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A Comparative evaluation of CBCT outcomes of two closed treatment methods in intracapsular condylar fractures
Vol. 123 No. 5 May 2017
A Comparative evaluation of CBCT outcomes of two closed treatment methods in intracapsular condylar fractures Yanmei Tang, MDS,a Xiaoling Wang, MDS,b Yanfei Zhu, BDS,c Huijun Sun, BDS,c and Min Zhu, DDS, PhDd Purpose. The cone beam computed tomography (CBCT) images of 2 closed treatments are compared for intracapsular condylar fractures (ICFs) to learn whether splint treatment could promote better radiologic outcomes. Patients and methods. Fifty-four patients with 60 sides of ICF were divided into 2 groups. In the control group (C-group), patients had a liquid diet for 1 month. In the trial group (T-group), patients wore splints with anterior elastic traction. Local CBCT images of the temporomandibular joint were obtained at T0 (mean 8.8 days), T1 (mean 37.4 days), and T3 (mean 3.3 months) after trauma. Six parameters, including 2 horizontal, 1 sagittal, and 3 vertical distances, were calculated using the coordinates of 10 points marked on CBCT sections. Statistical analysis included intragroup comparison at T0, T1, and T3, and intergroup comparison among subgroups classified by age and ICF types. Results. Compared to C-group, vertical distances were significantly changed in T-group, specifically in adults and patients with ICF type B. Significant changes at stage T1 were also observed in T-group. Conclusion. During the natural healing process, ICF healed in the displaced position and the stump tended to move closer to the joint fossa in the vertical dimension. Splint treatment with elastic traction was helpful to increase joint space and promote better radiologic healing shape. (Oral Surg Oral Med Oral Pathol Oral Radiol 2017;123:e141-e147)
Condylar fractures are very common in patients with mandibular fractures, and intracapsular condylar fractures (ICFs) comprise up to 65%, according to previous research.1 Closed treatments are commonly recommended for ICF patients with unchanged occlusal relationships.2 Patients need to undergo a period of rigid maxillomandibular fixation (MMF) with arch bars. However, Ellis et al. found that absolute passive immobilization was unfavorable for functional rehabilitation of the jaw.3,4 Thus, MMF was gradually abandoned and replaced by active immobilization of mandible, which means a period of liquid diet and restricted talking. Physiotherapeutic exercises are then started. Recently, another closed treatment for ICFs using occlusal splint was reported.5,6 This technique puts a fulcrum between the posterior teeth on the affected side and then applies elastic traction on self-drilling titanium screws inserted into anterior alveolar bone. This method aims to lower the stump of the mandibular ramus while Supported by Shanghai Summit & Plateau Disciplines. a Resident, Department of Oral & Craniomaxillofacial Science, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Key Laboratory of Stomatology, Shanghai, China. b Postgraduate, Clinic of Orthodontics, Medical Faculty of Ludwig Maximilians University, Munich, Germany. c Graduate Student, Department of Oral & Craniomaxillofacial Science, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Key Laboratory of Stomatology, Shanghai, China. d Professor, Department of Oral & Craniomaxillofacial Science, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Key Laboratory of Stomatology, Shanghai, China. Received for publication Jul 23, 2016; returned for revision Nov 6, 2016; accepted for publication Nov 25, 2016. Ó 2016 Elsevier Inc. All rights reserved. 2212-4403/$ - see front matter http://dx.doi.org/10.1016/j.oooo.2016.11.019
decreasing the vertical fall between the stump and the fragment of the condyle. It has exhibited effects in improving the healing shape of pediatric condylar fractures. However, some researchers observed condylar fragment movement during fracture repair in detail, as well as the difference between the 2 treatment methods above. Panoramic and posteroanterior radiographs have been widely used to assess the treatment results of condylar fractures.7 Angles and distances are measured to observe the angulation of fragment displacement and the reduction of mandibular ramus height after fracture.8-11 However, the assessment accuracy and sensitivity are greatly reduced in ICFs because of numerous superimpositions of structures adjacent to the condylar head. Characterized by thin slice scanning and high diagnostic accuracy, computed tomography (CT) has been chosen as a routine method of examination in facial trauma. Unfortunately, few researchers used CT images in accurate measurement of condylar fractures, and most articles evaluated the treatment outcomes of ICFs in a descriptive way.12-14 Since the late 1990s and the introduction of the dedicated cone beam computed tomography (CBCT)
Statement of Clinical Relevance Cone beam computed tomography (CBCT) evaluation revealed that during the natural healing process, mandibular condylar intracapsular fracture healed in its original fractured position. Soft splint with intermaxillary elastic traction was helpful to increase joint space and promote better radiologic healing shape of fractured condyles. e141
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scanners for the oral and maxillofacial region, numerous studies have been conducted on this new imaging technique.15 Compared to other imaging modalities, CBCT displays remarkable superiority due to its lower radiation dose, smaller size, and convenience in multiplanar reformation.16 Moreover, CBCT has been proven reliable and accurate in evaluating the condylar head surface and skeletal changes in patients with temporomandibular joint (TMJ) osteoarthrosis.16-18 Theoretically, it can be used to investigate intracapsular condylar fracture. The aim of this research was to observe the healing process of condylar head fractures using CBCT images. At the same time, analysis was carried out to compare the radiographic outcomes of 2 closed treatment methods for ICFs to discuss whether the stump descended after traction treatment, as assumed.
METHODS AND MATERIALS Patients From January 2009 to October 2014, 290 patients with condylar fractures visited the Department of Oral and Craniomaxillofacial Science. In total, 54 cases were selected, including 19 women and 35 men. The mean age of patients was 31.2 19.7 years (range 4-73). Detailed information is shown in Table I. This study was approved by the hospital’s institutional review board and was conducted in accordance with the guidelines of the Declaration of Helsinki. Cases included in this research met the following criteria: (1) diagnosed as ICF according to CBCT examination, (2) ICF with or without other fractured site of the mandible, but occlusal relationship was not obviously changed; (3) patients had both pretreatment and 1 month posttreatment CBCT image files; and (4) a follow-up period longer than 3 months. Exclusion criteria were as follows: (1) patients with congenital hypoplasia, (2) condylar neck fractures and condylar base fractures, (3) condylar stump dislocated out of joint fossa after fracture, (4) first visit >1 month after trauma, (5) patients who had been advised open reduction but refused, (6) either side of condyle had open reduction, and (7) patients with poor compliance. ICFs were grouped according to Loukota’s classification19 as type A (fracture through the medial part of the condyle without reduction of ramus height), type B (fracture line running through condylar lateral pole causing mandibular height loss), and type M (comminuted fracture). Treatment protocol Two treatment methods were proposed to patients, and decisions were made by patients themselves or their legal guardians. In the control group (C-group), patients
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Table I. File characteristics Items *
Sex
ICF* Agey Typey
Control
Trial
c2
P
10 17 26 1 11 17 10 6 12
9 18 22 5 12 30 14 13 5
0.081
.776
1.688
.194
0.874
.350
5.887
.053
Female Male Unilateral Bilateral Juveniles Adults A B M
*Counted by cases. y Counted by fractured sides.
