the modifications of the sagittal ramus split

8/10/2019 The Modifications of the Sagittal Ramus Split.

1/7Copyright 2014 The Authors. Published by Lippincott Williams & Wilkins on behalf of The American Society of Plastic Surgeons.PRS Global Open is a publication of the American Society of Plastic Surgeons.

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The historical development of orthognathic sur-gery has followed a rather stepwise, intermit-tent course. The first mandibular osteotomy is

considered to be Hullihens1procedure in 1849 forthe correction of a protruded alveolar mandibularsegment. The first osteotomy of the whole mandibu-

lar body for the correction of prognathism was per-formed by Blair2in 1897. He was also the first authorto present a classification of jaw deformities. The op-erations performed, described, and published by Blairand Angle3marked the beginning of the developmentof oral surgery. In 1953, the sagittal split osteotomyevolved into a procedure that could be accomplishedintraorally, without transfacial approaches and withoutleaving visible scars. The bilateral sagittal split osteoto-

my (BSSO) can be considered a milestone in surgeryin general.4,5The following review of the literature isan attempt to isolate the modifications, which markedsignificant advances of this technique.Copyright 2014 The Authors. Published by Lippincott

Williams & Wilkins on behalf of The American Society ofPlastic Surgeons. PRS Global Open is a publication of theAmerican Society of Plastic Surgeons. This is an open-accessarticle distributed under the terms of the Creative CommonsAttribution-NonCommercial-NoDerivatives 3.0 License,where it is permissible to download and share the workprovided it is properly cited. The work cannot be changed inany way or used commercially.

DOI: 10.1097/GOX.0000000000000127

From the Department of Cranio-Maxillofacial Surgery,Maastricht University Medical Center, Maastricht, The

Netherlands.Received for publication August 29, 2014; acceptedOctober 2, 2014.

Background:In 1953, the sagittal ramus split osteotomy was introduced byObwegeser. For many years, and in some countries still, this technique hasdefined the term oral and maxillofacial surgery.Methods:The basic design of the sagittal ramus split surgical procedureevolved very quickly. The original operation technique by Obwegeser wasshortly after improved by Dal Ponts modification. The second major im-provement of the basic technique was added by Hunsuck in 1967. Sincethen, the technical and biological procedure has been well defined. Reso-lution of the problems many surgeons encountered has, however, takenlonger. Some of these problems, such as the unfavorable split or the dam-age of the inferior alveolar nerve, have not been satisfactorily resolved.Results: Further modifications, with or without the application of newinstruments, have been introduced by Epker and Wolford, whose modifi-cation was recently elaborated by Bckmann. The addition of a fourth oste-otomy at the inferior mandibular border in an in vitro experiment led to asignificant reduction of the torque forces required for the mandibular split.Conclusions:The literature was reviewed, and the last modifications of thesuccessful traditional splitting procedure are presented narrowly. It indi-cates the better the split is preformatted by osteotomies, the less torqueforce is needed while splitting, giving more controle, a better predictabil-ity of the lingual fracture and maybe less neurosensory disturbances ofthe inferior alveolar nerve. (Plast Reconstr Surg Glob Open 2014;2:e271;doi: 10.1097/GOX.0000000000000127; Published online 16 December 2014.)

Roland Bckmann, MD, DDSJoeri Meyns, MD, DDS

Eric Dik, MD, DDSPeter Kessler, MD, DDS

The Modifications of the Sagittal Ramus SplitOsteotomy: A Literature Review

Disclosure: The authors have no financial interest todeclare in relation to the content of this article. A portionof the Article Processing Charge was paid for by PRSGlobal Open at the discretion of the Editor-in-Chief. Theremainder of the Article Processing Charge was paid forby the academic hospital Maastricht, The Netherlands.

Pediatric/Craniofacia

ORIGINAL ARTICLE



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REVIEW OF THE LITERATUREIn 1907, Blair2published the horizontal subcon-

dylar osteotomy of the mandible to correct class IIdysgnathias by advancement of the mandibular body.This technique required prolonged intermaxillaryfixation, which was already regarded as an inconve-nience due to a lack of bone contact between theosteotomized segments. A modification of this tech-nique was recently published again by Hgensli et al.6Using an overlapping segmentation technique andosteosynthesis plates, they claimed to achieve goodbone healing. Schuchardt7modified the horizontalflat osteotomy by introducing a technique in which acortical osteotomy was performed in an oblique waystarting from just above the lingula and reaching thebuccal cortex 1 cm more caudally without touchingthe intra-alveolar nerve (IAN). The Schuchardt op-eration could be performed intraorally and led to

