Background
Intertrochanteric hip fractures are common and, often, devastating injuries especially for the elderly. By 2050, the annual number of hip fractures worldwide is estimated to surpass 6.3 million due to an ageing demographic in many Western countries. In the USA alone, the number of hip fractures is estimated to increase from about 320,000 per year to 580,000 by 2040. This increasing demand creates significant tension for the health service in terms of staff and resources required to manage these patients. In the USA, healthcare costs for the management of hip fractures are estimated to exceed $10 billion per year [
1‐
6], whilst the impact on the UK health service is estimated to be $2 billion per year [
7]. These costs are driven not only by the costs of the acute surgical procedure but also the post-acute care, including rehabilitation. Whilst hip fracture surgery is highly effective, patients are likely to experience significant morbidity in terms of pain, discomfort and limited mobility during their recovery and in many cases are unlikely to achieve pre-fracture levels of function [
1,
4,
7]. Studies also suggest that there is an association between hip fracture and increased rates of mortality with 30% more deaths observed than the age-matched populations with and without hip fracture [
7‐
13]. However, some caution should be taken in interpreting such data, as individuals who experience a hip fracture may be inherently more fragile and susceptible to ill-health.
Currently, intertrochanteric hip fractures are usually treated with intramedullary or extramedullary fixation devices. The known clinical benefits of internal fixation are rapid mobilisation, accelerated rehabilitation and, more importantly, significant pain relief [
14,
15]. However, recent analyses have demonstrated that different devices suit different types of intertrochanteric fractures classified as stable/undisplaced fractures Orthopaedic Trauma Association (AO/OTA) classification A1 or displaced/unstable fractures AO/OTA classification A2 or A3 with the loss of the postero-medial buttress [
16‐
18]. For stable fractures, fixation with a compression hip screws (CHS) has been shown to provide excellent clinical outcomes, whereas for unstable fractures, the use of intramedullary fixation devices have been shown to deliver superior clinical outcomes compared with CHS [
16‐
18].
Two commonly used intramedullary fixation devices for displaced fractures are the proximal femoral nail anti-rotation (PFNA™) (Synthes, Solothurn, Switzerland) with a helical neck blade which provides rotational and angular stability and the TRIGEN
◊ INTERTAN (Smith & Nephew, Memphis, Tennessee) which has a unique design of two cephalocervical screws that interlock and allow controlled linear intraoperative compression of the intertrochanteric fracture and subsequent rotational stability of the head and neck fragment [
1,
14]. A number of studies have been conducted directly comparing these two devices to advise surgeons on device selection and best surgical practice [
14,
19‐
23]; however, the findings of these studies are inconsistent, making it harder for surgeons to identify the ideal treatment option. To address this, we have performed a meta-analysis including all of the current evidence comparing the efficacy of InterTAN with the PFNA.
Discussion
The incidence of intertrochanteric fractures is rising due to a steady increase in life expectancy which in turn increases demand for surgery. With the emergence of value-based healthcare, there is a growing scrutiny of how best to provide high-quality care in a clinically and cost-effective manner, acknowledging limited healthcare budgets [
1,
2]. Our study assessed the clinical performance of two most commonly used cephalomedullary nail devices for patients with unstable intertrochanteric fractures, InterTAN and PFNA, as outlined in our inclusion/exclusion criteria. We however accept that there are other devices which offer twin screw fixation such as the Aesculap Targon PFT® (B. Braun Hessen Germany) or the Orthofix VeroNail® (Orthofix, TX) as well as the other single screw devices such as Gamma 3 which were not the subject of our analysis. The findings from our meta-analysis confirm that InterTAN offers clinically and statistically significant benefits regarding revisions, long-term implant-related failures and post-operative pain compared to PFNA. No differences were observed between InterTAN and PFNA for non-unions and Harris Hip Score. For intraoperative outcomes, there was a difference in blood loss and fluoroscopy usage in favour of PFNA and there was no difference in operating times.