underwent no invasive treatment. They were instructed to immobilize the mandible by talking less and adhering to a liquid diet for 1 month after trauma. They then underwent physical exercises, including mouth opening and protrusive and lateral excursion exercises. In the trial group (T-group), patients wore a maxillary splint with soft pad(s) on the molars of the affected side(s), thus creating a fulcrum (Figure 1). Self-drilling mini screws were inserted into anterior alveolar bone. Vertical traction was applied by elastics (ORMCO, 3/16, 8 oz), approximately 500 to 600 g/side, for more than 22 h/d. Daily physical exercises started 1 month after trauma, and semi-rigid MMF was continued at night but gradually reduced. If patients reported fractures of the symphyseal, parasymphyseal, mandibular body, angle, or ramus, an open reduction internal fixation surgery was preferred. Three days after operation, closed treatment for ICF was started. In total, 6 cases were bilateral condylar fractures and 48 cases were unilateral. Twenty-one patients had concomitant mandibular fractures. Twenty-seven cases (28 sides of fractures) were in C-group and 27 cases (32 sides) were in T-group. A c2 test was carried out to ensure the 2 groups were comparable (Table I). CBCT assessment Patients underwent CBCT scan (3-D Multi-Image Morita Micro CT) before treatment (T0) and 1 month (T1) and 3 months (T3) after treatment. During scanning, patients stood in an upright position with maximum intercuspation while the Frankfort-horizontal plane was parallel to the floor. The cross cursor was focused on the center of the TMJ area. The tube voltage was 80 kV, tube current was 5 mA, exposure time was 20 seconds, field of view was 60 60 mm, voxel size was 1 mm, and slice thickness was 1 mm. All images were reconstructed using i-Dixel One Data Viewer (Version 1.27, Morita MFG). Measurement was operated on 3 windows, which displayed axial, coronal, and sagittal slices. Ten points were determined (Table II, Figure 2). The 3-D coordinates of each point were read. Measurement
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Fig. 1. Trial group treatment: A, self-drilling mini screws implanted in anterior alveolar bone; B, splint with a soft pad between posterior teeth, elastic traction on mini screws.
Table II. Points and landmarks Landmark X1 X2 X3 Y1 Y2 Z1 Z2 H1
H2
H3
Description Outermost point (external pole) of the stump, on coronal plane Innermost point on the fragment(s) Outmost point of the joint fossa, on the coronal plane Backmost point of the stump, on axial plane Headmost point of the fragment(s) Lowest point along the fracture line on stump of ramus, searching on coronal plane Lowest point of the fragment(s) In the narrowest vertical space between the stump and joint fossa on coronal plane, draw a vertical line to intersect with the fossa at H1 In the narrowest vertical space between the stump and joint fossa on coronal plane, draw a vertical line to intersect with the stump at H2 Vertex of the joint fossa
of each CBCT file was repeated 3 times, and mean values were recorded. Except for point H1, 9 points should be marked on the same typical sections of pre- and posttreatment images. Due to possible location change of the stump in the fossa, the narrowest vertical space on the coronal plane might change. Under this circumstance, posttreatment H20 was the same point as pretreatment H2, while posttreatment H10 was the intersection of the fossa and the vertical line through H2’. Six parameters were calculated using the coordinates of the 10 points (Table III, Figure 2). Data analysis Data included the 6 parameters listed above in the control and trial groups at T0, T1, and T3. SPSS software version 20.0 was used to analyze all data. Differences were considered significant at P < .05.
RESULTS Intra-group and inter-group comparison Twenty-eight sides of TMJ CBCT files were assessed in C-group, and 32 sides were included in T-group. First,
normal distribution and homogeneity of variance were tested. Then a paired-sample t test was used in intragroup comparison, and an independent sample t test was applied in intergroup comparison. Outcomes are listed in Table IV. In C-group, SFrX decreased significantly after 1 month’s active immobilization; thus, the fragment was closer to the stump in the horizontal direction. In the vertical direction, however, SFoZ also decreased in stage T1, suggesting that the stump was closer to the joint fossa. However, in T-group, the fracture healed gradually, as characterized by the fragment moving forward to the stump 3-dimensionally. Meanwhile, the position of the stump in the fossa significantly changed both vertically and horizontally. D-value (T0-T1) of SFoZ and NaH was negative, implying that the joint space was increased and the stump was drawn down and reduced medially. Outcomes of intergroup comparisons were characterized by significant differences in vertical dimension, such as SFrZ, SFoZ, and NaH. The assumption that the splint and intermaxillary elastic traction would work as a lever was valid. The traction treatment was effective in reducing the vertical fall between the fragment and the stump and beneficial in increasing the joint space. Age-related subgroups comparison In juveniles, 11 sides of ICF were included in C-group and 12 sides were included in T-group. In adults, 17 sides were in C-group and 20 sides were in T-group. Differences in the 6 items in T0 and T1 were calculated (T0-T1). An independent sample t test was applied. Figures 3 and 4 illustrate the 3 vertical items. In juveniles, D values (T0-T1) of the 6 items were not significantly different between control and trial groups. However, it is worth noting that the value of SFrZ (T0-T1) was negative in C-group but positive in T-group, which implies that without traction treatment, the vertical fall tends to increase with time. This trend went against fracture repair. Meanwhile, the value of SFoZ (T0-T1) was positive in C-group but negative in
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Fig. 2. Landmarks and calculated parameters: 10 points were fixed at first (not necessary on the same slice as the picture shows), then 2 horizontal, 1 sagittal, and 3 vertical distances were calculated.
Table III. Calculated parameters Item
Description
SFrX
Absolute difference between x coordinates of point X1 and X2, representing medial-lateral distance of stump and fragment. Absolute difference between y coordinates of point Y1 and Y2, representing anterior-posterior distance of stump and fragment. Absolute difference between z coordinates of point Z1 and Z2, representing vertical fall of the fragment from stump. On left side, subtract x coordinate of point X1 from point X3; on right side, subtract X3 from X1. It represents the inner-outer relation of stump in fossa. Positive means “in” while negative means “out.” Subtract z coordinate of point H2 from point H3. It reveals vertical position of the stump in fossa. Subtract z coordinate of point H2 from point H1. It represents the narrowest vertical joint space before treatment and its change after treatment.