a more sufficient medullary bone attachment. How-ever, without fixation of the proximal and distal seg-ments, this procedure only led to a minor reductionof complications. Trauner and Obwegeser4,5furtherdeveloped Schuchardts technique by increasing thegap between the horizontal cuts to 25 mm, requiringthe surgeon to address the IAN. Their innovationresulted from connecting 2 horizontal cortical cutsalong the lateral oblique ridge and leaving the poste-rior border of the ramus untouched. Eventually, thefracture of the ramus was achieved by chiseling alongthe lateral cortex. This procedure was called the sag-

ittal splitting procedure, and it kept the IAN intact.The wider distance between the lingual and buccalcuts increased the overlapping bony amount of thesegments, which rendered better stability and bet-ter results at a lower risk of pseudarthrosis (Fig. 1).Obwegeser revolutionized oral and maxillofacialsurgery by introducing the BSSO as a standardizedand safe procedure, which is performed worldwideto date in the originally described manner.

In times of osteosynthesis by wiring, Dal Ponts8modification advances and rotates the lower hori-zontal cut even further to the buccal cortex of the

mandibular body as a vertical cut between the firstand second molars. The angle created between thelingual and buccal cortical cuts was approximately90 degrees, leading to an extension of the connect-ing cut along the oblique line on the lateral man-dibular aspect through the mylohyoid groove on thelingual side (Fig. 2). In the same article, Dal Pontreported a less quoted alternative technique that hecalled the oblique retromolar osteotomy. The lin-gual horizontal corticotomy ended just behind thelingula. However, it was Hunsuck9who thought thatit was not necessary to make an actual cut through

the lingula as Dal Pont had done in his technique.

Fig. 1.The sagittal split as described by Obwegeser. The buc-cal and lingual osteotomy lines are indicated.

Fig. 2.The first modification of the sagittal split by Dal Pont.

The buccal and lingual osteotomy lines are indicated.



Bckmann et al. The Modifications of the Sagittal Ramus Split Osteotomy

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Hunsuck was convinced that the lingual split of theDal Pont osteotomy would occur naturally given thatchisels were used to split the mandible. The buccalvertical cut by Hunsuck was located at the union ofthe ascending ramus and the body of the mandiblein the tooth bearing region. In Hunsucks illustra-

tions, this area was just distal of the second molarrunning down to the mandibular notch anterior ofthe insertion point of the masseteric muscle (Fig. 3).As with Obwegeser, a single wire was placed at theanterior aspect of the ascending ramus at the heightof the occlusal plane. All 3 techniques by Obwegeser,Dal Pont, and Hunsuck required tunneling of thelingual pterygomandibular space with only minimalmuscular or periosteal stripping. A massetericoman-dibular tunnel was only necessary in the originaltechnique described by Obwegeser.4

In 1977, a very important article on the biologi-

cal basis of the BSSO was published by Bell andSchendel.10This article tried to explain some of theproblems biologically, and it laid the path for futuremodifications. It was a reminder that the clinicalsuccess of a surgical technique must be based on orproven or at least guided by laboratory research. TheBell and Schendel publication delineated the basicprinciples leading to the article published by Epkerin 1977.11Based on the growing knowledge on muscu-lar and temporomandibular joint function, a more

biological modification evolved. Wide reflection ofthe masseteric muscle to prevent relapse was deniedby Epker in favor of a 2-wire stabilization of bothsegments proximally low and distally high. There-fore, the condylar sag leading to relapse could beprevented. Furthermore, Epker refined the original

Dal Pont technique by explaining the buccal corti-cotomy in detail, emphasizing the need for a com-plete osteotomy of the inferior mandibular cortex toavoid bad splits.

Following the foundation of the Arbeitsge-meinschaft fr Osteosynthesefragen (AO) at Biel,Switzerland, in 1958, the next revolution started af-fecting the BSSO technique. In 1976, Spiessl12pub-lished their book New Concepts in Maxillofacial BoneSurgeryin which they introduced rigid internal fixa-tion in the form of interfragmentary bone screws.Their research showed that the screws added to the

stability of the fragments and decreased healingtime because of fragment compression osteosynthe-sis. In addition, Spiessl also favored the use of thinbone saws for precise osteotomies over thicker burrs,thereby saving as much bone as possible to reducethe gap between the split segments. Only small gapswere allowed for stable compression osteosynthesis.Spiessl also introduced a new osteotomy techniqueby removing the lingual aspect of the cortical boneplate covering the oblique line in the retromolar re-gion. By its removal, a good overview was created todiscern the cancellous and cortical bone structures

of the retromolar lingual mandible. He also per-formed the first preliminary anatomical studies onthe variation of the location of the mandibular nervein relation to the lateral mandibular cortex.

