Analysis between Retromandibular and Periangular Transmasseteric Approach for Fixation of Condylar Fracture - A Prospective Study.

INTRODUCTION: Condylar fractures make up for an average of 17.5%-52% of all mandibular fractures. The aim of the present study was to compare the ease, success, and complications between retromandibular and periangular transmasseteric approaches when used for open reduction and internal fixation of condylar fractures.
MATERIALS AND METHODS: A total 20 cases with condylar fracture, ten each for retromandibular and periangular transmasseteric approach, were included in the study. Patients were evaluated at 1 week, 1 month, 3 months, and 6 months. Postoperative occlusion, maximum mouth opening, range of movement, facial nerve function, visibility, convenience of plating, and time taken for exposure, fixation, and closure were recorded. Incidence of complications such as wound dehiscence, wound infection, hematoma, sialocele formation, Frey's syndrome, and hypertrophic scars were also evaluated.
RESULTS: The mean exposure time in the retromandibular approach was 10 min 31 s and 9 min 17 s in the periangular transmasseteric approach. The incidence of facial nerve injury was 2 of 10 patients in the retromandibular group and 3 of 10 patients in the periangular transmasseteric group, all of which resolved within 6 months. The incidence of sialocoele was 2 of 10 in the retromandibular group. The time taken for exposure of the fracture site was statistically significant between the two approaches (P = 0.048) with longer time required for retromandibular approach. DISCUSSION: It can be summarized that both the approaches are comparable and well suited for surgical management of condylar fractures. It was observed that in displaced condylar neck fractures, greater difficulty was experienced in the periangular transmasseteric approach than the retromandibular approach. Copyright:

INTRODUCTION

Condylar fractures make up for an average of 17.5%–52% of all mandibular fractures.[1] The most common causes of condylar fractures include road traffic accidents, personal violence, and fall from height.[2] It has been noted that the condylar fractures are the most controversial fractures regarding their management.[3] The decision for open reduction and fixation relies on the age of the patient, unilateral or bilateral fracture, level and displacement of the fracture, and presence of teeth.[1] Despite being the choice of most surgeons, the closed reduction has certain disadvantages such as malunion, deranged occlusion, and inappropriate function of the temporomandibular joint (TMJ).[4] Open reduction and internal fixation (ORIF) facilitates rapid return to pretraumatic function and a protected airway in asthmatic or epileptic patients.[5] The reported complications associated with surgical approach include infection, neurovascular injury, and scar formation.[6]

Earlier Zide and Kent introduced indications for open reduction of condylar fractures.[7] Other established criteria include severely displaced (>45° in the coronal or sagittal plane) fracture, 2–5 mm overlap leading due to shortening of the ramus when no other means can correct the deformity (class three molar relation and apertognathia).[8]

Numerous surgical approaches have been proposed for the treatment of condylar fractures: submandibular, preauricular, retroauricular, periangular, rhytidectomy, intraoral, retromandibular, and combinations thereof. An ideal surgical approach for the treatment of mandibular condyle fractures should have good accessibility and visibility with minimal trauma to the neurovascular structures which can be avoided with an endoscopic intraoral route.[910]

The purpose of this study was to compare the accessibility according to the level of fracture and complications encountered in retromandibular and periangular transmasseteric approach.

MATERIALS AND METHODS

This prospective study included a total of 20 cases with a condylar fracture who reported to the Department of Oral and Maxillofacial Surgery of a teaching hospital in Meerut. The patients were randomly allotted into two groups of ten fractures each. Group 1 represented retromandibular approach, whereas Group 2 represented periangular transmasseteric approach. The study was conducted in accordance with the World Medical Association Declaration of Helsinki. Patients were evaluated clinically and radiographically pre- and postoperatively at regular interval till 6 months. Patient's demographic data, level of fracture, maximum mouth opening, malocclusion, and TMJ function were recorded. Operators graded the visibility and convenience of plating. Visibility was graded as good when anterior and posterior border and the superoinferior view of the surgical field was adequate, fair when the visibility of the anterior border was compromised, and poor when the exposure was too limited to visualize the fracture line. The time taken for exposure of the surgical site and fixation was recorded. Postoperative complications such as infection, wound dehiscence, sialocele formation, Frey's syndrome, scar formation, and paralysis of the facial nerve were recorded.

