Accepted Manuscript A modified preauricular approach for treating intracapsular condylar fractures to prevent facial nerve injury: the supratemporalis approach Hui Li, DMD, Resident, Gang Zhang, MD, DMD, Associate Professor, Junhui Cui, MD, DMD, Attending Staff, Weilong Liu, DMD, Resident, Dilnu Dilxat, DMD, Resident, Lei Liu, MD, DMD, Professor PII:
S0278-2391(16)00005-7
DOI:
10.1016/j.joms.2015.12.013
Reference:
YJOMS 57073
To appear in:
Journal of Oral and Maxillofacial Surgery
Received Date: 28 October 2015 Revised Date:
15 December 2015
Accepted Date: 18 December 2015
Please cite this article as: Li H, Zhang G, Cui J, Liu W, Dilxat D, Liu L, A modified preauricular approach for treating intracapsular condylar fractures to prevent facial nerve injury: the supratemporalis approach, Journal of Oral and Maxillofacial Surgery (2016), doi: 10.1016/j.joms.2015.12.013. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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A modified preauricular approach for treating intracapsular condylar fractures to prevent facial nerve injury: the
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supratemporalis approach
Hui Li, DMD, * Gang Zhang, MD, DMD, # Junhui Cui, MD, DMD, ^
Weilong Liu, DMD, ◎ Dilnu Dilxat, DMD□ and Lei Liu, MD, DMD☆
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*Resident, Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China # Associate Professor, Department of Stomatology, Xinqiao Hospital, The Third Military Medical University, Chongqing, China ^Attending Staff, Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China ◎Resident, Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China □Resident, Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China ☆Professor, Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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This study was supported by the National Natural Foundation of China (81070802, 81271096), the National High Technology Research and Development Program of China (2011AA030107), Fundamental Research Funds for the Central Universities of China (2011SCUD4B14).
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Drs Li and Zhang were co-first authors. Address correspondence and reprint requests to Dr Liu: Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 People’s Republic of China; e-mail: [email protected]
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A modified preauricular approach for treating intracapsular condylar fractures to prevent facial nerve injury: the
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supratemporalis approach
Abstract
Purpose: The facial nerve remains at risk of injury with the preauricular
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approach and thus preservation of the functional integrity of the facial nerve is
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considered a significant factor in the success of temporomandibular joint surgery. The aim of this study was to prevent facial nerve injury using the supratemporalis approach in the treatment of intracapsular condylar fractures. Materials and Methods: In this prospective cohort study, the population
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consisted of patients diagnosed with intracapsular condylar fractures and received surgical treatment from July 2005 to May 2014. The patients were
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divided into 2 groups. The patients in the experimental group were treated
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with the supratemporalis approach, and the patients in the control group were treated with the traditional preauricular surgical technique. The primary outcome variable was facial never injury. The Continuity correction Chi-square and Student t test were used. Results: In all, 84 patients (112 sides) with intracapsular condylar fractures were treated surgically (56 men, 28 women; mean age = 29.85 years; range 4 70 years): 44 patients (64 sides) with the supratemporalis approach and 40
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patients (48 sides) with the traditional preauricular approach. Facial contours and functions recovered well postoperatively in all 84 patients. Seven cases of facial nerve injury, two of which were permanent, were observed in the
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traditional preauricular approach group, and no facial nerve injuries were observed in the supratemporalis approach. None of the study patients
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sustained auriculotemporal syndrome and wound infection complications. Conclusions: The supratemporalis approach prevented facial nerve injury
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and did not increase the frequency of other complications. Trial Registration: Clinicaltrials.gov (NCT02466269).
Key words: intracapsular condylar fractures; supratemporalis approach;
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facial nerve injury.
Clinical Relevance
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A modified preauricular approach, denoted the supratemporalis approach,
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was designed to treat intracapsular condylar fractures in preventing facial nerve injury. It prevented facial nerve injury and did not increase the frequency of other complications.
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Condylar fracture is one of the most common fractures in the mandibular region, with an incidence ranging from 29 to 52%.[1-5] Condylar fractures can cause a variety of problems -- malocclusion, restricted mandibular movement,
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limited mouth opening -- that are troublesome during patients’ daily and social lives. Thus, the optimal treatment should be undertaken as soon as possible. In recent years, there has been noticeable improvement in treating
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condylar fractures. However, condylar fractures are still more difficult to
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handle than other mandibular fractures because 1) there are many complex anatomic structures around the condyle in such a small area, 2) some serious complications, such as facial deformity and temporomandibular joint (TMJ) ankylosis, still happen sometimes,[6] and 3) when condylar fractures occur in
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children, they can cause mandibular growth disturbance, even severe mandibular deficiencies. The treatment of condylar fractures, therefore, is
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still a serious issue.
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Condyle fracture can be classified into intracapsular condylar fracture, condyle neck fracture, and subcondyle fracture according to the anatomic location of the fracture.[7] Of these three types, the intracapsular condylar fracture is most common, accounting for 65% of cases.[8] Treatment of intracapsular condylar fractures is not just difficult, it is associated with severe complications, such as TMJ ankylosis. [9] Hence, the management of intracapsular condylar fracture remains a challenge for oral and maxillofacial
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surgeons, demanding rich clinical experience. With rapid developments in internal fixation materials technology and surgical instruments, surgeons have begun to find surgical approach more
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desirable, not just for anatomic reduction of the fragments but the added insurance of an intact TMJ disc. It can also promote an early functional exercise.[10-13] Hence, surgical treatment (open reduction and rigid fixation
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with TMJ articular disc repositioning and fixation) is gradually becoming the
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preferred choice for intracapsular condylar fractures.[12, 14]
A well-chosen surgical incision is the first and key step during the surgical procedure for maximally preventing complications. Surgeons have commonly adopted the traditional preauricular approach for treating intracapsular
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condylar fractures. This classic preauricular approach was described by Rowe & Killey.[15-17] This technique has been favored for its advantages, including
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excellent access to the joint, simple manipulation of the fracture segments and
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invisible scar formation.[18-20] However, the facial nerve remains at risk of injury with the preauricular approach, which cannot be ignored. Some surgeons have reported unsatisfactory results with it, such as an inability to raise the eyebrows, the loss of ability to create forehead wrinkles, and ptosis.[21, 22] According to well-documented reports, the incidence of facial nerve paresis ranges from 1 to 32% following this surgery.[21, 23-25] Preservation of the functional integrity of the facial nerve is considered a
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significant factor in the success of TMJ surgery. Therefore, we present a modified preauricular approach to treat intracapsular condylar fractures: the supratemporalis approach. This approach maximally prevents the risk of
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facial nerve injury.
