- Email: [email protected]
Evaluation of an experimental oblique plate for osteosynthesis of mandibular condyle fractures
Accepted Manuscript Title: Evaluation of an experimental oblique plate for osteosynthesis of mandibular condyle fractures Author: Florian Wagner, Martin Strasz, Hannes Traxler, Kurt Schicho, Rudolf Seemann PII: DOI: Reference:
S2212-4403(17)31059-3 https://doi.org/doi:10.1016/j.oooo.2017.09.004 OOOO 1840
To appear in:
Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Received date: Revised date: Accepted date:
15-5-2017 4-8-2017 14-9-2017
Please cite this article as: Florian Wagner, Martin Strasz, Hannes Traxler, Kurt Schicho, Rudolf Seemann, Evaluation of an experimental oblique plate for osteosynthesis of mandibular condyle fractures, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology (2017), https://doi.org/doi:10.1016/j.oooo.2017.09.004. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Evaluation of an experimental oblique plate for osteosynthesis of mandibular condyle fractures Florian Wagner, MDa*, Martin Strasz, MD, DMDa, Hannes Traxler Ass.-Prof., MDb, Kurt Schicho, MD, PhDa, Rudolf Seemann, MD DMD PhDa a
University Clinic for Cranio- and Maxillofacial Surgery, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, Austria, Maxillofacial Surgeons
b
Department for Systematic Anatomy, Medical University of Vienna, Waehringer Strasse 13, Vienna, Austria, Anatomist
*
Corresponding author; University Clinic for Cranio- and Maxillofacial Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria Email: [email protected] Tel: +431 / 40400 / 42520; Fax: +431 / 40400 / 42530
Statement of clinical relevance Screw loosening and plate fractures are among the most frequent complications in open reduction and internal fixation of mandibular condyle fractures. The proposed oblique plate allows for stable bicortical fixation in a biomechanically ideal zone to address these problems. Conflict of Interest: none. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. All of the authors have contributed to and approved the final version of the manuscript. Keywords: Mandibular Condyle – Mandibular Fracture – Open Fracture Reduction – Internal Fracture Fixation Abstract Word Count: 179 Manuscript Word Count: 1850 Number of Figures: 6 Number of References: 39
Page 1 of 23
Statement of clinical relevance: Screw loosening and plate fractures are among the most frequent complications in open reduction and internal fixation of mandibular condyle fractures. The proposed oblique plate allows for stable bicortical fixation in a biomechanically ideal zone to address these problems.
Abstract Objective The aim of this study was to test the bone thickness and potential screw length for osteosynthesis of condylar base fractures (according to the Loukota classification) with an experimental titanium plate, placed in an ideal position against two types of conventional plates. Study Design After exclusion of completely edentulous mandibles 28 dentate macerated mandibles available at the time of the study were included. Linear regression models (LM) 1 & 2 compared the sums of the two cranial bone thicknesses and the three caudal thicknesses between the three different plate designs and linear models 3 & 4 tested the bone thickness in the two most cranial screw axes. Results Linear models 1&2 revealed significantly higher potential screw lengths for the experimental oblique plate. Equally, linear models 3&4 showed significantly higher bone thickness for the novel oblique plate. Conclusion The novel proposed oblique plate allows for favorable plate positioning in a biomechanically ideal location with sufficient amounts of local bone for stable plate fixation. When plates with 15° angulated screw holes are used, stable bicortical plate fixation can be achieved.
Page 2 of 23
Introduction Fractures of the mandible are the most frequently observed fractures in maxillofacial traumatology and condylar fractures account for 18.4 – 34.0% of all mandibular fractures.1-3 The ideal treatment method for condylar fractures is still discussed controversially in the literature: while simple nondislocated condylar fractures may heal on soft diet or closed treatment through intermaxillary (IMF) or maxillo-mandibular fixation (MMF), the treatment of complex and especially dislocated fractures often requires open reduction and internal fixation (ORIF) with titanium plates.4-7 Schneider et al. reported fractures with a deviation between 10 and 45 degrees and shortening of the ramus ≥ 2mm as absolute indications for ORIF, irrespective of the fracture level.5 If internal fixation with titanium plates is chosen, fracture stabilization of mandibular condyle fractures is ideally performed with application of two titanium plates in order to achieve functionally stable results. 8-12 However, anatomical and clinical limitations may result in the placement of a single plate only, especially when an intraoral approach is chosen.13, 14 In these cases the plate is then ideally placed parallel to the tensile stress lines, similar to the “Champy-Principle” in mandibular angle fractures.15 Although these tension lines run oblique below the mandibular notch, titanium plates are nowadays most frequently placed vertically at the posterior border of the mandible in the axis of the mandibular condyle. This region is subject to compressive forces during mastication, potentially contributing to osteosynthesis failures in patients treated with open reduction and internal fixation.16-18 Several studies proposed novel plate designs to allow for stable fixation with a single titanium plate.19-24 Unfortunately, the bone at the ideal plate position in the area below the mandibular notch is usually thin, consisting of a thin cortical plate only. Plate fixation with screws may be rendered unstable, causing frequent screw loosening16, 25 The aim of this study was to test the bone thickness and potential screw length for osteosynthesis of mandibular condyle fractures with an experimental titanium plate, placed in an ideal position against two types of conventional plates either placed in a conventional manner parallel to the posterior border or crossing the ramus sagittal running to the oblique line.
Page 3 of 23
Materials and Methods A cadaver study was conducted after approval of the ethical committee of the Medical University of Vienna was obtained (2238/2016). All of the macerated, adult mandibles available at the Anatomical Institute of the Medical University of Vienna at the time of the study were included independent of age and gender. Mandibles with macroscopic bony defects or congenital deformations were excluded from the study.