Surgical technique

Retromandibular approach (Group 1)

A standard retromandibular approach described by Hinds and Girotti in 1967 was followed.[11] A 3–4 cm incision, 5 mm below the earlobe, was made parallel to the posterior border of the mandible. A blunt dissection was carried out in superomedial direction till the capsule of the parotid gland and a suture was passed through the two cut sides to facilitate watertight closure and thereby prevent sialocele formation [Figure 1]. The gland was bluntly dissected with a curved hemostat in an anteromedial direction, parallel to the direction of the branches of the facial nerve. After identification of the posterior border of the mandible, pterygomasseteric sling was incised. The fibers of masseter muscle were stripped to gain exposure of the fracture site till sigmoid notch.

Figure 1

Suture through the substance of parotid capsule in the retromandibular approach

Periangular transmasseteric approach (Group 2)

A technique defined by Wilson et al. for transmasseteric approach was followed which is approximately 4 cm long curvilinear incision, 5 mm below and along the angle of the mandible[1213] [Figure 2]. After skin incision, dissection was continued in the subcutaneous plane, upward and superficial to the platysma till the zygomatic arch. The thin platysma muscle is held with tissue holding forceps and incised obliquely to expose the masseteric fascia overlying the masseter belly [Figure 3]. The area adjacent to the anterior edge of the parotid gland is relatively free of the branches of the facial nerve and hence ideal for further dissection. The parotid tissue was retracted posteriorly with retractors positioned horizontally, and the belly of masseter muscle was incised parallel to the fibers of the branches of the facial nerve to expose the periosteum. The periosteum was incised and the direction of retractor changed vertically to retract masseter in an upward pull manner to expose the fractured segment.

Figure 2

Incision marking for periangular transmasseteric incision

Figure 3

Exposure of masseter muscle in the periangular transmasseteric approach

The fixation of the fracture segments was performed as per the Meyer's line of osteosynthesis with either two miniplates or geometric three-dimensional plates[14] [Figures 4 and 5].

Figure 4

Fixation of fracture site with delta plate in the retromandibular approach

Figure 5

Fixation of fracture site with trapezoidal condylar plate in the periangular transmasseteric approach

RESULTS

The present study included 15 (75%) males and five (25%) females with a mean age of 29.2 ± 12.6 (range, 15–53 years). Road traffic accident was the most common (60%) cause, followed by fall from height in 30% of the cases and interpersonal violence in 10% of the cases.

Fourteen cases were associated with parasymphysis fracture, one case with contralateral mandibular body fracture, and one case with an ipsilateral zygomaticomaxillary complex fracture. Four cases reported with isolated condylar fractures. Bilateral condylar fracture was observed in four cases.

Group 1 included one (5%) condylar head, seven (35%) condylar neck, and two (10%) condylar base fractures. Group 2 included two (10%) condylar neck and eight (40%) condylar base fractures [Table 1].

Table 1

Fracture level

Level of fracture	Frequency (number of cases)	Total (%)
Condylar head
Group 1	1	1 (5)
Group 2	0
Condylar neck
Group 1	7	9 (45)
Group 2	2
Condylar base
Group 1	2	10 (50)
Group 2	8

Deviation with medial overlapping segments was seen in three (15%) cases, deviation with lateral overlapping segments in 11 (55%) cases, and deviation without overlapping in six (30%) cases. It was observed that Group 1 included three fractures with medial overlap, six fractures with lateral overlap, and one with no overlap between the segments. Group 2 included five fractures with lateral overlap and five fractures with no overlap [Table 2].