The purpose of the present study was to prevent the facial nerve injury using the supratemporalis approach in the treatment of intracapsular condylar
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fractures. The authors hypothesized that we could decrease facial nerve injury
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in patients with intracapsular condylar fractures through the supratemporalis approach. The specific aim of the study was to compare the two surgical approaches for treating intracapsular condylar fractures with regard to their prognoses and complications, to validate the effectiveness of the
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injury.
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supratemporalis approach presented in this study to prevent the facial nerve
Materials and Methods
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STUDY DESIGN AND SAMPLE To address the research purpose, the authors designed and implemented a
prospective cohort study that was approved by the Research Ethics Board of the Ethics Committee, West China Hospital of Stomatology, Sichuan University. The authors have read the Helsinki Declaration and have followed the guidelines in this investigation. All patients signed an informed consent
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document agreeing that all photographs and personal data could be used in medical publications, journals, textbooks, and electronic publications. The study population consisted of all patients diagnosed with intracapsular
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condylar fractures and received surgical treatment, from July 2005 to May 2014 at the Department of Oral & Maxillofacial Surgery at the West China Hospital of Stomatology, Sichuan University (Chengdu, China). The patients
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were divided into 2 groups. The patients in the experimental group were
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treated with the supratemporalis approach, and the patients in the control group were treated with the traditional preauricular surgical technique. To be included in the study sample, the patients had to have had clinical and
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imaging diagnoses of intracapsular condylar fractures, no previously surgical treatment, consented to the surgical treatment and fulfilled any of the following fracture situations: they had (1) a displaced fracture in which the
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ramus stump was dislocated laterally out of the glenoid fossa; (2) a fracture
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with reduction of the mandibular ramus height; (3) a fracture that caused serious occlusion disorders or an extreme limited maximum interincisal distance that could not be solved by closed treatment; (4) a fracture that displaced into the middle cranial fossa.[26-29] The patients were excluded as study subjects if they were diagnosed with an undisplaced or only slightly displaced fracture, refused the surgical treatment, had a traumatic scar at the temporal and preauricular regions that
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would affect placement of the planned incision and those with previous facial nerve injury.
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STUDY VARIABLES The primary predictor was surgical treatment choice. The primary outcome variable was facial never injury. Other variables related to the study were age,
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gender, postoperative occlusion, fractures reduction, postoperative maximum
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interincisal opening, auriculotemporal syndrome, and wound infection.
TECHNIQUE FOR THE EXPERIMENTAL GROUP For patients treated with the supratemporalis approach (n=44), a skin
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incision was made anterior to the tragus, extending from the earlobe and continuing superiorly to the crus of the helix. It then curved backward and upward into the temporal region posterior to the hairline for a length of
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approximately 4 cm. The temporal portion of the incision was shaped like a
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hockey stick and was made almost 45° to the zygomatic arch (Fig. 1A). The incision was then deepened to the superficial temporalis fascia. A flap that included skin, subcutaneous tissue and superficial temporal fascia was reflected anterior to the ear along the plane of the subgaleal fascia. Then, differing from the traditional preauricular surgical dissection plane, our modified incision was carried through the deep temporalis fascia and completely through the fat pat, exposing the temporal muscle. This plane lies
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on the surface of the temporalis muscle (Fig. 1 B, 1C). At the same depth, blunt dissection was performed inferior to the periosteum of the zygomatic arch and then continued until the medial surface of the zygomatic arch was
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exposed. A periosteal elevator was used to dissect the medial bone surface of the zygomatic arch. The flap, now consisting of skin, subcutaneous tissue, superficial temporalis fascia, subgaleal fascia and deep temporalis fascia (Fig.
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1D), could then easily be turned forward to expose the zygomatic arch
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completely. The added temporal fat pad could maximally reduce the incidence of damage to branches of the facial nerve (Fig. 2).
Below the zygomatic arch, the dissection then continued downward in the same plane to expose the capsule of the TMJ. The lower cavity of the TMJ
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was entered using a T-shaped incision through the lateral capsule. After opening the periosteum, the articular disc, head of the condyle, fragments, and
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ramus stump of the mandible were exposed. Once the fracture sites were
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identified, open reduction with internal fixation was performed (Fig. 1 E, 1F). The TMJ disc was repositioned and fixed to the condylar process, if necessary (Fig. 1G).
The wound was closed in layers. A suction drain was placed inside the
wound, and pressure dressing was applied for 48 h (Fig. 1H, 1I). Postoperatively, a soft diet and an early exercise of mouth opening movement were required of all the patients for at least 3 months. The patients were
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followed for 12 months to evaluate their prognoses and the frequency of
TECHNIQUE FOR THE CONTROL GROUP
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complications.
In the control group, treated with the traditional preauricular incision (n=40), the skin incision is located anterior to the tragus, running along the
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preauricular skin fold. It begins at the earlobe and extends superiorly to the
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crest of the helix and in some cases to the temporal region if necessary. Dissection continues through the subcutaneous tissues and superficial temporalis fascia, exposing the plane of the subgaleal fascia. The skin flap consists of skin, subcutaneous tissue and superficial temporalis fascia. At a
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point about 2 cm above the zygomatic arch, the superficial temporalis fascia is cut down to the fat layer of the deep temporal fascia, followed by sharp and
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blunt dissection to expose the zygomatic arch. The temporomandibular
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ligament and the joint capsule are then incised with subperiosteal dissection. Once the fracture site is identified, open reduction with internal fixation can proceed.[15-17] The subsequent surgical procedures and postoperative treatment of the patients were similar to those in the group with the supratemporalis approach.
