ORIGINAL ARTICLE

FIXATION OF MANDIBULAR OSTEOTOMIES: COMPARISON OFLOCKING AND NONLOCKING HARDWARE

Young Kim, MD, Jesse Smith, MD, Joel A. Sercarz, MD, Christian Head, MD,Elliot Abemayor, MD, PhD, Keith E. Blackwell, MD

Division of Head and Neck Surgery, Department of Surgery, David Geffen School of Medicine,University of California Los Angeles, Los Angeles, California. E-mail: kblackwe@ucla.edu

Accepted 10 August 2006Published online 24 January 2007 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/hed.20541

Abstract: Background. The outcome of patients undergoing

rigid plate fixation of symphyseal mandibular osteotomies for ex-

posure, resection, and reconstruction of tumors in the oral cavity

or oropharynx was analyzed to determine the impact of hard-

ware selection on complications.

Methods. Forty-five patients underwent titanium plate rigid

internal fixation of mandibular osteotomies during cancer resec-

tion and free flap reconstruction at an academic medical center.

The incidence of hardware-related complications and mandibu-

lar nonunion was compared in patients receiving either locking

hardware or nonlocking hardware.

Results. The incidence of osteotomy-related complications

in patients with an inferior border nonlocking mandibular fracture

plate was 21%. In the patients with locking hardware or an infe-

rior border nonlocking mandibular fracture plate combined with

a tension band, there were no hardware-related complications

and no mandibular nonunions. This difference was statistically

significant (v2 ¼ 6.01, p < .05).

Conclusions. Locking mandibular reconstruction plates are

associated with fewer complications than inferior border nonlocking

mandibular fracture plates for rigid fixation of mandibular osteoto-

mies in patients undergoing resection of head and neck cancer.VVC 2007 Wiley Periodicals, Inc. Head Neck 29: 453–457, 2007

Keywords: mandible; osteotomy; complications; nonunion;

infection

Adequate surgical exposure of the oral cavity,oropharynx, nasopharynx, skull base, or para-pharyneal space occasionally requires creation ofsymphyseal mandibular osteotomies. While firstdescribed during the 19th century, this approachfirst became widely utilized during the 1970s.1

Various methods of reconstruction of mandibulo-tomies have been described, including the use ofwire osteosynthesis, miniplates, reconstructionplates, and dynamic compression plates.

Locking mandibular reconstruction plates(LMRPs) have come into widespread clinic use forthe treatment of complex mandibular fracturesand mandibular continuity defects.2 LMRPs actas internal fixators that provide greater stabilityacross the osteotomy/fracture gap without theneed for intimate contact between the bone and

Presented at the AO/ASIF Advanced Symposium on Craniomaxillofacial

Reconstruction in Whistler, British Columbia on February 21, 2005.

Dr. Kim is now with the Johns Hopkins School of Medicine, Baltimore,Maryland.

Dr. Smith is now with the University of Texas Southwestern School ofMedicine, Dallas, Texas.

Dr. Kim has reported a financial interest/relationship with Synthes Max-illofacial as the recipient of a travel award and tuition grant. Dr. Smithhas reported a financial interest/relationship with Synthes Maxillofacialas the recipient of a tuition grant. Dr. Blackwell has reported a financialinterest/relationship with Synthes Maxillofacial as the recipient of a tui-tion grant.

Correspondence to: K. E. Blackwell

VVC 2007 Wiley Periodicals, Inc.

Mandibular Osteotomies HEAD & NECK—DOI 10.1002/hed May 2007 453

the plate.3 A critical theoretical advantage ofLMRPs is the decreased potential of screw loosen-ing which can promote infection.4

The purpose of this study was to evaluatewhether LMRPs have a practical advantage in thereconstruction of symphyseal mandibular osteoto-mies used for access in extirpative head and necksurgery. We compared the incidence of osteotomy-related complications in head and neck cancerpatients in which mandibulotomies were repairedwith either LMRPs or nonlocking mandibularfracture plates.

