J Oral Maxillofac Surg65:1758-1763, 2007

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mandibular fracture. In the absence of clinical symptoms, the patient declined plate removal. On finalfollow-up, fracture healing was considered clinically complete in all patients.

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doiConclusions: The 3D plating system described here is suitable for fixation of simple mandibular anglefractures and is an easy-to-use alternative to conventional miniplates. The system may be contraindicatedin patients in whom insufficient interfragmentary bone contact causes minor stability of the fracture. 2007 American Association of Oral and Maxillofacial SurgeonsJ Oral Maxillofac Surg 65:1758-1763, 2007

thods for open reduction of mandibular fracturesve changed and diversified enormously in recentcades, but there is still controversy regarding thetimal treatment.1 Today, open reduction and rigidernal fixation can be achieved with a variety offerent plating systems, some using an intraoral ap-oach and some an extraoral approach. The majoritysimple, nondisplaced or minimally displaced frac-es of the symphysis, parasymphysis, and mandibu-body can be adequately treated by osteosynthesisth 1 or 2 miniplates. Fixation of more complex

fractures, such as comminuted fractures and fracturesof the mandibular angle, is much more controversial.Mandibular angle fractures are considered the mostcritical of all mandibular fractures, as they are mostfrequently associated with complications, particularlyin relation to insufficient stability of fracture fixa-tion.2-4

The mandibular angle is one of the most frequentsites for fractures of the lower jaw, accounting forbetween 20% and 36% of all mandibular fractures.5-6

Generally, these fractures are treated surgically, byeither rigid or semirigid fixation2 techniques thatreflect almost opposite concepts of craniomaxillofa-cial osteosynthesis. Rigid fixation is promoted by theAO/ASIF (Arbeitsgemeinschaft fr Osteosynthesefra-gen/Association for the Study of Internal Fixation). Inthis concept, compression, tension, torsion, andshearing forces, which develop under functional load-ing, are neutralized by thick solid plates fixed alongthe lower border of the mandible by bicorticalscrews. In contrast, the Champy method of semirigidfixation uses one easily bendable monocorticalminiplate along an ideal osteosynthesis line.7 The de-

eived from the Department of Cranio-Maxillofacial Surgery,

iversity of Bern, Bern, Switzerland.

Senior Resident.

Senior Resident.

Professor and Head.

Address correspondence and reprint requests to Dr Zix: Depart-

nt of Cranio-Maxillofacial Surgery, University of Bern, Inselspital

-3010 Bern, Switzerland; e-mail: juergen.zix@insel.ch

007 American Association of Oral and Maxillofacial Surgeons

8-2391/07/6509-0014$32.00/0

:10.1016/j.joms.2007.03.013

1758Use of Straight and CTitanium Miniplates

at the MandJuergen Zix, MD, DMD,* Oli

Tateyuki Iizuka

Purpose: The aim of this follow-up study was to3-dimensional (3D) miniplate for open reduction atures.

Patients and Methods: In 20 consecutive patienttreated with open reduction and fixation using a 2 mpatients were systematically monitored until 6 monrecorded were infection, hardware failure, woundalveolar nerve.

Results: The mean operation time from incision ta mucosal wound dehiscence with no consequencremoval. All but 2 patients had normal sensory funcin one patient in whom a preceding surgical removed 3-DimensionalFracture Fixationlar Angle

Lieger, MD, DMD, and

DDS, PhD

uate the clinical usefulness of a new type ofonocortical fixation of mandibular angle frac-

comminuted mandibular angle fractures wereD miniplate system in a transoral approach. Allstoperatively. Among the outcome parameterscence, and sensory disturbance of the inferior

nd closure was 65 minutes. Two patients hadone developed an infection requiring a platemonths after surgery. Plate fracture occurred

f the third molar had been the reason for the

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ZIX ET AL 1759loping forces are neutralized by masticatory forcest produce a natural strain of compression along theerior border of the mandible. Both techniques areociated with disadvantages. An obvious disadvan-e of rigid fixation using compression and recon-uction plates is in many cases the need for antraoral approach. This approach increases opera-n time, and is accompanied by risks of damage tofacial nerve and of extraoral scar formation.8 An-er disadvantage of reconstruction plates comparedth miniplates is the more difficult and time consum-adaptation to the bone.