Data Collection A fracture of the condylar base according to the Loukota classification was hypothesized for the measurements.26 Three different titanium plate configurations were compared: a conventional straight 5-hole titanium plate, a conventional strut plate and an experimental straight 7-hole oblique plate (see Fig.1). The centers of the screw holes were marked and the bone thickness was measured with a precision sliding caliper with a maximum resolution of 0.01mm (Zürcher Model, Planer, Austria). The thickness measurements were performed in the two most cranial and the three most caudal holes of each plate. The thickness measurement caudal to the fracture line was performed orthogonal to the titanium plate for all three screw holes and plates; cranial to the fracture line the thickness was measured in a typical upwards looking drill angle of 15° within a plane orthogonal to the plate running through the holes (in case of the strut plate an anterior and a posterior plane was assumed, see Fig.1). All plates were temporarily fixed with elastic rubber bands in the desired ideal anatomical position (see Fig.2). The measurements were performed at both sides of the mandibles for each of the three plates. All measurement data were stored in a comma separated value (.csv) file for statistical analysis. Statistical Analysis Statistical analysis was performed with the open source statistical program “R” (version 2.15.1, http://cran.r-project.org). Linear regression models (LM1 & 2) compared the sums of the intrabony screw length for the two cranial screws (LM1) as well as the three caudal screws (LM2) between the three different plate designs. The models always tested the posteriorly placed conventional 5hole plate and the strut plate against the newly proposed oblique design as baseline. In a similar model equation linear models 3 & 4 tested the bone thickness in the two most cranial screw axes.
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Results After exclusion of all mandibles with macroscopic defects 28 macerated mandibles were included in this study. Linear model 1 revealed significant differences between the three different plate designs for the two most cranial screws (see Fig. 3). The potential intrabony screw length of the most cranial screws was significantly smaller for the conventional straight and strut plates when tested against the novel oblique plate (Residual standard error: 3.393 on 165 degrees of freedom, Multiple R2: 0.8852, Adjusted R2: 0.8838 F-statistic: 636.2 on 2 and 165 DF, p-value: <0.001). Linear model 2 showed significantly shorter potential screw lengths for the caudal screws for conventional straight and strut plates when tested against the experimental oblique plate (Residual standard error: 3.969 on 165 degrees of freedom, Multiple R2: 0.7992, Adjusted R2: 0.7967, Fstatistic: 328.3 on 2 and 165 DF, p-value: < 0.001). The mean potential screw length for the most caudal screw hole was 12.4±2.0mm for the oblique plate, 4.0±1.4mm for the straight plate and 4.9±1.3mm for the strut plate (see Fig. 4). Linear models 3 & 4 tested the bone thickness for the two most cranial screws (that would ideally be located in the fractured condylar neck) of the experimental oblique plate against the conventional straight and strut plates. Both models revealed significantly higher bone thickness in the region of the two most cranial screws (Linear model 3: Residual standard error: 3.736 on 165 degrees of freedom Multiple R2: 0.3079, Adjusted R2: 0.2995, F-statistic: 36.71 on 2 and 165 DF, pvalue < 0.001 and Linear model 4: Residual standard error: 1.442 on 165 degrees of freedom, Multiple R2: 0.9624, Adjusted R2: 0.962, F-statistic: 2112 on 2 and 165 DF, p-value < 0.001). The mean potential screw lengths for hole 1&2 were 13.4±5.5mm and 19.5±1.8mm for the oblique plate, 7.4±2.2mm and 3.3±1.3mm for the straight plate and 9.44±2.6mm and 5.2±1.2mm for the strut plate, respectively (see Fig. 5&6).
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Discussion Open reduction and internal fixation of mandibular condyle fractures has gained popularity due to good functional outcomes and high patient satisfaction.5, 27-29 While osteosynthesis with two plates is still regarded as the safest treatment method to withstand mastication forces and osteosynthesis failure, in high fracture lines even a single plate is a surgical challenge; confined space and small proximal fragments amplify this problem. Screw loosening and plate fractures are frequent complications and a major challenge in ORIF of mandibular condyle fractures; they are usually either observed on postoperative radiographs or at the time of plate removal. Numbers in the literature vary between 2.7 and 10.0%.18, 25, 30 Lauer et al. who removed plates on a regular base found an even higher rate of 15.8% of clinically silent screw loosening.19 The main reasons for screw loosening are poor fracture reduction and insufficient local bone thickness to achieve adequate plate stability. The introduction of locking plates aimed to conquer this problem: locking plates act as “fixateur interne”, allowing for adequate fracture stabilization compensating nonanatomical fracture reduction or imprecise plate adaption. Locking screws have threads on both ends and are fixed in the bone on one side and locked in the plate on the other side. Thus, dislocation of screws into the surrounding soft tissues and secondary inflammatory reactions can be prevented.31, 32 Locking plates however show higher rates of plate fracture, which may at least be partly explained by the fact that they allow for adequate fracture stabilization even in cases of insufficient (non-anatomic) fracture reduction and plate adaption, thus rendering the plate from load sharing to load bearing.18, 32 The present study aimed to evaluate the potential bone thickness for stable bicortical plate fixation for an experimental oblique plate versus two conventional plates. Significantly thicker bone was found in the cranial and caudal aspect for the experimental oblique plate, indicating that this novel plate allows for particularly favorable plate positioning in regions with sufficient amounts of bone thickness (see LM 1&2 and Fig 3&4). The plate can be positioned in a biomechanically ideal zone according to the tensile stress lines and the caudal screws can be inserted into the massive bony pillar of the oblique line, allowing for stable osteosynthesis.15-18 Normally, a 7-hole plate is used and screws are inserted into the anterior three and the posterior two holes (see Fig. 1). Thus, screws are located either anterior or posterior to the mandibular foramen and can be inserted safely without any danger to harm the inferior alveolar nerve (IAN). A variety of studies have aimed to evaluate the location of the mandibular foramen and relate it to the position of the lingula and the antilingula to allow for better intraoperative orientation.33-36 Hosapatna et al. investigated 50 dry adult mandibles and found that the antilingula, a bony tubercle found on the lateral aspect of the mandibular ramus, occurs in 50 percent on the right side and in 56 percent on the left side of mandibles.35 They reported, that the mandibular foramen was consistently located posterosuperior to the antilingula and that it can thus be used as a surgical landmark. This may be especially helpful during open reduction and internal fixation (ORIF) of ramus fractures, when the medial aspect of the ramus is normally not visualized. However, a Page 6 of 23
search of the literature yielded conflicting results regarding the existence of the antilingula and its use as a reliable landmark.33, 36 Da Fontoura et al. and Patil et al. reported, that the mandibular foramen can be adequately located when panoramic x-rays are used for measurements.34,
37
A
variety of authors found preoperative CT or CBCT scans to be helpful for three-dimensional evaluation of the position of the IAN, preoperative planning and minimization of intraoperative nerve injury.38, 39 Ideally, three screws or two plates would be used to stabilize the proximal fragment according to recent investigations.10-12,
25, 30
However, this is often clinically impossible, especially when the
proximal fragment is very small or when an intraoral approach is chosen. In these cases a single plate has to provide sufficient stabilization to allow for adequate bony healing. We found that the idealized angulation of the two cranial screw holes of the proposed novel plate with 15° cranially angulated screws resulted in significantly more intrabony screw fixation (see LM 3&4, Fig. 5&6), which might prove to be helpful in these cases. Furthermore, the angulation of the screw holes allows for simplified plate fixation, especially when an intraoral approach is chosen and space is limited.
