Abstract
The aim of this study was to compare the clinical and radiological outcomes of mandibular angle fractures (MAFs) managed with three-dimensional (3D) miniplates and standard miniplates (according to Champy’s principles). A prospective, randomized, controlled clinical study was carried out on 20 patients with MAFs, divided into two groups. Group A patients were treated with a single 1-mm 3D titanium miniplate; group B patients were treated with a single 2.0-mm standard titanium miniplate. Patients were followed for 6 months for infection, wound dehiscence, segmental mobility, malocclusion, mouth opening, hardware failure, hardware palpability, paraesthesia, and malunion/non-union. A densitometry analysis was performed using DIGORA software on digital panoramic radiographs to evaluate bone healing. Six complications occurred, representing a total rate of 30%. Three complications occurred in group A and three in group B, with identical complication rates of 30%. No major difference in terms of the radiographic assessment was observed between the two systems. The 3D curved strut plate is an effective treatment modality for the management of MAFs, with a complication rate comparable to that found with the standard miniplate. This trial is registered at ClinicalTrials.gov, number NCT01939015 .
Mandibular angle fractures (MAFs) are the most common mandibular fracture, accounting for 30% of all mandibular fractures. MAFs can be defined as a fracture line starting in the area where the anterior border of the mandibular ramus meets the body of the mandible, usually in the region of the third molar. The posterior position and biomechanics of the angle make the treatment of fractures in this region difficult, and not surprisingly MAFs generate more complications than other mandibular fractures. MAFs can also be described as favourable or unfavourable, with a potential effect on the treatment and prognosis. A favourable fracture occurs when the masseter and medial pterygoid muscle action on the proximal and distal segments of the fracture help to reduce it.
The large number of studies on the treatment of MAFs reflects the fact that a consensus has not been reached on a single, ideal treatment method. The scope of these methods is broad, including wire osteosynthesis, a single superior border miniplate (2.0-mm), a single inferior border plate (2.3- or 2.7-mm), two plates (one at the superior border and one at the inferior border), geometric plates, or a lag screw. Despite developments in the treatment of maxillofacial traumas, there is no agreement regarding the best and standard modality in the management of MAFs.
The term ‘three-dimensional miniplate’ is a misnomer, as the plates are not in fact three-dimensional (3D), but hold the fracture fragments rigidly by resisting the forces in three dimensions, namely shearing, bending, and torsional forces. The basic concept of 3D fixation as explained by Farmand is that a geometrically closed quadrangular plate secured with bone screws creates stability in three dimensions. The stability is gained over a defined surface area and is achieved by its configuration and not by thickness or length. The large free areas between the plate arms and minimal dissection permit a good blood supply to the bone.
The 3D plating system for mandibular fracture treatment is relatively new. The use of 3D miniplates in mandibular fractures has not yet become established. In a recently published survey of 104 North American and European AO/ASIF (Arbeitsgemeinshaft für Osteosynthesefragen/Association of the Study of Internal Fixation) surgeons, only 6% stated that they used this type of Plate. Moreover, only a few follow-up series have been presented in the literature, with few studies emphasizing the hardware-related advantages over standard miniplates and reconstruction plates. These advantages include the use of fewer plates and screws as compared to conventional miniplates to stabilize the bone fragments. Thus less foreign material is used and the operation time and overall costs of the treatment are reduced, as described by Zix et al. and Farmand and Dupoirieux. The 1.0-mm thick 3D plate is as stable as the much thicker 2.0-mm miniplate. This offers better bending stability and more resistance to out-of-plane movement or torque. In addition, the simultaneous stabilization of the tension and compression zones makes the 3D plate a time-saving alternative to conventional miniplates. Moreover, this system is simple to apply because of its malleability, compact design, and ease of application, as it requires little or no additional contouring.
The aim of this study was to compare the clinical and radiological outcomes of MAFs managed with standard miniplates used according to Champy’s principles, in which a single plate is fixed onto the superior border of the mandible, and MAFs managed with a 3D miniplate to the lateral aspect of the mandible.
Patients and methods
A prospective, randomized, double-blind, multicenter, controlled clinical trial was conducted from May 2011 to May 2014. A total of 20 patients with isolated mandibular fractures involving the symphysis, parasymphysis, body, or angle were included. The inclusion criterion was a MAF with a maximum 1 cm of displacement. Patients with a preoperative infection, those with comminuted fractures, and those who were medically compromised or not willing to return for follow-up were excluded. The patients were blinded to group allocation and were divided into two equal groups of 10 patients by computer-generated randomization. The allocation sequence was concealed from the researcher enrolling and assessing patients, in sequentially numbered, opaque, sealed and stapled envelopes. One investigator performed the generation of the random sequence and allocation concealment, while the assignment of the patients to the interventions was performed by another investigator.
