The 3-dimensional miniplate is more effective than the standard miniplate for the management of mandibular fractures: a meta-analysis

Mandibular fractures (MFs) are the second, most-frequent facial injuries that account for 15.5–59% of all facial fractures [1]. The miniplate osteosynthesis that provides stable fixation contributing to bone alignment and healing was first introduced by Michelet in 1973 and further developed by Champy in 1975 [2]. It is considered as a standard surgical treatment of MFs [3]. However, debates on the stability of this single-miniplate fixation for the repair of the angle fractures remain and two plates in symphyseal or parasymphyseal region have been implied to counter increase the torsional forces [4]. A century ago, an aluminum-made quadrangular plate with bone screws at the lower border of the mandible was recommended by Lambotte and considered being superior to wiring osteosynthesis for the management of MFs [5]. However, due to the lower biocompatibility of the material and the preference of closed reduction, this method has not been widely applied. Thereafter, various plating approaches intraoral or extraoral have been reported to stable internal fixation [6], and the common treatment for MFs is the standard Champy miniplate fixation [7]. Recently, the 3-dimensional (3D) miniplate, which consists of several holes miniplates interconnected by vertical cross struts, has been introduced into the treatment of MFs [8]. Characterized by the geometrically stable configuration, 3D plating system allows the easy adaptation of plate to bone without distortion, which contributes to meeting the requirements of semirigid fixation with lesser complications [9].

Although a spectrum of studies has compared the efficiency of the 3D miniplate and the standard miniplate in the management of MFs [8‐10], the optimum treatment was not defined due to different study designs, small sample sizes, and other factors. More recently, a review has been conducted by Al-Moraissi et al. to test whether there is a significant difference in the clinical outcomes between standard and 3D miniplate fixation in the management of mandibular angle fractures (MAFs) [11]. However, their meta-analysis only included 3 randomized controlled trials (RCTs) and 3 retrospective studies publishing in 2012–2013, and contained a relatively small sample size [11]. Besides, they also clarified the necessity of further investigation to reliably evaluate the postoperative complication rates between these two techniques without the isolation of MAF. Therefore, we retrieved the electronic databases up to August, 2015 and consequently included a set of 9 RCTs and 4 controlled clinical trials (CCTs), which were published in 2010–2015, in this meta-analysis to further compare the efficiency of these two miniplate fixations on postoperative complication rates in the management of MFs, attempting to provide a more reliable conclusion and determine the optimal strategy.

As the paper did not involve any human or animal, the ethical approval was not required.

For the management of MFs, the failure to achieve a stable condition in the right anatomical position that enables the undisturbed healing could result in malocclusion, infection or nonunion [14]. The 3D miniplate has the advantage of the simultaneous stabilization of the tension and compression zones [11], which might contribute to the lower incidence of postoperative complications and the good clinical results [24].

The outcome of malocclusion is evaluated by several studies comparing different miniplates for MFs. However, most of the studies find that there is not any pronounced difference between the two miniplates for MAFs [11, 25, 26], or that the incidence of malocclusion is not detected with both of the two miniplates [20]. While in the present meta-analysis, all the studies concerning the malocclusion [8, 14, 17‐19, 22] showed a relatively lower incidence with the 3D miniplate than with the standard miniplate. Moreover, the combined results indicated that 3D miniplate significantly decreased the incidence of malocclusion (RR 0.43, 95% CI 0.24–0.77, P = 0.004), compared with the standard miniplate. Notably, the combined results of the 9 RCTs indicated that 3D miniplate pronouncedly reduced the incidence of malocclusion, comparing with the standard miniplate. These collectively favored the advantage of 3D miniplate in the management of MFs. Unexpectedly, in the MAF subgroup, although 3D had a reduced effect on malocclusion compared with the standard, the difference was not significant. The plausible reason is that MAF is accounting for 30% of all the MFs, and any additional fracture may cause the instability at the fracture site, which may consequently impair the bone healing and be prone to malocclusion [11, 25]. In addition, in our study, the above studies that concerned malocclusion in our meta-analysis were not MAF, while most studies in the MAF subgroup did not evaluate the malocclusion outcome, which might reasonably explained the undesirable result without significance.