In the 1980s, Bell et al13,14and Steinhuser andRudzki-Janson15published 2-volume book sets aboutthe basic principles of the osteotomy techniques inorthognathic surgery. These books continue to beused as basic literature for those beginning to per-form orthognathic surgery. Whereas Bell failed tointroduce rigid screw fixation, Steinhuser did fol-low the principles of the AO and reported on it to

his American colleagues. Bell et al16

then switchedfrom the wire osteosynthesis to rigid fixation in 1985by adding a third volume to his existing 2-volumebook sets.

Nevertheless, the problem of injuring the infe-rior alveolar nerve remained. In 1986, using the newcomputed tomography scan technology at that time,Rajchel et al17suggested rethinking the position ofthe anterior buccal osteotomy. He was the first au-thor to report specifically on the mediolateral posi-tion of the mandibular nerve, and he concluded thatthe buccal vertical corticotomy has to be located in

the region of the first molar for the safety of the IAN.

Fig. 3.The modification of the lingual cut according to Hunsuck

and Epker. Notice the short horizontal cut on the lingual side.



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He described this region as a bony prominence, anextension of the lateral oblique line. Anatomically,this description is correct, as the area just distal tothe second molar is the region where the neurovas-cular bundle is most often located in direct contactwith the buccal cortex. Occasionally, the neurovas-

cular bundle and canal seem to be within the buccalcortical plate. The risk of injuring the inferior alveo-lar nerve is high.

Wolford et al18and Obwegeser and Hadjianghe-lou19reacted to this article. Wolford agreed on mov-ing the vertical cut further anterior in the region ofthe first and second molars to avoid direct traumato the inferior alveolar nerve. Furthermore, he wasin favor of using position screws over compressionscrews to prevent possible traumatic nerve compres-sion and condylar displacement. He was the firstauthor to recommend early mobilization of the

mandible resulting from the rigid osteosynthetic fix-ation. This early functional approach was intendedto mobilize the temporomandibular joints as earlyas possible. Obwegeser responded to the discussionstarted by Rajchel with an article titled Two ways totreat bird-face deformity. The interesting aspect ofthat article was his use of a vertical cut that was evenfurther forward than in any previously published ar-ticle. The vertical cut was located between the sec-ond premolar and first molar. Based on the studiesperformed by Rajchel, this modification is reason-able because depending on the location of the men-

tal foramen, the inferior alveolar nerve is usually stilllocated medially at that point.

Radiological studies on the lingual split design re-vealed that in the conventional technique, the splitusually occurred in the lingual cortical plate. A highlingual split made it impossible to place the thirdscrew inferiorly to the alveolar canal, as there wasno bone for fixation on the lingual side. Therefore,Wolford and Davis20introduced the concept of theinferior border split in 1990. A specially designedsaw was used to cut the inferior border, thus lead-ing to a low lingual split. Another advantage of the

Wolford modification was that the inferior alveolarnerve was less frequently found in the proximal seg-ment, where the nerve is more prone to trauma dueto tension, bad visualization, and separation of thenerve from the canal.

Rigid internal fixation has been the state-of-the-art fixation in orthognathic surgery since the 1980s.Its advantages are obvious: no rigid intermaxillaryfixation is necessary, which contributes to patientcomfort, and fragments tend not to displace afterthey have been rigidly, internally fixed, comparedwith fixation using wire osteosynthesis. The latter

advantage is extremely important because pull of

the masticatory and anterior neck muscles tends todislocate the fragments, particularly in the mandiblewhen advancing the mandible after a BSSO proce-dure.