Conclusion The novel proposed oblique plate allows for favorable plate positioning in a biomechanically ideal location with sufficient amounts of local bone for stable plate fixation. When plates with 15° angulated screw holes are used, stable bicortical plate fixation can be achieved. Nevertheless, anatomical reduction is the ultimate goal to guarantee for optimal stability and healing conditions. Future studies are being planned to evaluate the biomechanical resistance of the proposed plate in vivo.
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References 1.
Boffano P, Roccia F, Zavattero E, et al. European Maxillofacial Trauma (EURMAT) project: A multicentre and prospective study. J Cranio Maxill Surg. 2015;43:62-70.
2.
Rashid A, Eyeson J, Haider D, van Gijn D, Fan K. Incidence and patterns of mandibular fractures during a 5-year period in a London teaching hospital. Brit J Oral Max Surg. 2013;51:794-798.
3.
Morris C, Bebeau NP, Brockhoff H, Tandon R, Tiwana P. Mandibular Fractures: An Analysis of the Epidemiology and Patterns of Injury in 4,143 Fractures. J Oral Maxil Surg. 2015;73:951E951-951E912.
4.
Abdel-Galil K, Loukota R. Fractures of the mandibular condyle: evidence base and current concepts of management. Brit J Oral Max Surg. 2010;48:520-526.
5.
Schneider M, Erasmus F, Gerlach KL, et al. Open Reduction and Internal Fixation Versus Closed Treatment and Mandibulomaxillary Fixation of Fractures of the Mandibular Condylar Process: A Randomized, Prospective, Multicenter Study With Special Evaluation of Fracture Level. J Oral Maxil Surg. 2008;66:2537-2544.
6.
Valiati R, Ibrahim D, Abreu ME, et al. The treatment of condylar fractures: to open or not to open? A critical review of this controversy. Int J Med Sci. 2008;5:313-318.
7.
Nussbaum ML, Laskin DM, Best AM. Closed versus open reduction of mandibular condylar fractures in adults: a meta-analysis. J Oral Maxillofac Surg. 2008;66:1087-1092.
8.
Asprino L, Consani S, de Moraes M. A comparative biomechanical evaluation of mandibular condyle fracture plating techniques. J Oral Maxillofac Surg. 2006;64:452-456.
9.
Costa FW, Bezerra MF, Ribeiro TR, Pouchain EC, Saboia Vde P, Soares EC. Biomechanical analysis of titanium plate systems in mandibular condyle fractures: a systematized literature review. Acta Cir Bras. 2012;27:424-429.
10.
Conci RA, Tomazi FH, Noritomi PY, da Silva JV, Fritscher GG, Heitz C. Comparison of Neck Screw and Conventional Fixation Techniques in Mandibular Condyle Fractures Using 3Dimensional Finite Element Analysis. J Oral Maxillofac Surg. 2015;73:1321-1327.
11.
Pilling E, Eckelt U, Loukota R, Schneider K, Stadlinger B. Comparative evaluation of ten different condylar base fracture osteosynthesis techniques. Br J Oral Maxillofac Surg. 2010;48:527-531.
12.
Wagner A, Krach W, Schicho K, Undt G, Ploder O, Ewers R. A 3-dimensional finite-element analysis investigating the biomechanical behavior of the mandible and plate osteosynthesis in cases of fractures of the condylar process. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;94:678-686.
13.
Undt G, Kermer C, Rasse M, Sinko K, Ewers R. Transoral miniplate osteosynthesis of condylar neck fractures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 1999;88:534543. Page 8 of 23
14.
Haug RH, Brandt MT. Traditional versus endoscope-assisted open reduction with rigid internal fixation (ORIF) of adult mandibular condyle fractures: a review of the literature regarding current thoughts on management. J Oral Maxillofac Surg. 2004;62:1272-1279.
15.
Champy M, Wilk A, Schnebelen JM. [Tretment of mandibular fractures by means of osteosynthesis without intermaxillary immobilization according to F.X. Michelet's technic].
Die Behandlung der Mandibularfrakturen mittels Osteosynthese ohne intermaxillare Ruhigstellung nach der Technik von F.X. Michelet. Zahn Mund Kieferheilkd Zentralbl. 1975;63:339-341. 16.
Meyer C, Serhir L, Boutemi P. Experimental evaluation of three osteosynthesis devices used for stabilizing condylar fractures of the mandible. J Craniomaxillofac Surg. 2006;34:173-181.