SFrY
SFrZ SFoX
SFoZ NaH
T-group. The tendency of the stump to move closer to the joint fossa in the vertical dimension occurs during the natural healing process.
In adults, traction treatment had a significant effect on lowering the mandibular stump. Three vertical distances, SFrZ, SFoZ, and NaH, were significantly changed in T-group compared to C-group. As in juveniles, the fragment tended to move farther to the stump, and the stump moved closer to the fossa during fracture healing in adults in C-group. Fracture-typeerelated subgroups comparison According to Neff’s classification, cases were divided into types A, B, and M (Table I). For ICF patients with type A and type M fractures, C-group and T-group had no significant difference in change of stump position 3dimensionally (Figures 5 and 6). Nevertheless, for patients of type B, SFrZ was significantly decreased after treatment in T-group compared to C-group (Figure 7), thus promoting a better repair shape of the condylar head. Furthermore, the mean value of SFoZ (T0-T1) was positive in C-group, which revealed that the stump moved closer to the fossa during the healing process.
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Table IV. Intra-group and inter-group comparison of the 6 parameters Items SFrX
SFrY
SFrZ
SFoX
SFoZ
NaH
T0 T1 D (T0-T1) Intra-group Intergroup T0 T1 D(T0-T1) Intragroup Intergroup T0 T1 D (T0-T1) Intragroup Intergroup T0 T1 D (T0-T1) Intra-group Intergroup T0 T1 D (T0-T1) Intragroup Intergroup T0 T1 D (T0-T1) Intragroup Intergroup
Control
t P
t P
t P
t P
t P
t P
Trial
23.473 3.4142 24.444 2.6053 22.213 3.558 22.303 3.3314 1.260 1.0079 2.140 3.1068 6.613 3.898 0.000* 0.000* t ¼ 1.434 P ¼ .157 16.070 3.1622 15.122 3.5672 15.821 2.2398 14.627 3.2070 0.249 1.4829 0.495 1.3274 0.889 2.109 0.382 0.036* t ¼ 0.678 P ¼ .501 4.412 2.7724 5.801 2.4952 4.640 2.5272 4.996 2.5738 0.228 1.5787 0.805 1.3040 0.765 3.493 0.451 0.001* t ¼ 2.777 P ¼ .007* 1.317 1.8500 1.666 2.1208 0.086 1.9234 0.461 2.2387 1.231 1.3178 1.205 1.9839 4.941 3.437 0.000* 0.002* t ¼ 0.057 P ¼ .955 9.810 3.7613 8.362 2.5230 9.170 3.1986 9.192 2.6832 0.640 1.5570 0.830 1.6434 2.175 2.858 0.039* 0.008* t ¼ 3.543 P ¼ .001* 4.319 2.5172 2.919 1.9657 4.713 2.5853 4.276 2.4199 0.395 1.6269 1.357 1.8952 1.284 4.052 0.210 0.000* t ¼ 2.095 P ¼ .041*
*Significant difference existed.
Intragroup comparison at T0, T1, and T3 stage In this research, 24 patients had the third CBCT examination more than 3 months after trauma. Sixteen males and 8 females were included. Mean age was 29.2 years (range 4-73). Twenty-one cases were unilateral fractures and 3 cases were bilateral; 27 sides of fractures in total. Seven sides were in C-group, and 20 sides were in T-group. The mean time of the first CBCT examination was 10.2 days after trauma (T0). The mean period of treatment was 29.4 days. The second CBCT examination time was 38.6 days after trauma (T1). The third examination time was 4.6 months after fracture (T3). A one-way analysis of variance, followed by a least significant difference test, was used. If data were not normally distributed, a Friedman test was used. In most ICF cases, the fragment of condyle was anteriorly and inferiorly displaced because of the traction of the lateral pterygoid muscle. In C-group, no
Fig. 3. Intergroup comparison in juveniles.
Fig. 4. Intergroup comparison in adults.
significant fragment or stump position changes were observed by time due to sample size restriction. This study revealed that in the process of natural healing, fractures healed and adapted in the displaced position. It should not to be expected that the fragment returned to the initial place before fracture, even if early functional exercise was instructed. In T-group, position change by time was significant in SFrX, SFoX, and NaH. A column graph (Figure 8) with mean and standard deviation (SD) focuses on the vertical change. Outcomes of the least significant difference test found differences existed mainly in T0 versus T1 and T0 versus T3, but not in T1 versus T3, which is apparent in Figure 8. The data were inconsistent with the pathologic process of fracture. Since callus had formed in 4 weeks after fracture, traction treatment would not work well beyond 1 month after trauma.
DISCUSSION Using CBCT to investigate TMJ disease, a linear measuring method was adopted in most studies. A cursor was used to select points on acquired CBCT images, and the distances between points were calculated and automatically output by software.20-22 However, during the healing process of ICFs, the condyle
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Fig. 5. Intergroup comparison in intracapsular condylar fracture type A.
Fig. 7. Intergroup comparison in intracapsular condylar fracture type B.
Fig. 6. Intergroup comparison in intracapsular condylar fracture type M.
Fig. 8. Variation in the process of fracture healing in the trial group.
fragment was free to move in 3 directions. Furthermore, the stump of the mandible ramus could have changed position after therapeutic trials. If we want to observe the movement of the fragment as well as the position of the stump in the fossa, the direction should be taken into account. Thus, different from the “2 points, 1 line” method, a new “points-coordinateseprojection” method was tried in our research. Instead of calculating the direct linear distance, the line segment between 2 points was projected on the x, y, or z axis. Because the coordinates of points were given in the software i-Dixel One Data Viewer, the length of the projection was the absolute difference of the x, y, and z coordinates of the 2 points. Consequently, the relative movement of the fragment toward the mandibular ramus was observable in dimensions. In our research, it was found that during the fracture repair process, the fragment barely moved toward the stump in C-group, while in T-group, the vertical fall decreased after treatment. This result implies that without intervention, natural union of condylar fracture depends on the formation of callus between the 2 ends in the original fractured position. Significantly, the traction treatment helps to improve the union shape of the fractured condyle, especially in adults, who have
relatively limited ability of remodeling and adaptive changes. However, whether the improvement in radiologic shape could yield better functional results remains to be studied in the future. In addition, we paid close attention to the relative position of the stump and the joint fossa on coronal sectional imaging. As we know, TMJ ankylosis is one of the worst prognoses in condylar fracture. Of all the factors that affect the outcome of a condylar injury, the type of fracture is considered to play an important role.14 Especially in an intracapsular condylar fracture, types B and M have a less favorable prognosis and are most likely to precede ankylosis.1,7 The ankylosis commonly occurs lateral to the articulation. He et al.23 classified the relation between the stump of the ramus and the TMJ fossa into 3 grades: They found that if the stump had contact with the fossa or was laterally displaced out of the fossa, the incidence of ankylosis was highly increased.23 In other words, keeping the stump in the articulation and unattached to the articulation fossa decreases the risk of developing ankylosis. As we found in the CBCT assessment, the traction treatment did increase the joint space, especially in adults with ICF type B. During the reactive phase of fracture repair, hematoma and inflammation peaked.