Table 2

Deviation and displacement

Change	Group 1	Group 2	Total (%)
Deviation with medial overlapping segments	3	0	3 (15.0)
Deviation with lateral overlapping segments	6	5	11 (55.0)
Displacement without overlapping	1	5	6 (30.0)
Total			20 (100.0)

In Group 2, lateral overlap >5 mm was observed in five cases and five cases experienced anteromedial displacement >40°.

The visibility and accessibility in Group 1 was good for 70% of the cases, fair in 20% of the cases with a medially displaced condylar neck fracture, and poor in 10% of the cases with a medially displaced condylar head fracture. The convenience of plating in Group 1 was good for 60% of the cases, fair in 30% of the cases, and poor in 10% of the cases [Table 3].

Table 3

Visibility and convenience of plating

	Good	Fair	Poor	P
Visibility
Group 1	7	2	1	>0.05 (0.231)
Group 2	3	6	1
Convenience of plating
Group 1	6	3	1	>0.05 (0.305)
Group 2	3	2	5

In Group 2, visibility and accessibility was good for 30% of the cases, fair in 60% of the cases, and poor in 10% of the cases. The convenience of plating in Group 2 was good for 30% of the cases, fair in 20% of the cases, and poor in 50% of the cases of condylar neck fracture with displacement.

Miniplates were utilized for fixation in eight cases of Group 1 and Group 2 each. Delta plates were used in two cases of Group 1. Trapezoidal condylar plate and strut plate were used in one case each of Group 2 on random selection [Figures 6 and 7].

Figure 6

Bilateral fracture fixation with two miniplates and delta plate through retromandibular approach (radiograph)

Figure 7

Fixation with trapezoidal condylar plate through periangular transmasseteric approach (radiograph)

The mean exposure time for Group 1 was 631 s and Group 2 was 557 s. The exposure time differed significantly (P = 0.048) between the two surgical approaches, but the difference was not clinically significant. However, the difference in reduction and fixation time did not differ significantly between the two surgical techniques [Table 4].

Table 4

Comparison of time taken between the groups

Variable	Paired differences				Significant (two-tailed)
	Mean difference	SD	95% CI of the difference
			Lower	Upper
Pair 1: Exposure time	228.2	362.3	−31.0	487.4	0.048
Pair 2: Reduction time	−49.6	512.7	−416.3	317.1	0.767
Pair 3: Fixation time	−165.8	611.3	−603.1	271.5	0.413

SD=Standard deviation; CI=Confidence interval

The mean postoperative maximum mouth opening after 6 months in Group 1 was 35.1 ± 10 mm and 40.9 ± 5 mm in Group 2. During the 1st week postoperative evaluation, minor occlusal discrepancies were noticed in seven cases which were corrected with guiding elastics. On 1-month evaluation, occlusion was satisfactory in all the patients.

Scar perception was observed to be imperceptible (good) in 30% of Group 1 and slightly perceptible (fair) in rest of the cases. It was imperceptible (good) in 60% the cases of Group 2, slightly perceptible (fair) in 30% of the cases, and perceptible (poor) in 10% of the cases.

Facial nerve injury

On postoperative facial nerve assessment, the zygomatic, buccal, and marginal mandibular branch of the facial nerve was involved in two cases of Group 1, whereas buccal and marginal mandibular branch of the facial nerve was involved in three cases of Group 2. Facial nerve recovery was observed in all the cases on 3-month follow-up except in one case of Group 1 which was associated with development of TMJ ankylosis.

Wound infection was seen in two cases of Group 2 which resolved under antibiotic coverage. Wound dehiscence was observed in one case of Group 2 which resolved with resuturing. Sialocele formation was observed in two cases of Group 1 which was managed with aspiration, pressure dressing, and antisialagogues for 2–4 weeks.

