TECHNICAL STRATEGY
Management of Subcondylar Mandible Fractures in the Adult Patient Berit Hackenberg,*† Cameron Lee, BS,‡ and E. J. Caterson, MD, PhD,*§
Abstract: The treatment of subcondylar mandible fractures is a topic of debate and can be variable even though these fractures are commonly seen. Historically, the treatment algorithm was between open reduction and closed treatment. Now, recent technical advances regarding the use of the endoscope in the field of craniofacial surgery provide additional treatment options. This article aimed to evaluate 3 current management strategies: closed reduction with maxillomandibular fixation, open reduction with internal fixation, and endoscopic-assisted reduction with internal fixation. We present our rationale for surgical decision making and attempt to develop an algorithmic approach to subcondylar fractures. Ankylosis of the temporomandibular joint is a feared complication in these fractures that can lead to the decision to apply maxillomandibular fixation for potentially too short of a period. It is the condylar head fractures within the joint's capsule that contain the hemarthrosis that are often responsible for ankylosis. Subcondylar fractures are, by definition, below the attachment of the joint capsule and in general are devoid of ankylosis. Therefore, maxillomandibular fixation is recommended to be applied for a period of 4 to 6 weeks in most cases. Open reduction with internal fixation can increase the risk for facial nerve damage during the operative approach. However, open reduction is often necessary in fracture patterns with a high degree of displacement. In these cases, facial nerve monitoring can successfully mitigate risks to allow safe exposure for open reduction with internal fixation of subcondylar fractures. Endoscopic-assisted reduction with internal fixation combines the benefits of both techniques while minimizing their associated risks. Nevertheless, reduction can be difficult especially when there is significant medial displacement of the proximal fracture fragment. In our experience, the endoscopic option is optimal for What Is This Box? A QR Code is a matrix barcode readable by QR scanners, mobile phones with cameras, and smartphones. The QR Code links to the online version of the article. From the *Center for Surgery and Public Health, Brigham and Women’s Hospital, Boston, Massachusetts; †University of Heidelberg Medical School, Heidelberg, Germany; ‡Harvard School of Dental Medicine, Boston, Massachusetts; and §Division of Plastic Surgery, Brigham and Women’s Hospital, Boston, Massachusetts. Received May 14, 2013. Accepted for publication October 28, 2013. Address correspondence and reprint requests to Dr E. J. Caterson, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115; E-mail: [email protected] The authors report no conflicts of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000498
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mildly displaced fractures and for the patient with multiple injuries who cannot tolerate closed reduction. Key Words: Subcondylar mandible fracture, open reduction, maxillomandibular fixation, endoscopic, treatment algorithm (J Craniofac Surg 2014;25: 166–171)
I
n the polytrauma patient, facial fractures are commonly seen, with 12% to 56% of cases involving the mandible.1,2 The ascending or vertical component of the mandible is especially vulnerable, and approximately 30% of all mandible fractures are confined to that area.3 Despite this frequency of occurrence, management of these patients is controversial and treatment is variable.4–7 Anatomically, the subcondylar region is the distal aspect of the condylar process. It is superiorly bound by the sigmoid notch line and anteriorly bound by an oblique line joining the sigmoid notch and the masseteric tuberosity8 (Fig. 1). This region is clinically significant because of the presence of the facial nerve and the temporomandibular joint (TMJ), both of which may be functionally impaired by the fracture itself or the operative treatment. Different degrees of dislocation, displacement, comminution, and fracture lines depend on the magnitude of force, the point of application, its transmission, and the patient's occlusal position at the moment of impact. The resulting clinical spectrum challenges the surgeon to use a range of techniques with different risk profiles to achieve outcomes that are both functionally and esthetically pleasing. This article aimed to evaluate 3 current management strategies in the adult patient: closed reduction with maxillomandibular fixation (MMF), open reduction with internal fixation (ORIF), and endoscopic-assisted reduction with internal fixation (ERIF). We present our rationale for surgical decision making and attempt to develop an algorithmic approach to subcondylar fractures. This article can represent a cohesive methodology to guide complex surgical decision making with the goal of aiding craniofacial surgeons in the selection of approaches for this complex fracture pattern. Many studies published in the previous 2 decades have focused on comparing surgical outcomes between closed reduction and open reduction.4,5,9–16 In 1998, Jacobovicz et al reported the first endoscopic open repair of a complex mandibular injury, and techniques of both endoscopic-assisted and pure endoscopic repairs have been reported in the literature more recently.17–22 Although not as prevalent as the standard open and closed approaches, the endoscopic approach revives this classic debate by adding yet another viable treatment option to the management of subcondylar mandible fractures. The present study highlights our experience treating subcondylar fractures in light of current surgical techniques and technology. Three management modalities and their indications are discussed: MMF, ORIF, and ERIF. Each treatment option is presented, highlighting its specific strengths and weaknesses along with clinical examples. Finally, we provide a treatment algorithm based on this experience that derives a structural basis for our decision making with regard to clinical and radiographic findings. In
The Journal of Craniofacial Surgery • Volume 25, Number 1, January 2014
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The Journal of Craniofacial Surgery • Volume 25, Number 1, January 2014
FIGURE 1. Postoperative CT of a subcondylar fracture of the mandible. A, Sigmoid notch line; B, oblique line connecting the sigmoid notch and the masseteric tuberosity.
addition, we recognized that there are significant variations in clinical practice that can often dictate care. It is important for the craniofacial surgeon to be facile with all 3 approaches discussed in this article. It is also pertinent to state that, with proper facial nerve monitoring, the open transparotid approach is safe and reliable and it can allow for surgical comfort to potentially achieve direct anatomic reduction when indicated in nearly all subcondylar fractures.