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The traction treatment helped reduce the tension at the TMJ site and maintain the local strain in the reparative phase.24 None of the patients included in this study reported the symptoms of TMJ ankylosis. Moreover, it is worth mentioning that the traction treatment only works within 1 month after injury. With the formation of callus, the broken ends start to establish a stable position relationship. By this time, it is more important to start physical exercise and to activate the functional remodeling.
CONCLUSION In summary, CBCT evaluation revealed that during the natural healing process, mandibular condylar intracapsular fracture healed in the original fractured position. Soft splint with intermaxillary elastic traction was helpful to increase joint space and to promote better radiologic healing shape of fractured condyle. Thanks to Jiajie Zang, PhD, for professional advice related to statistical analysis and to Dr. Jiewen Dai for valuable comments. REFERENCES 1. He D, Yang C, Chen M, Jiang B, Wang B. Intracapsular condylar fracture of the mandible: our classification and open treatment experience. J Oral Maxillofac Surg. 2009;67:1672-1679. 2. Zachariades N, Mezitis M, Mourouzis C, Papadakis D, Spanou A. Fractures of the mandibular condyle: a review of 466 cases. Literature review, reflections on treatment and proposals. J Craniomaxillofac Surg. 2006;34:421-432. 3. Ellis E. Condylar process fractures of the mandible. Facial Plast Surg. 2000;16:193-206. 4. Ellis E, Throckmorton GS. Treatment of mandibular condylar process fractures: biological considerations. J Oral Maxillofac Surg. 2005;63:115-134. 5. Wu Y, Long X, Fang W, et al. Management of paediatric mandibular condylar fractures with screw-based semi-rigid intermaxillary fixation. Int J Oral Maxillofac Surg. 2012;41:55-60. 6. Wu Y, Long X, Deng M, Cai H, Meng Q, Li B Screw-based intermaxillary traction combined with occlusal splint for treatment of pediatric mandibular condylar fracture. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2015;29:397-401. 7. Hlawitschka M, Eckelt U. Assessment of patients treated for intracapsular fractures of the mandibular condyle by closed techniques. J Oral Maxillofac Surg. 2002;60:784-791. 8. Yang WG, Chen CT, Tsay PK, Chen YR. Functional results of unilateral mandibular condylar process fractures after open and closed treatment. J Trauma. 2002;52:498-503. 9. Hlawitschka M, Loukota R, Eckelt U. Functional and radiological results of open and closed treatment of intracapsular (diacapitular) condylar fractures of the mandible. Int J Oral Maxillofac Surg. 2005;34:597-604. 10. Veras RB, Kriwalsky MS, Eckert AW, Schubert J, Maurer P. Long-term outcomes after treatment of condylar fracture by intraoral access: a functional and radiologic assessment. J Oral Maxillofac Surg. 2007;65:1470-1476.
ORIGINAL ARTICLE Tang et al. e147 11. Vesnaver A, Ahcan U, Rozman J. Evaluation of surgical treatment in mandibular condyle fractures. J Craniomaxillofac Surg. 2012;40:647-653. 12. Choi BH. Comparison of computed tomography imaging before and after functional treatment of bilateral condylar fractures in adults. Int J Oral Maxillofac Surg. 1996;25:30-33. 13. Yamashita Y, Inoue M, Aijima R, Danjo A, Goto M. Threedimensional evaluation of healing joint morphology after closed treatment of condylar fractures. Int J Oral Maxillofac Surg. 2016;45:292-296. 14. Ferretti C, Bryant R, Becker P, Lawrence C. Temporomandibular joint morphology following post-traumatic ankylosis in 26 patients. Int J Oral Maxillofac Surg. 2005;34:376-381. 15. De Vos W, Casselman J, Swennen GR. Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: a systematic review of the literature. Int J Oral Maxillofac Surg. 2009;38:609-625. 16. Krishnamoorthy B, Mamatha N, Kumar VA. TMJ imaging by CBCT: current scenario. Ann Maxillofac Surg. 2013;3:80-83. 17. Yadav S, Palo L, Mahdian M, Upadhyay M, Tadinada A. Diagnostic accuracy of 2 cone-beam computed tomography protocols for detecting arthritic changes in temporomandibular joints. Am J Orthod Dentofacial Orthop. 2015;147:339-344. 18. Liu MQ, Chen HM, Yap AU, Fu KY. Condylar remodeling accompanying splint therapy: a cone-beam computerized tomography study of patients with temporomandibular joint disk displacement. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012;114:259-265. 19. Loukota RA, Neff A, Rasse M. Nomenclature/classification of fractures of the mandibular condylar head. Br J Oral Maxillofac Surg. 2010;48:477-478. 20. Sander AK, Martini M, Konermann AC, Meyer U, Wenghoefer M. Freehand condyle-positioning during orthognathic surgery: postoperative cone-beam computed tomography shows only minor morphometric alterations of the temporomandibular joint position. J Craniofac Surg. 2015;26:14711476. 21. Manjula WS, Tajir F, Murali RV, Kumar SK, Nizam M. Assessment of optimal condylar position with cone-beam computed tomography in south Indian female population. J Pharm Bioall Sci. 2015;7(suppl 1):S121-S124. 22. Goulart DR, Munoz P, Olate S, de Moraes M, Farina R. No differences in morphological characteristics between hyperplastic condyle and class III condyle. Int J Oral Maxillofac Surg. 2015;44:1281-1286. 23. He D, Cai Y, Yang C. Analysis of temporomandibular joint ankylosis caused by condylar fracture in adults. J Oral Maxillofac Surg. 2014;72:763.e761-763.e769. 24. Davis KM, Griffin KS, Chu TG, et al. Muscle-bone interactions during fracture healing. J Musculoskelet Neuronal Interact. 2015;15:1-9. Reprint requests: Min Zhu, DDS, PhD No. 500 QuXi Road Huangpu District Shanghai 200011 People’s Republic of China [email protected]
A Comparative evaluation of CBCT outcomes of two closed treatment methods in intracapsular condylar fractures Yanmei Tang, MDS,a Xiaoling Wang, MDS,b Yanfei Zhu, BDS,c Huijun Sun, BDS,c and Min Zhu, DDS, PhDd Purpose. The cone beam computed tomography (CBCT) images of 2 closed treatments are compared for intracapsular condylar fractures (ICFs) to learn whether splint treatment could promote better radiologic outcomes. Patients and methods. Fifty-four patients with 60 sides of ICF were divided into 2 groups. In the control group (C-group), patients had a liquid diet for 1 month. In the trial group (T-group), patients wore splints with anterior elastic traction. Local CBCT images of the temporomandibular joint were obtained at T0 (mean 8.8 days), T1 (mean 37.4 days), and T3 (mean 3.3 months) after trauma. Six parameters, including 2 horizontal, 1 sagittal, and 3 vertical distances, were calculated using the coordinates of 10 points marked on CBCT sections. Statistical analysis included intragroup comparison at T0, T1, and T3, and intergroup comparison among subgroups classified by age and ICF types. Results. Compared to C-group, vertical distances were significantly changed in T-group, specifically in adults and patients with ICF type B. Significant changes at stage T1 were also observed in T-group. Conclusion. During the natural healing process, ICF healed in the displaced position and the stump tended to move closer to the joint fossa in the vertical dimension. Splint treatment with elastic traction was helpful to increase joint space and promote better radiologic healing shape. (Oral Surg Oral Med Oral Pathol Oral Radiol 2017;123:e141-e147)