Group A patients underwent osteosynthesis using 1-mm 3D miniplates (Leibinger GmbH, Germany) ( Fig. 1 ), whereas group B patients underwent osteosynthesis using 2.0-mm conventional miniplates. They were informed of the need for a 6-month follow-up.
The patients were required to provide informed consent or to state refusal to participate in the study. Patient information was documented on a consent form. The study was approved by the institutional ethics and scientific research committees before commencement. This trial is registered at ClinicalTrials.gov, number NCT01939015 .
Surgical technique
All patients underwent general anaesthesia via nasoendotracheal intubation. To obtain pre-injury occlusion, maxillomandibular fixation (MMF) was done by arch bar, screws, or eyelet wiring. The approach to the fracture site was intraoral or transbuccal, depending on the site of the fracture and accessibility. The extraction of teeth in the line of the fracture, including impacted third molars, was performed if indicated. Once proper occlusion was achieved, fractures were fixed with either a 1-mm titanium 3D miniplate or a single 2.0-mm titanium conventional miniplate along Champy’s line of ideal osteosynthesis, using monocortical screws. The 3D plates were placed in such a way that the horizontal bars were perpendicular to the fracture line and the vertical ones parallel to it; the plate was placed in the neutral zone (on the lateral cortex) ( Fig. 2 ). This technique follows the principle of 3D fixation of Farmand and Dupoirieux.
After confirming the pre-injury occlusion and achieving proper haemostasis, the incision site was closed layer-wise using 3-0 Vicryl and 3-0 silk sutures. The duration of surgery, measured from the beginning of plate adaptation to the complete fixation, was recorded for both groups. All patients received intravenous antibiotics from the time of admission until discharge. Following this, patients were prescribed a 3-day course of oral antibiotics. Postoperatively, no MMF was done for 24 h. After that, the status of the occlusion was checked, and if there was any occlusal discrepancy, MMF was done for 5 days. Patients were instructed to maintain a soft diet for 4 weeks.
Assessment
Patients were followed over a period of 6 months with follow-up assessments at 1 week and at 1, 2, 3, and 6 months. The assessor (E.A.) was blinded to the study group and checked for wound dehiscence, infection, trismus, postoperative occlusion, segmental mobility between fracture fragments, hardware palpability, and hardware failure (plate fracture). Malocclusion and hardware palpability were assessed based on patient complaints.
A radiological assessment using panoramic radiographs was performed preoperatively and at 1 week and 6 months after surgery to monitor the pattern of healing at the fracture site ( Figs 3–6 ). Densitometry was performed using DIGORA software (SOREDEX, Finland) by determining two fixed points across the fracture line and measuring the mean bone density value across the fracture line for each patient. Analysis and measurements were performed by the same assessor twice in order to eliminate the intra-observer error; the mean was then calculated and recorded for further statistical analysis ( Fig. 7 ). Parametric data were evaluated by independent samples t -test. Non-parametric data were analyzed by χ 2 test. SPSS version 17 software (SPSS, Inc., Chicago, IL, USA) was used for the analysis; a P -value less than 0.05 was considered statistically significant.
Results
Twenty patients met the inclusion criteria and were included in the study. There were 16 males and four females. Group A comprised eight men and two women; their mean age was 27 ± 0.9 years. Group B comprised eight men and two women; their mean age was 25.5 ± 6.8 years. The aetiology of the fracture was assault in six patients (30%), road traffic accident in 10 (50%), falls in two (10%), and sports injury in two (10%). The mean delay from trauma to admission was 8.2 ± 1.5 days for group A and 8.5 ± 1.4 days for group B.
The mean duration of the procedure (plate adaptation to the definitive fixation) was 39.7 ± 9.1 min for group A and 33 ± 4.6 min for group B. There was no statistically significant difference in operative time between the two groups ( P = 0.141).
There were 19 patients with a tooth in the line of the fracture in the two groups; two third molars in group A and five in group B were extracted during the operation.
All patients in both groups had inadequate mouth opening on the immediate postoperative day. The mean mouth opening at 3 months postoperative was 36.2 ± 1.2 mm for group A and 36.5 ± 1.9 mm for group B. There was no significant difference in mean mouth opening between the two groups ( P = 0.719).
All patients in both groups had satisfactory postoperative occlusion. No case in either group had segmental mobility, paraesthesia, or malunion/non-union. Wound dehiscence occurred in one patient in group B (10%); this was not statistically significant ( P = 0.296). An infection occurred during the first 2 months in one patient in group A (10%) and one patient in group B (10%), which was not statistically significant ( P = 1.000). These infections were treated by drainage of pus, wound debridement, and antibiotics for 5 days. Another patient in group B required plate removal due to an infection that occurred beyond 2 months; additional fixation was not required. Two patients in group A (20%) reported palpable hardware; this was not statistically significant ( P = 0.121). The comparison of clinical outcomes between group A and group B is summarized in Table 1 .