Closed Reduction Closed reduction has historically been the standard treatment option for subcondylar fractures of the mandible.7 Its widespread use is attributed to the idea that closed reduction results in fewer complications with similar functional and esthetic outcomes compared with ORIF. For instance, complications such as facial nerve damage and excessive scarring are significantly decreased because of the noninvasive nature of this approach.23 However, as highlighted by the ongoing debate, a consensus regarding outcomes between open and closed reduction is not evident in the literature. In short, some studies conclude that both approaches produce roughly similar results,10,13,24,25 whereas others have associated an array of unfavorable outcomes with closed reduction.4,16,26,27 These include facial asymmetry, deviation upon mouth opening, skeletal malocclusion, and chronic pain of the TMJ.14,16,28 The fact that many of these parameters lack standardization in time course of treatment further obscures the debate. Larger studies with consistent parameters are needed to reassess outcomes with the surgical techniques and technology present today. However, it is unlikely that a trial large enough will deliver granular evidence to conclusively quell this debate. Another controversial point regarding closed reduction is the length of time a patient should spend in MMF. Many surgeons choose to apply fixation for a very short period (ie, 2 wk) to avoid
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ankylosis of the TMJ secondary to forced immobilization during MMF.29 Although the etiology of ankylosis is not completely understood, it is hypothesized that trauma leading to intracapsular hematoma results in fibrosis and excessive bone formation, ultimately causing hypomobility of the affected side.30,31 Given the current hypothesis, we believe that ankylosis of the TMJ is a manifestation of direct injury within the joint capsule or the condylar head itself. It is imperative to point out that as a result, there should be a lower risk for ankylosis in subcondylar fractures compared with fractures of the condylar head. Therefore, we advocate to closely examine the position of the fracture line relative to the joint capsule and to use a longer period of MMF if there is no involvement of the condylar head, disk, or capsule. It is our experience that a longer period of MMF results in better union of the fractured segments with no increase in the incidence of ankylosis. In a nondisplaced fracture or minimally displaced fracture with a functional occlusion, we recommend 4 to 6 weeks of MMF followed by 2 to 3 weeks of guiding elastics (Fig. 2). The same treatment applies in the case of a nondisplaced bilateral fracture. However, this scenario is less common because the force parameters to cause the bilateral fracture are often greater and tend to displace the fracture fragments, significantly necessitating ORIF.32
Open Reduction With Internal Fixation Open reduction with internal fixation is generally used in complex mandibular fractures that necessitate direct anatomic reduction. This approach allows the surgeon to access the fracture directly via a preauricular, submandibular, retromandibular transparotid, or retromandibular transmasseteric incision.33 However, the major risk in treating subcondylar fractures with ORIF is the potential to damage the facial nerve. Both permanent and transient paresthesias are reported in the literature, although most cases after ORIF seem to be transient.34,35 In addition, scarring at the surgical site may embody a cosmetic burden to the patient, leading to dissatisfaction despite functionally successful results. Hypertrophic scars in particular are most perceivable and result in 7.5% of scars generated by ORIF.34 Conversely, the benefit of achieving a superior anatomic reduction and thereby better functional outcome makes ORIF desirable in more complex cases. Patients are also able to mobilize the injury site directly after surgery and avoid a prolonged period of MMF. Open reduction with internal fixation is thus indicated for patients lacking functional occlusion with a displaced fracture not amenable to an endoscopic technique. In these cases, we believe that the functional outcome achievable through open reduction outweighs the procedure's operative risks, which can also be mitigated with facial nerve monitoring. The goal of ORIF is to provide optimal fracture reduction while minimizing damage to the facial nerve. We do this using the following approach. First, an incision is made 8 mm anterior to the standard preauricular incision that would normally be on the
FIGURE 2. A, Computed tomography showing bilateral nondisplaced fracture of the subcondylar mandible. B, Maxillomandibular fixation.
© 2014 Mutaz B. Habal, MD
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FIGURE 3. A, Computed tomography showing bilateral displaced fracture of the subcondylar mandible. B, Facial nerve monitoring. C, Blunt dissection of the facial nerve.
tragus. One problem of the standard preauricular incision is that it hinders access to the mandible by forcing one to approach the fracture at a near parallel angle. By placing the incision 8 mm anterior to the tragus, the mandible can be approached at a perpendicular angle, easing plate and screw fixation. Note that shifting the incision anteriorly poses no risk to the facial nerve, which is virtually never found within 8 mm of the tragus.36 Facial nerve monitoring is used to evaluate facial nerve activity during the procedure. This aspect is critical in minimizing damage to the facial nerve. After identification of each branch, the facial nerve is carefully separated using blunt dissection (Fig. 3). Displaying the facial nerve in this manner is time consuming but significantly lowers the risk for damage when working between its upper and lower divisions. Reduction of the subcondylar fracture is performed normally. However, in the case of a medial displacement, a threaded reduction tool should be readily available in the operating room. This direction of displacement is common because of the insertion of the lateral pterygoid muscle and its action.6 Wound closure is achieved by closing the parotid fascia separate from the skin. To address esthetic concerns regarding the anteriorly positioned scar, 6 to 12 months postoperatively, the scar can be shifted and repositioned in the direct preauricular position under local anesthesia. In our experience, the scar is well hidden by this routine, and the low-risk scar revision can be dictated by patient desire. Overall, this approach is beneficial in that it allows for a simpler anatomic
reduction during the first surgery with a perpendicular approach to the fracture at no ultimately esthetic cost to the patient. In our experience, risk for permanent paresthesia is not significantly increased provided the facial nerve dissection is performed properly under constant monitoring.