DATA COLLECTION
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Data from the patients’ charts, physical examinations, surgical procedures and postoperative surgery-related morbidity were recorded. Facial nerve function was evaluated preoperatively and at 24 h and 1 week postoperatively
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by 3 experienced surgeons according to the following abilities: The patients were instructed to raise their eyebrows, wrinkle the forehead, gently close the eyes, blow the cheek and smile. Paralysis of the facial nerve was deemed to
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have occurred if these motions were not achieved. Facial nerve function was
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reassessed at 3, 6 and 12 months postoperatively. All the patients were followed up for at least for 12 months. The preoperative and postoperative imaging data from plain radiography and/or computed tomography (CT) were collected for all patients to evaluate their fractures condition and provide
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evidence during the follow-up.
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STATISTICAL ANALYSIS
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The Continuity correction Chi-square and Student t test were used for statistical analyses. All statistical analyses were calculated using SPSS for Windows, version 19 (IBM Corp, Armonk, NY). A P < 0.05 was considered statistically significant.
Results A total of 84 patients with intracapsular condylar fractures (112 sides) were
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included in the study: 49 with bilateral condylar fractures and 35 with unilateral condylar fractures. They included 56 male (66.7%) and 28 female (33.3%) patients with a mean age of 29.85+14.47 years (range 4 - 70 years).
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Patients were divided into 2 groups: 40 patients (48 sides) in whom the traditional preauricular approach was used and 44 patients (64 sides) in whom the supratemporalis approach used. All 84 patients with 112 intracapsular
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condylar fractures completed the study, and all of the surgical procedures
groups is presented in Table 1.
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were finished successfully. Comparison of all study variables between the 2
The reductions were ideal and the fixations reliable. All the patients experienced significant improvement with regard to both aesthetic
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appearance and function.
The anatomic and approximately anatomic fracture reduction rates were
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91.7% in the traditional preauricular approach group and 95.3% in the
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supratemporalis approach group. There was no statistical difference between the two groups in the reduction aspect (P=0.693). All patients in both groups had normal occlusion (P=1). The results for the postoperative maximum interincisal opening were also excellent in both groups. The average postoperative maximum interincisal opening was 34.59mm in the traditional preauricular approach group and 33.70mm in the supratemporalis approach group (P= 0.079).
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Facial nerve injuries were present in 7 of the 40 patients with the traditional preauricular approach. Among them, loss of the ability to wrinkle the forehead was observed in five patients, although it returned to normal
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function within 6 months. Ptosis was seen in seven patients in this group but gradually receded after 4 months in five patients. All of the patients smiled symmetrically without mouth blowing. No facial nerve palsy was noted after
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surgery in the group with the supratemporalis approach. There was a dramatic
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decrease in the incidence of facial nerve injuries in the group with the supratemporalis approach (P=0.012). All other factors did not significantly affect this complication (Table 2). These results showed that surgical
(Table 3).
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treatment choice had a significant effect on the rate of facial nerve injury
No patients in either group experienced postoperative auriculotemporal
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Discussion
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syndrome and wound infection.
The purpose of the present study was to prevent the facial nerve injury
using the supratemporalis approach in the treatment of intracapsular condylar fractures. The authors hypothesized that we could decrease facial nerve injury in patients with intracapsular condylar fractures through the supratemporalis approach. The specific aim of the study was to compare the two surgical approaches for treating intracapsular condylar fractures with regard to their
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prognoses and complications, to validate the effectiveness of the supratemporalis approach presented in this study to prevent the facial nerve injury. We obtained ideal reduction and reliable fixation with a zero incidence
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of facial nerve injury in the supratemporalis approach group, whereas 7 patients in the traditional preauricular approach group suffered facial nerve weakness 1 day postoperatively. There was thus a dramatic decrease in the
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incidence of facial nerve injury in the supratemporalis approach group. The
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results of this study confirmed the hypothesis that facial nerve injuries could be prevented using the supratemporalis approach.
It should be also noted that the reductions were ideal and the fixations reliable in both groups. And all the 84 patients experienced significant
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improvement with regard to both aesthetic appearance and function. No patients in either group experienced postoperative auriculotemporal
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syndrome and wound infection. The supratemporalis approach did not increase the frequency of other complications.
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According to the studies of Babakurban et al.[30] and Krayenbühl et al.[31],
the anatomic levels of soft tissues that are encountered in the temporal area during TMJ surgery, from outside in, are skin, subcutaneous tissue, superficial temporal fascia, subgaleal fascia (loose areolar tissue), superficial layer of the deep temporal fascia, superficial temporal fat pad, deep layer of the deep temporal fascia, temporal muscle and periosteum. Proceeding from the skin to
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the periosteum, there are three fascial layers in the lower temporal region: superficial temporalis fascia and deep temporalis fascia. The latter divide into two layers approximately 2−3 cm above the zygomatic arch. They are named
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the superficial and deep layers. Between the two layers, there is a fat pat, called the superficial temporal fat pad.[32, 33] Cranial to the superotemporal line, there is only a single sheet of fascia in continuity with the pericranium. In
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our clinical experience, however, we have found that the deep temporalis
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fascia is not separated into two layers there is only one sheet of fascia 2−3 cm above the zygomatic arch. Thus, the superficial temporal fat pad is closely attached above the temporal muscle at that level.
The temporal branch and the zygomatic branch of the facial nerve lie in a
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condensation of superficial fascia, deep temporalis fascia and periosteum over the zygomatic arch. According to Weinberg,[25] the branch of the facial nerve
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that is most vulnerable to injury during dissection in the TMJ is the temporal
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branch because it lies more superficially than the other branches between the superficial layer of the deep temporal fascia and the superficial temporal fascia. When properly conducted, the traditional preauricular approach to the TMJ decreases damage to the temporal branch of the facial nerve. The nerve, however, is occasionally found deep within the superficial fat pad.[25] This anatomic variation may result in injury to the facial nerve during subfascial dissection.[34,
35]
The facial nerve is considered damaged if the
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ability to wrinkle the ipsilateral forehead is lost or there is a reduction in the depth of the wrinkles, if there is inability to raise the eyebrows, and if ptosis is observed any of which could cause an asymmetric appearance and
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dysfunction.
