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Journal of Plastic and Reconstructive Surgery logoLink to Journal of Plastic and Reconstructive Surgery
. 2024 Mar 1;3(2):71–78. doi: 10.53045/jprs.2023-0046

The Treatment of Mandibular Condylar Fractures Using an Internal Distraction Device during a 7-year Period

Taichi Takada 1,✉, Naoya Oshima 1, Yuki Iwashina 1, Mine Ozaki 1
PMCID: PMC11912985  PMID: 40104162

Abstract

Objectives:

Mandibular condylar fractures are common, accounting for approximately 25%-50% of all mandibular fractures. However, the optimal therapeutic method remains controversial. We have used an internal distraction device for treating mandibular condylar fractures for the past 7 years. The aim of this study was to analyze our clinical outcomes.

Methods:

We retrospectively analyzed the medical charts of 62 patients with mandibular condylar fractures (84 joints) treated by internal distraction device fixation from April 2015 to June 2022 at our hospital.

Results:

The patients were 34 males and 28 females (mean age of 49.7 years at surgery). At 3 months postoperatively, the mean mouth opening width was 42.3 mm. Postoperative complications included temporary facial nerve paralysis of a temporal branch (6 patients) and breakage of the device during attachment (22 patients, 24 joints). In all cases in which the device was broken, it was removed within a few weeks, and satisfactory results in terms of mouth opening were obtained.

Conclusions:

This method is recommended as a treatment option for mandibular condylar fractures because of its simplicity and satisfactory results compared with other methods.

Keywords: mandibular condylar fracture, internal distraction device, open reduction and internal fixation, facial nerve paralysis

Introduction

Mandibular condylar fractures are relatively common, accounting for approximately 25%-50% of all mandibular fractures1,2). Such fractures are treated conservatively or with closed reduction because the surgical technique involved in open reduction and internal fixation (ORIF) is complex and entails potential complications such as facial nerve paralysis and salivary gland disorders. However, conservative treatment reportedly can cause a decrease in the length of the mandibular branch on the affected side, resulting in malocclusion, mandibular movement disorder, mandibular deviation during mouth opening, and even temporomandibular joint (TMJ) disorder3,4). It has also been reported that a lack of mouth opening training due to pain and a prolonged period of intermaxillary fixation may each be a factor in the development of TMJ ankylosis5,6). Conversely, some reported ORIFs for a mandibular condylar fracture below the low neck produced better results than conservative treatment7-9). Systematic reviews and meta-analyses suggest that ORIF provides better oral and jaw functional outcomes for treating mandibular condylar fractures in adults, hastening both the recovery of maxillofacial function and the return to social activities, as compared with conservative treatment10-12).

The selection of the ORIF method is largely influenced by the surgeon's experience and preference, making it difficult to objectively compare treatment options. Several methods for treating mandibular condylar fractures have been described by various research groups, and each method has its own advantages and disadvantages. There is still no consensus regarding the use of optional therapeutic methods13). Under these circumstances, we have been using a traction technique involving an internal distraction device14) to treat mandibular condylar fractures in our department since 2006. In this method, the device is attached to the articular tubercle of the zygomatic arch and mandibular angle. The mandibular branch is pulled for several months as a consolidation period to prevent the anatomical shortening of its length and morphological remodeling of the TMJ. Reports on the application of ORIF have found that the indication for surgery is determined according to the location of the fracture site, whether it is at the base or lower neck of the mandibular condyle15,16). In contrast, our method can be performed regardless of the fracture site and type, with a low risk of complications and minimal invasiveness17). In this study, we retrospectively analyzed the clinical outcomes of 62 cases (84 joints) of mandibular condylar fractures treated with an internal distraction device between 2015 and 2022. Additionally, we examined the treatment options for these cases and discussed pertinent literature on the subject.

Methods

Patient profiles

Sixty-two patients with mandibular condylar fractures (84 joints) who sought consultation at our department between April 2015 and June 2022 and who underwent a surgical procedure using an internal distraction device were enrolled in this study. The procedures were applied to cases in which TMJ function could not be restored with conservative treatment and closed reduction. The patients were 34 males and 28 females ranging in age from 8 to 83 years (mean, 49.7 years). The fractures were unilateral and bilateral in 40 and 22 patients, respectively. As depicted in Figure 1a, b, the patients' fracture sites were classified based on the system described by Kubo et al. (Figure 1a)18) as “head” (n = 2), “upper neck” (n = 36), “lower neck” (n = 27), and “base” (n = 19). The fracture types were classified based on the system described by MacLennan (Figure 1b)19) as “no displacement” (n = 6), “deviation” (n = 17), “displacement” (n = 21), “deviation-dislocation” (n = 5), and “displacement-dislocation” (n = 35). Other facial fractures associated with mandibular condylar fractures included mandibular body fractures (n = 32); zygomatic arch fractures (n = 2); LeFort I, II, and III fractures (n = 1); Lefort I fractures along with mandibular body fractures (n = 2); LeFort I and II fractures along with mandibular body fractures (n = 1); and zygomatic and mandibular body fractures (n = 1). We retrospectively analyzed these cases with regard to the final mouth opening distance data, complications, and breakage of the internal distraction device.