17.
Meyer C, Kahn J-L, Boutemi P, Wilk A. Photoelastic analysis of bone deformation in the region of the mandibular condyle during mastication. J Craniomaxillofac Surg. 2002;30:160169.
18.
Seemann R, Undt G, Lauer G, et al. Is failure of condylar neck osteosynthesis predictable based on orthopantomography? Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2011;111:362-371.
19.
Lauer G, Pradel W, Schneider M, Eckelt U. A new 3-dimensional plate for transoral endoscopic-assisted osteosynthesis of condylar neck fractures. J Oral Maxillofac Surg. 2007;65:964-971.
20.
Aquilina P, Parr WC, Chamoli U, Wroe S. Finite element analysis of patient-specific condyle fracture plates: a preliminary study. Craniomaxillofac Trauma Reconstr. 2015;8:111-116.
21.
de Jesus GP, Vaz LG, Gabrielli MF, et al. Finite element evaluation of three methods of stable fixation of condyle base fractures. Int J Oral Maxillofac Surg. 2014;43:1251-1256.
22.
Darwich MA, Albogha MH, Abdelmajeed A, Darwich K. Assessment of the Biomechanical Performance of 5 Plating Techniques in Fixation of Mandibular Subcondylar Fracture Using Finite Element Analysis. J Oral Maxillofac Surg. 2016;74:794 e791-798.
23.
Celegatti Filho TS, Rodrigues DC, Lauria A, Moreira RW, Consani S. Development plates for stable internal fixation: Study of mechanical resistance in simulated fractures of the mandibular condyle. J Craniomaxillofac Surg. 2015;43:158-161.
24.
Meyer C, Martin E, Kahn JL, Zink S. Development and biomechanical testing of a new osteosynthesis plate (TCP) designed to stabilize mandibular condyle fractures. J Craniomaxillofac Surg. 2007;35:84-90.
25.
Hammer B, Schier P, Prein J. Osteosynthesis of condylar neck fractures: a review of 30 patients. Br J Oral Maxillofac Surg. 1997;35:288-291.
26.
Loukota RA, Eckelt U, De Bont L, Rasse M. Subclassification of fractures of the condylar process of the mandible. Br J Oral Maxillofac Surg. 2005;43:72-73.
27.
Rutges JP, Kruizinga EH, Rosenberg A, Koole R. Functional results after conservative treatment of fractures of the mandibular condyle. Br J Oral Maxillofac Surg. 2007;45:30-34.
Page 9 of 23
28.
Kommers SC, van den Bergh B, Forouzanfar T. Quality of life after open versus closed treatment for mandibular condyle fractures: a review of literature. J Craniomaxillofac Surg. 2013;41:e221-225.
29.
Kyzas PA, Saeed A, Tabbenor O. The treatment of mandibular condyle fractures: a metaanalysis. J Craniomaxillofac Surg. 2012;40:e438-452.
30.
Choi BH, Yi CK, Yoo JH. Clinical evaluation of 3 types of plate osteosynthesis for fixation of condylar neck fractures. J Oral Maxillofac Surg. 2001;59:734-737; discussion 738.
31.
Ellis E, 3rd, Graham J. Use of a 2.0-mm locking plate/screw system for mandibular fracture surgery. J Oral Maxillofac Surg. 2002;60:642-645; discussion 645-646.
32.
Seemann R, Frerich B, Muller S, et al. Comparison of locking and nonlocking plates in the treatment of mandibular condyle fractures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;108:328-334.
33.
Monnazzi MS, Passeri LA, Gabrielli MF, Bolini PD, de Carvalho WR, da Costa Machado H. Anatomic study of the mandibular foramen, lingula and antilingula in dry mandibles, and its statistical relationship between the true lingula and the antilingula. Int J Oral Maxillofac Surg. 2012;41:74-78.
34.
da Fontoura RA, Vasconcellos HA, Campos AE. Morphologic basis for the intraoral vertical ramus osteotomy: anatomic and radiographic localization of the mandibular foramen. J Oral Maxillofac Surg. 2002;60:660-665; discussion 665-666.
35.
Hosapatna M, Ankolekar VH, D'Souza AS, Deepika C, D'Souza A. The study of antilingula and its relation to the lingula and mandibular foramen, the presence of mylohyoid bridging in dry mandibles of South Indian population. J Maxillofac Oral Surg. 2015;14:308-311.
36.
Hogan G, Ellis E, 3rd. The "antilingula"--fact or fiction? J Oral Maxillofac Surg. 2006;64:1248-1254.
37.
Patil K, Guledgud MV, Bhattacharya PT. Reliability of Panoramic Radiographs in the Localization of Mandibular Foramen. J Clin Diagn Res. 2015;9:ZC35-38.
38.
Yu IH, Wong YK. Evaluation of mandibular anatomy related to sagittal split ramus osteotomy using 3-dimensional computed tomography scan images. Int J Oral Maxillofac Surg. 2008;37:521-528.
39.
Levine MH, Goddard AL, Dodson TB. Inferior alveolar nerve canal position: a clinical and radiographic study. J Oral Maxillofac Surg. 2007;65:470-474.
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Figure 1. Schematic drawing of the three investigated plate designs (from left to right): experimental oblique plate, conventional straight 5-hole plate, strut plate. The two cranial screw holes (above the fracture line) of each plate are displayed in white and the three caudal screw holes (below the fracture line) are displayed in black. The two cranial screws that are ideally inserted in a 15° angle are shown schematically. The course of the inferior alveolar nerve is shown in grey. Figure 2. Experimental arrangement: All plates were temporarily fixed with elastic rubber bands in the desired ideal anatomical position. Figure 3. Boxplot representing the sum of the intrabony screw length of the two cranial screws for the three different plate designs. Figure 4. Boxplot representing the sum of the intrabony screw length of the three caudal screws for the three different plate designs. Figure 5. Boxplot representing the sum of the intrabony screw length of the most cranial screw (=hole 1) for the three different plate designs. Figure 6. Boxplot representing the sum of the intrabony screw length of the second most cranial screw (=hole 2) for the three different plate designs.
