- Email: [email protected]
Biportal transparotid dissection in the retromandibular approach for condylar fracture osteosynthesis: Efficacy of a novel technique
Journal Pre-proof
Biportal Transparotid Dissection in the Retromandibular Approach for Condylar Fracture Osteosynthesis: Efficacy of a Novel Technique Mohamed Abdelwahab MD , Emily A. Spataro MD , Noha A. Elkholy MD , Ahmed El-Degwi MD , Sam P. Most MD PII: DOI: Reference:
S1748-6815(19)30554-6 https://doi.org/10.1016/j.bjps.2019.11.044 PRAS 6349
To appear in:
Journal of Plastic, Reconstructive & Aesthetic Surgery
Received date: Accepted date:
25 August 2019 22 November 2019
Please cite this article as: Mohamed Abdelwahab MD , Emily A. Spataro MD , Noha A. Elkholy MD , Ahmed El-Degwi MD , Sam P. Most MD , Biportal Transparotid Dissection in the Retromandibular Approach for Condylar Fracture Osteosynthesis: Efficacy of a Novel Technique, Journal of Plastic, Reconstructive & Aesthetic Surgery (2019), doi: https://doi.org/10.1016/j.bjps.2019.11.044
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2019 Published by Elsevier Ltd on behalf of British Association of Plastic, Reconstructive and Aesthetic Surgeons.
Biportal Transparotid Dissection in the Retromandibular Approach for Condylar Fracture Osteosynthesis: Efficacy of a Novel Technique
Authors: Mohamed Abdelwahab MD1,2, Emily A. Spataro MD3, Noha A. Elkholy MD2, Ahmed ElDegwi, MD2, Sam P. Most MD1 Affiliation: 1
Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head &
Neck Surgery, Stanford University School of Medicine, Stanford, California. 2
Department of Otolaryngology-Head & Neck Surgery, Mansoura University Faculty of
Medicine, Mansoura, Egypt. 3
Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head &
Neck Surgery, Washington University School of Medicine Corresponding Author: Mohamed Abdelwahab, MD Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head & Neck Surgery, Stanford University School of Medicine 801 Welch Road, Stanford, CA 94305 [email protected] / [email protected] Word Count: 1933
1
ABSTRACT Objective: Facial nerve injury is a primary complication of open surgical management of condylar fractures. A new modification of the retromandibular transparotid approach, the “biportal transparotid dissection” (BTD), was developed to reduce these injuries in accidental nerve exposure. Design: Prospective cohort study Setting: Tertiary referral center Methods: Patients managed by retromandibular transparotid approach for condylar fractures at Department of Otolaryngology – Head and Neck Surgery, Mansoura University were included between November 2015 and August 2019 with exclusion of cases managed endoscopically or by a closed approach. Three groups were identified; Group A included patients undergoing the BTD technique, which entails transparotid dissection above and below exposed nerve branches and minimal nerve retraction; Group B included patients undergoing traditional dissection and nerve retraction away from the surgical field; Group C included patients with unidentified facial nerve branches. The function of facial nerve branches was documented postoperatively. Results: Fifty-seven fractures were included in the study. Facial nerve branches’ injury occurred in thirteen cases (22.8%): two (of ten) in Group A (20%), seven (of ten) in Group B (70%) and four (of 37) in Group C (10.81%). Compared to patients with non-exposed branches, Group A and B were found to have 2.06 (p=0.447) and 19.25 (p=0.001) greater odds of nerve injury,
2
respectively. Results showed significant faster nerve recovery in the BTD group compared to traditional dissection (mean 5 versus 9 weeks) (p=0.015). Conclusion and relevance: Although avoiding facial nerve exposure minimizes injury the most, BTD approach reduces exposed nerve injury compared to the traditional method. Keywords: Condylar fracture, retromandibular, biportal, transparotid, facial nerve.
Introduction Although the condyle is a frequent location of mandibular fractures, debate still exists regarding the best approach to their management 1. Recently, surgeons are increasingly utilizing open surgical repair compared to closed management.2 Many factors affect the decision making in choosing the best option for each patient, including the location of the fracture, side affected, patient age, comorbidities, associated fractures, and degree or direction of displacement.3 Additionally, the surgeon’s training and experience have a major impact on management decisions and surgical approach. Different open surgical approaches have been described, falling into two main categories: extraoral and intraoral. Common extraoral approaches include pre-auricular, retromandibular, submandibular and rhytidectomy incisions. The most used approach in the literature is the retromandibular approach.4 Subcutaneous dissection can either be retroparotid, transparotid, or a combination of both. The endoscopic intraoral approach has been recently used with advantages of avoiding common extraoral complications such as facial nerve injury, yet requires specialized
3
training and instrumentation, as well as may present increased difficulty in accessing certain types of fractures.5 Factors favoring surgical management of condylar fractures include restoration of the anatomy and physiology of the temporal mandibular joint, with improved functional rehabilitation. In addition, failure to restore the functionality of this joint leads to restricted mouth opening that can progress to ankylosis, malocclusion, permanent reduction of ramus height, mandibular deviation and subsequent stomatognathic system impairment. These complications may require additional interventions which are burdensome for both patients and the healthcare system.6, 7 Despite these advantages to open surgical management of condylar fractures, the primary drawbacks are surgery-related complications. These complications include facial nerve injury, sialocele, salivary fistula, Frey’s syndrome, unaesthetic scar, wound infection, hematoma and auricular anesthesia.8 Facial nerve injury, which can either be temporary or permanent, is the primary concern and has been a common research topic during the last several years.9-13 Therefore, in this prospective cohort study, a novel modification of the transparotid retromandibular approach to condylar fractures was developed to minimize risk of injury to exposed facial nerve branches. This approach has been termed the “biportal transparotid dissection (BTD)”. Additionally, the efficacy of this approach in reducing facial nerve injury was compared to traditional transparotid dissection with exposed nerve, as well as cases without nerve exposure.