It has been indicated that the infection rate of patients with angle fractures using 3D miniplate was as low as 9% [27] or 8.2% [28]. Nevertheless, different results of the comparison between 3D miniplate and the standard miniplate on the incidence of infection were presented. Several studies observed that the infection rate of 3D miniplate was relatively lower than the standard [9, 23], while others indicated a comparable efficiency between these two techniques [10, 16], which might be due to the excessive implant material [16]. Notably, the pooled results in this meta-analysis exhibited a 23% induction of the incidence of infection rate using 3D miniplate, compared to the standard method, though without significant difference.

Hardware failure is a significant complication of MFs [6]. Although 3D miniplate was testified stable for the treatment of simple MAFs with low complication rates [29], its hardware-related advantages over the conventional miniplates were only emphasized by a small handful of studies [30, 31]. Due to the limited samples, hardware failure is not detected in several cases, therefore, several studies discover that there are no significant differences between 3D and the standard miniplates for the management of MFs [20, 26]. However, a meta-analysis favors the use of 3D miniplate for it could pronouncedly decrease the incidence of hardware failure, when compared to the standard miniplate for the treatment of MAFs (RR 0.18, 95% CI 0.05–0.6, P = 0.005) [11]. In accordance with this study, we found that the incidence of hardware failure, based on the overall result or the MAF subgroup result, was markedly lower using the 3D miniplate than the standard. Notably, when stratified by different 3D miniplate sizes, it was found in other size (8 holes or 10 holes) subgroup, the hardware failure was significantly decreased applying 3D than standard. These collectively supported the superiority of 3D miniplate. Moreover, based on the subgroup analysis by size, it might be inferred that large size of the 3D miniplate with more holes could contribute to the successful treatment.

According to the Champy technique, the standard miniplate needs to be placed on the external oblique line, which leads to the proximity to incision, whereas the 3D miniplate could easily avoid this situation as it is covered by the masseter along the buccal cortex, well away from the incision [15, 21], and this might be the reason for differences between the two miniplates in the incidence of wound dehiscence. The pooled results integrating 6 studies in this meta-analysis indicated a dramatic reduction (64%) in the incidence of wound dehiscence using 3D miniplate than the standard, however, without significant difference (P = 0.07), which might be due to the small sample size.

The displacement of the segments is the major cause that leads to sensory abnormalities. Thus, paresthesia might be detected in all the miniplates after surgery [11]. For most studies that did not detect significant differences between these two miniplates, the pooled results based on 7 studies in the present meta-analysis revealed a minor decrease in the incidence of paresthesia, without significant difference. Moreover, in either of the subgroups stratified by different fracture regions, the results were the same.

Although the study favored the 3D miniplate in the management of MFs and there lacked pronounced heterogeneity, several limitations should be discussed. Although more RCTs and CCTs were included in the present meta-analysis, the sample sizes remained small. Besides, the quality of the CCTs was considered as low for most of them did not mention the blind design. Moreover, several outcomes such as nonunion/malunion, malocclusion, and wound dehiscence need to be further assessed because the incidences of these factors were not detected in most studies. Therefore, more high-quality RCTs with larger sample sizes were required to provide more precise assessment. In addition, 3D miniplate is much more complicated, leads to larger incisions, and has a much higher cost than the standard miniplate. There are a multitude of fractures types among MFs (such as condylar neck fractures, angle fractures, or parasymphyseal fractures); thus, the fracture type being more suitable with 3D miniplate should be deeply explored.

In conclusion, our meta-analysis suggests that 3D miniplate is superior to the standard miniplate on the reduction of postoperative complication rates in the management of MFs. The size of 3D miniplate with more holes (8 or 10) might contribute to the successful treatment. However, more high-quality RCTs are warranted to confirm these findings, and the MF subtype being more suitable with 3D miniplate should be deeply explored.