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S2212-4403(17)31059-3 https://doi.org/doi:10.1016/j.oooo.2017.09.004 OOOO 1840
To appear in:
Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Received date: Revised date: Accepted date:
15-5-2017 4-8-2017 14-9-2017
Please cite this article as: Florian Wagner, Martin Strasz, Hannes Traxler, Kurt Schicho, Rudolf Seemann, Evaluation of an experimental oblique plate for osteosynthesis of mandibular condyle fractures, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology (2017), https://doi.org/doi:10.1016/j.oooo.2017.09.004. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Evaluation of an experimental oblique plate for osteosynthesis of mandibular condyle fractures Florian Wagner, MDa*, Martin Strasz, MD, DMDa, Hannes Traxler Ass.-Prof., MDb, Kurt Schicho, MD, PhDa, Rudolf Seemann, MD DMD PhDa a
University Clinic for Cranio- and Maxillofacial Surgery, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, Austria, Maxillofacial Surgeons
b
Department for Systematic Anatomy, Medical University of Vienna, Waehringer Strasse 13, Vienna, Austria, Anatomist
*
Corresponding author; University Clinic for Cranio- and Maxillofacial Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria Email: [email protected] Tel: +431 / 40400 / 42520; Fax: +431 / 40400 / 42530
Statement of clinical relevance Screw loosening and plate fractures are among the most frequent complications in open reduction and internal fixation of mandibular condyle fractures. The proposed oblique plate allows for stable bicortical fixation in a biomechanically ideal zone to address these problems. Conflict of Interest: none. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. All of the authors have contributed to and approved the final version of the manuscript. Keywords: Mandibular Condyle – Mandibular Fracture – Open Fracture Reduction – Internal Fracture Fixation Abstract Word Count: 179 Manuscript Word Count: 1850 Number of Figures: 6 Number of References: 39
Page 1 of 23
Statement of clinical relevance: Screw loosening and plate fractures are among the most frequent complications in open reduction and internal fixation of mandibular condyle fractures. The proposed oblique plate allows for stable bicortical fixation in a biomechanically ideal zone to address these problems.
Abstract Objective The aim of this study was to test the bone thickness and potential screw length for osteosynthesis of condylar base fractures (according to the Loukota classification) with an experimental titanium plate, placed in an ideal position against two types of conventional plates. Study Design After exclusion of completely edentulous mandibles 28 dentate macerated mandibles available at the time of the study were included. Linear regression models (LM) 1 & 2 compared the sums of the two cranial bone thicknesses and the three caudal thicknesses between the three different plate designs and linear models 3 & 4 tested the bone thickness in the two most cranial screw axes. Results Linear models 1&2 revealed significantly higher potential screw lengths for the experimental oblique plate. Equally, linear models 3&4 showed significantly higher bone thickness for the novel oblique plate. Conclusion The novel proposed oblique plate allows for favorable plate positioning in a biomechanically ideal location with sufficient amounts of local bone for stable plate fixation. When plates with 15° angulated screw holes are used, stable bicortical plate fixation can be achieved.
Page 2 of 23
Introduction Fractures of the mandible are the most frequently observed fractures in maxillofacial traumatology and condylar fractures account for 18.4 – 34.0% of all mandibular fractures.1-3 The ideal treatment method for condylar fractures is still discussed controversially in the literature: while simple nondislocated condylar fractures may heal on soft diet or closed treatment through intermaxillary (IMF) or maxillo-mandibular fixation (MMF), the treatment of complex and especially dislocated fractures often requires open reduction and internal fixation (ORIF) with titanium plates.4-7 Schneider et al. reported fractures with a deviation between 10 and 45 degrees and shortening of the ramus ≥ 2mm as absolute indications for ORIF, irrespective of the fracture level.5 If internal fixation with titanium plates is chosen, fracture stabilization of mandibular condyle fractures is ideally performed with application of two titanium plates in order to achieve functionally stable results. 8-12 However, anatomical and clinical limitations may result in the placement of a single plate only, especially when an intraoral approach is chosen.13, 14 In these cases the plate is then ideally placed parallel to the tensile stress lines, similar to the “Champy-Principle” in mandibular angle fractures.15 Although these tension lines run oblique below the mandibular notch, titanium plates are nowadays most frequently placed vertically at the posterior border of the mandible in the axis of the mandibular condyle. This region is subject to compressive forces during mastication, potentially contributing to osteosynthesis failures in patients treated with open reduction and internal fixation.16-18 Several studies proposed novel plate designs to allow for stable fixation with a single titanium plate.19-24 Unfortunately, the bone at the ideal plate position in the area below the mandibular notch is usually thin, consisting of a thin cortical plate only. Plate fixation with screws may be rendered unstable, causing frequent screw loosening16, 25 The aim of this study was to test the bone thickness and potential screw length for osteosynthesis of mandibular condyle fractures with an experimental titanium plate, placed in an ideal position against two types of conventional plates either placed in a conventional manner parallel to the posterior border or crossing the ramus sagittal running to the oblique line.
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Materials and Methods A cadaver study was conducted after approval of the ethical committee of the Medical University of Vienna was obtained (2238/2016). All of the macerated, adult mandibles available at the Anatomical Institute of the Medical University of Vienna at the time of the study were included independent of age and gender. Mandibles with macroscopic bony defects or congenital deformations were excluded from the study.