4
Methods This cohort study was approved by the institutional review board of the Mansoura University Faculty of Medicine with adherence to the STROBE guidelines.
Patients were
prospectively enrolled who had condylar fractures deemed appropriate for open surgical management with a retromandibular approach by the Otolaryngology Department at the Mansoura University Emergency Hospital between November 2015 and August 2019. Inclusion criteria included patients with reduced vertical height of the mandible and/or malocclusion. Patients with comminuted condylar fractures, incomplete fissure fractures, associated neurological insult or prolonged ICU admission were excluded. Surgical technique The technique is shown schematically in Figure 1 (a and b). The surgical approach was performed by the same surgeons (M. A. and N. E.). A retromandibular incision was made, followed by transparotid dissection parallel to the facial nerve branches. If one or more facial nerve branches were encountered during this dissection, the nerve was managed by two different approaches sequentially distributed to each group. The first group, defined as Group A, were managed with the BTD approach. The BTD approach entails creating dissection ports above and below the identified facial nerve branch, thus creating a superior port and an inferior port (see Figure 1 and 2). Gentle retraction is then placed on the inferior port, and superior retraction placed on the superior port, thus not retracting the nerve branch directly. After exposure of the fracture and achieving proper reduction, a fracture plate is introduced from one port, usually the inferior, and fixated with screws through both the superior and inferior port. Creating the two ports allows both for minimal retraction on the nerve, as well as improved exposure to both the proximal and distal portions of the condylar fracture. 5
The second approach to fractures with exposed nerve, defined as Group B, were managed with the more traditional method of the transparotid retromandibular approach, shown schematically in Figure 1-c. This approach involves dissection of the exposed nerve branch, followed by retraction of the nerve and surrounding parotid tissue away from the mandible to expose the fracture site. Patients who did not have exposed nerve during transparotid dissection where defined as Group C. Postoperatively, facial function was evaluated and reported on postoperative day 1, 7 and 14, followed by weekly intervals if any facial nerve injury was present to determine when resolution occurred or if damage was permanent. Partial or complete impairment of any branch was reported. Statistical analysis Data analysis was performed using the statistical software program SPSS for Windows (version 21, USA). Results were expressed as number (percentages) for categorical variables. Univariable logistic regression was used to determine odds ratios and 95% confidence intervals (CIs) comparing risk of facial nerve injury between the three surgical approaches (Group A, B, and C). The difference in healing time of facial nerve injury between the 3 groups was analyzed using one-way ANOVA. For all statistical examinations, results were considered significant at pvalue ≤ 0.05. Results In this prospective cohort study, 49 patients were included (41 males and 8 females), with 57 condylar fractures. Patient age ranged from 16 to 48 years old, and 7 of the 49 patients had no other mandibular fractures. Mechanisms of injury were traffic accidents for 35 patients, assault
6
for 6 patients, indoor accidents (slipping) for 4 patients and falls for 4 patients. Of these, 33 fractures involved medial displacement of the condyle, while 24 involved lateral displacement. One or more facial nerve branches were identified in 20 fractures; 10 were managed using the BTD method (Group A), while the other 10 were managed by the usual dissection and retraction of the facial nerve away from the operative field (Group B). Facial nerve branches were not identified during transparotid dissection in the remaining 35 fractures (Group C). Facial nerve injury occurred in 14 fracture repairs: 2 in Group A (20%), 7 in Group B (70%) and 4 in Group C (10.81%) (see Table 1). Among patients with postoperative facial nerve injury, the buccal branch was most commonly affected, followed by the marginal mandibular branch and then the zygomatic branch, as shown in Table 1. None of the patients had permanent facial paralysis. Univariable logistic regression was performed to assess the odds of facial nerve injury of the BTD method (Group A) and traditional nerve dissection (Group B) compared to nerve injury with no identified nerve (Group C). Group A was found to have 2.06 greater odds of nerve injury yet nonsignificant compared to Group C (95% CI 0.075 – 3.13, p=0.447), while Group B was found to have 19.25 greater odds of nerve injury compared to Group C (95% CI 3.50 – 105.87, p= 0.001), however wide confidence interval was observed due to the low sample size (see Table 1). When facial nerve injury did occur, healing time ranged from 4 to 14 weeks (see Table 2). Average healing time was significantly lower for the BTD group (5.25 weeks), and more similar to the unexposed nerve group (average 5.75 weeks), compared to the traditional method group (average 9 weeks) (p=0.015). An example of a patient having the BTD with complete recovery is shown in Figure 3.