With these problems in mind, we have presented a safer surgical dissection plane: the supratemporalis approach. In contrast to the conventional technique
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used in the traditional preauricular approach, the separation plane with our
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supratemporalis approach is located between the deep temporal fascia and the temporalis (Fig. 2). Using this modified surgical technique, we can maximally prevent facial nerve injury.
Maximum protection of the facial nerve requires well-designed surgical
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dissection. The anatomic variations of the temporal branch of the facial nerve make it vulnerable to injury during surgical dissection in the temporal region.
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The nerve occasionally lies within the superficial temporal fat pad. Our
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modification of the skin incision was carried through the deep temporalis fascia with the fat tissue, exposing the temporal muscle. The most critical difference between the two groups lies in the separation of the temporalis and temporal fascia in the temporal region. During separation in the supratemporalis approach group, the facial nerve was well protected by the superficial temporal fat pad, temporal fascia and superficial temporal fascia. Hence, we prevented injuring the facial nerve, especially the temporal branch
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in these patients. The supratemporalis approach is also favored for its precise tissue plane during the dissection. The obvious temporal muscle fibers, exposed during the supratemporalis approach, represent the only sure
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landmark.
Despite good results using the supratemporalis approach presented in this study, a multicenter clinical study with large sample size is still required to
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confirm the safety and efficacy of supratemporalis approach in preventing
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facial nerve injury.
Conclusion
In conclusion, the supratemporalis approach provides excellent exposure of
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the surgical field with minimal complications. Compared with the traditional approach, the supratemporalis approach effectively prevents injury to the
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facial nerve. We therefore suggest this surgical method as a routine approach
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to treat intracapsular condylar fractures.
Acknowledgments
We deeply thank the patients and their families for participation in the
study. We thank Dr. Lanfeng Ye for his support in this study. This study was supported by the National Natural Foundation of China (81070802, 81271096), the National High Technology Research and Development
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Program of China (2011AA030107), Fundamental Research Funds for the
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Central Universities of China (2011SCUD4B14).
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29. Zide MF, Kent JN: Indications for open reduction of mandibular condyle fractures. Journal of Oral and Maxillofacial Surgery 41:89, 1983 30. Babakurban ST, Cakmak O, Kendir S, Elhan A, Quatela VC: Temporal branch of the facial
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Figures and table legends: Figure 1 Surgical photographs of the deep subfascial approach. A, The incision.
E, F, Reduction and fixation of the fracture. G, Repositioning the disc after fixation.
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D, Exposure of the zygomatic arch.
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B, C, An additional protective flap above the fibers of the temporalis muscle.
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H, I, The incision was closed in layers. Suction drains were used in all patients.
Fig. 2. Supratemporalis approach through the temporal region. Note the dissection planes
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for the deep subfascial approach.
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Table 1. Comparison of study variables between the 2 groups.
Table 2. Bivariate analysis between study variables and facial nerve injury.
Table 3. Comparison of facial nerve injury between the 2 groups.
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Supratemporalis Approach Group
Traditional Approach Group
P Value
44(52.4) 27.87±15.34
40(47.6) 32.02±13.29
Not applicable 0.19
13(29.5) 31(70.5) 44(100) 61(95.3) 3(4.7) 33.70±2.31 0(0)
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Sample sizes, n (%) Age, mean ± SD (yr) Gender, n (%) Female Male Normal occlusion postoperatively, n (%) Fractures reduction, n (%) Anatomic and approximately anatomic Non-anatomic Average maximum interincisal distance (mm) Auriculotemporal syndrome, n (%) Wound infection, n (%)
15(37.5) 25(62.5) 40(100)
0(0)
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1
Not applicable
0(0)
Not applicable
Pearson Chi-square, Continuity Correction Chi-square test and Student t test for the analysis.
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0.44
44(91.7) 4(8.3) 34.59±2.44 0(0)
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Study Variables
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Table 1. COMPARISON OF STUDY VARIABLES BETWEEN THE 2 GROUPS
0.69 0.08
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Table 2. BIVARIATE ANALYSIS BETWEEN STUDY VARIABLES AND FACIAL NERVE INJURY Facial Nerve Injury Study Variables
P Value No
Sample sizes, n (%)
7(8.3)
77(91.7)
Not applicable
Age, mean ± SD (yr)
32.71±3.25
29.59±15.06
0.15
Gender, n (%) Female
5(71.4)
Male
2(28.6) 7(100)
51(66.2)
26(33.8) 77(100)
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Normal occlusion postoperatively, n (%)
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Yes
Fractures reduction, n (%)
1 1
6(75.0)
99(95.2)
Non-anatomic
2(25.0)
5(4.8)
33.43±1.81
34.86±2.64
0.17
0(0)
0(0)
Not applicable
0(0)
0(0)
Not applicable
Average maximum interincisal distance(mm) Auriculotemporal syndrome, n (%) Wound infection, n (%)
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Anatomic and approximately anatomic
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Continuity Correction Chi-square test and Student t test for the analysis.
0.13
Table 3. COMPARISON OF FACIAL NERVE INJURY BETWEEN THE 2 GROUPS ACCEPTED MANUSCRIPT Facial Nerve Injury
Surgical Treatment
P Value
Yes
No
Supratemporalis approach, (n)
0
44
Traditional approach, (n)
7
33
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Continuity Correction Chi-square test for the analysis.
0.01
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S0278-2391(16)00005-7
DOI:
10.1016/j.joms.2015.12.013
Reference:
YJOMS 57073
To appear in:
Journal of Oral and Maxillofacial Surgery
Received Date: 28 October 2015 Revised Date:
15 December 2015
Accepted Date: 18 December 2015
Please cite this article as: Li H, Zhang G, Cui J, Liu W, Dilxat D, Liu L, A modified preauricular approach for treating intracapsular condylar fractures to prevent facial nerve injury: the supratemporalis approach, Journal of Oral and Maxillofacial Surgery (2016), doi: 10.1016/j.joms.2015.12.013. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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A modified preauricular approach for treating intracapsular condylar fractures to prevent facial nerve injury: the
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supratemporalis approach
Hui Li, DMD, * Gang Zhang, MD, DMD, # Junhui Cui, MD, DMD, ^
Weilong Liu, DMD, ◎ Dilnu Dilxat, DMD□ and Lei Liu, MD, DMD☆
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*Resident, Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China # Associate Professor, Department of Stomatology, Xinqiao Hospital, The Third Military Medical University, Chongqing, China ^Attending Staff, Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China ◎Resident, Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China □Resident, Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China ☆Professor, Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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This study was supported by the National Natural Foundation of China (81070802, 81271096), the National High Technology Research and Development Program of China (2011AA030107), Fundamental Research Funds for the Central Universities of China (2011SCUD4B14).