Condylar fractures are very common in patients with mandibular fractures, and intracapsular condylar fractures (ICFs) comprise up to 65%, according to previous research.1 Closed treatments are commonly recommended for ICF patients with unchanged occlusal relationships.2 Patients need to undergo a period of rigid maxillomandibular fixation (MMF) with arch bars. However, Ellis et al. found that absolute passive immobilization was unfavorable for functional rehabilitation of the jaw.3,4 Thus, MMF was gradually abandoned and replaced by active immobilization of mandible, which means a period of liquid diet and restricted talking. Physiotherapeutic exercises are then started. Recently, another closed treatment for ICFs using occlusal splint was reported.5,6 This technique puts a fulcrum between the posterior teeth on the affected side and then applies elastic traction on self-drilling titanium screws inserted into anterior alveolar bone. This method aims to lower the stump of the mandibular ramus while Supported by Shanghai Summit & Plateau Disciplines. a Resident, Department of Oral & Craniomaxillofacial Science, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Key Laboratory of Stomatology, Shanghai, China. b Postgraduate, Clinic of Orthodontics, Medical Faculty of Ludwig Maximilians University, Munich, Germany. c Graduate Student, Department of Oral & Craniomaxillofacial Science, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Key Laboratory of Stomatology, Shanghai, China. d Professor, Department of Oral & Craniomaxillofacial Science, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Key Laboratory of Stomatology, Shanghai, China. Received for publication Jul 23, 2016; returned for revision Nov 6, 2016; accepted for publication Nov 25, 2016. Ó 2016 Elsevier Inc. All rights reserved. 2212-4403/$ - see front matter http://dx.doi.org/10.1016/j.oooo.2016.11.019
decreasing the vertical fall between the stump and the fragment of the condyle. It has exhibited effects in improving the healing shape of pediatric condylar fractures. However, some researchers observed condylar fragment movement during fracture repair in detail, as well as the difference between the 2 treatment methods above. Panoramic and posteroanterior radiographs have been widely used to assess the treatment results of condylar fractures.7 Angles and distances are measured to observe the angulation of fragment displacement and the reduction of mandibular ramus height after fracture.8-11 However, the assessment accuracy and sensitivity are greatly reduced in ICFs because of numerous superimpositions of structures adjacent to the condylar head. Characterized by thin slice scanning and high diagnostic accuracy, computed tomography (CT) has been chosen as a routine method of examination in facial trauma. Unfortunately, few researchers used CT images in accurate measurement of condylar fractures, and most articles evaluated the treatment outcomes of ICFs in a descriptive way.12-14 Since the late 1990s and the introduction of the dedicated cone beam computed tomography (CBCT)
Statement of Clinical Relevance Cone beam computed tomography (CBCT) evaluation revealed that during the natural healing process, mandibular condylar intracapsular fracture healed in its original fractured position. Soft splint with intermaxillary elastic traction was helpful to increase joint space and promote better radiologic healing shape of fractured condyles. e141
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scanners for the oral and maxillofacial region, numerous studies have been conducted on this new imaging technique.15 Compared to other imaging modalities, CBCT displays remarkable superiority due to its lower radiation dose, smaller size, and convenience in multiplanar reformation.16 Moreover, CBCT has been proven reliable and accurate in evaluating the condylar head surface and skeletal changes in patients with temporomandibular joint (TMJ) osteoarthrosis.16-18 Theoretically, it can be used to investigate intracapsular condylar fracture. The aim of this research was to observe the healing process of condylar head fractures using CBCT images. At the same time, analysis was carried out to compare the radiographic outcomes of 2 closed treatment methods for ICFs to discuss whether the stump descended after traction treatment, as assumed.
METHODS AND MATERIALS Patients From January 2009 to October 2014, 290 patients with condylar fractures visited the Department of Oral and Craniomaxillofacial Science. In total, 54 cases were selected, including 19 women and 35 men. The mean age of patients was 31.2 19.7 years (range 4-73). Detailed information is shown in Table I. This study was approved by the hospital’s institutional review board and was conducted in accordance with the guidelines of the Declaration of Helsinki. Cases included in this research met the following criteria: (1) diagnosed as ICF according to CBCT examination, (2) ICF with or without other fractured site of the mandible, but occlusal relationship was not obviously changed; (3) patients had both pretreatment and 1 month posttreatment CBCT image files; and (4) a follow-up period longer than 3 months. Exclusion criteria were as follows: (1) patients with congenital hypoplasia, (2) condylar neck fractures and condylar base fractures, (3) condylar stump dislocated out of joint fossa after fracture, (4) first visit >1 month after trauma, (5) patients who had been advised open reduction but refused, (6) either side of condyle had open reduction, and (7) patients with poor compliance. ICFs were grouped according to Loukota’s classification19 as type A (fracture through the medial part of the condyle without reduction of ramus height), type B (fracture line running through condylar lateral pole causing mandibular height loss), and type M (comminuted fracture). Treatment protocol Two treatment methods were proposed to patients, and decisions were made by patients themselves or their legal guardians. In the control group (C-group), patients
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Table I. File characteristics Items *
Sex
ICF* Agey Typey
Control
Trial
c2
P
10 17 26 1 11 17 10 6 12
9 18 22 5 12 30 14 13 5
0.081
.776
1.688
.194
0.874
.350
5.887
.053
Female Male Unilateral Bilateral Juveniles Adults A B M
*Counted by cases. y Counted by fractured sides.