In essence, a sagittal split osteotomy can be fixedin 3 ways: using lag screws, positional screws, and

miniplates with monocortical screws. Lag screwswere introduced by Spiessl21 and were later popu-larized by Paulus and Steinhuser.22 Three screwsare usually used, engaging the buccal cortex of theproximal fragment and the lingual cortex of the dis-tal fragments. Screw threads only engage the lingualcortex. Positional screws are most likely used moreoften and follow the same principle as lag screws inthat usually 3 screws are used, engaging both cor-tices. The difference is that the fragments are notpulled together as tightly as in the case of lag screwsbecause screw threads engage both cortices. The

principle of the use of miniplates was introduced byMichelet et al.23Michelet and Champy started to usesmall osteosynthesis plates with monocortical screwsin trauma and orthognathic patients, thus introduc-ing the term functional stability versus rigid com-pression osteosynthesis as defined by the AO. Theadvantages of miniplate fixation are well document-ed in the literature.2426

Recently, distraction osteogenesis (DO) for man-dibular retrognathia has become of increasing inter-est. Although randomized clinical trials are lacking,some support was found for DO having advantages

over the classical BSSO in the surgical treatment oflow and normal mandibular plane angle patientsneeding greater advancement of more than 7 mm.The technique of bone splitting tends to prefer theDal Pont osteotomy as this approach enables betterfixation of the distraction device. Long-term resultsas presented by de Lange and coworkers showed noadvantage of DO against the classical splitting pro-cedures. There might be an indication for DO inextreme cases of mandibular micrognathia as, forexample, in syndromal diseases.2729

However, the introduction of DO in combina-

tion with ultrasonic bone-cutting surgery (piezosur-gery) has changed the way of cutting the mandibularbone.30The piezosurgery medical devices allow theefficient cutting of mineralized, hard tissues withminimal trauma to soft tissues. The advantages in-clude minimal risks to critical soft structures, such asthe vessels and nerve in the mandibular canal. Theoblique osteotomy line can be placed in the retro-molar region and runs from the anterobuccal sidein a posteromedian direction to the lingual side ofthe mandibular body. Due to the osteogenic effect ofDO, a wide overlap of bone segments as in the classi-

cal BSSO is not required. Thus, the introduction of




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piezosurgery in combination with DO seems to putthe old osteotomy techniques into perspective.

Despite a large number of variations of the origi-nal ObwegeserDal Pont splitting technique, the riskof unexpected fractures is a major disadvantage ofthe BSSO,31known as bad splits. Previous reports

have cited an incidence of bad splits of up to 5% de-spite improved preoperative diagnostics. In addition,the temporary or lasting damage of the IAN remainsrelevant. According to the literature, postoperativedamage varies from 13% to 40%.32,33

Teerijoki-Oksa et al34identified the splitting ma-neuver itself as one of the 2 main risks of damag-ing the IAN. It is common sense that a sufficientlydeep cut to the inferior mandibular rim is crucial fora good splitting. This problem has previously beenaddressed by Wolford and Davis20with the develop-ment of a special cutting saw. Due to its design and

consequent risk of damaging the facial artery, thisinstrument never became popular.

In their studies, Bckmann et al35 continued toinvestigate the advantages of adding a fourth cau-dal osteotomy parallel with inferior mandibular rim(Figs. 46). Wolfords hypothesis was that weakeningthe inferior mandibular border would result in theproximal cortical border of the ramus as the onlycortex to split spontaneously. In doing so, one may

achieve a more predictable splitting (Fig. 7). Theacquired data confirmed the theory.35In the animalcadaver study, it could be demonstrated that withsupport of a fourth osteotomy, a reasonable splittingresult was always possible to achieve, staying off theIAN during the splitting procedure at the same time.

DISCUSSIONThe literature review indicates that all of the

major aspects of the design of the sagittal split tech-nique were in place with Hunsucks modificationof the basic ObwegeserDal Pont technique. Thefact that there are continued attempts to improvethis technique is a testament to the understandingof the value of this 60-year-old procedure.35 Thesubsequent modifications have generally focusedon the attempts to manage or minimize the intra-or postsurgical problems that have since emerged.The major problems include neurological injuries,

Fig. 4.Introduction of the caudal (fourth) osteotomy. As theosteotomy reaches the mandibular angle, it allows the sur-

geon to split the mandible as if opening a book.

Fig. 5.Buccal view of the fourth osteotomy line in a humanmandible mounted on a test rack.

Fig. 6.Oscillating saw in situ for preparation of the fourth os-teotomy line at the inferior mandibular rim. An L-shield pro-

tects the surrounding soft tissue and guides the saw.


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7/7Copyright 2014 The Authors. Published by Lippincott Williams & Wilkins on behalf of The American Society of Plastic Surgeons.


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15. Steinhuser EW, Rudzki-Janson IM. KieferorthopdischeChirurgie. 2. Behandlungsablauf bei typischen Dysgnathieformen, Vol. 2. Berlin: Quintessenz-Verlag; 1994.