Endoscopic-Assisted Reduction With Internal Fixation Different techniques have been suggested in the literature regarding the use of the endoscope for the repair of subcondylar fractures.17,20,37–39 Many authors have reached the conclusion that this approach combines the benefits of both closed and open reduction. Documented benefits that have been described and agreed upon are limited scarring and decreased risk to the facial nerve during the surgery. Furthermore, the illuminated field grants the surgeon, the assistant, the scrub nurse, and the observers a more accessible view. Different authors have used the endoscope either via an extraoral incision placed below the angle of the mandible or via an intraoral incision.20,40 In our hands, we find introduction of an endoscope through an intraoral oblique line incision facile. This approach further embraces the hallmark of endoscopic surgery by minimizing scarring because extraoral tissue dissection is limited to the small stab incisions required for the placement of the trochar. It is also noteworthy that the intraoral access forces the surgeon to approach the fracture in line with the mandibular bone. This
FIGURE 4. A, Radiograph showing large unilateral pneumothorax. Closed reduction with maxillomandibular fixation is relatively contraindicated in this patient. B, Endoscopic setup. C, Intraoperative endoscopic picture of plate fixation. LT, patient's left side.
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makes reduction technically more challenging and not always possible. Therefore, we reserve this approach for laterally displaced fractures, fractures with minimal medial displacement, and fractures rotated anteriorly in the sagittal plane. It is of greater value in patients with no or minor displacements, who are not optimal candidates for several weeks of MMF (Fig. 4). Although endoscopic approaches have shown benefits, they also have their limitations, namely, in cases with significant bony displacement we are now trending toward ORIF with facial nerve monitoring.
DISCUSSION Although the techniques mentioned above each have an array of strengths and weaknesses, the general aim of fracture reduction is always to restore premorbid form and function without harming the patient. However, determining the optimal treatment for each case is not a simple task, and the aim of this article was to make an effort to clarify the best approach for each patient. The diversity of surgical techniques, materials, and perhaps more importantly fracture type and location challenges us to make the correct decision for each individual patient. It is implicit in this article that with an open approach coupled with facial nerve monitoring, nearly all subcondylar fractures can be reduced effectively but at the cost of increased operative time and the need for additional facial nerve monitoring technology. Figure 5 outlines our treatment algorithm in approaching subcondylar fractures of the mandible. The figure is based on current literature and our clinical experience. We begin with the first assessment of the patient's functional occlusion and premature contact and correlate this occlusion with the amount of displacement on the computed tomographic (CT) scan. This information is coupled
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with further clinical evaluation including the patient's medical history and personal preferences, allowing the patient and the surgeon to arrive at a shared decision. Note that we have excluded children from the patient population discussed because different challenges are expected in a growing mandible and such considerations exceed the scope of this article.15 If the patient presents with a preserved occlusion, we generally opt to perform a closed reduction. Upon CT examination, a nondisplaced fracture may be treated with either 6 weeks of a soft diet or MMF for 4 to 6 weeks, depending on patient preference and normal findings from a functional examination. In a minimally displaced fracture, our decision is based upon further evaluation of functional status. When the patient shows no infringement regarding the range of mandibular motion, deviation on opening, or intercuspation of the teeth, and when this patient can tolerate MMF, we recommend closed reduction. In the case of significant functional infringement such as loss of vertical height or if the patient is unable to tolerate MMF, we choose to approach and repair the fracture endoscopically. It is our opinion that restoring any loss in vertical height is imperative in achieving premorbid form and function. In the case of a minimally displaced fracture, ERIF is technically simple, provides restoration of vertical height relative to closed reduction, and allows us to avoid the operative morbidities associated with a facial nerve dissection. We assert that ERIF promises to replace MMF in 2 specific scenarios: one, when patients cannot tolerate a period of MMF because of poor dentition or comorbidities (Table 1), and two, when a fracture is displaced with significant functional impairment but not significantly enough to warrant ORIF. If the patient presents with his/her dentition not in functional occlusion, we expect the CT scan to show a low or high degree of
FIGURE 5. Algorithm for the treatment of subcondylar fractures of the mandible in the adult patient.
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TABLE 1. Conversion of MMF Into ERIF Relative Contraindications for the Use of MMF Respiratory compromise (eg, due to trauma, flail chest, pneumothorax, infection, asthma, chronic obstructive pulmonary disease) Nutritional status Noncompliance, psychiatric comorbidity Oral health (eg, edentulous patient, gross periodontal disease, gross caries) Other comorbidities (eg, seizure disorder)
displacement. In these cases, restoration of premorbid form and function is highly dependent on the approach taken by the surgeon. It is our experience that superior outcomes are achieved through the use of ERIF or ORIF rather than closed reduction. Although many surgeons advocate for closed reduction when possible, we believe that secondary healing of the fracture site can result in potential malunion, facial asymmetry, deviation on mouth opening, and chronic TMJ problems. Although there may be concerns regarding facial nerve injury, such complications are negligible in ERIF and minimized using the previously described surgical approach under facial nerve monitoring for ORIF. In fractures with minimal displacement and those that seem amenable to reduction via the endoscopic approach, ERIF should be considered the primary treatment option. Indications for ERIF include laterally displaced fractures in the coronal plane, fractures rotated anteriorly in the sagittal plane, and fractures with a minimal degree of medial displacement. In the latter case, reduction may be slightly more difficult and a threaded k-wire or condylar reduction tool should be available. Fractures with a low degree of displacement not amenable to ERIF should be treated with ORIF to best restore premorbid form and function. Subcondylar fractures with a high degree of displacement are always treated with ORIF. As previously stated, ORIF results in superior fracture reduction of complex fractures not attainable through other surgical techniques. This approach regarding the use of ORIF is well established in both the literature and clinical practice. Lastly, the presence of a bilateral fracture does not necessarily influence the treatment plan. As long as both sides are nondisplaced, MMF can still be applied. In the case of displacement with loss of vertical height, we recommend operating with ERIF or ORIF on the safer side—typically the fracture that is lower and provides a larger proximal segment for fixation. When considering internal fixation, the proximal segment should always be optimally large enough to place at least 2 screws superior to the fracture.