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Drs Li and Zhang were co-first authors. Address correspondence and reprint requests to Dr Liu: Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 People’s Republic of China; e-mail: [email protected]
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A modified preauricular approach for treating intracapsular condylar fractures to prevent facial nerve injury: the
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supratemporalis approach
Abstract
Purpose: The facial nerve remains at risk of injury with the preauricular
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approach and thus preservation of the functional integrity of the facial nerve is
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considered a significant factor in the success of temporomandibular joint surgery. The aim of this study was to prevent facial nerve injury using the supratemporalis approach in the treatment of intracapsular condylar fractures. Materials and Methods: In this prospective cohort study, the population
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consisted of patients diagnosed with intracapsular condylar fractures and received surgical treatment from July 2005 to May 2014. The patients were
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divided into 2 groups. The patients in the experimental group were treated
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with the supratemporalis approach, and the patients in the control group were treated with the traditional preauricular surgical technique. The primary outcome variable was facial never injury. The Continuity correction Chi-square and Student t test were used. Results: In all, 84 patients (112 sides) with intracapsular condylar fractures were treated surgically (56 men, 28 women; mean age = 29.85 years; range 4 70 years): 44 patients (64 sides) with the supratemporalis approach and 40
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patients (48 sides) with the traditional preauricular approach. Facial contours and functions recovered well postoperatively in all 84 patients. Seven cases of facial nerve injury, two of which were permanent, were observed in the
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traditional preauricular approach group, and no facial nerve injuries were observed in the supratemporalis approach. None of the study patients
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sustained auriculotemporal syndrome and wound infection complications. Conclusions: The supratemporalis approach prevented facial nerve injury
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and did not increase the frequency of other complications. Trial Registration: Clinicaltrials.gov (NCT02466269).
Key words: intracapsular condylar fractures; supratemporalis approach;
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facial nerve injury.
Clinical Relevance
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A modified preauricular approach, denoted the supratemporalis approach,
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was designed to treat intracapsular condylar fractures in preventing facial nerve injury. It prevented facial nerve injury and did not increase the frequency of other complications.
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Condylar fracture is one of the most common fractures in the mandibular region, with an incidence ranging from 29 to 52%.[1-5] Condylar fractures can cause a variety of problems -- malocclusion, restricted mandibular movement,
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limited mouth opening -- that are troublesome during patients’ daily and social lives. Thus, the optimal treatment should be undertaken as soon as possible. In recent years, there has been noticeable improvement in treating
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condylar fractures. However, condylar fractures are still more difficult to
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handle than other mandibular fractures because 1) there are many complex anatomic structures around the condyle in such a small area, 2) some serious complications, such as facial deformity and temporomandibular joint (TMJ) ankylosis, still happen sometimes,[6] and 3) when condylar fractures occur in
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children, they can cause mandibular growth disturbance, even severe mandibular deficiencies. The treatment of condylar fractures, therefore, is
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still a serious issue.
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Condyle fracture can be classified into intracapsular condylar fracture, condyle neck fracture, and subcondyle fracture according to the anatomic location of the fracture.[7] Of these three types, the intracapsular condylar fracture is most common, accounting for 65% of cases.[8] Treatment of intracapsular condylar fractures is not just difficult, it is associated with severe complications, such as TMJ ankylosis. [9] Hence, the management of intracapsular condylar fracture remains a challenge for oral and maxillofacial
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surgeons, demanding rich clinical experience. With rapid developments in internal fixation materials technology and surgical instruments, surgeons have begun to find surgical approach more
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desirable, not just for anatomic reduction of the fragments but the added insurance of an intact TMJ disc. It can also promote an early functional exercise.[10-13] Hence, surgical treatment (open reduction and rigid fixation
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with TMJ articular disc repositioning and fixation) is gradually becoming the
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preferred choice for intracapsular condylar fractures.[12, 14]
A well-chosen surgical incision is the first and key step during the surgical procedure for maximally preventing complications. Surgeons have commonly adopted the traditional preauricular approach for treating intracapsular
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condylar fractures. This classic preauricular approach was described by Rowe & Killey.[15-17] This technique has been favored for its advantages, including
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excellent access to the joint, simple manipulation of the fracture segments and
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invisible scar formation.[18-20] However, the facial nerve remains at risk of injury with the preauricular approach, which cannot be ignored. Some surgeons have reported unsatisfactory results with it, such as an inability to raise the eyebrows, the loss of ability to create forehead wrinkles, and ptosis.[21, 22] According to well-documented reports, the incidence of facial nerve paresis ranges from 1 to 32% following this surgery.[21, 23-25] Preservation of the functional integrity of the facial nerve is considered a
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significant factor in the success of TMJ surgery. Therefore, we present a modified preauricular approach to treat intracapsular condylar fractures: the supratemporalis approach. This approach maximally prevents the risk of
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facial nerve injury.
The purpose of the present study was to prevent the facial nerve injury using the supratemporalis approach in the treatment of intracapsular condylar
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fractures. The authors hypothesized that we could decrease facial nerve injury
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in patients with intracapsular condylar fractures through the supratemporalis approach. The specific aim of the study was to compare the two surgical approaches for treating intracapsular condylar fractures with regard to their prognoses and complications, to validate the effectiveness of the
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injury.