7
Discussion Open surgical management of condylar fractures is becoming more common compared to more conservative management, especially with literature increasingly supporting this approach.1,4,13,14 The primary advantage of open treatment is minimized healing time and improved functionality of the mandible and temporomandibular joint, yet the primary disadvantage is facial nerve injury. Despite advocacy of the open technique, there is controversy regarding which surgical approach is optimal, however the retromandibular transparotid approach is most often used.14 Therefore, the authors describe BTD as a new modification of this approach to minimize the risk of injury in exposed facial nerve branches, with the goal of developing ports above and below the nerve to minimize traction injury to the exposed nerve (branch) during fracture exposure compared to the usual dissection method. The effectiveness of this method was shown with a larger, though non-significant difference in nerve injury rates using BTD (OR 2.06, p= 0.447) compared to no nerve exposure, versus a larger and statistically significant difference in nerve injury rates using the traditional method when compared to no nerve exposure (OR 19.25, p= 0.001). Additionally, BTD showed statistically significant faster nerve recovery (mean 5.25 weeks) compared to traditional dissection (mean 9 weeks), with no significant difference when compared to nerve recovery period in the non-exposure group (mean 5.75 weeks). In a systematic review regarding outcomes of open surgical treatment for condylar fractures, complications of various approaches were assessed. Although transparotid dissection was associated with a higher frequency of temporary facial nerve injury compared to a nontransparotid approach, permeant facial nerve dysfunction was more commonly with the nontransparotid approach (0.07% after a transparotid approach, and 0.4% after a non-transparotid
8
approach).4 Full recovery was documented to be from a week to more than 6 months. 4 The authors contributed this difference to greater traction with non-transparotid dissection compared to a transparotid dissection. Results in this study showed no permanent injury to facial nerve branches, and temporary injury occurred in approximately 22.8% of fractures treated, which is an acceptable percentage compared to previous studies (temporary injury reported from 0 to 33%).4,15-17 Temporary injury was most frequent among exposed facial nerves treated by traditional retraction and least among unexposed branches. Additionally, recovery time for nerve injury was significantly greater for the traditional retraction group. These findings support those of the systematic review, as less retraction of the nerve intraoperatively leads to a lower rate of facial nerve dysfunction postoperatively. As unexposed nerves suffered the least amount of temporary injury, surrounding tissue may provide additional protection of the facial nerve from these traction forces. Several other factors can make the facial nerve more prone to paresis postoperatively. In addition to approach choice, dissection and retraction of the nerve, the degree and direction of condylar displacement, tissue handling, duration of procedure, the surgeon’s experience and the amount of subcutaneous tissue can make the facial nerve more prone to injury.4,14,15 The narrowness of the field, especially if surgeons try to adopt a smaller aesthetic incision, may necessitate extra traction on the nerve especially in medially displaced proximal segments. The level of the fracture is another factor involved in determining the appropriate approach, which can subsequently affect facial nerve function. Although the retromandibular approach has been recommended in condylar neck and subcondylar fractures14, the BTD in the retromandibular approach can provide improved access to higher fractures (see Figure 4). The superior dissection port above the exposed facial nerve branch gives access to the proximal fracture segment, and 9
allows better access for plate adaptation, drilling and screw fixation. Thus, ORIF of noncomminuted fractures reaching the lower condylar head can be accessed while still preserving the facial nerve with minimal traction. The primary limitation of this study is the relatively small sample size particularly in the exposed nerve groups, which is reflected in the wide confidence interval when determining the odds of facial nerve injury. Additionally, those assessing facial function and recovery postoperative were not blinded to the surgical technique used. This work also reflects only a single institution and single team experience. Future plans are to include blinded studies on a wider scale with possible multicenter involvement. Finally, a scale for severity of facial nerve injury was not utilized, as instead it was believed that detecting which branch was affected, and the time needed for full recovery can be a better estimate of injury severity in this study. Conclusion BTD is a newly-described modification to address exposed facial nerve branches in the retromandibular transparotid approach to condylar osteosynthesis. Although avoiding facial nerve exposure minimizes nerve injury the most, the BTD approach reduces nerve injury compared to the traditional dissection in accidentally-exposed branches, and may be associated with quicker recovery time when temporary injuries occur. Conflict of interest statement: None Financial Disclosure Statement: None to declare References 1. Kim B-K, Kwon Y-D, Ohe JY, Choi Y-H, Choi B-J. Usefulness of the retromandibular transparotid approach for condylar neck and condylar base fractures. Journal of Craniofacial Surgery 2012: 23: 712-15. 10
2. Hou J, Chen L, Wang T, et al. A new surgical approach to treat medial or low condylar fractures: the minor parotid anterior approach. Oral surgery, oral medicine, oral pathology and oral radiology 2014: 117: 283-88. 3. Neff A, Cornelius C-P, Rasse M, Dalla Torre D, Audigé L. The comprehensive AOCMF classification system: condylar process fractures-level 3 tutorial. Craniomaxillofacial trauma & reconstruction 2014: 7: S044. 4. Rozeboom A, Dubois L, Bos R, Spijker R, de Lange J. Open treatment of condylar fractures via extraoral approaches: A review of complications. Journal of Cranio-Maxillofacial Surgery 2018. 5. Nogami S, Takahashi T, Yamauchi K, et al. Clinical comparison between the retromandibular approach for reduction and fixation and endoscope-assisted open reduction and internal fixation for mandibular condyle fractures. Journal of Craniofacial Surgery 2012: 23: 1815-18. 6. Spiessl B. Rigid internal fixation of fractures of the lower jaw. Reconstruction surgery and traumatology 1972: 13: 124-40. 7. Derfoufi L, Delaval C, Goudot P, Yachouh J. Complications of condylar fracture osteosynthesis. Journal of Craniofacial Surgery 2011: 22: 1448-51. 8. Bouchard C, Perreault M-H. Postoperative complications associated with the retromandibular approach: a retrospective analysis of 118 subcondylar fractures. Journal of Oral and Maxillofacial Surgery 2014: 72: 370-75. 9. Bhutia O, Kumar L, Jose A, Roychoudhury A, Trikha A. Evaluation of facial nerve following open reduction and internal fixation of subcondylar fracture through retromandibular transparotid approach. British Journal of Oral and Maxillofacial Surgery 2014: 52: 236-40.