Data Collection A fracture of the condylar base according to the Loukota classification was hypothesized for the measurements.26 Three different titanium plate configurations were compared: a conventional straight 5-hole titanium plate, a conventional strut plate and an experimental straight 7-hole oblique plate (see Fig.1). The centers of the screw holes were marked and the bone thickness was measured with a precision sliding caliper with a maximum resolution of 0.01mm (Zürcher Model, Planer, Austria). The thickness measurements were performed in the two most cranial and the three most caudal holes of each plate. The thickness measurement caudal to the fracture line was performed orthogonal to the titanium plate for all three screw holes and plates; cranial to the fracture line the thickness was measured in a typical upwards looking drill angle of 15° within a plane orthogonal to the plate running through the holes (in case of the strut plate an anterior and a posterior plane was assumed, see Fig.1). All plates were temporarily fixed with elastic rubber bands in the desired ideal anatomical position (see Fig.2). The measurements were performed at both sides of the mandibles for each of the three plates. All measurement data were stored in a comma separated value (.csv) file for statistical analysis. Statistical Analysis Statistical analysis was performed with the open source statistical program “R” (version 2.15.1, http://cran.r-project.org). Linear regression models (LM1 & 2) compared the sums of the intrabony screw length for the two cranial screws (LM1) as well as the three caudal screws (LM2) between the three different plate designs. The models always tested the posteriorly placed conventional 5hole plate and the strut plate against the newly proposed oblique design as baseline. In a similar model equation linear models 3 & 4 tested the bone thickness in the two most cranial screw axes.
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Results After exclusion of all mandibles with macroscopic defects 28 macerated mandibles were included in this study. Linear model 1 revealed significant differences between the three different plate designs for the two most cranial screws (see Fig. 3). The potential intrabony screw length of the most cranial screws was significantly smaller for the conventional straight and strut plates when tested against the novel oblique plate (Residual standard error: 3.393 on 165 degrees of freedom, Multiple R2: 0.8852, Adjusted R2: 0.8838 F-statistic: 636.2 on 2 and 165 DF, p-value: <0.001). Linear model 2 showed significantly shorter potential screw lengths for the caudal screws for conventional straight and strut plates when tested against the experimental oblique plate (Residual standard error: 3.969 on 165 degrees of freedom, Multiple R2: 0.7992, Adjusted R2: 0.7967, Fstatistic: 328.3 on 2 and 165 DF, p-value: < 0.001). The mean potential screw length for the most caudal screw hole was 12.4±2.0mm for the oblique plate, 4.0±1.4mm for the straight plate and 4.9±1.3mm for the strut plate (see Fig. 4). Linear models 3 & 4 tested the bone thickness for the two most cranial screws (that would ideally be located in the fractured condylar neck) of the experimental oblique plate against the conventional straight and strut plates. Both models revealed significantly higher bone thickness in the region of the two most cranial screws (Linear model 3: Residual standard error: 3.736 on 165 degrees of freedom Multiple R2: 0.3079, Adjusted R2: 0.2995, F-statistic: 36.71 on 2 and 165 DF, pvalue < 0.001 and Linear model 4: Residual standard error: 1.442 on 165 degrees of freedom, Multiple R2: 0.9624, Adjusted R2: 0.962, F-statistic: 2112 on 2 and 165 DF, p-value < 0.001). The mean potential screw lengths for hole 1&2 were 13.4±5.5mm and 19.5±1.8mm for the oblique plate, 7.4±2.2mm and 3.3±1.3mm for the straight plate and 9.44±2.6mm and 5.2±1.2mm for the strut plate, respectively (see Fig. 5&6).
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Discussion Open reduction and internal fixation of mandibular condyle fractures has gained popularity due to good functional outcomes and high patient satisfaction.5, 27-29 While osteosynthesis with two plates is still regarded as the safest treatment method to withstand mastication forces and osteosynthesis failure, in high fracture lines even a single plate is a surgical challenge; confined space and small proximal fragments amplify this problem. Screw loosening and plate fractures are frequent complications and a major challenge in ORIF of mandibular condyle fractures; they are usually either observed on postoperative radiographs or at the time of plate removal. Numbers in the literature vary between 2.7 and 10.0%.18, 25, 30 Lauer et al. who removed plates on a regular base found an even higher rate of 15.8% of clinically silent screw loosening.19 The main reasons for screw loosening are poor fracture reduction and insufficient local bone thickness to achieve adequate plate stability. The introduction of locking plates aimed to conquer this problem: locking plates act as “fixateur interne”, allowing for adequate fracture stabilization compensating nonanatomical fracture reduction or imprecise plate adaption. Locking screws have threads on both ends and are fixed in the bone on one side and locked in the plate on the other side. Thus, dislocation of screws into the surrounding soft tissues and secondary inflammatory reactions can be prevented.31, 32 Locking plates however show higher rates of plate fracture, which may at least be partly explained by the fact that they allow for adequate fracture stabilization even in cases of insufficient (non-anatomic) fracture reduction and plate adaption, thus rendering the plate from load sharing to load bearing.18, 32 The present study aimed to evaluate the potential bone thickness for stable bicortical plate fixation for an experimental oblique plate versus two conventional plates. Significantly thicker bone was found in the cranial and caudal aspect for the experimental oblique plate, indicating that this novel plate allows for particularly favorable plate positioning in regions with sufficient amounts of bone thickness (see LM 1&2 and Fig 3&4). The plate can be positioned in a biomechanically ideal zone according to the tensile stress lines and the caudal screws can be inserted into the massive bony pillar of the oblique line, allowing for stable osteosynthesis.15-18 Normally, a 7-hole plate is used and screws are inserted into the anterior three and the posterior two holes (see Fig. 1). Thus, screws are located either anterior or posterior to the mandibular foramen and can be inserted safely without any danger to harm the inferior alveolar nerve (IAN). A variety of studies have aimed to evaluate the location of the mandibular foramen and relate it to the position of the lingula and the antilingula to allow for better intraoperative orientation.33-36 Hosapatna et al. investigated 50 dry adult mandibles and found that the antilingula, a bony tubercle found on the lateral aspect of the mandibular ramus, occurs in 50 percent on the right side and in 56 percent on the left side of mandibles.35 They reported, that the mandibular foramen was consistently located posterosuperior to the antilingula and that it can thus be used as a surgical landmark. This may be especially helpful during open reduction and internal fixation (ORIF) of ramus fractures, when the medial aspect of the ramus is normally not visualized. However, a Page 6 of 23
search of the literature yielded conflicting results regarding the existence of the antilingula and its use as a reliable landmark.33, 36 Da Fontoura et al. and Patil et al. reported, that the mandibular foramen can be adequately located when panoramic x-rays are used for measurements.34,
37
A
variety of authors found preoperative CT or CBCT scans to be helpful for three-dimensional evaluation of the position of the IAN, preoperative planning and minimization of intraoperative nerve injury.38, 39 Ideally, three screws or two plates would be used to stabilize the proximal fragment according to recent investigations.10-12,
25, 30
However, this is often clinically impossible, especially when the
proximal fragment is very small or when an intraoral approach is chosen. In these cases a single plate has to provide sufficient stabilization to allow for adequate bony healing. We found that the idealized angulation of the two cranial screw holes of the proposed novel plate with 15° cranially angulated screws resulted in significantly more intrabony screw fixation (see LM 3&4, Fig. 5&6), which might prove to be helpful in these cases. Furthermore, the angulation of the screw holes allows for simplified plate fixation, especially when an intraoral approach is chosen and space is limited.