Figure 1.

Figure 1.

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Schematic of the fracture sites and types of mandibular condylar fracture.

a: The mandibular condyle is a mandibular subunit defined by an oblique line running backward from the sigmoid notch to the upper masseteric tuberosity. The mandibular condyle consists of four subregions: the head, the upper and lower parts of the neck, and the base (Adapted from Kubo S et al. Japanese Journal of Oral and Maxillofacial Surgery. 1983; 29: 1794-805).

b: The types of mandibular condylar fractures are classified as follows. “No displacement” indicates no deviation of the bone fragment. “Deviation” indicates that fragments are in contact with each other and the mandibular head remains within the joint. “Displacement” indicates that fragments are not in contact with each other and that the mandibular head remains within the joint. “Dislocation” is defined as the mandibular head escaping from within the joint (Adapted from MacLennan WD et al. Br J Plast Surg. 1952; 5: 122-128).

Operative technique

The internal distraction device (NAVID System 3D, Medical U&A, Osaka, Japan) consisted of three parts: a shaft (Figure 2a), a fixation plate (Figure 2b), and a movable plate (Figure 2c). The lengths of the shafts used were 75, 95, and 115 mm, depending on the patient's facial size and morphology. Intermaxillary fixations were routinely performed in a standard manner before the device was attached. In cases with other associated fractures and condylar fractures, these associated fractures were remedied before condylar fractures treatment. Skin incisions were made at the posterior margin of the sideburn and at a finger-width below the inferior margin of the mandibular angle. The articular tubercle of the zygomatic arch and the mandibular angle were exposed through them to allow the placement of a plate at each of these sites. The device was fixed to the articular tubercle of the zygomatic arch with a fixation plate and to the mandibular angle with a movable plate (Figure 3). The shaft of the distraction device was passed subcutaneously through each incision. During this procedure, the device was set parallel to the mandibular branch.

Figure 2.

Figure 2.

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Photo of the internal distraction device. a: The shaft, which is available in 75-, 95-, and 115-mm lengths; this is the 95-mm length. b: The fixation plate, which consists of a plate with three screw holes, a hinge section, and a socket. The fixation plate has two variable directions. c: The movable plate, which consists of a plate with four screw holes, a hinge section, and a socket. The plate has one variable direction.

Figure 3.

Figure 3.

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Photo of an internal distraction device fixed to a skull model. The fixation plate is fixed to the articular tubercle of the zygomatic arch, and the movable plate is fixed to the mandibular angle.

Intermaxillary fixation was temporarily released, and the part of the shaft outside the wound at the mandibular angle was rotated so that there was an approximately 2-mm gap between the maxillary and mandibular molars on the affected side. Intermaxillary fixation was performed again before the surgery was completed. Computed tomography (CT) was performed within 1 week postoperatively to evaluate the positional relationship between the device and the mandibular condyle on coronal section images. In cases where the gap between the mandibular fossa and the mandibular condyle was less than 2-3 mm, the appropriate length of distraction was achieved using the outside shaft. The outside shaft was then cut off from the mandibular angle. Intermaxillary fixation was maintained continuously for 1 week postoperatively, followed by only nighttime fixation for 1-4 weeks, depending on the state of reduction. During the attachment of the device, periodic facial CT and orthopantomography examinations were performed to monitor the position of the condylar head and to confirm whether the distraction device had broken. The device was removed approximately 4 months after attachment.

Results

The average mouth opening width at the 3-month postoperative mark was 42.3 mm, as observed in 48 patients for whom confirmed records of mouth opening were available at that specific time point. Mouth opening width improved in all 62 patients. Among them, two patients had a mouth opening width of only 30 mm at 6 months postoperatively. Temporary paralysis of the temporal branch of the facial nerve was recognized in 6 of the 62 patients, but 5 of those 6 patients recovered completely within 6 months after surgery. A 53-year-old female patient achieved a 45-mm mouth opening at 6 months after surgery; however, she had residual unilateral incomplete paralysis of a temporal branch even at 4 years after surgery. At 4.5 years after surgery, she underwent an eyebrow lift with threads.