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supratemporalis approach presented in this study to prevent the facial nerve
Materials and Methods
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STUDY DESIGN AND SAMPLE To address the research purpose, the authors designed and implemented a
prospective cohort study that was approved by the Research Ethics Board of the Ethics Committee, West China Hospital of Stomatology, Sichuan University. The authors have read the Helsinki Declaration and have followed the guidelines in this investigation. All patients signed an informed consent
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document agreeing that all photographs and personal data could be used in medical publications, journals, textbooks, and electronic publications. The study population consisted of all patients diagnosed with intracapsular
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condylar fractures and received surgical treatment, from July 2005 to May 2014 at the Department of Oral & Maxillofacial Surgery at the West China Hospital of Stomatology, Sichuan University (Chengdu, China). The patients
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were divided into 2 groups. The patients in the experimental group were
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treated with the supratemporalis approach, and the patients in the control group were treated with the traditional preauricular surgical technique. To be included in the study sample, the patients had to have had clinical and
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imaging diagnoses of intracapsular condylar fractures, no previously surgical treatment, consented to the surgical treatment and fulfilled any of the following fracture situations: they had (1) a displaced fracture in which the
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ramus stump was dislocated laterally out of the glenoid fossa; (2) a fracture
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with reduction of the mandibular ramus height; (3) a fracture that caused serious occlusion disorders or an extreme limited maximum interincisal distance that could not be solved by closed treatment; (4) a fracture that displaced into the middle cranial fossa.[26-29] The patients were excluded as study subjects if they were diagnosed with an undisplaced or only slightly displaced fracture, refused the surgical treatment, had a traumatic scar at the temporal and preauricular regions that
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would affect placement of the planned incision and those with previous facial nerve injury.
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STUDY VARIABLES The primary predictor was surgical treatment choice. The primary outcome variable was facial never injury. Other variables related to the study were age,
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gender, postoperative occlusion, fractures reduction, postoperative maximum
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interincisal opening, auriculotemporal syndrome, and wound infection.
TECHNIQUE FOR THE EXPERIMENTAL GROUP For patients treated with the supratemporalis approach (n=44), a skin
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incision was made anterior to the tragus, extending from the earlobe and continuing superiorly to the crus of the helix. It then curved backward and upward into the temporal region posterior to the hairline for a length of
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approximately 4 cm. The temporal portion of the incision was shaped like a
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hockey stick and was made almost 45° to the zygomatic arch (Fig. 1A). The incision was then deepened to the superficial temporalis fascia. A flap that included skin, subcutaneous tissue and superficial temporal fascia was reflected anterior to the ear along the plane of the subgaleal fascia. Then, differing from the traditional preauricular surgical dissection plane, our modified incision was carried through the deep temporalis fascia and completely through the fat pat, exposing the temporal muscle. This plane lies
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on the surface of the temporalis muscle (Fig. 1 B, 1C). At the same depth, blunt dissection was performed inferior to the periosteum of the zygomatic arch and then continued until the medial surface of the zygomatic arch was
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exposed. A periosteal elevator was used to dissect the medial bone surface of the zygomatic arch. The flap, now consisting of skin, subcutaneous tissue, superficial temporalis fascia, subgaleal fascia and deep temporalis fascia (Fig.
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1D), could then easily be turned forward to expose the zygomatic arch
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completely. The added temporal fat pad could maximally reduce the incidence of damage to branches of the facial nerve (Fig. 2).
Below the zygomatic arch, the dissection then continued downward in the same plane to expose the capsule of the TMJ. The lower cavity of the TMJ
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was entered using a T-shaped incision through the lateral capsule. After opening the periosteum, the articular disc, head of the condyle, fragments, and
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ramus stump of the mandible were exposed. Once the fracture sites were
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identified, open reduction with internal fixation was performed (Fig. 1 E, 1F). The TMJ disc was repositioned and fixed to the condylar process, if necessary (Fig. 1G).
The wound was closed in layers. A suction drain was placed inside the
wound, and pressure dressing was applied for 48 h (Fig. 1H, 1I). Postoperatively, a soft diet and an early exercise of mouth opening movement were required of all the patients for at least 3 months. The patients were
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followed for 12 months to evaluate their prognoses and the frequency of
TECHNIQUE FOR THE CONTROL GROUP
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complications.
In the control group, treated with the traditional preauricular incision (n=40), the skin incision is located anterior to the tragus, running along the
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preauricular skin fold. It begins at the earlobe and extends superiorly to the
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crest of the helix and in some cases to the temporal region if necessary. Dissection continues through the subcutaneous tissues and superficial temporalis fascia, exposing the plane of the subgaleal fascia. The skin flap consists of skin, subcutaneous tissue and superficial temporalis fascia. At a
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point about 2 cm above the zygomatic arch, the superficial temporalis fascia is cut down to the fat layer of the deep temporal fascia, followed by sharp and
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blunt dissection to expose the zygomatic arch. The temporomandibular
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ligament and the joint capsule are then incised with subperiosteal dissection. Once the fracture site is identified, open reduction with internal fixation can proceed.[15-17] The subsequent surgical procedures and postoperative treatment of the patients were similar to those in the group with the supratemporalis approach.
DATA COLLECTION
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Data from the patients’ charts, physical examinations, surgical procedures and postoperative surgery-related morbidity were recorded. Facial nerve function was evaluated preoperatively and at 24 h and 1 week postoperatively
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by 3 experienced surgeons according to the following abilities: The patients were instructed to raise their eyebrows, wrinkle the forehead, gently close the eyes, blow the cheek and smile. Paralysis of the facial nerve was deemed to
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have occurred if these motions were not achieved. Facial nerve function was
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reassessed at 3, 6 and 12 months postoperatively. All the patients were followed up for at least for 12 months. The preoperative and postoperative imaging data from plain radiography and/or computed tomography (CT) were collected for all patients to evaluate their fractures condition and provide
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evidence during the follow-up.
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STATISTICAL ANALYSIS
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The Continuity correction Chi-square and Student t test were used for statistical analyses. All statistical analyses were calculated using SPSS for Windows, version 19 (IBM Corp, Armonk, NY). A P < 0.05 was considered statistically significant.