Unstable intertrochanteric fractures treated with cephalomedullary intramedullary devices are commonly associated with mild pain [
14]. However, Yu et al. [
14] proposed that long-term pain arises due to implant failures including lag screw cutout, shaft fractures or lateral protrusions of the distal end of the nail into the diaphysis [
14]. In line with the proposed association between implant failure and long-term pain, our study demonstrated that the use of InterTAN resulted in a significant reduction in implant-related failures and reduced hip and thigh pain (50% fewer patients reported pain
p = 0.0005). Although a direct causal relationship cannot be established from our analysis, it adds further weight to the conclusion by Yu et al. [
14]. A potential explanation for the improved performance of InterTAN arises from its design which includes two integrated, interlocking lag screws that utilise a hybrid worm gear mechanism permitting better intraoperative fracture reduction and controlled compression of the intertrochanteric fracture. In addition, the trapezoidal proximal end of the nail may prevent uncontrolled shortening during fracture healing and limit varus collapse [
1,
14]. Further analysis is required to substantiate the relationship between the mechanism of action and clinical outcomes.
The procedural outcomes identified that InterTAN was associated with a marginal increase in operative time (operation time and fluoroscopy usage) as well as an increase in blood loss. Although the studies did not identify the causes of this, differences in operative techniques associated with each device may explain this. For example, the trapezoidal proximal end of the InterTAN device may require additional reaming of the intramedullary canal, which can result in extended operative and fluoroscopy time. However, the differences seen in the study are marginal when considered in the context of the entire procedure. Similarly, marginal differences were observed in blood loss, which is most likely an association with the longer surgical time associated with InterTAN. Nonetheless, Zhang et al. [
22] cautioned against choosing implants based on these parameters as they are likely to be influenced by other factors, instead preferring to base such decisions on the long-term efficacy of implants.
One factor that impacts complication rates, especially of intramedullary nail implants, is the dimension of the nail, i.e. long or short nails [
22,
31‐
33]. In four out of the six studies, nail dimensions were reported and the range for InterTAN was 18–20 cm whilst PFNA was 20 to 28 cm which are deemed to be short nails. Zhang [
22] and Li [
31] noted that the use of long PFNA nails in patients improved the clinical outcomes compared to short nails especially failure rates and pain. Other authors that have looked at long and short PFNA nails and found no difference in clinical outcomes except for intraoperative outcomes such as operating time and blood loss which favour the smaller nails [
32‐
34]. Although our meta-analysis found significant differences in clinical outcomes between InterTAN and PFNA, we cannot be certain that nail dimension did not contribute to the outcomes. Further research on the relationship between nail length and outcomes would be beneficial.
The study attempted to employ innovative techniques to consider all available relevant data on the performance of InterTAN and PFNA. Systematic reviewing has typically been constrained to the use of randomised controlled trials on the basis that this study design minimises any potential for bias. However, it should be acknowledged that in doing so, RCTs often limit their external validity by applying strict inclusion/exclusion criteria and creating an environment that may not be reflective of typical practice. Whilst observational studies are potentially subject to more bias, they do provide useful insights into product performance in real-world practice settings. Furthermore, in the case of surgical interventions where RCTs are often small in size, observational studies can often provide far larger samples, as is the case with the current study. Methods that can combine these two sources of data remain relatively immature, although there is an increasing body of evidence that has sought to do so in order to make the best use of all available data to inform treatment decisions.
Any uncertainty in the appropriateness of combining datasets can be addressed by considering the different sources of data separately, seeking consistency and running sensitivity analyses based on the single sources of data. In the current study, both the RCT and observational evidence consistently suggested that patients treated with InterTAN have a significantly lower risk of complications than those treated with PFNA, including the risk of revisions, cutout, varus collapse and shaft fractures. The consistency of findings across the studies and the relatively large magnitude of effect, i.e. 73% and 84% reduction in revisions and post-operative complications respectively, increase the credibility of our findings.
There are limitations associated with this study. The trials we included in the analysis suffered from some methodological limitations, as do many other surgical trials. For instance, most of the RCTs included in our analyses had small patient numbers whilst the observational studies, as expected, had bigger patient numbers. This may have resulted in an imprecise estimation of effects from RCTs. We also noted that two of the studies [
19,
22] included both stable and unstable fractures although the majority of fractures were unstable. To complicate things further, the results were not reported according to the stability of the fracture. Clearly, we would have liked the results to have been reported according to fracture stability to be certain which sub-group of patients benefit most from the interventions that they received. We therefore were unable to explore if the treatment effects were influenced by fracture stability in this particular study. Nonetheless when these studies were removed from the analysis in sensitivity analysis, the results remained statistically significant with the treatment effect improving slightly from 84% reduction in implant failures to 87%
p = 0.0001.