Two cases of subjectively perceived malocclusion were observed. Neither TMJ ankylosis nor salivary gland disorders were observed in any cases. The internal fixation device broke during its attachment in 22 patients (24 joints) of the total series of 62 patients (84 joints) (Figure 4). These 22 patients were 15 males (17 joints) and 7 females (7 joints) with a mean age of 53.45 years (Figure 5). Of the 24 devices that broke, 21 broke at the hinge of the movable plate (Figure 6a), and the remaining 3 devices broke at the hinge of the fixation plate (Figure 6b). The average time until breakage was 69.1 days (Figure 7). Of the cases in which breakage occurred, only one required surgery to attach a new device, which occurred on the 19th postoperative day. In all other cases of breakage, the device was removed within a few weeks after it was broken, and clinically satisfactory results were nevertheless obtained.

Figure 4.

Figure 4.

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The numbers of internal fixation device breakage and no-breakage cases by age.

[footnote] Device breakage during implantation occurred in 22 cases (24 joints) out of a total of 62 cases (84 joints).

Figure 5.

Figure 5.

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The numbers of cases of internal fixation device breakage by gender and age. [footnote] There were 15 male patients (17 joints) and 7 female patients (7 joints), with a mean patient age of 53.45 years.

Figure 6.

Figure 6.

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Intraoperative findings. a: A movable plate damaged at the hinges. b: A fixation plate damaged at the hinges.

Figure 7.

Figure 7.

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The numbers of patients and the numbers of days until breakage were identified. [footnote] For patients whose device broke more than 30 days after surgery, the device was removed as soon as the breakage was identified and still satisfactory results were later obtained.

We also observed 10 cases (11 joints) in which the shaft was pulled out of the socket of the fixation plate during device attachment (Figure 8) and 1 case (1 joint) in which the shaft was pulled out of the socket of the movable plate. The fixation plates in the three cases spontaneously came off the articular tubercle of the zygomatic arch.

Figure 8.

Figure 8.

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3D-CT findings of the case whose shaft was disconnected from the socket of the fixation plate.

A two-dimensional scatterplot of the final width of mouth opening against the duration of the attachment of the device indicates a poor correlation (Figure 9). The Pearson product-moment correlation coefficient between these two variables was 0.132.

Figure 9.

Figure 9.

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A two-dimensional scatterplot shows the relationship between the duration of device attachment and the width of mouth opening. The finally measured mouth opening width was defined as the value. [footnote] Red dots indicate cases with damage or dislodgement, and blue dots indicate cases without damage or dislodgement.

Representative case

A 26-year-old male suffered from bilateral mandibular condyles and mandibular body fractures because of a motorcycle accident. His symptoms were malocclusion, indicating an anterior open bite, and trismus (Figure 10a, b). The proposed method was performed 13 days after the accident (Figure 11a, b, c). During the attachment of the devices, including the period of intermaxillary fixation after the completion of the intermaxillary fixation, he had good occlusion and no problem with food intake. Four months after the first surgery, the devices were removed. Six months later, his mouth opening width was 43 mm (Figure 12a, b).

Figure 10.

Figure 10.

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Case: 26-year-old male who suffered from bilateral mandibular condyles and body fractures. a: Imaging findings of the coronal section of a CT scan. This image shows bilateral mandibular condyle fractures. b: Anterior open bite is shown.

Figure 11.

Figure 11.

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Intraoperative, imaging, and examination findings. a: Intraoperative photograph taken immediately after the attachment of the internal distraction device. b: Postoperative coronal section of a CT image. c: Postoperative 3D CT image.

Figure 12.

Figure 12.

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Clinical findings at 6 months after the removal of the device. a: Malocclusion was improved. b: The mouth opening widths were sufficient, and the width achieved was 43 mm.

Discussion

Factors to be considered when selecting a method for the treatment of a mandibular condylar fracture include the difficulty of securing the surgical field for ORIF, the risk of facial nerve injury, the cosmetic appearance of the surgical scar, and the expected postoperative jaw movement function15,20). One of the advantages of internal distraction device fixation is the minimal exposure of the surgical field necessary for plate fixation. With the exception of highly obese patients, the approach to the articular tubercle of the zygomatic arch and mandibular angle is easy and does not require facial nerve identification.