Nevertheless, the operative time can be prolonged because of the more technically challenging reduction of displaced segments compared with the open approach. Therefore, we see the main benefit of ERIF in replacing MMF in patients who cannot tolerate the prolonged fixation with closed reduction. This becomes pivotal in the trauma patient because concomitant injuries such as pneumothorax, flail chest, and other respiratory compromising conditions are frequently observed in maxillofacial fractures.41 Reductions requiring ORIF are a potential source of injury to the facial nerve. Damage to this delicate structure may result in paresthesia of the facial muscles ranging from mild to severe and from transient to permanent. The preauricular incision may lead to a difficult reduction in which damage to the undissected facial nerve occurs through excessive tissue retraction. Our approach to managing the facial nerve is slightly different. The anteriorly placed incision (8 mm in front of the external auditory canal) necessitates dissection of the individual branches of the nerve, allowing direct visualization to avoid injury. Dissecting and separating the individual branches, if done properly under facial nerve monitoring, may actually reduce the probability of paresthesia through direct vision. However, this additional dissection effort comes with the great benefit of a perpendicular access to the fracture easing the difficulty of reduction in nearly every fracture pattern. The treatment of subcondylar mandible fractures remains a topic of debate. The discussion focused historically on whether open or closed reduction achieved better outcomes regarding premorbid form and function while minimizing morbidity associated with treatment. Recent technical advances within the field of endoscopic surgery have added yet another treatment modality, further challenging the surgeon to choose the best option for his/her patients. We conclude that the main benefits of ERIF are found in the replacement of MMF in selected patients. This is clinically significant when MMF is not a viable option for the patient or when there is a mild functional discrepancy that can be restored with ERIF but does not warrant ORIF. However, the duration of MMF should be 4 to 6 weeks when performing closed reduction on a true subcondylar fracture. When ORIF is necessary, surgeons should consider becoming familiar working with the facial nerve under monitoring to improve anatomic reduction. Lastly, in the era of shared decision making, patients' choices always need to be considered. In general, an algorithm may inform or provide a structural basis for this decision making to not only ensure the best outcome for our patients but also serve as a point of discussion in the management of this complex fracture pattern.
CONCLUSIONS
REFERENCES
In cases in which closed reduction is the management technique of choice, the duration of MMF varies between institutions. The main concern is finding a balance between attaining fracture reduction and avoiding ankylosis of the TMJ. Given the anatomic location of a subcondylar fracture, we believe that fractures properly diagnosed as within this region are at low risk for ankylosis. In a subcondylar fracture, one will generally not observe trauma to the joint capsule or the condylar head. As such, we recommend a period of MMF for at least 4 to 6 weeks, with an additional period of 2 to 3 weeks of guiding elastics in patients in whom closed fixation is possible. Compared with the rather short duration of 2 weeks,5 a longer period of MMF works toward achieving maximal union and healing of the fracture. The endoscopic approach provides surgeons with a third viable option for treating subcondylar fractures. It combines the benefits of ORIF and MMF while minimizing their associated risks.
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6. Lee JW, Lee YC, Kuo YL. Reappraisal of the surgical strategy in treatment of mandibular condylar fractures. Plast Reconstr Surg 2010;125:609–619 7. Baker AW, McMahon J, Moos KF. Current consensus on the management of fractures of the mandibular condyle. A method by questionnaire. Int J Oral Maxillofac Surg 1998;27:258–266 8. AO Foundation. Mandible - diagnosis - AO surgery reference. Available at: https://www2.aofoundation.org/wps/portal/!ut/p/c0/ 04_SB8K8xLLM9MSSzPy8xBz9CP0os3hng7BARydDRwN 3QwMDA08zTzdvvxBjIwN_I_2CbEdFADiM_QM!/?segment= Mandible&bone=CMF&classification=91-Condylar process and head, simple and complex&teaserTitle=&showPage= diagnosis&contentUrl=srg/91/01-Diagnosis/ao_srg_diag_condyle_all.jsp. Accessed April 24, 2013 9. Vural E. Treatment of adult subcondylar mandibular fractures: closed vs open vs endoscopic approach. Arch Otolaryngol Head Neck Surg 2004;130:1228–1230 10. Santler G, Karcher H, Ruda C, et al. Fractures of the condylar process: surgical versus nonsurgical treatment. J Oral Maxillofac Surg 1999;57:392–397; discussion 397–8 11. Konstantinovic VS, Dimitrijevic B. Surgical versus conservative treatment of unilateral condylar process fractures: clinical and radiographic evaluation of 80 patients. J Oral Maxillofac Surg 1992;50:349–352; discussion 352–3 12. Palmieri C, Ellis EIII, Throckmorton G. Mandibular motion after closed and open treatment of unilateral mandibular condylar process fractures. J Oral Maxillofac Surg 1999;57:764–775; discussion 775–6 13. Danda AK, Muthusekhar MR, Narayanan V, et al. Open versus closed treatment of unilateral subcondylar and condylar neck fractures: a prospective, randomized clinical study. J Oral Maxillofac Surg 2010;68:1238–1241 14. Haug RH, Assael LA. Outcomes of open versus closed treatment of mandibular subcondylar fractures. J Oral Maxillofac Surg 2001;59:370–375; discussion 375–6 15. Zachariades N, Mezitis M, Mourouzis C, et al. Fractures of the mandibular condyle: a review of 466 cases. Literature review, reflections on treatment and proposals. J Craniomaxillofac Surg 2006;34:421–432 16. Worsaae N, Thorn JJ. Surgical versus nonsurgical treatment of unilateral dislocated low subcondylar fractures: a clinical study of 52 cases. J Oral Maxillofac Surg 1994;52:353–360; discussion 360–1 17. Mueller R. Endoscopic treatment of facial fractures. Facial Plast Surg 2008;24:78–91 18. Kellman RM, Cienfuegos R. Endoscopic approaches to subcondylar fractures of the mandible. Facial Plast Surg 2009;25:23–28 19. Kellman RM. Endoscopically assisted repair of subcondylar fractures of the mandible: an evolving technique. Arch Facial Plast Surg 2003;5:244–250 20. Troulis MJ. Endoscopic open reduction and internal rigid fixation of subcondylar fractures. J Oral Maxillofac Surg 2004;62:1269–1271 21. Pham AM, Strong EB. Endoscopic management of facial fractures. Curr Opin Otolaryngol Head Neck Surg 2006;14:234–241 22. Jacobovicz J, Lee C, Trabulsy PP. Endoscopic repair of mandibular subcondylar fractures. Plast Reconstr Surg 1998;101:437–441 23. Haug RH, Brandt MT. Closed reduction, open reduction, and endoscopic assistance: current thoughts on the management of