11
10. Choi K-Y, Yang J-D, Chung H-Y, Cho B-C. Current concepts in the mandibular condyle fracture management part I: overview of condylar fracture. Archives of plastic surgery 2012: 39: 291. 11. Girotto R, Mancini P, Balercia P. The retromandibular transparotid approach: our clinical experience. Journal of Cranio-Maxillofacial Surgery 2012: 40: 78-81. 12. Salgarelli AC, Anesi A, Bellini P, et al. How to improve retromandibular transmasseteric anteroparotid approach for mandibular condylar fractures: our clinical experience. International journal of oral and maxillofacial surgery 2013: 42: 464-69. 13. Kanno T, Sukegawa S, Tatsumi H, et al. The retromandibular transparotid approach for reduction and rigid internal fixation using two locking miniplates in mandibular condylar neck fractures. International journal of oral and maxillofacial surgery 2014: 43: 177-84. 14. Al-Moraissi EA, Louvrier A, Colletti G, et al. Does the surgical approach for treating mandibular condylar fractures affect the rate of seventh cranial nerve injuries? A systematic review and meta-analysis based on a new classification for surgical approaches. Journal of Cranio-Maxillofacial Surgery 2018: 46: 398-412. 15. Bindra S, Choudhary K, Sharma P, Sheorain A, Sharma C. Management of mandibular sub condylar and condylar fractures using retromandibular approach and assessment of associated surgical complications. Journal of maxillofacial and oral surgery. 2010;9:355-362. 16. Manisali M, Amin M, Aghabeigi B, Newman L. Retromandibular approach to the mandibular condyle: a clinical and cadaveric study. International journal of oral and maxillofacial surgery. 2003;32:253-256. 17. Meeran NA, Selvakumar T. Transparotid approach for subcondylar fracture─ a retrospective study of 20 cases. Arch Oral Sci Res. 2012;2:31-33.
12
Figure Legends Figure 1 showing a schematic illustration of the biportal transparotid dissection “BTD”. A: Superior port created, B: inferior port created. C: Traditional retraction. Figure 2 showing the BTD intraoperatively with the pre and postoperative 3D CT scans. A: The superior dissection port performed above the identified facial nerve branches, showing the proximal portion of plate fixation. B: The inferior dissection port performed below the identified facial nerve branches showing the distal portion of plate fixation. C: 3D CT scan of the patient preoperatively. D: 3D CT scan of the patient postoperatively. Figure 3 showing an example of a patient with facial affection and recovery. A: Patient with BTD through a retromandibular approach performed for his left condylar fracture showing left facial weakness: zygomatic branch paresis, buccal and marginal mandibular branch temporal paralysis. B: Same patient 5 weeks postoperatively with resolution of facial weakness. Figure 4 showing an example of a high condylar fracture managed by the BTD A: Preoperative 3D CT scan of a bilateral high-neck / head condylar fractures. B & C: Postoperative 3D CT scan of the same patient using the BTD method (right and left sides respectively). 13
Table 1: Facial Nerve Injury by Surgical Approach
BTD
Traditional Method
Unexposed Nerve
(Group A)
(Group B)
(Group C)
Total Fractures
10
10
37
FN affected No (%)
2 (20 %)
7 (70 %)
4 (10.81 %)
FN not affected No (%)
8 (80 %)
3 (30 %)
33 (89.19 %)
Permanent FN affection
Nil
Nil
Nil
Marginal mandibular
1/ 2
5/7
1/4
Buccal
2/2
6/7
4/4
Zygomatic
1/2
3/7
0/4
Odds Ratio of Facial Nerve Injury
2.06
19.25
Reference Value
95% CI
0.075 – 3.13
3.50 – 105.87
Reference Value
p-value
0.447
Affected branches
0.001
14
**
Reference Value
Table 2: Average healing time of Facial Nerve Injury by Surgical Method BTD
Traditional Method
Unexposed Nerve
(Group A)
(Group B)
(Group C)
p-value
Average Healing Time (weeks) (standard
5.25 (1.71)
9.17 (2.14)
deviation)
15
*
5.75 (1.70)
0.015
16
17
18
19
20
21
22
23
Biportal Transparotid Dissection in the Retromandibular Approach for Condylar Fracture Osteosynthesis: Efficacy of a Novel Technique Mohamed Abdelwahab MD , Emily A. Spataro MD , Noha A. Elkholy MD , Ahmed El-Degwi MD , Sam P. Most MD PII: DOI: Reference:
S1748-6815(19)30554-6 https://doi.org/10.1016/j.bjps.2019.11.044 PRAS 6349
To appear in:
Journal of Plastic, Reconstructive & Aesthetic Surgery
Received date: Accepted date:
25 August 2019 22 November 2019
Please cite this article as: Mohamed Abdelwahab MD , Emily A. Spataro MD , Noha A. Elkholy MD , Ahmed El-Degwi MD , Sam P. Most MD , Biportal Transparotid Dissection in the Retromandibular Approach for Condylar Fracture Osteosynthesis: Efficacy of a Novel Technique, Journal of Plastic, Reconstructive & Aesthetic Surgery (2019), doi: https://doi.org/10.1016/j.bjps.2019.11.044
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2019 Published by Elsevier Ltd on behalf of British Association of Plastic, Reconstructive and Aesthetic Surgeons.