A disadvantage of semirigid fixation is doubt overether single miniplate fixation is sufficiently stablefractures that cannot be adequately reduced.9,10

ese shortcomings of rigid and semirigid fixation ledthe development of 3-dimensional (3D) miniplates,nsisting of 2 4-hole miniplates joined by 4 intercon-cting cross struts.11 Unlike compression and recon-uction plates, their stability does not derive fromthickness of the plate. In combination with the

ews monocortically fixed to the outer corticalis,rectangular plate forms a cuboid, which possessesstability. Although experimental studies on biome-anics12-14 have confirmed sufficient stability of theplating system, only a few studies have previouslyorted clinical experiences with these plates in theatment of mandibular angle fractures.14,15 The aimthis study was to evaluate the treatment results ofen reduction and fracture fixation using the 3Dting system for fixation of simple mandibular anglectures.

tients and Methods

This study included 20 consecutive patients withncomminuted mandibular angle fractures, whichre treated with a 2 mm 3D miniplate (Universalndible System, Stryker-Leibinger, Freiburg, Ger-ny). All operations were conducted by a team ofo senior residents from the Department of Cranio-xillofacial Surgery, Inselspital, University HospitalBern. Surgery was performed in a standardizednner and patients were systematically followed upstoperatively according to a prospective protocol.On admission clinical features such as age, gender,e of trauma, and duration from trauma to admis-n were recorded. Preoperative radiological exami-tion was performed using either panoramic radio-phs or computed tomography scans, dependingthe patients medical condition. The radiologicaldings preoperatively recorded were: status of den-on (dentate, partially dentate, or edentulous), pres-ce of tooth in the line of fracture, fracture site,esence of additional mandibular fractures, and de-e of fracture dislocation. Based on assessment ofalignment of the mandibular canal, as seen on thenoramic radiograph, the amount of displacements classified into one of three groups: 1) minimallyplaced fracture, if the mal-alignment of the canals less than 50% of the height of the canal, 2)derately displaced fracture, if the vertical extent offracture displacement was greater than 50%, but

s than the entire height of the canal, and 3) se-rely displaced fracture, if the mal-alignment wasater than the full height of the canal.The operation was performed under general anes-sia with nasotracheal intubation. Prior to openuction, arch bars were placed in all dentate pa-nts for intraoperative maxillomandibular fixation.plates were placed using a transoral approach andated with 8 monocortical screws (2 mm diameter,m or 8 mm length) with a standard percutaneoushnique using a trocar. Depending on the fracturealization and the available space, either a straightte design (Fig 1A) or a curved 3D plate design (Fig) was used.Both plates consisted of grade II titanium and had aofile height of 1 mm. The width of the intercon-

URE 1. A, Straight 3-dimensional (3D) plate (1 mm profile height,ker-Leibinger, Freiburg, Germany). B, Curved 3D plate (1 mmfile height, Stryker-Leibinger).

et al. 3D Titanium Miniplates for Fracture Fixation. J Oralxillofac Surg 2007.

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1760 3D TITANIUM MINIPLATES FOR FRACTURE FIXATIONcting cross struts and the bars was 0.8 mm. Thegth of the bars was 5 mm for the straight plate, andm for the upper border and 2 mm for the lower

rder of the curved plate. All plates were placedar the tension trajectories of the mandible. Theerconnecting cross struts were placed parallel, to-rd the fracture line.Indications for tooth extraction were extensiveriodontal damage and fracture of the root. Becausene of the teeth in the fracture line met these crite-, no extractions were necessary. Concomitant frac-es of the mandibular symphysis, parasymphysis, ordy were fixated with 2 4-hole 2 mm miniplates atsuperior and inferior borders. In cases of maloc-sion, soft elastics were used to help correct theclusion. Concurrent condylar or subcondylar frac-es were treated closed by postoperative intermax-ry fixation for 21 days. Drains were not used in anythe patients.For antibiotic prophylaxis, amoxicillin/clavulanicid 1.2 g was administered 3 times per day intrave-usly from admission up to 24 hours postopera-ely, and 1 g 2 times per day orally for an additionalays. The patients were advised to rinse their mouthimes daily with a 0.1% chlorhexidine solution untiloval of the arch bars. Soft diet was strongly rec-mended for 6 weeks postoperatively.Panoramic radiographs for evaluation of adequacysurgical reduction and plate localization were takenfore discharge (Fig 2). Planned follow-up intervalsre 1, 2, 6, and 12 weeks postoperatively. Postsur-al complications, defined as a need for furtherervention, were recorded prospectively over ae span of at least 6 months postsurgery.