MATERIALS AND METHODS

This series is composed of 45 consecutive patientswho underwent symphyseal mandibular osteoto-mies between 1995 and 2005 during the treatmentof advanced tumors arising in the oral cavity ororopharynx. These patients make up a relativelysmall subpopulation of a total of 603 patients whounderwent surgical resection and free flap recon-struction for treatment of tumors arising in theoral cavity or oropharynx during that time period.Patients were stratified into 3 groups, dependinguponwhether they receivedLMRPs (n¼ 23) (here-after referred to as the L group), inferior bordernonlocking mandibular fracture plates (n ¼ 19)(hereafter referred to the NL1 group), or inferiorbordernonlockingmandibular fractureplates com-bined with superior border tension bands (n ¼ 3)(hereafter referred to as the NL2 group). Table 1summarizes the patient and tumor characteris-tics, which were similar in the 3 groups of

patients. Preoperative comorbidity level, whichwe have shown to be a statistically significantpredictor of postoperative complications in thispatient population,5 was similar among all groupsof patients. All patients received preoperative orpostoperative external beam radiation therapy.One patient in the L group and 1 patient in theNL1 goup died of recurrent cancer after postoper-ative periods of 8 and 10 months without experi-encing osteotomy-related complications. All otherpatients met a minimum 1 year postoperativefollow-up.

Characteristics of the osteotomies made andthe hardware used in this series are summarizedin Table 2. Mandibular osteotomies were createdusing a hand-held saggital oscillating saw in amidline (n ¼ 43) or paramedian (n ¼ 2) positionusing continuous saline irrigation. In dentate pa-tients, a mandibular incisor tooth was extractedat the site of the osteotomy, to prevent dental rootinjury that might cause tooth devitalization andserve as a source of infection. Titanium plate fixa-tion was achieved using commercially availablemandibular hardware. In all cases, the mandibu-lar hardware was first contoured to the intactmandible, then applied to the intact mandiblewith 6 screws, and finally removed prior to mak-ing the osteotomy. This was done to facilitate thecorrect estimation of the mandible contour and tohelp preserve the correct postoperative dentalocclusion. Plates were positioned along the infe-rior border of the mandible, with 3 bicorticalscrews placed on both sides of the osteotomy. Inthe 3 patients in the NL2 group, a second 4-holesuperior border tension band miniplate usingmonocortical 2.0-mm screws was placed when dis-traction or instability of the superior aspect of theosteotomy was noted while reapplying the inferiorborder plate.

Postoperative dietary outcomes and patientdentition were determined by reviewing physi-

Table 1. Profile of the patients.

Patient

characteristics

NL1 group,

n ¼ 19

NL2 group,

n ¼ 3

L Group,

n ¼ 23

Age, range (median) 19–72 (57) 29–47 (41) 44–84 (58)

Sex

Male 16 3 17

Female 3 0 6

Preoperative

comorbidity,

mean ASA status

2.0 1 2.0

Cancer stage

3 3 0 5

4 15 4 18

Primary tumor site

Oral cavity 6 1 8

Oropharynx 13 2 15

Preop radiation

therapy

4 0 6

Postop radiation

therapy

15 3 17

Table 2. Osteotomy and hardware characteristics.

Osteotomy/hardware

characteristics

NL1 group,

n ¼ 19

NL2 group,

n ¼ 3

L group,

n ¼ 23

Position of mandibular osteotomy

Midline 18 2 23

Paramedian 1 1 0

Inferior border plate screw diameter

2.0 mm 0 0 1

2.3 mm 6 1 7

2.7 mm 13 2 15

454 Mandibular Osteotomies HEAD & NECK—DOI 10.1002/hed May 2007

cian progress notes, speech pathologist progressnotes, and of postoperative modified barium swal-low studies and mandibular radiographs whenavailable.

Results were assessed for statistical significanceby use of the chi-square test using an Internet-based statistical calculator (www.georgetown.edu/faculty/ballc/webtools/web_chi.html). Statisticalsignificance was set at a level of p< .05.

RESULTS

Analysis of postoperative diets showed that therewas no statistically significant association betweenthe incidence of osteotomy-related complicationsand the postoperative time period after whichpatients resumed oral alimentation, although atrend toward increased complications with earlyoral alimentation was noted (v2 ¼ 4.61, p < .1)(Table 3). There was no statistically significantdifference in the time to resumption of oral alimen-tation when comparing the L group, NL1 group,and NL2 group (v2 ¼ 7.63, p < .2) (Table 4). It wasnot possible to accurately determine the status ofall of the patients’ dentition in this retrospectiveseries. However, dental status probably did notplay a significant role in the incidence of osteot-omy-related complications in this series. Reviewof Panorex radiographs in the 4 patients whodeveloped osteotomy-related complications revealedthat these patients had full anterior mandibledentition with normal bone height at the time ofundergoing mandibular osteotomy, indicatingthat the osteotomy-related complications were not

related to poor mandibular bone stock in patientswith atrophic, edentulousmandibles. Furthermore,all patients in this series had significant dyspha-gia causing consistently poormasticatory functionduring the period of mandibular osteotomy heal-ing. Thirty-two of 45 patients (71%) were depend-ent upon gastrostomy tube feedings for longerthan 6 weeks after surgery. Even those patientswho resumed oral nutrition during the mandibu-lar osteotomy healing phase had significant dys-phagia that prevented mastication of solid foods,as their diets were limited to liquids or soft foods.

