical and biomechanical reports that support intramedullary intertrochanteric fracture fixation without any distal interlocking screw/s (Table 2).32–36
Rosenblum et al36 evaluated the proximal strain distribution in locked and unlocked cephalomedullary nails. Eight pairs of fresh, frozen cadaveric femurs, osteotomized to simulate stable 2-part and unstable 4-part intertrochanteric fractures, were axially loaded to 1800 N either in a static locked or in an unlocked mode. The authors found that distal interlocking did not change the pattern of the proximal femoral strain. However, this study did not take into account the dynamic loading conditions, nor the common rotational forces, which represent more the actual clinical scenario of a patient mobilized after fixation.
Kane et al in a series of publications have assessed rotational stiffness in a stable intertrochanteric fracture model. Locked nails provided a statistically significant stiffer construct than unlocked ones in these models, which also resulted in statistically lower yield torque compared with unlocked bone-nail constructs.37 Unlocked and dynamically locked constructs were equivalent as far as catastrophic failure torque magnitude and were found to be superior regarding plastic deformation. The authors suggested that locked distal constructs may fatigue and break earlier when subjected to torsional loading in the clinical setting.33,34 This mode of failure was also described in a clinical series for unstable 33.A3 fractures as an indicator of delayed union or nonunion, often leading to implant failure and revision surgery.38
Lately, the concept of angle stable nailing with toggle-free distal interlocking screws has been introduced to clinical practice.39 Conventionally, toggle of distal interlocking is allowed through the slight intentional oversizing of nail holes of approximately 0.13 mm to limit binding of the screw to the nail hole during screw insertion. As observed in the study of Citak et al,40 in the presence of osteoporosis, this toggle is higher and allows more than 15 degrees of rotation of the femur around the nail under physiologic loading. However, angle stable distal interlocking may cause delayed healing or nonunion by producing a construct of limited load sharing with the bone, putting interlocking hardware into further stress and early fatigue failure.41,42
Alongside of having distal locking screws acting as stress risers that cause subsequent implant breakage, distal interlocking has been associated with soft-tissue irritation, as well as distal, femoral secondary fractures, because of either the large size of the screws for certain smaller femurs22 or as a result of poor insertion technique.43–45 Furthermore, iatrogenic vascular accidents have been reported during screw hole drilling, screw insertion, or when too long of a screw is used. The profunda femoris or superficial femoral artery can be at risk when a short nail is inserted,46 and, as Yang et al47 reported, for some patients presenting with intertrochanteric fractures, the superficial femoral artery is quite close (<10 mm) to the medial femur cortex, while the extremity is held at the usual position of closed reduction of intertrochanteric fractures (ie, internal rotation and adduction).
Technically, distal locking for long nails continues to be a topic, despite the development of numerous devices and techniques (free hand with fluoroscopy, mechanical jigs, nail-mounted mechanical jigs, assisted targeting devices).48 The increased radiation exposure intraoperatively, the prolonged operative time, and the creation of stress risers after mistargeting, or the eccentric insertion of locking screws predisposing to their fatigue failure constitute contemporary concerns relevant to distal interlocking of intertrochanteric fractures.49–51
Currently, distal locking is dictated in intertrochanteric fractures with either severe comminution, or subtrochanteric distal extension, or in the presence of gross osteopenia and ballooning of the femoral diaphysis, to avoid painful toggling of the nail into the diaphyseal canal at the early stages, and malunion in the form of loss of femoral length, malalignment, and rotational deformity.