sults

The mean age of the 17 male (85%) and 3 female%) patients was 33.9 years (range 18 to 59 years).st of the patients (85%) were fully dentate. Three

URE 2. Panoramic radiograph with curved 3-dimensional plate ince.

et al. 3D Titanium Miniplates for Fracture Fixation. J Oralxillofac Surg 2007.tients were partially dentate and none were eden-ous. Interpersonal violence was the most commonology (35%), followed by falls (20%), car accidents%), fractures following tooth extractions (15%),d skiing or cycling accidents (10% and 5%, respec-ely). The mean duration from trauma to admissions 25.3 hours (range 2 hours to 156 hours), and thean interval from trauma to surgery was 51.7 hoursnge 8 hours to 168 hours).Radiologically, the dislocation of the fractures wasged as severe in 2 cases, moderate in 2 cases, andnimal in 16 cases. A concomitant fracture wasesent in 8 patients (40%). The second most com-n fracture was at the contralateral parasymphysispatients), followed by condylar fracture (2 pa-nts) and fractures of the mandibular body (1 pa-nt). In 14 patients (70%) a molar was present in thee of fracture, but in none of the cases was it nec-ary to remove the tooth during the operation. Thean operation time from incision to wound closures 65 minutes (range 45 min to 110 min). Ten of thectures were treated with the curved 3D miniplated ten with the straight 3D miniplate. Two patientsth associated condyle fractures were treated withbsequent maxillomandibular fixation for a meanriod of 21 days. Guiding elastics were used postop-tively in 4 patients in order to adjust the occlusion.Postoperatively, none of the patients developed anection. Two patients with a mucosal wound dehis-nce had to be treated with local chlorhexidinesing, but there were no further consequences. In a-year-old male patient treated with the straight 3Dte, a plate fracture occurred. In this particular case,angular fracture had occurred 5 days after a sur-al removal of a third molar without any additionaluma. The plate fracture was radiologically detectedeeks postoperatively. Postoperative panoramic ra-graphs with the straight 3D plate in place taken atimmediate postoperative stage and 4 weeks post-

eratively are shown in Figures 3A and B. Clinically,wever, the patient had no symptoms, and he there-e declined removal of the plate. In the groupated with the curved strut plate, no hardware com-cations were seen. No case of non- or malunions recorded. For clinical assessment of fracture heal-and condition of the hardware a routine plateoval was aspired in all cases but was refused by 9

tients. For all 11 patients who underwent plateoval, complete bone healing was observed at the

cture site (Fig 4).The function of the inferior alveolar nerve waseoperatively examined in 16 patients. In the re-ining 4 patients, preoperative sensory testing wast possible due to their impaired medical condition.operatively, 6 patients had sensory deficits due toir injury. Two patients with normal preoperative

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ZIX ET AL 1761sation developed sensory deficits after the opera-n. All but 2 patients had normal sensory function ofinferior alveolar nerve 3 months after surgery. The

cases with remaining hyposensibility had had aere traumatic dislocation of the fracture.

scussion

The use of 3D miniplates in mandibular fractureation has not yet become established. In a recentlyblished survey of 104 North American and Euro-an AO/ASIF surgeons, only 6% stated that they uses type of plate.1 Only 4 studies presenting eithermechanical or preliminary clinical findings withs plate type have been published.11,13-15 Of these,ly 2 reported clinical outcome of fracture fixationecifically of the mandibular angle.14,15 Guimond et5 and the work group of Feledy14 evaluated theirnical results of the use of curved 2 mm angle struttes (Synthes, Paoli, PA) in 37 and 22 patients,pectively. To our knowledge, ours is the first re-rt on the clinical use of a different 3D miniplate ofUniversal Mandibular Plating System (Stryker/

ibinger, Freiburg, Germany).Both previous studies on the use of the curved 2

angle strut plate for angular fracture treat-nt14,15 reported low complication rates and con-ded that the 3D plate is a predictable alternative to

URE 3. A, Postoperative panoramic radiograph with straightimensional (3D) plate in place, taken at the immediate postopera-stage. B, Panoramic radiograph, with fractured straight 3D plate,en 4 weeks postoperatively.