Among the NL1 group, there were 4 patients(21%) who experienced osteotomy-related compli-cations (Table 5). All 4 cases with osteotomy-related complications occurred in patients with asingle inferior border 6-hole nonlocking mandibu-lar fracture plate without a superior border plate.All of the osteotomy-related complications occurredwithin 6 months of surgery. Of the 4 patients withthe osteotomy-related complications, 3 received2.7-mm screws and 1 received 2.3-mm screws.One patient experienced a minor complicationconsisting of an exposed plate secondary to intra-oral suture line dehiscence during the early post-operative period. This was successfully managedwith conservativemeasures, with the wound heal-ing by secondary intention, although the patient’spostoperative radiation therapy was delayed for afew weeks to allow for complete wound healingbefore starting radiation. Three patients devel-oped major complications that required reopera-tion. Two patients had infected hardware second-ary to loose screws which required hardwareremoval, with the infections resolving after hard-ware removal in both patients. Both of thesepatients was seen with the infection shortly afterthe completion of postoperative radiotherapy.Another patient was seen with a major complica-tion of mandibular nonunion 6 months after sur-gery followed by postoperative radiation therapythat required repeat open reduction and internalfixation using a LMRP and a cancellous iliac bone

Table 3. Association between time to oral alimentation and

osteotomy-related complications.

Time to

oral

alimentation

Osteotomy-

related

complication

No osteotomy-

related

complication

1–2 wk 1 2

2–6 wk 2 9

>6 wk 1 31

Table 4. Time to oral alimentation.

Time to oral

alimentation,

weeks after

surgery L group NL1 group NL2 group

1–2 wk 0 2 1

2–6 wk 4 6 1

>6 wk 19 11 1

Table 5. Osteotomy-related complications.

Complications

NL1 group,

n ¼ 19

NL2 group,

n ¼ 3

L group,

n ¼ 23

Any osteotomy-

related complication

4 (21)* 0 (0)* 0 (0)*

Infected hardware 2 0 0

Exposed hardware 1 0 0

Nonunion 1 0 0

*Values in parentheses indicate percentages.

Mandibular Osteotomies HEAD & NECK—DOI 10.1002/hed May 2007 455

graft. No osteotomy-related complications wereobserved among the 3 patients in the NL2 group.

Among the L group, 1 patient developed cellu-litis of his chin that did not respond to antibiotictherapy 8 months after surgery. He underwentsurgical exploration for the presumed diagnosis ofinfected hardware but was found to have a localrecurrence of his cancer as the etiology of his cel-lulitis. At the time of surgery, the plate wasremoved, but no loose hardware was noted, andthe mandibular osteotomy was well healed. Thiscase of plate removal was not considered to be ahardware-related complication but was ratherattributed to the nature of his recurrent cancer.No hardware complications or mandibular non-unions were noted among the L group.

Statistical analysis showed that the differencein the incidence of osteotomy-related complica-tions between the NL group (21%), the NL2 group(0%), and the L group (0%) was statistically sig-nificant (v2¼ 6.01, p< .05). In terms of the diame-ter of the screws used in this series, there was noapparent correlation between the screw diameterand osteotomy-related complications within theNL group. Of the 4 patients with the osteotomyrelated complications, 3 received 2.7-mm screwsand 1 received 2.3-mm screws, approximatelyreflecting the same ratio of screw diameters usedin all patients in this series.

DISCUSSION

The current series demonstrate that mandibularosteotomy-related complications occur less fre-quently after fixation using LMRPs when com-pared with inferior border nonlocking mandibularfracture plates. Mandibular osteotomies are occa-sionally but not frequently needed to provide expo-sure for extirpation and reconstruction of tumorslocated in the oral cavity and oropharynx. Mosttumors in these locations are optimally managedby either mandibular arch sparing approaches(transoral resection, degloving approaches, trans-pharyngeal approaches, and marginal mandi-bulectomy), when the mandible is clinically andradiographically uninvolved, or segmental mandi-bulectomy, when there is suspicion of mandibularbone invasion or fear of inadequate margins withmandible sparing approaches. In the current se-ries, mandibular osteotomies were only performedin 7.5% of 603 patients undergoing resection andfree flap reconstruction for tumors of the oral cav-ity and oropharynx over a 10-year period.