DISCUSSION

Various approaches have been described as per the level of fracture in recent literature. Newman observed that the majority of the affected patients were in the second and third decades of life.[15] In the present study, the age ranged between 15 and 53 years, with an average age of 29 years. Wong and Badar illustrate that males commonly experienced condylar fracture.[161718] The present study revealed that males are affected more commonly than females (3:1). Sawazaki et al. mentioned that road traffic accident was the most common cause of condylar fracture (55.33%).[19] In the present study, road traffic accidents were encountered in 60% of the cases, fall from height in 30% of the cases, and interpersonal violence in 10% of the cases. This consensus also tallies with a study by Ellis et al. which states that motor vehicle accidents attribute to 36.1%, fall: 36.3%, and assaults: 24.3% of condylar fractures.[20] Condylar fractures are generally caused by indirect force and considered as coup-contrecoup injuries. In a study performed by Mahgoub et al., condylar fractures were associated with anterior mandibular fractures in 52.5%, angle 12.5%, body fractures 10%, and isolated condylar fracture in 25% of the cases.[21] In the present study, 75% of condylar fractures were associated with parasymphysis or mandibular body fractures and 20% of the cases experienced isolated condylar fracture. Unilateral condyle fractures are seldom associated with fractures of the zygomatic complex which was observed in one (5%) case, this can be explained due to direct lateral traumatic force and fracture of slender condylar neck.[22]

In a review of 175 condylar fractures by Reddy et al., 50% of the cases were subcondylar, 31.45% were condylar neck, and 18.54% were condylar head fractures.[23] Author observed 50% condylar base, 45% condylar neck, and 5% condylar head fracture, which is proportionate with the incidence in studies by Reddy et al. and Zachariades et al.[8]

Medial displacement of condylar fracture is commonly encountered due to the pull of lateral pterygoid muscle. Zachariades et al. reported medial displacement in 77% of the cases, lateral in 23% of the cases, and no contact in 7% of the cases.[8] In the current study, deviation with medial overlapping segments was seen in 15%, lateral overlapping in 55%, and deviation without overlapping in 30% of the cases.

Magnetic resonance imaging of condylar fracture may reveal medial displacement of the disc, especially in sagittal fracture. If it is not treated early, it can be associated with formation of fibrous adhesions between two raw surfaces leading to ankylosis.[24] In the present study, one case with medially displaced condylar head fracture required extracorporeal approach via retromandibular incision who developed TMJ ankylosis. Xiang et al. observed that surgically treated condylar fractures developed postoperative ankylosis in 5% of the cases which was limited to condylar head fracture with a damaged disc.[25]

Narayanan suggested that when the displacement is >35° in either the coronal or the sagittal plane, there is compromised blood supply which requires ORIF to prevent malunion.[26] In the present study, six cases showed a deviation >40°. Vertical overlap >4 mm treated by the closed method can lead to persistent telescoping of the ramus, occlusal cant, and facial asymmetry.[27] Bindal et al. observed that if overlapping is <3.25 ± 0.6 mm, facial symmetry was not greatly affected.[28] In the current study, 14 cases had overlap >5 mm which were managed by ORIF.

Good anatomical reduction leads to early return to function due to adaptation of dental and neuromuscular components.[29] Yang and Patil and Devlin et al. reported minor occlusal discrepancies in 8.5% of the cases and 4.7% of the cases, respectively, in retromandibular approach.[3031] Özkan et al. reported one case of deteriorated occlusion, whereas Narayanan et al. reported satisfactory occlusion in all the cases treated with transmasseteric approach.[3233] In the present study, two patients of the retromandibular group and five patients of the periangular transmasseteric group had minor occlusal discrepancy which were easily corrected with guiding elastics for a period of 7–15 days and did not require any surgical intervention.

Parihar et al. in a comparative study observed better mean mouth opening in the transparotid group (41.67 mm) than the periangular transmasseteric group (40.8) after 6 months.[34] The results of the present study in terms of mouth opening were more or less similar to the above-mentioned study which was 31–46 mm in retromandibular group (except one case which developed TMJ ankylosis) and 32–49 mm in periangular transmasseteric group.