Biportal Transparotid Dissection in the Retromandibular Approach for Condylar Fracture Osteosynthesis: Efficacy of a Novel Technique
Authors: Mohamed Abdelwahab MD1,2, Emily A. Spataro MD3, Noha A. Elkholy MD2, Ahmed ElDegwi, MD2, Sam P. Most MD1 Affiliation: 1
Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head &
Neck Surgery, Stanford University School of Medicine, Stanford, California. 2
Department of Otolaryngology-Head & Neck Surgery, Mansoura University Faculty of
Medicine, Mansoura, Egypt. 3
Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head &
Neck Surgery, Washington University School of Medicine Corresponding Author: Mohamed Abdelwahab, MD Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head & Neck Surgery, Stanford University School of Medicine 801 Welch Road, Stanford, CA 94305 [email protected] / [email protected] Word Count: 1933
1
ABSTRACT Objective: Facial nerve injury is a primary complication of open surgical management of condylar fractures. A new modification of the retromandibular transparotid approach, the “biportal transparotid dissection” (BTD), was developed to reduce these injuries in accidental nerve exposure. Design: Prospective cohort study Setting: Tertiary referral center Methods: Patients managed by retromandibular transparotid approach for condylar fractures at Department of Otolaryngology – Head and Neck Surgery, Mansoura University were included between November 2015 and August 2019 with exclusion of cases managed endoscopically or by a closed approach. Three groups were identified; Group A included patients undergoing the BTD technique, which entails transparotid dissection above and below exposed nerve branches and minimal nerve retraction; Group B included patients undergoing traditional dissection and nerve retraction away from the surgical field; Group C included patients with unidentified facial nerve branches. The function of facial nerve branches was documented postoperatively. Results: Fifty-seven fractures were included in the study. Facial nerve branches’ injury occurred in thirteen cases (22.8%): two (of ten) in Group A (20%), seven (of ten) in Group B (70%) and four (of 37) in Group C (10.81%). Compared to patients with non-exposed branches, Group A and B were found to have 2.06 (p=0.447) and 19.25 (p=0.001) greater odds of nerve injury,
2
respectively. Results showed significant faster nerve recovery in the BTD group compared to traditional dissection (mean 5 versus 9 weeks) (p=0.015). Conclusion and relevance: Although avoiding facial nerve exposure minimizes injury the most, BTD approach reduces exposed nerve injury compared to the traditional method. Keywords: Condylar fracture, retromandibular, biportal, transparotid, facial nerve.
Introduction Although the condyle is a frequent location of mandibular fractures, debate still exists regarding the best approach to their management 1. Recently, surgeons are increasingly utilizing open surgical repair compared to closed management.2 Many factors affect the decision making in choosing the best option for each patient, including the location of the fracture, side affected, patient age, comorbidities, associated fractures, and degree or direction of displacement.3 Additionally, the surgeon’s training and experience have a major impact on management decisions and surgical approach. Different open surgical approaches have been described, falling into two main categories: extraoral and intraoral. Common extraoral approaches include pre-auricular, retromandibular, submandibular and rhytidectomy incisions. The most used approach in the literature is the retromandibular approach.4 Subcutaneous dissection can either be retroparotid, transparotid, or a combination of both. The endoscopic intraoral approach has been recently used with advantages of avoiding common extraoral complications such as facial nerve injury, yet requires specialized
3
training and instrumentation, as well as may present increased difficulty in accessing certain types of fractures.5 Factors favoring surgical management of condylar fractures include restoration of the anatomy and physiology of the temporal mandibular joint, with improved functional rehabilitation. In addition, failure to restore the functionality of this joint leads to restricted mouth opening that can progress to ankylosis, malocclusion, permanent reduction of ramus height, mandibular deviation and subsequent stomatognathic system impairment. These complications may require additional interventions which are burdensome for both patients and the healthcare system.6, 7 Despite these advantages to open surgical management of condylar fractures, the primary drawbacks are surgery-related complications. These complications include facial nerve injury, sialocele, salivary fistula, Frey’s syndrome, unaesthetic scar, wound infection, hematoma and auricular anesthesia.8 Facial nerve injury, which can either be temporary or permanent, is the primary concern and has been a common research topic during the last several years.9-13 Therefore, in this prospective cohort study, a novel modification of the transparotid retromandibular approach to condylar fractures was developed to minimize risk of injury to exposed facial nerve branches. This approach has been termed the “biportal transparotid dissection (BTD)”. Additionally, the efficacy of this approach in reducing facial nerve injury was compared to traditional transparotid dissection with exposed nerve, as well as cases without nerve exposure.