Results A total of 84 patients with intracapsular condylar fractures (112 sides) were
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included in the study: 49 with bilateral condylar fractures and 35 with unilateral condylar fractures. They included 56 male (66.7%) and 28 female (33.3%) patients with a mean age of 29.85+14.47 years (range 4 - 70 years).
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Patients were divided into 2 groups: 40 patients (48 sides) in whom the traditional preauricular approach was used and 44 patients (64 sides) in whom the supratemporalis approach used. All 84 patients with 112 intracapsular
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condylar fractures completed the study, and all of the surgical procedures
groups is presented in Table 1.
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were finished successfully. Comparison of all study variables between the 2
The reductions were ideal and the fixations reliable. All the patients experienced significant improvement with regard to both aesthetic
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appearance and function.
The anatomic and approximately anatomic fracture reduction rates were
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91.7% in the traditional preauricular approach group and 95.3% in the
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supratemporalis approach group. There was no statistical difference between the two groups in the reduction aspect (P=0.693). All patients in both groups had normal occlusion (P=1). The results for the postoperative maximum interincisal opening were also excellent in both groups. The average postoperative maximum interincisal opening was 34.59mm in the traditional preauricular approach group and 33.70mm in the supratemporalis approach group (P= 0.079).
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Facial nerve injuries were present in 7 of the 40 patients with the traditional preauricular approach. Among them, loss of the ability to wrinkle the forehead was observed in five patients, although it returned to normal
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function within 6 months. Ptosis was seen in seven patients in this group but gradually receded after 4 months in five patients. All of the patients smiled symmetrically without mouth blowing. No facial nerve palsy was noted after
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surgery in the group with the supratemporalis approach. There was a dramatic
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decrease in the incidence of facial nerve injuries in the group with the supratemporalis approach (P=0.012). All other factors did not significantly affect this complication (Table 2). These results showed that surgical
(Table 3).
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treatment choice had a significant effect on the rate of facial nerve injury
No patients in either group experienced postoperative auriculotemporal
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Discussion
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syndrome and wound infection.
The purpose of the present study was to prevent the facial nerve injury
using the supratemporalis approach in the treatment of intracapsular condylar fractures. The authors hypothesized that we could decrease facial nerve injury in patients with intracapsular condylar fractures through the supratemporalis approach. The specific aim of the study was to compare the two surgical approaches for treating intracapsular condylar fractures with regard to their
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prognoses and complications, to validate the effectiveness of the supratemporalis approach presented in this study to prevent the facial nerve injury. We obtained ideal reduction and reliable fixation with a zero incidence
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of facial nerve injury in the supratemporalis approach group, whereas 7 patients in the traditional preauricular approach group suffered facial nerve weakness 1 day postoperatively. There was thus a dramatic decrease in the
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incidence of facial nerve injury in the supratemporalis approach group. The
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results of this study confirmed the hypothesis that facial nerve injuries could be prevented using the supratemporalis approach.
It should be also noted that the reductions were ideal and the fixations reliable in both groups. And all the 84 patients experienced significant
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improvement with regard to both aesthetic appearance and function. No patients in either group experienced postoperative auriculotemporal
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syndrome and wound infection. The supratemporalis approach did not increase the frequency of other complications.
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According to the studies of Babakurban et al.[30] and Krayenbühl et al.[31],
the anatomic levels of soft tissues that are encountered in the temporal area during TMJ surgery, from outside in, are skin, subcutaneous tissue, superficial temporal fascia, subgaleal fascia (loose areolar tissue), superficial layer of the deep temporal fascia, superficial temporal fat pad, deep layer of the deep temporal fascia, temporal muscle and periosteum. Proceeding from the skin to
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the periosteum, there are three fascial layers in the lower temporal region: superficial temporalis fascia and deep temporalis fascia. The latter divide into two layers approximately 2−3 cm above the zygomatic arch. They are named
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the superficial and deep layers. Between the two layers, there is a fat pat, called the superficial temporal fat pad.[32, 33] Cranial to the superotemporal line, there is only a single sheet of fascia in continuity with the pericranium. In
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our clinical experience, however, we have found that the deep temporalis
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fascia is not separated into two layers there is only one sheet of fascia 2−3 cm above the zygomatic arch. Thus, the superficial temporal fat pad is closely attached above the temporal muscle at that level.
The temporal branch and the zygomatic branch of the facial nerve lie in a
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condensation of superficial fascia, deep temporalis fascia and periosteum over the zygomatic arch. According to Weinberg,[25] the branch of the facial nerve
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that is most vulnerable to injury during dissection in the TMJ is the temporal
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branch because it lies more superficially than the other branches between the superficial layer of the deep temporal fascia and the superficial temporal fascia. When properly conducted, the traditional preauricular approach to the TMJ decreases damage to the temporal branch of the facial nerve. The nerve, however, is occasionally found deep within the superficial fat pad.[25] This anatomic variation may result in injury to the facial nerve during subfascial dissection.[34,
35]
The facial nerve is considered damaged if the
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ability to wrinkle the ipsilateral forehead is lost or there is a reduction in the depth of the wrinkles, if there is inability to raise the eyebrows, and if ptosis is observed any of which could cause an asymmetric appearance and
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dysfunction.
With these problems in mind, we have presented a safer surgical dissection plane: the supratemporalis approach. In contrast to the conventional technique
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used in the traditional preauricular approach, the separation plane with our
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supratemporalis approach is located between the deep temporal fascia and the temporalis (Fig. 2). Using this modified surgical technique, we can maximally prevent facial nerve injury.
Maximum protection of the facial nerve requires well-designed surgical
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dissection. The anatomic variations of the temporal branch of the facial nerve make it vulnerable to injury during surgical dissection in the temporal region.
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The nerve occasionally lies within the superficial temporal fat pad. Our
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modification of the skin incision was carried through the deep temporalis fascia with the fat tissue, exposing the temporal muscle. The most critical difference between the two groups lies in the separation of the temporalis and temporal fascia in the temporal region. During separation in the supratemporalis approach group, the facial nerve was well protected by the superficial temporal fat pad, temporal fascia and superficial temporal fascia. Hence, we prevented injuring the facial nerve, especially the temporal branch
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in these patients. The supratemporalis approach is also favored for its precise tissue plane during the dissection. The obvious temporal muscle fibers, exposed during the supratemporalis approach, represent the only sure
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landmark.