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Management of Subcondylar Mandible Fractures in the Adult Patient Berit Hackenberg,*† Cameron Lee, BS,‡ and E. J. Caterson, MD, PhD,*§
Abstract: The treatment of subcondylar mandible fractures is a topic of debate and can be variable even though these fractures are commonly seen. Historically, the treatment algorithm was between open reduction and closed treatment. Now, recent technical advances regarding the use of the endoscope in the field of craniofacial surgery provide additional treatment options. This article aimed to evaluate 3 current management strategies: closed reduction with maxillomandibular fixation, open reduction with internal fixation, and endoscopic-assisted reduction with internal fixation. We present our rationale for surgical decision making and attempt to develop an algorithmic approach to subcondylar fractures. Ankylosis of the temporomandibular joint is a feared complication in these fractures that can lead to the decision to apply maxillomandibular fixation for potentially too short of a period. It is the condylar head fractures within the joint's capsule that contain the hemarthrosis that are often responsible for ankylosis. Subcondylar fractures are, by definition, below the attachment of the joint capsule and in general are devoid of ankylosis. Therefore, maxillomandibular fixation is recommended to be applied for a period of 4 to 6 weeks in most cases. Open reduction with internal fixation can increase the risk for facial nerve damage during the operative approach. However, open reduction is often necessary in fracture patterns with a high degree of displacement. In these cases, facial nerve monitoring can successfully mitigate risks to allow safe exposure for open reduction with internal fixation of subcondylar fractures. Endoscopic-assisted reduction with internal fixation combines the benefits of both techniques while minimizing their associated risks. Nevertheless, reduction can be difficult especially when there is significant medial displacement of the proximal fracture fragment. In our experience, the endoscopic option is optimal for What Is This Box? A QR Code is a matrix barcode readable by QR scanners, mobile phones with cameras, and smartphones. The QR Code links to the online version of the article. From the *Center for Surgery and Public Health, Brigham and Women’s Hospital, Boston, Massachusetts; †University of Heidelberg Medical School, Heidelberg, Germany; ‡Harvard School of Dental Medicine, Boston, Massachusetts; and §Division of Plastic Surgery, Brigham and Women’s Hospital, Boston, Massachusetts. Received May 14, 2013. Accepted for publication October 28, 2013. Address correspondence and reprint requests to Dr E. J. Caterson, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115; E-mail: [email protected] The authors report no conflicts of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000498
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mildly displaced fractures and for the patient with multiple injuries who cannot tolerate closed reduction. Key Words: Subcondylar mandible fracture, open reduction, maxillomandibular fixation, endoscopic, treatment algorithm (J Craniofac Surg 2014;25: 166–171)
I
n the polytrauma patient, facial fractures are commonly seen, with 12% to 56% of cases involving the mandible.1,2 The ascending or vertical component of the mandible is especially vulnerable, and approximately 30% of all mandible fractures are confined to that area.3 Despite this frequency of occurrence, management of these patients is controversial and treatment is variable.4–7 Anatomically, the subcondylar region is the distal aspect of the condylar process. It is superiorly bound by the sigmoid notch line and anteriorly bound by an oblique line joining the sigmoid notch and the masseteric tuberosity8 (Fig. 1). This region is clinically significant because of the presence of the facial nerve and the temporomandibular joint (TMJ), both of which may be functionally impaired by the fracture itself or the operative treatment. Different degrees of dislocation, displacement, comminution, and fracture lines depend on the magnitude of force, the point of application, its transmission, and the patient's occlusal position at the moment of impact. The resulting clinical spectrum challenges the surgeon to use a range of techniques with different risk profiles to achieve outcomes that are both functionally and esthetically pleasing. This article aimed to evaluate 3 current management strategies in the adult patient: closed reduction with maxillomandibular fixation (MMF), open reduction with internal fixation (ORIF), and endoscopic-assisted reduction with internal fixation (ERIF). We present our rationale for surgical decision making and attempt to develop an algorithmic approach to subcondylar fractures. This article can represent a cohesive methodology to guide complex surgical decision making with the goal of aiding craniofacial surgeons in the selection of approaches for this complex fracture pattern. Many studies published in the previous 2 decades have focused on comparing surgical outcomes between closed reduction and open reduction.4,5,9–16 In 1998, Jacobovicz et al reported the first endoscopic open repair of a complex mandibular injury, and techniques of both endoscopic-assisted and pure endoscopic repairs have been reported in the literature more recently.17–22 Although not as prevalent as the standard open and closed approaches, the endoscopic approach revives this classic debate by adding yet another viable treatment option to the management of subcondylar mandible fractures. The present study highlights our experience treating subcondylar fractures in light of current surgical techniques and technology. Three management modalities and their indications are discussed: MMF, ORIF, and ERIF. Each treatment option is presented, highlighting its specific strengths and weaknesses along with clinical examples. Finally, we provide a treatment algorithm based on this experience that derives a structural basis for our decision making with regard to clinical and radiographic findings. In
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FIGURE 1. Postoperative CT of a subcondylar fracture of the mandible. A, Sigmoid notch line; B, oblique line connecting the sigmoid notch and the masseteric tuberosity.