The extracorporeal approach for fixation of severely displaced condylar fracture fragments was introduced by Nam in 1981 for accurate anatomical reduction.[35] It is commonly associated with complications such as avascular necrosis, condylar resorption, arthrosis due to the loss of periosteal blood supply, detachment from the lateral pterygoid muscle, and injury to the disc.[36] In the present study, one case with a condylar head fracture in retromandibular group required an extracorporeal approach and later presented with clinical and radiographic sign of TMJ ankylosis.

Adequate visualization of the anterior and posterior borders of the condylar segments as well as position of the condylar head in the glenoid fossa is the prerequisite for accurate anatomical reduction and fixation. Yang and Patil observed adequate visibility in 29% of condylar neck and 71% of subcondylar fractures with retromandibular approach and excellent accessibility.[30] Accessibility to the fracture site is required for proper instrumentation, anatomical reduction, protection of the surrounding vital structures, and fixation. Narayanan et al. observed that the periangular transmasseteric approach offers excellent access to the fractured condyle.[33]

In the present study, the visibility and accessibility in retromandibular group was good for 70% of the cases, fair in 20% of displaced condylar neck fractures, and poor in 10% of condylar head fractures. Ease of fixation was adequate for miniplates as well as delta plates except one case of condylar head which required extracorporeal approach. In the periangular transmasseteric group, visibility and accessibility was good for 30% of the cases, fair in 60% of the displaced condylar fracture with medial or lateral displacement, and poor in 10% of the high condylar neck fractures. Inadequate visibility was observed when the fracture segment was displaced medially and in condylar neck fracture despite use of miniplates, trapezoidal condylar plate, or strut plate. Surgeons also observed that perpendicular placement of screws in the fractured proximal stump was difficult in condylar neck fracture compared to retromandibular approach. This shortcoming can be overcome by the application of the angulated system.

Excessive duration of exposure not only increases the chances of infection but also increases fatigue for the surgeons. In the current study, the mean time for exposure with retromandibular and periangular approach was 10 min 31 s and 9 min 17 s, respectively, which was statistically significant (P = 0.048) but not clinically. In a study by Kshirsagar et al., the average duration of surgery was 32 min with retromandibular approach.[37] Trost et al. observed that the mean time taken for surgery was 45 min with high cervical periangular transmasseteric anteroparotid approach.[38] In the present study, the mean time taken for completion of surgical procedure was 43 min 40 s and 46 min 5 s in retromandibular approach and periangular approach, respectively, which was comparable with Kshirsagar et al. and Trost et al.[3738]

Bouchard and Perreault reported 11.9% of the cases of infection associated with retromandibular approach, whereas in the present study no case of infection was observed with retromandibular approach.[39] Trost et al. reported 2.6% incidence of infection with periangular approach, whereas in the present study, wound infection was encountered in 20% of the cases which resolved with debridement and antibiotic coverage.[38] Among these cases, one patient with a history of substance abuse and alcoholism required second surgery for debridement and removal of implant. Koshy et al. reported that the incidence of infection increases (60%–72%) after ORIF in chronic smokers, alcoholics, and substance abusers.[40]

Bouchard and Perreault and Yang and Patil reported 3.4% and 8% incidence of salivary fistulae formation, respectively, with retromandibular approach.[3039] In the present study, sialocele formation was observed in 20% of the cases of retromandibular group and none in periangular group, as the dissection through the substance of parotid gland was avoided. During the initial phase of the study, two cases of sialocele formation were encountered, and thereafter, care was taken to perform water tight closure of parotid capsule by passing a suture through the capsule during dissection which allows meticulous closure. After undertaking this maneuver, no case of sialocele was noticed.