Conclusion The novel proposed oblique plate allows for favorable plate positioning in a biomechanically ideal location with sufficient amounts of local bone for stable plate fixation. When plates with 15° angulated screw holes are used, stable bicortical plate fixation can be achieved. Nevertheless, anatomical reduction is the ultimate goal to guarantee for optimal stability and healing conditions. Future studies are being planned to evaluate the biomechanical resistance of the proposed plate in vivo.
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References 1.
Boffano P, Roccia F, Zavattero E, et al. European Maxillofacial Trauma (EURMAT) project: A multicentre and prospective study. J Cranio Maxill Surg. 2015;43:62-70.
2.
Rashid A, Eyeson J, Haider D, van Gijn D, Fan K. Incidence and patterns of mandibular fractures during a 5-year period in a London teaching hospital. Brit J Oral Max Surg. 2013;51:794-798.
3.
Morris C, Bebeau NP, Brockhoff H, Tandon R, Tiwana P. Mandibular Fractures: An Analysis of the Epidemiology and Patterns of Injury in 4,143 Fractures. J Oral Maxil Surg. 2015;73:951E951-951E912.
4.
Abdel-Galil K, Loukota R. Fractures of the mandibular condyle: evidence base and current concepts of management. Brit J Oral Max Surg. 2010;48:520-526.
5.
Schneider M, Erasmus F, Gerlach KL, et al. Open Reduction and Internal Fixation Versus Closed Treatment and Mandibulomaxillary Fixation of Fractures of the Mandibular Condylar Process: A Randomized, Prospective, Multicenter Study With Special Evaluation of Fracture Level. J Oral Maxil Surg. 2008;66:2537-2544.
6.
Valiati R, Ibrahim D, Abreu ME, et al. The treatment of condylar fractures: to open or not to open? A critical review of this controversy. Int J Med Sci. 2008;5:313-318.
7.
Nussbaum ML, Laskin DM, Best AM. Closed versus open reduction of mandibular condylar fractures in adults: a meta-analysis. J Oral Maxillofac Surg. 2008;66:1087-1092.
8.
Asprino L, Consani S, de Moraes M. A comparative biomechanical evaluation of mandibular condyle fracture plating techniques. J Oral Maxillofac Surg. 2006;64:452-456.
9.
Costa FW, Bezerra MF, Ribeiro TR, Pouchain EC, Saboia Vde P, Soares EC. Biomechanical analysis of titanium plate systems in mandibular condyle fractures: a systematized literature review. Acta Cir Bras. 2012;27:424-429.
10.
Conci RA, Tomazi FH, Noritomi PY, da Silva JV, Fritscher GG, Heitz C. Comparison of Neck Screw and Conventional Fixation Techniques in Mandibular Condyle Fractures Using 3Dimensional Finite Element Analysis. J Oral Maxillofac Surg. 2015;73:1321-1327.
11.
Pilling E, Eckelt U, Loukota R, Schneider K, Stadlinger B. Comparative evaluation of ten different condylar base fracture osteosynthesis techniques. Br J Oral Maxillofac Surg. 2010;48:527-531.
12.
Wagner A, Krach W, Schicho K, Undt G, Ploder O, Ewers R. A 3-dimensional finite-element analysis investigating the biomechanical behavior of the mandible and plate osteosynthesis in cases of fractures of the condylar process. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;94:678-686.
13.
Undt G, Kermer C, Rasse M, Sinko K, Ewers R. Transoral miniplate osteosynthesis of condylar neck fractures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 1999;88:534543. Page 8 of 23
14.
Haug RH, Brandt MT. Traditional versus endoscope-assisted open reduction with rigid internal fixation (ORIF) of adult mandibular condyle fractures: a review of the literature regarding current thoughts on management. J Oral Maxillofac Surg. 2004;62:1272-1279.
15.
Champy M, Wilk A, Schnebelen JM. [Tretment of mandibular fractures by means of osteosynthesis without intermaxillary immobilization according to F.X. Michelet's technic].
Die Behandlung der Mandibularfrakturen mittels Osteosynthese ohne intermaxillare Ruhigstellung nach der Technik von F.X. Michelet. Zahn Mund Kieferheilkd Zentralbl. 1975;63:339-341. 16.
Meyer C, Serhir L, Boutemi P. Experimental evaluation of three osteosynthesis devices used for stabilizing condylar fractures of the mandible. J Craniomaxillofac Surg. 2006;34:173-181.
17.
Meyer C, Kahn J-L, Boutemi P, Wilk A. Photoelastic analysis of bone deformation in the region of the mandibular condyle during mastication. J Craniomaxillofac Surg. 2002;30:160169.