addition, we recognized that there are significant variations in clinical practice that can often dictate care. It is important for the craniofacial surgeon to be facile with all 3 approaches discussed in this article. It is also pertinent to state that, with proper facial nerve monitoring, the open transparotid approach is safe and reliable and it can allow for surgical comfort to potentially achieve direct anatomic reduction when indicated in nearly all subcondylar fractures.
Closed Reduction Closed reduction has historically been the standard treatment option for subcondylar fractures of the mandible.7 Its widespread use is attributed to the idea that closed reduction results in fewer complications with similar functional and esthetic outcomes compared with ORIF. For instance, complications such as facial nerve damage and excessive scarring are significantly decreased because of the noninvasive nature of this approach.23 However, as highlighted by the ongoing debate, a consensus regarding outcomes between open and closed reduction is not evident in the literature. In short, some studies conclude that both approaches produce roughly similar results,10,13,24,25 whereas others have associated an array of unfavorable outcomes with closed reduction.4,16,26,27 These include facial asymmetry, deviation upon mouth opening, skeletal malocclusion, and chronic pain of the TMJ.14,16,28 The fact that many of these parameters lack standardization in time course of treatment further obscures the debate. Larger studies with consistent parameters are needed to reassess outcomes with the surgical techniques and technology present today. However, it is unlikely that a trial large enough will deliver granular evidence to conclusively quell this debate. Another controversial point regarding closed reduction is the length of time a patient should spend in MMF. Many surgeons choose to apply fixation for a very short period (ie, 2 wk) to avoid
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ankylosis of the TMJ secondary to forced immobilization during MMF.29 Although the etiology of ankylosis is not completely understood, it is hypothesized that trauma leading to intracapsular hematoma results in fibrosis and excessive bone formation, ultimately causing hypomobility of the affected side.30,31 Given the current hypothesis, we believe that ankylosis of the TMJ is a manifestation of direct injury within the joint capsule or the condylar head itself. It is imperative to point out that as a result, there should be a lower risk for ankylosis in subcondylar fractures compared with fractures of the condylar head. Therefore, we advocate to closely examine the position of the fracture line relative to the joint capsule and to use a longer period of MMF if there is no involvement of the condylar head, disk, or capsule. It is our experience that a longer period of MMF results in better union of the fractured segments with no increase in the incidence of ankylosis. In a nondisplaced fracture or minimally displaced fracture with a functional occlusion, we recommend 4 to 6 weeks of MMF followed by 2 to 3 weeks of guiding elastics (Fig. 2). The same treatment applies in the case of a nondisplaced bilateral fracture. However, this scenario is less common because the force parameters to cause the bilateral fracture are often greater and tend to displace the fracture fragments, significantly necessitating ORIF.32
Open Reduction With Internal Fixation Open reduction with internal fixation is generally used in complex mandibular fractures that necessitate direct anatomic reduction. This approach allows the surgeon to access the fracture directly via a preauricular, submandibular, retromandibular transparotid, or retromandibular transmasseteric incision.33 However, the major risk in treating subcondylar fractures with ORIF is the potential to damage the facial nerve. Both permanent and transient paresthesias are reported in the literature, although most cases after ORIF seem to be transient.34,35 In addition, scarring at the surgical site may embody a cosmetic burden to the patient, leading to dissatisfaction despite functionally successful results. Hypertrophic scars in particular are most perceivable and result in 7.5% of scars generated by ORIF.34 Conversely, the benefit of achieving a superior anatomic reduction and thereby better functional outcome makes ORIF desirable in more complex cases. Patients are also able to mobilize the injury site directly after surgery and avoid a prolonged period of MMF. Open reduction with internal fixation is thus indicated for patients lacking functional occlusion with a displaced fracture not amenable to an endoscopic technique. In these cases, we believe that the functional outcome achievable through open reduction outweighs the procedure's operative risks, which can also be mitigated with facial nerve monitoring. The goal of ORIF is to provide optimal fracture reduction while minimizing damage to the facial nerve. We do this using the following approach. First, an incision is made 8 mm anterior to the standard preauricular incision that would normally be on the
FIGURE 2. A, Computed tomography showing bilateral nondisplaced fracture of the subcondylar mandible. B, Maxillomandibular fixation.