Ellis et al. reported unesthetic scars in 7.5% of cases with retromandibular approach.[41] Parihar et al. observed hypertrophic scar formation in 17% of cases of transparotid approach and none in periangular approach.[34] As the retromandibular approach is designed to place the incision in the posterior ramal shadow, none of the patients in the present study complained about esthetics of scar. On operator observation, imperceptible scar (good) was noticed in 30% of the cases and slightly perceptible (fair) in 70% of the cases. In the periangular approach, on patient's observation, scar was imperceptible (good) in 60% of the cases and slightly perceptible (fair) in 30% of the cases. One patient who was more concerned about esthetics of scar despite it being hidden in the neck crease, but he declined secondary revision.

The chances of injury to the branches of the facial nerve is a common limitation of surgical approaches to the condylar process. The preauricular approach has been associated with a wide range of incidence of facial nerve injury (3.2%–42.9%).[4243] The submandibular approach is preferred for reduction and fixation of low subcondylar and mandibular angle fractures but with reported (5.3%–48.1%) incidence of facial nerve injury.[44] Intraoral approaches may put the facial nerve at risk, particularly with the use of transfacial trocars.[45]

Bouchard and Perreault reported a 22% incidence of temporary facial nerve paresis with retromandibular approach which recovered within 6 months. Only one case was reported with permanent facial nerve palsy after 5 years.[39] The incidence of permanent facial nerve injury is rare and has been reported by Handschel et al. in submandibular approach and Iizuka et al.[4647] Yang and Patil and Bhutia et al. reported 16.6% and 20% incidence of facial nerve injury with retromandibular approach, respectively.[30] The buccal nerve was most frequently involved followed by the marginal mandibular nerve which took around 6 months to recover.[48]

Wilson et al. described the transmasseteric approach, which reduced the occurrence of salivary fistula and damage to the facial nerve.[12] According to Yang and Bhutia et al., the increased incidence of facial nerve injury was encountered when the fractured condylar segment was medially displaced or dislocated out of the glenoid fossa, as the reduction puts greater traction on branches of the facial nerve leading to neuropraxia or axonotmesis.[3048] According to Raveh et al., excessive traction by the retractors or electrocauterization of vessels close to the facial nerve primarily causes injury to the nerve.[49] Functional recovery in neuropraxia occurs within 0–12 weeks. However, during the postoperative period, as edema increases, the inflow of nutrients to the nerve decreases. This results in axonal death (axonotmesis) and retrograde degeneration. However, the endoneurium stays intact and axons regrow through the channels which leads to late recovery of function (3–6 months).[50]

In the present study on postoperative facial nerve assessment, the zygomatic, buccal, and marginal mandibular branches were injured in two cases of retromandibular approach which recovered within 3 months except in one case which was also associated with the development of signs of TMJ ankylosis.

Trost et al. showed that the damage to the facial nerve can be minimized if a transmasseteric approach is used.[38] During the periangular transmasseteric approach, the masseter muscle is exposed as it lies covered with the parotidomasseteric fascia, at this point of dissection, the branches of facial nerve run underneath the masseteric fascia. As the masseter is incised and retracted posteriorly and superiorly, the branches of facial nerve which lie under the fascia may get injured due to traction. In case of parotid hypertrophy, incision of the masseter can extend under the gland further increasing the likelihood of injury to the branches of the facial nerve.[13] In the present study, the periangular transmasseteric group required greater retraction in displaced fractures of the condylar neck and base which resulted in transient traction injury of buccal and marginal mandibular branches in three cases.

This study is in conjunction with the observations of Neff that the periangular approach is most suited for the management of condylar fractures up to the height of sigmoid notch with minimal injury to the facial nerve.[51] On the other hand, the retromandibular approach can be applied for condylar fracture reduction with minimal morbidity to the facial nerve irrespective of the level of fracture as has been reported by Al-Moraissi et al.[52]

CONCLUSION

The results of the present study conclude that both the approaches are equally effective for ORIF of condylar base fractures but displaced condylar neck fractures, the retromandibular approach is preferable due to limited access and difficult instrumentation with periangular transmasseteric approach. Large sample size and multicentric study may further shed light on the findings of the current study.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.