18.
Seemann R, Undt G, Lauer G, et al. Is failure of condylar neck osteosynthesis predictable based on orthopantomography? Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2011;111:362-371.
19.
Lauer G, Pradel W, Schneider M, Eckelt U. A new 3-dimensional plate for transoral endoscopic-assisted osteosynthesis of condylar neck fractures. J Oral Maxillofac Surg. 2007;65:964-971.
20.
Aquilina P, Parr WC, Chamoli U, Wroe S. Finite element analysis of patient-specific condyle fracture plates: a preliminary study. Craniomaxillofac Trauma Reconstr. 2015;8:111-116.
21.
de Jesus GP, Vaz LG, Gabrielli MF, et al. Finite element evaluation of three methods of stable fixation of condyle base fractures. Int J Oral Maxillofac Surg. 2014;43:1251-1256.
22.
Darwich MA, Albogha MH, Abdelmajeed A, Darwich K. Assessment of the Biomechanical Performance of 5 Plating Techniques in Fixation of Mandibular Subcondylar Fracture Using Finite Element Analysis. J Oral Maxillofac Surg. 2016;74:794 e791-798.
23.
Celegatti Filho TS, Rodrigues DC, Lauria A, Moreira RW, Consani S. Development plates for stable internal fixation: Study of mechanical resistance in simulated fractures of the mandibular condyle. J Craniomaxillofac Surg. 2015;43:158-161.
24.
Meyer C, Martin E, Kahn JL, Zink S. Development and biomechanical testing of a new osteosynthesis plate (TCP) designed to stabilize mandibular condyle fractures. J Craniomaxillofac Surg. 2007;35:84-90.
25.
Hammer B, Schier P, Prein J. Osteosynthesis of condylar neck fractures: a review of 30 patients. Br J Oral Maxillofac Surg. 1997;35:288-291.
26.
Loukota RA, Eckelt U, De Bont L, Rasse M. Subclassification of fractures of the condylar process of the mandible. Br J Oral Maxillofac Surg. 2005;43:72-73.
27.
Rutges JP, Kruizinga EH, Rosenberg A, Koole R. Functional results after conservative treatment of fractures of the mandibular condyle. Br J Oral Maxillofac Surg. 2007;45:30-34.
Page 9 of 23
28.
Kommers SC, van den Bergh B, Forouzanfar T. Quality of life after open versus closed treatment for mandibular condyle fractures: a review of literature. J Craniomaxillofac Surg. 2013;41:e221-225.
29.
Kyzas PA, Saeed A, Tabbenor O. The treatment of mandibular condyle fractures: a metaanalysis. J Craniomaxillofac Surg. 2012;40:e438-452.
30.
Choi BH, Yi CK, Yoo JH. Clinical evaluation of 3 types of plate osteosynthesis for fixation of condylar neck fractures. J Oral Maxillofac Surg. 2001;59:734-737; discussion 738.
31.
Ellis E, 3rd, Graham J. Use of a 2.0-mm locking plate/screw system for mandibular fracture surgery. J Oral Maxillofac Surg. 2002;60:642-645; discussion 645-646.
32.
Seemann R, Frerich B, Muller S, et al. Comparison of locking and nonlocking plates in the treatment of mandibular condyle fractures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;108:328-334.
33.
Monnazzi MS, Passeri LA, Gabrielli MF, Bolini PD, de Carvalho WR, da Costa Machado H. Anatomic study of the mandibular foramen, lingula and antilingula in dry mandibles, and its statistical relationship between the true lingula and the antilingula. Int J Oral Maxillofac Surg. 2012;41:74-78.
34.
da Fontoura RA, Vasconcellos HA, Campos AE. Morphologic basis for the intraoral vertical ramus osteotomy: anatomic and radiographic localization of the mandibular foramen. J Oral Maxillofac Surg. 2002;60:660-665; discussion 665-666.
35.
Hosapatna M, Ankolekar VH, D'Souza AS, Deepika C, D'Souza A. The study of antilingula and its relation to the lingula and mandibular foramen, the presence of mylohyoid bridging in dry mandibles of South Indian population. J Maxillofac Oral Surg. 2015;14:308-311.
36.
Hogan G, Ellis E, 3rd. The "antilingula"--fact or fiction? J Oral Maxillofac Surg. 2006;64:1248-1254.
37.
Patil K, Guledgud MV, Bhattacharya PT. Reliability of Panoramic Radiographs in the Localization of Mandibular Foramen. J Clin Diagn Res. 2015;9:ZC35-38.
38.
Yu IH, Wong YK. Evaluation of mandibular anatomy related to sagittal split ramus osteotomy using 3-dimensional computed tomography scan images. Int J Oral Maxillofac Surg. 2008;37:521-528.
39.
Levine MH, Goddard AL, Dodson TB. Inferior alveolar nerve canal position: a clinical and radiographic study. J Oral Maxillofac Surg. 2007;65:470-474.
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Figure 1. Schematic drawing of the three investigated plate designs (from left to right): experimental oblique plate, conventional straight 5-hole plate, strut plate. The two cranial screw holes (above the fracture line) of each plate are displayed in white and the three caudal screw holes (below the fracture line) are displayed in black. The two cranial screws that are ideally inserted in a 15° angle are shown schematically. The course of the inferior alveolar nerve is shown in grey. Figure 2. Experimental arrangement: All plates were temporarily fixed with elastic rubber bands in the desired ideal anatomical position. Figure 3. Boxplot representing the sum of the intrabony screw length of the two cranial screws for the three different plate designs. Figure 4. Boxplot representing the sum of the intrabony screw length of the three caudal screws for the three different plate designs. Figure 5. Boxplot representing the sum of the intrabony screw length of the most cranial screw (=hole 1) for the three different plate designs. Figure 6. Boxplot representing the sum of the intrabony screw length of the second most cranial screw (=hole 2) for the three different plate designs.
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