Regarding the risk of facial nerve injury, ORIF causes temporary facial nerve palsy in 8.3% and permanent facial nerve palsy in 0.3% of cases, according to a meta-analysis reported by Guerrero et al.21). In the present case series, comprising all patients treated with internal distraction device fixation, temporary paralysis of the temporal branch of the facial nerve occurred in 5 of the 62 patients (8.1%) and permanent incomplete temporal branch paralysis occurred in 1 of the 62 patients (1.6%), the occurrences of which were similar to those of ORIF.

Regarding the cosmetic aspect, our method results in a 2-cm-long scar at the posterior margin of the sideburn and a 3-cm-long scar at a finger-width below the inferior margin of the mandibular angle. The lengths of scars resulting from internal distraction device fixation were considered comparable to those of other surgical techniques22).

In the meta-analysis by Guerrero et al., malocclusion occurred in 11% of cases with conservative treatment and in 4% with ORIF21), whereas in our case series, it occurred in 3.2% (2/62 cases) following internal distraction device fixation. Thus, the malocclusion development rate of internal distraction device fixation is assumed to be similar to that of ORIF.

Vanpoecke et al. reported that 28 of 84 patients had mouth opening widths of less than 40 mm at 3 months after injury with conservative treatment alone23). Guerrero et al. described in their meta-analysis that the mean mouth opening width with conservative treatment alone was 41.6 mm and that with ORIF was 41.4 mm21). Our outcome (a mean of 42.3 mm at 3 months postoperatively) is comparable or slightly superior to these outcomes. We also observed two patients with only a 30-mm mouth opening at 6 months postoperatively. The average mouth opening widths in men and women in Japan are 55.5 and 50.6 mm, respectively24), and these two patients would be diagnosed as having trismus by definition, which is a width <40 mm25). Both of them were over 70 years old. Thus, advanced age could be a risk factor for poor functional outcome associated with the internal distraction device fixation procedure.

In this study, device breakage or shaft dislodgement from the socket of either plate occurred in 36 of the 62 patients. Device breakage or dislodgement did not seem to be directly associated with poor mouth opening outcomes (Figure 9). However, when it was broken or dislodged, an unusual noise was observed in six patients and one patient experienced pain upon mouth opening. The longer the device remains in the patient, the more likely it will break. This is an unavoidable complication as it relates to the strength of the medical instrument. However, the scatterplot of mouth opening against the duration of device fixation (Figure 9) indicated that at least 1 month of fixation could be sufficient for a satisfactory outcome. By contrast, we attribute the dislodgement of the device to a technical error rather than to the device's design. The shaft becomes disengaged from the fixation plate by rotating the shaft counterclockwise for approximately five revolutions. Therefore, when the movable plate is moved toward the mandibular angle along the shaft up to the optimal position, it is necessary to rotate the movable plate itself but not the shaft. However, if the surgeon rotates the shaft when trying to move the movable plate upward, it can dislodge the shaft from the fixation plate. This complication can be prevented by rotating the movable plate at the mandibular angle while the surgeon holds the shaft tightly. In any case, both breakage and dislodgement of the internal distraction device are considered major problems of the present method.

The results of the present study suggest that the internal distraction device fixation procedure is useful as a treatment option for mandibular condylar fracture while minimizing the risk of facial nerve injury, the appearance of the surgical scar, and the impact on postoperative jaw movement function. Conversely, it entails risks associated with the device. On the basis of the results of this study, we propose the following therapeutic strategy: If the internal distraction device can be kept in place for at least 1 month after surgery, the purpose of this method is fulfilled and the consolidation period of 3-4 months proposed for this method17) can be shortened. Whether the device should be reattached after it breaks within 1 month is a matter for further research.

In principle, the internal distraction device fixation procedure requires two surgeries, which is also one of the disadvantages of the method compared to the other ORIF methods. However, this method has been performed at several institutions, including ours, with similarly good results compared to other methods21-23). We believe that it is a good therapeutic option for mandibular condylar fractures.

Summary

Compared with standard ORIF procedures, the method described in this study is characterized by simplicity, lower risk, and reduced invasiveness. However, breakage and dislodgement of the device are serious problems. Another disadvantage is that this method requires two surgeries under general anesthesia. The method can still be considered a treatment option for mandibular condylar fractures because it provides excellent results that are comparable to those of other more invasive methods.

Author Contributions: TT wrote the manuscript. MO, NO, and YI supervised the study. All of the authors were involved in the patients' treatment.

Conflicts of Interest: There are no conflicts of interest.

Ethical Approval: Not applicable.

Consent to Participate, Consent for Publication: The patient gave his fully provided informed consent to be treated by this method and to publish his case and images.

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