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FIGURE 3. A, Computed tomography showing bilateral displaced fracture of the subcondylar mandible. B, Facial nerve monitoring. C, Blunt dissection of the facial nerve.
tragus. One problem of the standard preauricular incision is that it hinders access to the mandible by forcing one to approach the fracture at a near parallel angle. By placing the incision 8 mm anterior to the tragus, the mandible can be approached at a perpendicular angle, easing plate and screw fixation. Note that shifting the incision anteriorly poses no risk to the facial nerve, which is virtually never found within 8 mm of the tragus.36 Facial nerve monitoring is used to evaluate facial nerve activity during the procedure. This aspect is critical in minimizing damage to the facial nerve. After identification of each branch, the facial nerve is carefully separated using blunt dissection (Fig. 3). Displaying the facial nerve in this manner is time consuming but significantly lowers the risk for damage when working between its upper and lower divisions. Reduction of the subcondylar fracture is performed normally. However, in the case of a medial displacement, a threaded reduction tool should be readily available in the operating room. This direction of displacement is common because of the insertion of the lateral pterygoid muscle and its action.6 Wound closure is achieved by closing the parotid fascia separate from the skin. To address esthetic concerns regarding the anteriorly positioned scar, 6 to 12 months postoperatively, the scar can be shifted and repositioned in the direct preauricular position under local anesthesia. In our experience, the scar is well hidden by this routine, and the low-risk scar revision can be dictated by patient desire. Overall, this approach is beneficial in that it allows for a simpler anatomic
reduction during the first surgery with a perpendicular approach to the fracture at no ultimately esthetic cost to the patient. In our experience, risk for permanent paresthesia is not significantly increased provided the facial nerve dissection is performed properly under constant monitoring.
Endoscopic-Assisted Reduction With Internal Fixation Different techniques have been suggested in the literature regarding the use of the endoscope for the repair of subcondylar fractures.17,20,37–39 Many authors have reached the conclusion that this approach combines the benefits of both closed and open reduction. Documented benefits that have been described and agreed upon are limited scarring and decreased risk to the facial nerve during the surgery. Furthermore, the illuminated field grants the surgeon, the assistant, the scrub nurse, and the observers a more accessible view. Different authors have used the endoscope either via an extraoral incision placed below the angle of the mandible or via an intraoral incision.20,40 In our hands, we find introduction of an endoscope through an intraoral oblique line incision facile. This approach further embraces the hallmark of endoscopic surgery by minimizing scarring because extraoral tissue dissection is limited to the small stab incisions required for the placement of the trochar. It is also noteworthy that the intraoral access forces the surgeon to approach the fracture in line with the mandibular bone. This
FIGURE 4. A, Radiograph showing large unilateral pneumothorax. Closed reduction with maxillomandibular fixation is relatively contraindicated in this patient. B, Endoscopic setup. C, Intraoperative endoscopic picture of plate fixation. LT, patient's left side.
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makes reduction technically more challenging and not always possible. Therefore, we reserve this approach for laterally displaced fractures, fractures with minimal medial displacement, and fractures rotated anteriorly in the sagittal plane. It is of greater value in patients with no or minor displacements, who are not optimal candidates for several weeks of MMF (Fig. 4). Although endoscopic approaches have shown benefits, they also have their limitations, namely, in cases with significant bony displacement we are now trending toward ORIF with facial nerve monitoring.
DISCUSSION Although the techniques mentioned above each have an array of strengths and weaknesses, the general aim of fracture reduction is always to restore premorbid form and function without harming the patient. However, determining the optimal treatment for each case is not a simple task, and the aim of this article was to make an effort to clarify the best approach for each patient. The diversity of surgical techniques, materials, and perhaps more importantly fracture type and location challenges us to make the correct decision for each individual patient. It is implicit in this article that with an open approach coupled with facial nerve monitoring, nearly all subcondylar fractures can be reduced effectively but at the cost of increased operative time and the need for additional facial nerve monitoring technology. Figure 5 outlines our treatment algorithm in approaching subcondylar fractures of the mandible. The figure is based on current literature and our clinical experience. We begin with the first assessment of the patient's functional occlusion and premature contact and correlate this occlusion with the amount of displacement on the computed tomographic (CT) scan. This information is coupled
Subcondylar Mandible Fractures
with further clinical evaluation including the patient's medical history and personal preferences, allowing the patient and the surgeon to arrive at a shared decision. Note that we have excluded children from the patient population discussed because different challenges are expected in a growing mandible and such considerations exceed the scope of this article.15 If the patient presents with a preserved occlusion, we generally opt to perform a closed reduction. Upon CT examination, a nondisplaced fracture may be treated with either 6 weeks of a soft diet or MMF for 4 to 6 weeks, depending on patient preference and normal findings from a functional examination. In a minimally displaced fracture, our decision is based upon further evaluation of functional status. When the patient shows no infringement regarding the range of mandibular motion, deviation on opening, or intercuspation of the teeth, and when this patient can tolerate MMF, we recommend closed reduction. In the case of significant functional infringement such as loss of vertical height or if the patient is unable to tolerate MMF, we choose to approach and repair the fracture endoscopically. It is our opinion that restoring any loss in vertical height is imperative in achieving premorbid form and function. In the case of a minimally displaced fracture, ERIF is technically simple, provides restoration of vertical height relative to closed reduction, and allows us to avoid the operative morbidities associated with a facial nerve dissection. We assert that ERIF promises to replace MMF in 2 specific scenarios: one, when patients cannot tolerate a period of MMF because of poor dentition or comorbidities (Table 1), and two, when a fracture is displaced with significant functional impairment but not significantly enough to warrant ORIF. If the patient presents with his/her dentition not in functional occlusion, we expect the CT scan to show a low or high degree of
FIGURE 5. Algorithm for the treatment of subcondylar fractures of the mandible in the adult patient.