4
Methods This cohort study was approved by the institutional review board of the Mansoura University Faculty of Medicine with adherence to the STROBE guidelines.
Patients were
prospectively enrolled who had condylar fractures deemed appropriate for open surgical management with a retromandibular approach by the Otolaryngology Department at the Mansoura University Emergency Hospital between November 2015 and August 2019. Inclusion criteria included patients with reduced vertical height of the mandible and/or malocclusion. Patients with comminuted condylar fractures, incomplete fissure fractures, associated neurological insult or prolonged ICU admission were excluded. Surgical technique The technique is shown schematically in Figure 1 (a and b). The surgical approach was performed by the same surgeons (M. A. and N. E.). A retromandibular incision was made, followed by transparotid dissection parallel to the facial nerve branches. If one or more facial nerve branches were encountered during this dissection, the nerve was managed by two different approaches sequentially distributed to each group. The first group, defined as Group A, were managed with the BTD approach. The BTD approach entails creating dissection ports above and below the identified facial nerve branch, thus creating a superior port and an inferior port (see Figure 1 and 2). Gentle retraction is then placed on the inferior port, and superior retraction placed on the superior port, thus not retracting the nerve branch directly. After exposure of the fracture and achieving proper reduction, a fracture plate is introduced from one port, usually the inferior, and fixated with screws through both the superior and inferior port. Creating the two ports allows both for minimal retraction on the nerve, as well as improved exposure to both the proximal and distal portions of the condylar fracture. 5
The second approach to fractures with exposed nerve, defined as Group B, were managed with the more traditional method of the transparotid retromandibular approach, shown schematically in Figure 1-c. This approach involves dissection of the exposed nerve branch, followed by retraction of the nerve and surrounding parotid tissue away from the mandible to expose the fracture site. Patients who did not have exposed nerve during transparotid dissection where defined as Group C. Postoperatively, facial function was evaluated and reported on postoperative day 1, 7 and 14, followed by weekly intervals if any facial nerve injury was present to determine when resolution occurred or if damage was permanent. Partial or complete impairment of any branch was reported. Statistical analysis Data analysis was performed using the statistical software program SPSS for Windows (version 21, USA). Results were expressed as number (percentages) for categorical variables. Univariable logistic regression was used to determine odds ratios and 95% confidence intervals (CIs) comparing risk of facial nerve injury between the three surgical approaches (Group A, B, and C). The difference in healing time of facial nerve injury between the 3 groups was analyzed using one-way ANOVA. For all statistical examinations, results were considered significant at pvalue ≤ 0.05. Results In this prospective cohort study, 49 patients were included (41 males and 8 females), with 57 condylar fractures. Patient age ranged from 16 to 48 years old, and 7 of the 49 patients had no other mandibular fractures. Mechanisms of injury were traffic accidents for 35 patients, assault
6
for 6 patients, indoor accidents (slipping) for 4 patients and falls for 4 patients. Of these, 33 fractures involved medial displacement of the condyle, while 24 involved lateral displacement. One or more facial nerve branches were identified in 20 fractures; 10 were managed using the BTD method (Group A), while the other 10 were managed by the usual dissection and retraction of the facial nerve away from the operative field (Group B). Facial nerve branches were not identified during transparotid dissection in the remaining 35 fractures (Group C). Facial nerve injury occurred in 14 fracture repairs: 2 in Group A (20%), 7 in Group B (70%) and 4 in Group C (10.81%) (see Table 1). Among patients with postoperative facial nerve injury, the buccal branch was most commonly affected, followed by the marginal mandibular branch and then the zygomatic branch, as shown in Table 1. None of the patients had permanent facial paralysis. Univariable logistic regression was performed to assess the odds of facial nerve injury of the BTD method (Group A) and traditional nerve dissection (Group B) compared to nerve injury with no identified nerve (Group C). Group A was found to have 2.06 greater odds of nerve injury yet nonsignificant compared to Group C (95% CI 0.075 – 3.13, p=0.447), while Group B was found to have 19.25 greater odds of nerve injury compared to Group C (95% CI 3.50 – 105.87, p= 0.001), however wide confidence interval was observed due to the low sample size (see Table 1). When facial nerve injury did occur, healing time ranged from 4 to 14 weeks (see Table 2). Average healing time was significantly lower for the BTD group (5.25 weeks), and more similar to the unexposed nerve group (average 5.75 weeks), compared to the traditional method group (average 9 weeks) (p=0.015). An example of a patient having the BTD with complete recovery is shown in Figure 3.