underwent no invasive treatment. They were instructed to immobilize the mandible by talking less and adhering to a liquid diet for 1 month after trauma. They then underwent physical exercises, including mouth opening and protrusive and lateral excursion exercises. In the trial group (T-group), patients wore a maxillary splint with soft pad(s) on the molars of the affected side(s), thus creating a fulcrum (Figure 1). Self-drilling mini screws were inserted into anterior alveolar bone. Vertical traction was applied by elastics (ORMCO, 3/16, 8 oz), approximately 500 to 600 g/side, for more than 22 h/d. Daily physical exercises started 1 month after trauma, and semi-rigid MMF was continued at night but gradually reduced. If patients reported fractures of the symphyseal, parasymphyseal, mandibular body, angle, or ramus, an open reduction internal fixation surgery was preferred. Three days after operation, closed treatment for ICF was started. In total, 6 cases were bilateral condylar fractures and 48 cases were unilateral. Twenty-one patients had concomitant mandibular fractures. Twenty-seven cases (28 sides of fractures) were in C-group and 27 cases (32 sides) were in T-group. A c2 test was carried out to ensure the 2 groups were comparable (Table I). CBCT assessment Patients underwent CBCT scan (3-D Multi-Image Morita Micro CT) before treatment (T0) and 1 month (T1) and 3 months (T3) after treatment. During scanning, patients stood in an upright position with maximum intercuspation while the Frankfort-horizontal plane was parallel to the floor. The cross cursor was focused on the center of the TMJ area. The tube voltage was 80 kV, tube current was 5 mA, exposure time was 20 seconds, field of view was 60 60 mm, voxel size was 1 mm, and slice thickness was 1 mm. All images were reconstructed using i-Dixel One Data Viewer (Version 1.27, Morita MFG). Measurement was operated on 3 windows, which displayed axial, coronal, and sagittal slices. Ten points were determined (Table II, Figure 2). The 3-D coordinates of each point were read. Measurement
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Fig. 1. Trial group treatment: A, self-drilling mini screws implanted in anterior alveolar bone; B, splint with a soft pad between posterior teeth, elastic traction on mini screws.
Table II. Points and landmarks Landmark X1 X2 X3 Y1 Y2 Z1 Z2 H1
H2
H3
Description Outermost point (external pole) of the stump, on coronal plane Innermost point on the fragment(s) Outmost point of the joint fossa, on the coronal plane Backmost point of the stump, on axial plane Headmost point of the fragment(s) Lowest point along the fracture line on stump of ramus, searching on coronal plane Lowest point of the fragment(s) In the narrowest vertical space between the stump and joint fossa on coronal plane, draw a vertical line to intersect with the fossa at H1 In the narrowest vertical space between the stump and joint fossa on coronal plane, draw a vertical line to intersect with the stump at H2 Vertex of the joint fossa
of each CBCT file was repeated 3 times, and mean values were recorded. Except for point H1, 9 points should be marked on the same typical sections of pre- and posttreatment images. Due to possible location change of the stump in the fossa, the narrowest vertical space on the coronal plane might change. Under this circumstance, posttreatment H20 was the same point as pretreatment H2, while posttreatment H10 was the intersection of the fossa and the vertical line through H2’. Six parameters were calculated using the coordinates of the 10 points (Table III, Figure 2). Data analysis Data included the 6 parameters listed above in the control and trial groups at T0, T1, and T3. SPSS software version 20.0 was used to analyze all data. Differences were considered significant at P < .05.
RESULTS Intra-group and inter-group comparison Twenty-eight sides of TMJ CBCT files were assessed in C-group, and 32 sides were included in T-group. First,
normal distribution and homogeneity of variance were tested. Then a paired-sample t test was used in intragroup comparison, and an independent sample t test was applied in intergroup comparison. Outcomes are listed in Table IV. In C-group, SFrX decreased significantly after 1 month’s active immobilization; thus, the fragment was closer to the stump in the horizontal direction. In the vertical direction, however, SFoZ also decreased in stage T1, suggesting that the stump was closer to the joint fossa. However, in T-group, the fracture healed gradually, as characterized by the fragment moving forward to the stump 3-dimensionally. Meanwhile, the position of the stump in the fossa significantly changed both vertically and horizontally. D-value (T0-T1) of SFoZ and NaH was negative, implying that the joint space was increased and the stump was drawn down and reduced medially. Outcomes of intergroup comparisons were characterized by significant differences in vertical dimension, such as SFrZ, SFoZ, and NaH. The assumption that the splint and intermaxillary elastic traction would work as a lever was valid. The traction treatment was effective in reducing the vertical fall between the fragment and the stump and beneficial in increasing the joint space. Age-related subgroups comparison In juveniles, 11 sides of ICF were included in C-group and 12 sides were included in T-group. In adults, 17 sides were in C-group and 20 sides were in T-group. Differences in the 6 items in T0 and T1 were calculated (T0-T1). An independent sample t test was applied. Figures 3 and 4 illustrate the 3 vertical items. In juveniles, D values (T0-T1) of the 6 items were not significantly different between control and trial groups. However, it is worth noting that the value of SFrZ (T0-T1) was negative in C-group but positive in T-group, which implies that without traction treatment, the vertical fall tends to increase with time. This trend went against fracture repair. Meanwhile, the value of SFoZ (T0-T1) was positive in C-group but negative in
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Fig. 2. Landmarks and calculated parameters: 10 points were fixed at first (not necessary on the same slice as the picture shows), then 2 horizontal, 1 sagittal, and 3 vertical distances were calculated.
Table III. Calculated parameters Item
Description
SFrX
Absolute difference between x coordinates of point X1 and X2, representing medial-lateral distance of stump and fragment. Absolute difference between y coordinates of point Y1 and Y2, representing anterior-posterior distance of stump and fragment. Absolute difference between z coordinates of point Z1 and Z2, representing vertical fall of the fragment from stump. On left side, subtract x coordinate of point X1 from point X3; on right side, subtract X3 from X1. It represents the inner-outer relation of stump in fossa. Positive means “in” while negative means “out.” Subtract z coordinate of point H2 from point H3. It reveals vertical position of the stump in fossa. Subtract z coordinate of point H2 from point H1. It represents the narrowest vertical joint space before treatment and its change after treatment.