et al. 3D Titanium Miniplates for Fracture Fixation. J Oralxillofac Surg 2007.nventional miniplates. The authors emphasizedt the strut plates have some hardware-related ad-ntages over conventional miniplates and recon-uction plates. One advantage is easy application,ich avoids a time-consuming extraoral approachd associated complications. Another advantage isplified adaptation to the bone, without distortiondisplacement of the fracture, as well as the simul-eous stabilization at both the superior and inferiorrders, making the 3D plates a time-saving alterna-e to conventional miniplates.11 In the study byledy et al,14 as well as in our study, the easierplication was reflected in a reduced average oper-ng time (55 and 65 minutes, respectively).Another advantage of 3D plates is their improvedmechanical stability compared with conventionalniplates. The first biomechanical study of 3D platess conducted by Farmand.11 Unfortunately, very lit-information is available about the type of plates

ed in this experimental study in pig mandibles.rmand found that the 3D 1 mm plate was as stablethe much thicker 2-0 miniplate (Steinhuser plate),ich is designed for 1-plate fixation of mandibularctures, because the overall stability of the Stein-user plate was limited by the stability of the screwne interface. Feledy and coworkers compared thematrix plate (Synthes) with paired miniplates in a

FIGURE 4. Curved 3-dimensional plate at plate removal.

et al. 3D Titanium Miniplates for Fracture Fixation. J Oralxillofac Surg 2007.

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1762 3D TITANIUM MINIPLATES FOR FRACTURE FIXATIONmechanical experiment, and found better bendingbility and more resistance to out-of-plane move-nt in the 3D plating system.14

It has been claimed that mobility of fragments is ausative factor in postoperative infections. Becauseection is the most common complication in man-ular fractures, the improvement of plate stabilityght be a way to minimize this problem.3,16 With thee of open reduction and internal fixation, the re-rted incidence of infection ranges from 3% to%.9,17 Infection rates in the clinical studies on 3Dtes are 5.4% (2 out of 37)15 and 9% (2 out of 22),14

ich is in the normal range of current standards ofre in managing angle fractures. Hence, taking intocount the small number of patients treated in ourdy, the infection rate of 0% is very favorable.In addition to infection, sensory deficit is a problemquently seen in connection with mandibular frac-es. In our study, a sensory deficit was related to theury in 75% of the observed cases, whereas only 25%re caused by the treatment. This agrees with an-er study on 3D plates, which also found that thein cause of sensory deficit in mandibular anglectures was the trauma itself.15 The most probableson for intraoperative damage to the nerve is frac-e manipulation, rather than drilling and screwcement close to the nerve. In our study the nervection recovered within the first 3 months afterrgery. Only in 2 cases with severe traumatic dislo-tion of the bony fragments was persistent sensorysfunction noted on final follow-up. This is consis-t with previous studies, which found that the in-ence of persistent inferior alveolar nerve deficits isated to the degree of fracture displacement.15,18

The most important complication observed in ourdy was a fracture of a straight 3D plate. Such ate failure was not observed in the previous studiesthe curved 2 mm angle strut plate.14,15 In analyzingcause of plate fractures, several factors have to be

nsidered. Besides the technical aspects, such as theterial and the form of the plate, there are somergical factors which contribute to weakening of ate. Multiple bending and improper placement ofplate, as well as insufficient fracture reduction or

erdrilling of the screw holes, have negative effectsthe stability of the fixation, resulting in a platecture.14,19

In our patient in whom a mandibular fracture hadcurred after a third molar removal, however, theson for the hardware failure most likely lies in theuced interfragmentary cross-sectional bone sur-e at the fracture site. A significant amount of con-t surface is lost by removal of a tooth from thecture line itself, and this contact is additionallyuced by associated removal of bone around therd molar to be extracted. The stability of the frac-e fixation is achieved by friction force between thegments and the stability of the plate itself. In ourtient, stability caused by the interfragmentary bonentact was reduced, and accordingly the plate wasreasingly loaded.Another contributing factor to the plate fracture inr patient may be the gracile design of the plate. Inth plate designs the width and the thickness of thers are only 0.8 mm and 1 mm, respectively, whichults in a comparably small cross section of thesers. Moreover, the lengthwise bars in the straight 3Dte are longer than those of the curved plate, whichadditionally unfavorable from the biomechanicalndpoint. We assume that these bars are too weakwithstand bite forces in an angle fracture withuced interfragmentary bone surface and stability.In a previous study, a 3D plate similar to the oneed in our study was biomechanically tested ineep mandibles.13 In this study the 3D plate showedformation of the bars in bending of more than 230Even though the authors concluded that the 3Dte is stable enough for the treatment of anglectures, the results of their study suggest that me-anically the lengthwise bars of the plate are a weakint anyway.In conclusion, our preliminary results suggest that3D plating system described here is a suitable