7
Discussion Open surgical management of condylar fractures is becoming more common compared to more conservative management, especially with literature increasingly supporting this approach.1,4,13,14 The primary advantage of open treatment is minimized healing time and improved functionality of the mandible and temporomandibular joint, yet the primary disadvantage is facial nerve injury. Despite advocacy of the open technique, there is controversy regarding which surgical approach is optimal, however the retromandibular transparotid approach is most often used.14 Therefore, the authors describe BTD as a new modification of this approach to minimize the risk of injury in exposed facial nerve branches, with the goal of developing ports above and below the nerve to minimize traction injury to the exposed nerve (branch) during fracture exposure compared to the usual dissection method. The effectiveness of this method was shown with a larger, though non-significant difference in nerve injury rates using BTD (OR 2.06, p= 0.447) compared to no nerve exposure, versus a larger and statistically significant difference in nerve injury rates using the traditional method when compared to no nerve exposure (OR 19.25, p= 0.001). Additionally, BTD showed statistically significant faster nerve recovery (mean 5.25 weeks) compared to traditional dissection (mean 9 weeks), with no significant difference when compared to nerve recovery period in the non-exposure group (mean 5.75 weeks). In a systematic review regarding outcomes of open surgical treatment for condylar fractures, complications of various approaches were assessed. Although transparotid dissection was associated with a higher frequency of temporary facial nerve injury compared to a nontransparotid approach, permeant facial nerve dysfunction was more commonly with the nontransparotid approach (0.07% after a transparotid approach, and 0.4% after a non-transparotid
8
approach).4 Full recovery was documented to be from a week to more than 6 months. 4 The authors contributed this difference to greater traction with non-transparotid dissection compared to a transparotid dissection. Results in this study showed no permanent injury to facial nerve branches, and temporary injury occurred in approximately 22.8% of fractures treated, which is an acceptable percentage compared to previous studies (temporary injury reported from 0 to 33%).4,15-17 Temporary injury was most frequent among exposed facial nerves treated by traditional retraction and least among unexposed branches. Additionally, recovery time for nerve injury was significantly greater for the traditional retraction group. These findings support those of the systematic review, as less retraction of the nerve intraoperatively leads to a lower rate of facial nerve dysfunction postoperatively. As unexposed nerves suffered the least amount of temporary injury, surrounding tissue may provide additional protection of the facial nerve from these traction forces. Several other factors can make the facial nerve more prone to paresis postoperatively. In addition to approach choice, dissection and retraction of the nerve, the degree and direction of condylar displacement, tissue handling, duration of procedure, the surgeon’s experience and the amount of subcutaneous tissue can make the facial nerve more prone to injury.4,14,15 The narrowness of the field, especially if surgeons try to adopt a smaller aesthetic incision, may necessitate extra traction on the nerve especially in medially displaced proximal segments. The level of the fracture is another factor involved in determining the appropriate approach, which can subsequently affect facial nerve function. Although the retromandibular approach has been recommended in condylar neck and subcondylar fractures14, the BTD in the retromandibular approach can provide improved access to higher fractures (see Figure 4). The superior dissection port above the exposed facial nerve branch gives access to the proximal fracture segment, and 9
allows better access for plate adaptation, drilling and screw fixation. Thus, ORIF of noncomminuted fractures reaching the lower condylar head can be accessed while still preserving the facial nerve with minimal traction. The primary limitation of this study is the relatively small sample size particularly in the exposed nerve groups, which is reflected in the wide confidence interval when determining the odds of facial nerve injury. Additionally, those assessing facial function and recovery postoperative were not blinded to the surgical technique used. This work also reflects only a single institution and single team experience. Future plans are to include blinded studies on a wider scale with possible multicenter involvement. Finally, a scale for severity of facial nerve injury was not utilized, as instead it was believed that detecting which branch was affected, and the time needed for full recovery can be a better estimate of injury severity in this study. Conclusion BTD is a newly-described modification to address exposed facial nerve branches in the retromandibular transparotid approach to condylar osteosynthesis. Although avoiding facial nerve exposure minimizes nerve injury the most, the BTD approach reduces nerve injury compared to the traditional dissection in accidentally-exposed branches, and may be associated with quicker recovery time when temporary injuries occur. Conflict of interest statement: None Financial Disclosure Statement: None to declare References 1. Kim B-K, Kwon Y-D, Ohe JY, Choi Y-H, Choi B-J. Usefulness of the retromandibular transparotid approach for condylar neck and condylar base fractures. Journal of Craniofacial Surgery 2012: 23: 712-15. 10
2. Hou J, Chen L, Wang T, et al. A new surgical approach to treat medial or low condylar fractures: the minor parotid anterior approach. Oral surgery, oral medicine, oral pathology and oral radiology 2014: 117: 283-88. 3. Neff A, Cornelius C-P, Rasse M, Dalla Torre D, Audigé L. The comprehensive AOCMF classification system: condylar process fractures-level 3 tutorial. Craniomaxillofacial trauma & reconstruction 2014: 7: S044. 4. Rozeboom A, Dubois L, Bos R, Spijker R, de Lange J. Open treatment of condylar fractures via extraoral approaches: A review of complications. Journal of Cranio-Maxillofacial Surgery 2018. 5. Nogami S, Takahashi T, Yamauchi K, et al. Clinical comparison between the retromandibular approach for reduction and fixation and endoscope-assisted open reduction and internal fixation for mandibular condyle fractures. Journal of Craniofacial Surgery 2012: 23: 1815-18. 6. Spiessl B. Rigid internal fixation of fractures of the lower jaw. Reconstruction surgery and traumatology 1972: 13: 124-40. 7. Derfoufi L, Delaval C, Goudot P, Yachouh J. Complications of condylar fracture osteosynthesis. Journal of Craniofacial Surgery 2011: 22: 1448-51. 8. Bouchard C, Perreault M-H. Postoperative complications associated with the retromandibular approach: a retrospective analysis of 118 subcondylar fractures. Journal of Oral and Maxillofacial Surgery 2014: 72: 370-75. 9. Bhutia O, Kumar L, Jose A, Roychoudhury A, Trikha A. Evaluation of facial nerve following open reduction and internal fixation of subcondylar fracture through retromandibular transparotid approach. British Journal of Oral and Maxillofacial Surgery 2014: 52: 236-40.