SFrY
SFrZ SFoX
SFoZ NaH
T-group. The tendency of the stump to move closer to the joint fossa in the vertical dimension occurs during the natural healing process.
In adults, traction treatment had a significant effect on lowering the mandibular stump. Three vertical distances, SFrZ, SFoZ, and NaH, were significantly changed in T-group compared to C-group. As in juveniles, the fragment tended to move farther to the stump, and the stump moved closer to the fossa during fracture healing in adults in C-group. Fracture-typeerelated subgroups comparison According to Neff’s classification, cases were divided into types A, B, and M (Table I). For ICF patients with type A and type M fractures, C-group and T-group had no significant difference in change of stump position 3dimensionally (Figures 5 and 6). Nevertheless, for patients of type B, SFrZ was significantly decreased after treatment in T-group compared to C-group (Figure 7), thus promoting a better repair shape of the condylar head. Furthermore, the mean value of SFoZ (T0-T1) was positive in C-group, which revealed that the stump moved closer to the fossa during the healing process.
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Table IV. Intra-group and inter-group comparison of the 6 parameters Items SFrX
SFrY
SFrZ
SFoX
SFoZ
NaH
T0 T1 D (T0-T1) Intra-group Intergroup T0 T1 D(T0-T1) Intragroup Intergroup T0 T1 D (T0-T1) Intragroup Intergroup T0 T1 D (T0-T1) Intra-group Intergroup T0 T1 D (T0-T1) Intragroup Intergroup T0 T1 D (T0-T1) Intragroup Intergroup
Control
t P
t P
t P
t P
t P
t P
Trial
23.473 3.4142 24.444 2.6053 22.213 3.558 22.303 3.3314 1.260 1.0079 2.140 3.1068 6.613 3.898 0.000* 0.000* t ¼ 1.434 P ¼ .157 16.070 3.1622 15.122 3.5672 15.821 2.2398 14.627 3.2070 0.249 1.4829 0.495 1.3274 0.889 2.109 0.382 0.036* t ¼ 0.678 P ¼ .501 4.412 2.7724 5.801 2.4952 4.640 2.5272 4.996 2.5738 0.228 1.5787 0.805 1.3040 0.765 3.493 0.451 0.001* t ¼ 2.777 P ¼ .007* 1.317 1.8500 1.666 2.1208 0.086 1.9234 0.461 2.2387 1.231 1.3178 1.205 1.9839 4.941 3.437 0.000* 0.002* t ¼ 0.057 P ¼ .955 9.810 3.7613 8.362 2.5230 9.170 3.1986 9.192 2.6832 0.640 1.5570 0.830 1.6434 2.175 2.858 0.039* 0.008* t ¼ 3.543 P ¼ .001* 4.319 2.5172 2.919 1.9657 4.713 2.5853 4.276 2.4199 0.395 1.6269 1.357 1.8952 1.284 4.052 0.210 0.000* t ¼ 2.095 P ¼ .041*
*Significant difference existed.
Intragroup comparison at T0, T1, and T3 stage In this research, 24 patients had the third CBCT examination more than 3 months after trauma. Sixteen males and 8 females were included. Mean age was 29.2 years (range 4-73). Twenty-one cases were unilateral fractures and 3 cases were bilateral; 27 sides of fractures in total. Seven sides were in C-group, and 20 sides were in T-group. The mean time of the first CBCT examination was 10.2 days after trauma (T0). The mean period of treatment was 29.4 days. The second CBCT examination time was 38.6 days after trauma (T1). The third examination time was 4.6 months after fracture (T3). A one-way analysis of variance, followed by a least significant difference test, was used. If data were not normally distributed, a Friedman test was used. In most ICF cases, the fragment of condyle was anteriorly and inferiorly displaced because of the traction of the lateral pterygoid muscle. In C-group, no
Fig. 3. Intergroup comparison in juveniles.
Fig. 4. Intergroup comparison in adults.
significant fragment or stump position changes were observed by time due to sample size restriction. This study revealed that in the process of natural healing, fractures healed and adapted in the displaced position. It should not to be expected that the fragment returned to the initial place before fracture, even if early functional exercise was instructed. In T-group, position change by time was significant in SFrX, SFoX, and NaH. A column graph (Figure 8) with mean and standard deviation (SD) focuses on the vertical change. Outcomes of the least significant difference test found differences existed mainly in T0 versus T1 and T0 versus T3, but not in T1 versus T3, which is apparent in Figure 8. The data were inconsistent with the pathologic process of fracture. Since callus had formed in 4 weeks after fracture, traction treatment would not work well beyond 1 month after trauma.
DISCUSSION Using CBCT to investigate TMJ disease, a linear measuring method was adopted in most studies. A cursor was used to select points on acquired CBCT images, and the distances between points were calculated and automatically output by software.20-22 However, during the healing process of ICFs, the condyle
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Fig. 5. Intergroup comparison in intracapsular condylar fracture type A.
Fig. 7. Intergroup comparison in intracapsular condylar fracture type B.
Fig. 6. Intergroup comparison in intracapsular condylar fracture type M.
Fig. 8. Variation in the process of fracture healing in the trial group.
fragment was free to move in 3 directions. Furthermore, the stump of the mandible ramus could have changed position after therapeutic trials. If we want to observe the movement of the fragment as well as the position of the stump in the fossa, the direction should be taken into account. Thus, different from the “2 points, 1 line” method, a new “points-coordinateseprojection” method was tried in our research. Instead of calculating the direct linear distance, the line segment between 2 points was projected on the x, y, or z axis. Because the coordinates of points were given in the software i-Dixel One Data Viewer, the length of the projection was the absolute difference of the x, y, and z coordinates of the 2 points. Consequently, the relative movement of the fragment toward the mandibular ramus was observable in dimensions. In our research, it was found that during the fracture repair process, the fragment barely moved toward the stump in C-group, while in T-group, the vertical fall decreased after treatment. This result implies that without intervention, natural union of condylar fracture depends on the formation of callus between the 2 ends in the original fractured position. Significantly, the traction treatment helps to improve the union shape of the fractured condyle, especially in adults, who have
relatively limited ability of remodeling and adaptive changes. However, whether the improvement in radiologic shape could yield better functional results remains to be studied in the future. In addition, we paid close attention to the relative position of the stump and the joint fossa on coronal sectional imaging. As we know, TMJ ankylosis is one of the worst prognoses in condylar fracture. Of all the factors that affect the outcome of a condylar injury, the type of fracture is considered to play an important role.14 Especially in an intracapsular condylar fracture, types B and M have a less favorable prognosis and are most likely to precede ankylosis.1,7 The ankylosis commonly occurs lateral to the articulation. He et al.23 classified the relation between the stump of the ramus and the TMJ fossa into 3 grades: They found that if the stump had contact with the fossa or was laterally displaced out of the fossa, the incidence of ankylosis was highly increased.23 In other words, keeping the stump in the articulation and unattached to the articulation fossa decreases the risk of developing ankylosis. As we found in the CBCT assessment, the traction treatment did increase the joint space, especially in adults with ICF type B. During the reactive phase of fracture repair, hematoma and inflammation peaked.