Cephalomedullary nails, as alternatives to the sliding hip screw for the management of intertrochanteric fractures, have evolved significantly since their first introduction. Currently, the fourth generation of such nails is available, incorporating changes and advances to the initial designs. Clinicians and biomechanical engineers, together with all orthopaedic trauma industry partners, have developed the basic concepts over 3 decades of research.12,15,52,53
The physiologic loading of a nail–bone construct of an intertrochanteric fracture patient treated with a cephalomedullary nail comprises of 3 forces: torsion, compression of the medial aspect of the nail, and tension on the lateral aspect. In the single-legged stance of a walking cycle, the femoral head sustains at least 3 times the body weight of loads because of contracture of the abductors muscles. The load bearing of any intramedullary nailing is largely dependent on the fracture pattern and the achieved reduction.12,28 When cortical contact across the fracture site is achieved, a large portion of the compressive loads will be supported by the cortices; however, in the absence of cortical contact, the compressive and rotational loads are transmitted distally through the nail to the distal interlocking screws. From these basic facts, certain questions arise, that is, to define the actual threshold of axial and rotational stability needed for uneventful healing of a stable intertrochanteric fracture; if this is achieved even without a long nail or without distal interlocking; and also the threshold of failure of unstable intertrochanteric fracture nail–bone constructs.12,28
At the same time, the primary target of a proximal femoral fracture fixation, especially for the frail elderly patients, is mobilization and full weight-bearing as soon as possible after the surgery. Moreover, because the percentage of cognitive impairment of the elderly with a neck of femur fracture is 38% higher than for their peers,54 there are higher chances that any other mobilization advice will not be followed. Thus, implant-bone constructs that allow early full weight-bearing and can outlast the generally delayed healing rates of fractures in the elderly population,55 are required.
The first generations of short cephalomedullary nails have been associated with unacceptable high rates (5%–23%) of perioperative periprosthetic fractures, attributed to nail jamming and abutment to the posterolateral cortex, to their high proximal nail valgus angle, to their excessively large distal diameters, inherent high material stiffness (stainless steel vs. titanium nails), as well as to poor canal preparation and distal interlocking insertion techniques.43,44,56 Subsequently, the use of a long cephalomedullary nail was adopted by many, to avoid such complications, with the additional benefit of spanning the whole femur, in theory, preventing a future periprosthetic fracture. Gradually, the additional concerns of increased blood loss after reaming, elongation of operative time, increased radiation exposure for distal interlocking, effective distal targeting, and anterior encroachment of the nail at the supracondylar region (because of their nonanatomical design with a radius of curvature of ≥2.0), have challenged the use of long cephalomedullary nails, especially for the stable subtypes of intertrochanteric fractures.6,22
Substantial modifications in cephalomedullary nail properties and design characteristics have definitely improved the performance of these devices. The improved characteristics of newer-generation short and long nails include the flexibility of the materials (titanium alloys), replication of the specific anatomic characteristics of the femur from databanks of hundreds of cadavers as far as the radius of curvature, the version and size of the proximal femur, the neck shaft angle, as well as the development of tapered stems and smaller locking screws.22
Unfortunately, high level of clinical evidence does not exist to allow the scientific community to reach safe conclusions regarding the optimal use of cephalomedullary nails, their indications, and clinically relevant advantages over the SHS, at least as far as stable intertrochanteric fractures. The comparison of clinical end points between studies using nails of different generations, designs, and characteristics of the existing meta-analysis remains frustratingly inconclusive.13,15,57
The absence of robust evidence extends also to the specific characteristics of the nails, as far as the 2 aspects of intramedullary fixation of intertrochanteric fractures that were the subject of this article. Despite the fact that the above studies demonstrate that the rates of complications are similar in both long and short nails, caution must be exercised when interpreting these results because of lack of robust evidence. Especially for unstable fractures or those with reverse obliquity (33.A3), it is our belief that there is no adequate evidence to support any deviation from the current practice, which is consistent with the use of a long statically locked nail.
Difficulties on informed consent, recruitment, and follow-up of any cohort of this population for research purposes, because of the high incidence of comorbidities, dementia, high mortality, and dropout rates, may explain the absence of prospective high-quality evidence. Future studies should include functional outcome parameters, radiological outcome, and patient-reported outcomes. A well-designed, large-series randomized trial comparing long versus short nails with or without distal interlocking for the management of intertrochanteric fractures would be beneficial to the clinicians to balance meaningfully their decision making.
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