16. Bell WH, Proffit WR, White RP. Surgical Correction ofDentofacial Deformities, Vol. 3. Philadelphia: W.B. SaundersCompany; 1985.

17. Rajchel J, Ellis E III, Fonseca RJ. The anatomical location

of the mandibular canal: its relationship to the sagittalramus osteotomy. Int J Adult Orthodon Orthognath Surg.1986;1:3747.

18. Wolford LM, Bennett MA, Rafferty CG. Modification ofthe mandibular ramus sagittal split osteotomy. Oral SurgOral Med Oral Pathol. 1987;64:146155.

19. Obwegeser HL, Hadjianghelou O. Two ways to cor-rect bird-face deformity. Oral Surg Oral Med Oral Pathol.1987;64:507518.

20. Wolford LM, Davis WM Jr. The mandibular inferior bor-der split: a modification in the sagittal split osteotomy.J Oral Maxillofac Surg. 1990;48:9294.

21. Spiessl B. The sagittal splitting osteotomy for correction ofmandibular prognathism. Clin Plast Surg. 1982;9:491507.

22. Paulus GW, Steinhauser EW. A comparative study of wireosteosynthesis versus bone screws in the treatment ofmandibular prognathism. Oral Surg Oral Med Oral Pathol.1982;54:26.

23. Michelet FX, Benoit JP, Festal F, et al. [Fixation withoutblocking of sagittal osteotomies of the rami by means ofendo-buccal screwed plates in the treatment of antero-posterior abnormalities]. Rev Stomatol Chir Maxillofac.1971;72:531537.

24. Stoelinga PJ, Borstlap WA. The fixation of sagittal splitosteotomies with miniplates: the versatility of a technique.J Oral Maxillofac Surg. 2003;61:14711476.

25. Borstlap WA, Stoelinga PJ, Hoppenreijs TJ, et al.Stabilisation of sagittal split advancement osteotomieswith miniplates: a prospective, multicentre study with

two-year follow-up. Part I. Clinical parameters. Int J OralMaxillofac Surg. 2004;33:433441.

26. Borstlap WA, Stoelinga PJ, Hoppenreijs TJ, et al.Stabilisation of sagittal split advancement osteotomieswith miniplates: a prospective, multicentre study withtwo-year follow-up. Part IIIcondylar remodelling andresorption. Int J Oral Maxillofac Surg. 2004;33:649655.

27. Schreuder WH, Jansma J, Bierman MW, et al. Distractionosteogenesis versus bilateral sagittal split osteotomy for

advancement of the retrognathic mandible: a review ofthe literature. Int J Oral Maxillofac Surg. 2007;36:103110.

28. Wiltfang J, Hirschfelder U, Neukam FW, et al. Long-termresults of distraction osteogenesis of the maxilla and mid-face. Br J Oral Maxillofac Surg. 2002;40:473479.

29. Baas EM, Pijpe J, de Lange J. Long term stability ofmandibular advancement procedures: bilateral sagittalsplit osteotomy versus distraction osteogenesis. Int J OralMaxillofac Surg. 2012;41:137141.

30. Rana M, Gellrich NC, Rana M, et al. Evaluation of surgi-cally assisted rapid maxillary expansion with piezosurgeryversus oscillating saw and chisel osteotomya random-ized prospective trial. Trials. 2013;14:49.

31. Kriwalsky MS, Maurer P, Veras RB, et al. Risk factorsfor a bad split during sagittal split osteotomy. Br J OralMaxillofac Surg. 2008;46:177179.

32. Colella G, Cannavale R, Vicidomini A, et al. Neurosensorydisturbance of the inferior alveolar nerve after bilat-eral sagittal split osteotomy: a systematic review. J OralMaxillofac Surg. 2007;65:17071715.

33. Nesari S, Kahnberg KE, Rasmusson L. Neurosensoryfunction of the inferior alveolar nerve after bilateral sagit-tal ramus osteotomy: a retrospective study of 68 patients.Int J Oral Maxillofac Surg. 2005;34:495498.

34. Teerijoki-Oksa T, Jskelinen SK, Forssell K, et al. Riskfactors of nerve injury during mandibular sagittal split os-teotomy. Int J Oral Maxillofac Surg. 2002;31:3339.

35. Bckmann R, Schn P, Frotscher M, et al. Pilot studyof modification of the bilateral sagittal split osteotomy

(BSSO) in pig mandibles. J Craniomaxillofac Surg.2011;39:169172.

the modifications of the sagittal ramus split

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