thod for fixation of simple mandibular angle frac-es. They seem to be an easy-to-use alternative tonventional miniplates, though a direct comparisonother fixation techniques cannot be made becausers is not a controlled study. However, its applica-n should to be limited to cases where the fracturee has sufficient interfragmentary stability. Takingpossible mechanical weakness of the lengthwise

rs into account, the curved 3D plate can be consid-d more stable and possibly more safe for fractureation than the straight plate.

ferencesGear AJ, Apasova E, Schmitz JP, et al: Treatment modalities formandibular angle fractures. J Oral Maxillofac Surg 63:655, 2005Iizuka T, Lindqvist C, Hallikainen D, et al: Infection after rigidinternal fixation of mandibular fractures: A clinical and radio-logic study. J Oral Maxillofac Surg 49:585, 1991Lamphier J, Ziccardi V, Ruvo A, et al: Complications of man-dibular fractures in an urban teaching center. J Oral MaxillofacSurg 61:745, 2003Ellis E 3rd: Treatment methods for fractures of the mandibularangle. J Craniomaxillofac Trauma 2:28, 1996Fridrich KL, Pena-Velasco G, Olson RA: Changing trends withmandibular fractures: A review of 1,067 cases. J Oral MaxillofacSurg 50:586, 1992Ogundare BO, Bonnick A, Bayley N: Pattern of mandibularfractures in an urban major trauma center. J Oral MaxillofacSurg 61:713, 2003Champy M, Lodde JP: Mandibular synthesis. Placement of thesynthesis as a function of mandibular stress. Rev Stomatol ChirMaxillofac 77:971, 1976

8. Raveh J, Vuillemin T, Ladrach K, et al: Plate osteosynthesis of367 mandibular fractures. The unrestricted indication for theintraoral approach. J Craniomaxillofac Surg 15:244, 1987

9. Levy FE, Smith RW, Odland RM, et al: Monocortical miniplatefixation of mandibular angle fractures. Arch Otolaryngol HeadNeck Surg 117:149, 1991

10. Schierle HP, Schmelzeisen R, Rahn B: Experimental studies ofthe biomechanical stability of different miniplate configura-tions for the mandibular angle. Fortschr Kiefer Gesichtschir41:166, 1996

11. Farmand M: Experiences with the 3-D miniplate osteosynthesis inmandibular fractures. Fortschr Kiefer Gesichtschir 41:85, 1996

12. Piffko J, Homann Ch, Schuon R, et al: Experimental study onthe biomechanical stability of different internal fixators for usein the mandible. Mund Kiefer Gesichtschir 7:1, 2003

13. Wittenberg JM, Mukherjee DP, Smith BR, et al: Biomechanicalevaluation of new fixation devices for mandibular angle frac-tures. Int J Oral Maxillofac Surg 26:68, 1997

14. Feledy J, Caterson EJ, Steger S, et al: Treatment of mandibularangle fractures with a matrix miniplate: A preliminary report.Plast Reconstr Surg 114:1711, 2004

15. Guimond C, Johnson JV, Marchena JM: Fixation of mandibularangle fractures with a 2.0-mm 3-dimensional curved angle strutplate. J Oral Maxillofac Surg 63:209, 2005

16. Maloney PL, Lincoln RE, Coyne CP: A protocol for themanagement of compound mandibular fractures based onthe time from injury to treatment. J Oral Maxillofac Surg59:879, 2001

17. Ellis E: Treatment methods for fractures of the mandibularangle. Int J Oral Maxillofac Surg 28:243, 1999

18. Marchena JM, Padwa BL, Kaban LB: Sensory abnormalitiesassociated with mandibular fractures: Incidence and naturalhistory. J Oral Maxillofac Surg 56:822, 1998

19. Katakura A, Shibahara T, Noma H, et al: Material analysis of AOplate fracture cases. J Oral Maxillofac Surg 62:348, 2004

ZIX ET AL 1763

Use of Straight and Curved 3-Dimensional Titanium Miniplates for Fracture Fixation at the Mandibular AnglePatients and MethodsResultsDiscussionReferences