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TABLE 1. Conversion of MMF Into ERIF Relative Contraindications for the Use of MMF Respiratory compromise (eg, due to trauma, flail chest, pneumothorax, infection, asthma, chronic obstructive pulmonary disease) Nutritional status Noncompliance, psychiatric comorbidity Oral health (eg, edentulous patient, gross periodontal disease, gross caries) Other comorbidities (eg, seizure disorder)
displacement. In these cases, restoration of premorbid form and function is highly dependent on the approach taken by the surgeon. It is our experience that superior outcomes are achieved through the use of ERIF or ORIF rather than closed reduction. Although many surgeons advocate for closed reduction when possible, we believe that secondary healing of the fracture site can result in potential malunion, facial asymmetry, deviation on mouth opening, and chronic TMJ problems. Although there may be concerns regarding facial nerve injury, such complications are negligible in ERIF and minimized using the previously described surgical approach under facial nerve monitoring for ORIF. In fractures with minimal displacement and those that seem amenable to reduction via the endoscopic approach, ERIF should be considered the primary treatment option. Indications for ERIF include laterally displaced fractures in the coronal plane, fractures rotated anteriorly in the sagittal plane, and fractures with a minimal degree of medial displacement. In the latter case, reduction may be slightly more difficult and a threaded k-wire or condylar reduction tool should be available. Fractures with a low degree of displacement not amenable to ERIF should be treated with ORIF to best restore premorbid form and function. Subcondylar fractures with a high degree of displacement are always treated with ORIF. As previously stated, ORIF results in superior fracture reduction of complex fractures not attainable through other surgical techniques. This approach regarding the use of ORIF is well established in both the literature and clinical practice. Lastly, the presence of a bilateral fracture does not necessarily influence the treatment plan. As long as both sides are nondisplaced, MMF can still be applied. In the case of displacement with loss of vertical height, we recommend operating with ERIF or ORIF on the safer side—typically the fracture that is lower and provides a larger proximal segment for fixation. When considering internal fixation, the proximal segment should always be optimally large enough to place at least 2 screws superior to the fracture.
Nevertheless, the operative time can be prolonged because of the more technically challenging reduction of displaced segments compared with the open approach. Therefore, we see the main benefit of ERIF in replacing MMF in patients who cannot tolerate the prolonged fixation with closed reduction. This becomes pivotal in the trauma patient because concomitant injuries such as pneumothorax, flail chest, and other respiratory compromising conditions are frequently observed in maxillofacial fractures.41 Reductions requiring ORIF are a potential source of injury to the facial nerve. Damage to this delicate structure may result in paresthesia of the facial muscles ranging from mild to severe and from transient to permanent. The preauricular incision may lead to a difficult reduction in which damage to the undissected facial nerve occurs through excessive tissue retraction. Our approach to managing the facial nerve is slightly different. The anteriorly placed incision (8 mm in front of the external auditory canal) necessitates dissection of the individual branches of the nerve, allowing direct visualization to avoid injury. Dissecting and separating the individual branches, if done properly under facial nerve monitoring, may actually reduce the probability of paresthesia through direct vision. However, this additional dissection effort comes with the great benefit of a perpendicular access to the fracture easing the difficulty of reduction in nearly every fracture pattern. The treatment of subcondylar mandible fractures remains a topic of debate. The discussion focused historically on whether open or closed reduction achieved better outcomes regarding premorbid form and function while minimizing morbidity associated with treatment. Recent technical advances within the field of endoscopic surgery have added yet another treatment modality, further challenging the surgeon to choose the best option for his/her patients. We conclude that the main benefits of ERIF are found in the replacement of MMF in selected patients. This is clinically significant when MMF is not a viable option for the patient or when there is a mild functional discrepancy that can be restored with ERIF but does not warrant ORIF. However, the duration of MMF should be 4 to 6 weeks when performing closed reduction on a true subcondylar fracture. When ORIF is necessary, surgeons should consider becoming familiar working with the facial nerve under monitoring to improve anatomic reduction. Lastly, in the era of shared decision making, patients' choices always need to be considered. In general, an algorithm may inform or provide a structural basis for this decision making to not only ensure the best outcome for our patients but also serve as a point of discussion in the management of this complex fracture pattern.
CONCLUSIONS
REFERENCES
In cases in which closed reduction is the management technique of choice, the duration of MMF varies between institutions. The main concern is finding a balance between attaining fracture reduction and avoiding ankylosis of the TMJ. Given the anatomic location of a subcondylar fracture, we believe that fractures properly diagnosed as within this region are at low risk for ankylosis. In a subcondylar fracture, one will generally not observe trauma to the joint capsule or the condylar head. As such, we recommend a period of MMF for at least 4 to 6 weeks, with an additional period of 2 to 3 weeks of guiding elastics in patients in whom closed fixation is possible. Compared with the rather short duration of 2 weeks,5 a longer period of MMF works toward achieving maximal union and healing of the fracture. The endoscopic approach provides surgeons with a third viable option for treating subcondylar fractures. It combines the benefits of ORIF and MMF while minimizing their associated risks.
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