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The traction treatment helped reduce the tension at the TMJ site and maintain the local strain in the reparative phase.24 None of the patients included in this study reported the symptoms of TMJ ankylosis. Moreover, it is worth mentioning that the traction treatment only works within 1 month after injury. With the formation of callus, the broken ends start to establish a stable position relationship. By this time, it is more important to start physical exercise and to activate the functional remodeling.
CONCLUSION In summary, CBCT evaluation revealed that during the natural healing process, mandibular condylar intracapsular fracture healed in the original fractured position. Soft splint with intermaxillary elastic traction was helpful to increase joint space and to promote better radiologic healing shape of fractured condyle. Thanks to Jiajie Zang, PhD, for professional advice related to statistical analysis and to Dr. Jiewen Dai for valuable comments. REFERENCES 1. He D, Yang C, Chen M, Jiang B, Wang B. Intracapsular condylar fracture of the mandible: our classification and open treatment experience. J Oral Maxillofac Surg. 2009;67:1672-1679. 2. Zachariades N, Mezitis M, Mourouzis C, Papadakis D, Spanou A. Fractures of the mandibular condyle: a review of 466 cases. Literature review, reflections on treatment and proposals. J Craniomaxillofac Surg. 2006;34:421-432. 3. Ellis E. Condylar process fractures of the mandible. Facial Plast Surg. 2000;16:193-206. 4. Ellis E, Throckmorton GS. Treatment of mandibular condylar process fractures: biological considerations. J Oral Maxillofac Surg. 2005;63:115-134. 5. Wu Y, Long X, Fang W, et al. Management of paediatric mandibular condylar fractures with screw-based semi-rigid intermaxillary fixation. Int J Oral Maxillofac Surg. 2012;41:55-60. 6. Wu Y, Long X, Deng M, Cai H, Meng Q, Li B Screw-based intermaxillary traction combined with occlusal splint for treatment of pediatric mandibular condylar fracture. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2015;29:397-401. 7. Hlawitschka M, Eckelt U. Assessment of patients treated for intracapsular fractures of the mandibular condyle by closed techniques. J Oral Maxillofac Surg. 2002;60:784-791. 8. Yang WG, Chen CT, Tsay PK, Chen YR. Functional results of unilateral mandibular condylar process fractures after open and closed treatment. J Trauma. 2002;52:498-503. 9. Hlawitschka M, Loukota R, Eckelt U. Functional and radiological results of open and closed treatment of intracapsular (diacapitular) condylar fractures of the mandible. Int J Oral Maxillofac Surg. 2005;34:597-604. 10. Veras RB, Kriwalsky MS, Eckert AW, Schubert J, Maurer P. Long-term outcomes after treatment of condylar fracture by intraoral access: a functional and radiologic assessment. J Oral Maxillofac Surg. 2007;65:1470-1476.
ORIGINAL ARTICLE Tang et al. e147 11. Vesnaver A, Ahcan U, Rozman J. Evaluation of surgical treatment in mandibular condyle fractures. J Craniomaxillofac Surg. 2012;40:647-653. 12. Choi BH. Comparison of computed tomography imaging before and after functional treatment of bilateral condylar fractures in adults. Int J Oral Maxillofac Surg. 1996;25:30-33. 13. Yamashita Y, Inoue M, Aijima R, Danjo A, Goto M. Threedimensional evaluation of healing joint morphology after closed treatment of condylar fractures. Int J Oral Maxillofac Surg. 2016;45:292-296. 14. Ferretti C, Bryant R, Becker P, Lawrence C. Temporomandibular joint morphology following post-traumatic ankylosis in 26 patients. Int J Oral Maxillofac Surg. 2005;34:376-381. 15. De Vos W, Casselman J, Swennen GR. Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: a systematic review of the literature. Int J Oral Maxillofac Surg. 2009;38:609-625. 16. Krishnamoorthy B, Mamatha N, Kumar VA. TMJ imaging by CBCT: current scenario. Ann Maxillofac Surg. 2013;3:80-83. 17. Yadav S, Palo L, Mahdian M, Upadhyay M, Tadinada A. Diagnostic accuracy of 2 cone-beam computed tomography protocols for detecting arthritic changes in temporomandibular joints. Am J Orthod Dentofacial Orthop. 2015;147:339-344. 18. Liu MQ, Chen HM, Yap AU, Fu KY. Condylar remodeling accompanying splint therapy: a cone-beam computerized tomography study of patients with temporomandibular joint disk displacement. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012;114:259-265. 19. Loukota RA, Neff A, Rasse M. Nomenclature/classification of fractures of the mandibular condylar head. Br J Oral Maxillofac Surg. 2010;48:477-478. 20. Sander AK, Martini M, Konermann AC, Meyer U, Wenghoefer M. Freehand condyle-positioning during orthognathic surgery: postoperative cone-beam computed tomography shows only minor morphometric alterations of the temporomandibular joint position. J Craniofac Surg. 2015;26:14711476. 21. Manjula WS, Tajir F, Murali RV, Kumar SK, Nizam M. Assessment of optimal condylar position with cone-beam computed tomography in south Indian female population. J Pharm Bioall Sci. 2015;7(suppl 1):S121-S124. 22. Goulart DR, Munoz P, Olate S, de Moraes M, Farina R. No differences in morphological characteristics between hyperplastic condyle and class III condyle. Int J Oral Maxillofac Surg. 2015;44:1281-1286. 23. He D, Cai Y, Yang C. Analysis of temporomandibular joint ankylosis caused by condylar fracture in adults. J Oral Maxillofac Surg. 2014;72:763.e761-763.e769. 24. Davis KM, Griffin KS, Chu TG, et al. Muscle-bone interactions during fracture healing. J Musculoskelet Neuronal Interact. 2015;15:1-9. Reprint requests: Min Zhu, DDS, PhD No. 500 QuXi Road Huangpu District Shanghai 200011 People’s Republic of China [email protected]