Despite good results using the supratemporalis approach presented in this study, a multicenter clinical study with large sample size is still required to
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confirm the safety and efficacy of supratemporalis approach in preventing
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facial nerve injury.
Conclusion
In conclusion, the supratemporalis approach provides excellent exposure of
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the surgical field with minimal complications. Compared with the traditional approach, the supratemporalis approach effectively prevents injury to the
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facial nerve. We therefore suggest this surgical method as a routine approach
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to treat intracapsular condylar fractures.
Acknowledgments
We deeply thank the patients and their families for participation in the
study. We thank Dr. Lanfeng Ye for his support in this study. This study was supported by the National Natural Foundation of China (81070802, 81271096), the National High Technology Research and Development
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Program of China (2011AA030107), Fundamental Research Funds for the
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Central Universities of China (2011SCUD4B14).
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12. Hlawitschka M, Eckelt U: Assessment of patients treated for intracapsular fractures of the mandibular condyle by closed techniques. Journal of oral and maxillofacial surgery 60:784, 2002 13. Long X, Li X, Cheng Y, Yang X, Qin L, Qiao Y, Deng M: Preservation of disc for treatment of traumatic temporomandibular joint ankylosis. Journal of oral and maxillofacial surgery 63:897, 2005 14. Haug RH, Assael LA: Outcomes of open versus closed treatment of mandibular subcondylar fractures. Journal of oral and maxillofacial surgery 59:370, 2001 15. Rowe N: Surgery of the temporomandibular joint. Proceedings of the Royal Society of Medicine 65:383, 1972 16. Rowe NL, Killey HC: Fractures of the facial skeleton. Churchill Livingstone, 1968 17. Al-Kayat A, Bramley P: A modified pre-auricular approach to the temporomandibular joint and malar arch. British Journal of Oral Surgery 17:91, 1980 18. Mohan A, Kumar KJ, Venkatesh V, Kumar BP, Patil K: Comparison of preauricular approach
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nerve and its relationship to fascial layers. Archives of facial plastic surgery 12:16, 2010 31. Krayenbühl N, Isolan GR, Hafez A, Yaşargil MG: The relationship of the fronto-temporal branches of the facial nerve to the fascias of the temporal region: a literature review applied to practical anatomical dissection. Neurosurgical review 30:8, 2007 32. Kim S, Matic DB: The anatomy of temporal hollowing: the superficial temporal fat pad. Journal of Craniofacial Surgery 16:760, 2005 33. Campiglio G, Candiani P: Anatomical study on the temporal fascial layers and their relationships with the facial nerve. Aesthetic plastic surgery 21:69, 1997 34. Politi M, Toro C, Cian R, Costa F, Robiony M: The deep subfascial approach to the temporomandibular joint. Journal of oral and maxillofacial surgery 62:1097, 2004 35. Luo W, Wang L, Jing W, Zheng X, Long J, Tian W, Liu L: A new coronal scalp technique to treat craniofacial fracture: The supratemporalis approach. Oral surgery, oral medicine, oral pathology
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Figures and table legends: Figure 1 Surgical photographs of the deep subfascial approach. A, The incision.
E, F, Reduction and fixation of the fracture. G, Repositioning the disc after fixation.
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D, Exposure of the zygomatic arch.
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B, C, An additional protective flap above the fibers of the temporalis muscle.
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H, I, The incision was closed in layers. Suction drains were used in all patients.
Fig. 2. Supratemporalis approach through the temporal region. Note the dissection planes
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for the deep subfascial approach.
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Table 1. Comparison of study variables between the 2 groups.
Table 2. Bivariate analysis between study variables and facial nerve injury.
Table 3. Comparison of facial nerve injury between the 2 groups.
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Supratemporalis Approach Group
Traditional Approach Group
P Value
44(52.4) 27.87±15.34
40(47.6) 32.02±13.29
Not applicable 0.19
13(29.5) 31(70.5) 44(100) 61(95.3) 3(4.7) 33.70±2.31 0(0)
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Sample sizes, n (%) Age, mean ± SD (yr) Gender, n (%) Female Male Normal occlusion postoperatively, n (%) Fractures reduction, n (%) Anatomic and approximately anatomic Non-anatomic Average maximum interincisal distance (mm) Auriculotemporal syndrome, n (%) Wound infection, n (%)
15(37.5) 25(62.5) 40(100)
0(0)
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Not applicable
0(0)
Not applicable
Pearson Chi-square, Continuity Correction Chi-square test and Student t test for the analysis.
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0.44
44(91.7) 4(8.3) 34.59±2.44 0(0)
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Study Variables
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Table 1. COMPARISON OF STUDY VARIABLES BETWEEN THE 2 GROUPS
0.69 0.08
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Table 2. BIVARIATE ANALYSIS BETWEEN STUDY VARIABLES AND FACIAL NERVE INJURY Facial Nerve Injury Study Variables
P Value No
Sample sizes, n (%)
7(8.3)
77(91.7)
Not applicable
Age, mean ± SD (yr)
32.71±3.25
29.59±15.06
0.15
Gender, n (%) Female
5(71.4)
Male
2(28.6) 7(100)
51(66.2)
26(33.8) 77(100)
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Normal occlusion postoperatively, n (%)
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Yes
Fractures reduction, n (%)
1 1
6(75.0)
99(95.2)
Non-anatomic
2(25.0)
5(4.8)
33.43±1.81
34.86±2.64
0.17
0(0)
0(0)
Not applicable
0(0)
0(0)
Not applicable
Average maximum interincisal distance(mm) Auriculotemporal syndrome, n (%) Wound infection, n (%)
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Anatomic and approximately anatomic
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0.13
Table 3. COMPARISON OF FACIAL NERVE INJURY BETWEEN THE 2 GROUPS ACCEPTED MANUSCRIPT Facial Nerve Injury
Surgical Treatment
P Value
Yes
No
Supratemporalis approach, (n)
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44
Traditional approach, (n)
7
33
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Continuity Correction Chi-square test for the analysis.
0.01
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