11
10. Choi K-Y, Yang J-D, Chung H-Y, Cho B-C. Current concepts in the mandibular condyle fracture management part I: overview of condylar fracture. Archives of plastic surgery 2012: 39: 291. 11. Girotto R, Mancini P, Balercia P. The retromandibular transparotid approach: our clinical experience. Journal of Cranio-Maxillofacial Surgery 2012: 40: 78-81. 12. Salgarelli AC, Anesi A, Bellini P, et al. How to improve retromandibular transmasseteric anteroparotid approach for mandibular condylar fractures: our clinical experience. International journal of oral and maxillofacial surgery 2013: 42: 464-69. 13. Kanno T, Sukegawa S, Tatsumi H, et al. The retromandibular transparotid approach for reduction and rigid internal fixation using two locking miniplates in mandibular condylar neck fractures. International journal of oral and maxillofacial surgery 2014: 43: 177-84. 14. Al-Moraissi EA, Louvrier A, Colletti G, et al. Does the surgical approach for treating mandibular condylar fractures affect the rate of seventh cranial nerve injuries? A systematic review and meta-analysis based on a new classification for surgical approaches. Journal of Cranio-Maxillofacial Surgery 2018: 46: 398-412. 15. Bindra S, Choudhary K, Sharma P, Sheorain A, Sharma C. Management of mandibular sub condylar and condylar fractures using retromandibular approach and assessment of associated surgical complications. Journal of maxillofacial and oral surgery. 2010;9:355-362. 16. Manisali M, Amin M, Aghabeigi B, Newman L. Retromandibular approach to the mandibular condyle: a clinical and cadaveric study. International journal of oral and maxillofacial surgery. 2003;32:253-256. 17. Meeran NA, Selvakumar T. Transparotid approach for subcondylar fracture─ a retrospective study of 20 cases. Arch Oral Sci Res. 2012;2:31-33.
12
Figure Legends Figure 1 showing a schematic illustration of the biportal transparotid dissection “BTD”. A: Superior port created, B: inferior port created. C: Traditional retraction. Figure 2 showing the BTD intraoperatively with the pre and postoperative 3D CT scans. A: The superior dissection port performed above the identified facial nerve branches, showing the proximal portion of plate fixation. B: The inferior dissection port performed below the identified facial nerve branches showing the distal portion of plate fixation. C: 3D CT scan of the patient preoperatively. D: 3D CT scan of the patient postoperatively. Figure 3 showing an example of a patient with facial affection and recovery. A: Patient with BTD through a retromandibular approach performed for his left condylar fracture showing left facial weakness: zygomatic branch paresis, buccal and marginal mandibular branch temporal paralysis. B: Same patient 5 weeks postoperatively with resolution of facial weakness. Figure 4 showing an example of a high condylar fracture managed by the BTD A: Preoperative 3D CT scan of a bilateral high-neck / head condylar fractures. B & C: Postoperative 3D CT scan of the same patient using the BTD method (right and left sides respectively). 13
Table 1: Facial Nerve Injury by Surgical Approach
BTD
Traditional Method
Unexposed Nerve
(Group A)
(Group B)
(Group C)
Total Fractures
10
10
37
FN affected No (%)
2 (20 %)
7 (70 %)
4 (10.81 %)
FN not affected No (%)
8 (80 %)
3 (30 %)
33 (89.19 %)
Permanent FN affection
Nil
Nil
Nil
Marginal mandibular
1/ 2
5/7
1/4
Buccal
2/2
6/7
4/4
Zygomatic
1/2
3/7
0/4
Odds Ratio of Facial Nerve Injury
2.06
19.25
Reference Value
95% CI
0.075 – 3.13
3.50 – 105.87
Reference Value
p-value
0.447
Affected branches
0.001
14
**
Reference Value
Table 2: Average healing time of Facial Nerve Injury by Surgical Method BTD
Traditional Method
Unexposed Nerve
(Group A)
(Group B)
(Group C)
p-value
Average Healing Time (weeks) (standard
5.25 (1.71)
9.17 (2.14)
deviation)
15
*
5.75 (1.70)
0.015
16
17
18
19
20
21
22
23