Complications related to the mandibular oste-otomy can be classified as minor or major. Minorcomplications such as localized wound infections,fistulas, or limited plate exposures are successfullytreated with conservative medical treatments.Major complications, on the other hand, requiresurgical interventions, and include nonunionsand osteoradionecrosis. Eisen et al reported 20%osteotomy-related complications, whereas Daiet al found nearly 50% osteotomy-related compli-cations.6,7 Although it is difficult to extract mean-ingful information by comparing different seriesthat use different methods of creating and recon-structing mandibular osteotomies, it is clear thatthe complications frommidlinemandibular osteot-omies can be unfortunately common.

Historically, Shah et al used both wire osteo-synthesis and 2 miniplates for osteotomy repairand showed comparable rates of osteotomy-related complications.8 Sullivan et al showed ina retrospective study that rigid plate fixationreduced osteotomy complication rates. Theyreported 5.3% overall complication rate withplate fixation, in comparison with 30% complica-tion rate with wire fixation.9 McCann et al com-pared dynamic compression plates and recon-struction plates in their study. Although theyshowed no statistical differences in complicationrate, they favored using reconstruction plates toavoid potential malocclusions with compressionplates.10 Currently, most mandibular osteotomyrepairs are performed with rigid plate fixationwithout compression.

The current series demonstrated that use ofLMRPs resulted in a lower incidence of osteot-omy-related complications when compared withinferior border nonlocking mandibular fractureplates. However, this conclusion needs to beviewed in a critical light based upon the chronol-ogy of the current series. All 4 cases of osteotomy-related complications occurred between 1997 and1999 in patients in whom the osteotomy wasrepaired using inferior border nonlocking man-dibular fracture plates. It is possible that the com-plications occurred secondary to a design flawwith the particular plating system that was usedin these cases, which is no longer marketed in theUnited States. Therefore, the increased incidenceof complications associated with this outdatedplating system may not necessarily be relevant tocurrently available nonlocking mandibular frac-ture plates. In addition, low profile locking man-dibular fracture plates are now widely available,and theymay offer the same advantages of LMRPs

456 Mandibular Osteotomies HEAD & NECK—DOI 10.1002/hed May 2007

seen in this series. It should also be noted that thecomplications all occurred during the first half ofthis 10-year clinical experience, so that theincreased incidence of complications may be areflection of a learning curve experienced by thesenior author and primary surgeon (KEB).

No osteotomy complications were noted in oursmall experience using an inferior border nonlock-ing mandibular fracture plate with a superior bor-der tension band. Indeed, biomechanical analysisof bite forces transmitted across symphyseal man-dibular osteotomies has shown that a combinationof an inferior border plate and a superior bordertension band provides the optimal neutralizationof bending and torsion moments.11 However, ourcurrent experience with this approach in 3patients is too small to draw meaningful conclu-sions from this clinical series, as the incidence ofcomplications was not statistically differentbetween the NL1 and NL2 groups (v2 ¼ 1.90, p <.20).

Cost issues also need to be considered whenevaluating the utility of locking versus nonlockinghardware. With regard to the plating system cur-rently preferred by the senior author, the totalcharge for a LMRP and six 2.3-mmdiameter 12-mmlong locking screws is $1113, while the totalcharge for an inferior border nonlockingmandibularfracture plate and six 2.3-mm diameter 12-mm longnonlocking screws is $626. An intermediate chargeof $877 results from combining an inferior bordernonlocking fracture plate with a tension band. It islikely that the cost differential between locking andnonlocking hardware would be completely offsetand justified after considering the additional treat-ment costs incurred in treating the complicationsseen in theNL1 group.

In conclusion, LMRPs results in a lower inci-dence of osteotomy-related complications whencompared with inferior border nonlocking man-dibular fracture plates for fixation of symphysealmandibular osteotomies. LMRPs are highly effec-tive for fixation of mandibular osteotomies createdfor exposure, resection, and reconstruction oftumors arising in the oral cavity and oropharynx.

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