Experience with 220 cases of mandibular reconstruction

40 M. Benoist

Therapie der chronischen Unterkieferosteomyelitis. Dtsch. zahn/irztl. Z. 31 (1976) 787

Mo~alem, R.: Osteomyelitis of the jaw. Proc. roy. Soc. Med. 38 (1945) 452

Obwegeser, H.: Aktives chirurgisches Vorgehen bei der Osteomyelitis mandibulae. Oest. Stomat. 57 (1960) 216

Obwegeser, H.: Probleme und M6glichkeiten der Un- terkieferresektion und gleichzeitigen Rekonstruk- tion auf dem oralen Operationsweg. Schweiz. Mschr. Zahnheilk. 73 (1963) 830

Obwegeser, H.: Erfahrungen mit der einzeitigen Un- terkieferresektion und -rekonstruktion auf dem oralen Operationsweg. Oest. Z. Stmnat. T. 62 (1965) 261

Obwegeser, H.: Operation for primary repair of the lower jaw after tumour resection via the intraoral approach. Exerpta Medica International Congress Series No. 98. Plastic Surgery of Head and Ne& Tumours Proceeding First Annum Meeting of the Swiss Society of Plastic and Reconstructive Sur- geons, Locarno 1965

Obwegeser, H.: Simultaneous resection and reconstruction of parts of the mandible via the intraoral route. Oral Surg. 21 (1966) 693

Obwegeser, H.: Primary repair of the mandible by the intraoral route after partial resection in cases with and without preoperative infection. Brit. J. Plast. Surg. 21 (1968) 282

Sailer, H. F.: Experiences with intraoral partial resection and simultaneous reconstruction of the mandible in preoperatively non-infected cases. J. max.-fac. Surg. 2 (1974) 173

Steinhardt, G.: Bew/ihrte Operationsmethoden bei ,,semimalignen" Geschwfilsten der Kiefer. Dtsch. Zahn-, Mund- u. Kieferheilk. 49 (1967) 124

Tillmann, K.: Erfahrungen mit der Dekorfikation nach Mowlem-Obwegeser bei der chronischen Osteomyelitis. Dtsch. Stomat. 21 (1972) 643

Trauner, R.: Die Osteomyelitis der Kiefer. In: K. Schuchardt, Fortschr. Kiefer- u. Gesichtschir., Bd. IX. Thieme, Stuttgart 1964

Hugo L. Obwegeser, M.D., D.M.D. Hermann F. Sailer, M.D., D.M.D. Kielerchirurgische Universitgaskllnlk, PIattenstrasse 11, CH-8028 Ziirich

J. max.-fac. Surg, 6 (1978) 40-49

Experience with 220 Cases of Mandibular Reconstruction*

Michel BENOIST

Clinic of Stomatology and Maxillo-Facial Surgery (Head: Prof. P. Cern~a, M.D.) University of Paris, France

Summary Extensive resections of the mandible are usually carried out for malignant tumours or non-malignant tumours with a tendency to reccur, such as ameloblastomas. These hemi-resections include the ascending and horizontal ramus of the mandible. Such mutilations have serious functional and aesthetic consequences. In order to avoid these drawba&s we use two sorts of implants. The first are made from metallic and plastic materials. They are used when patients are too weak to support a bone graft, when there is insufficient soft tissue coverage, or when a recurrence of the turnout is feared. In order to be well tolerated they must be made of materials which are fully accepted by the tissues. For the plastic part we use methyl-methacrylate and, for the metal part, "duratlium". The second type is used to maintain a bone graft in good position. It is completely metaIlic. The pattern is made in wax and

':" Paper read at the 3rd Congress of the E. A. M. F. S., London, September 1976.

reproduced in durallium. They are made and adjusted in the same way as plastic implants. The results are analysed separately covering two periods. In the first (1955-1967), the failures have been relatively large (25 %). During the second period (1967-1974), a better choice of operative indications and a more precise technique gave better results (failure: 13 °/0).

Key-Words: Mandibular defects; Implants; Bone graft; Mandibular reconstruction.

Introduction

The desirability of immediate reconstruction, after surgical resection of the mandible, is obvious. For several years, maxillo-facial surgeons have attempted to minimize the disadvantages of this mutilation using implants or bone grafts. Claude Martin (1889) was probably the first who made a mandibular implant. Later, Conley (1951,

0301-0503/78 1300-0040 $ 05.00 © 1978 Georg Thieme Publishers

Mandibular Reconstruction - Experience with 220 Cases 41

1953), Millard (1965, 1970) have published results using this method. These mandibular resections involve the ascending ramus and a more or less extensive segment of the mandibular arch. Some are "terminal", i.e. the bone segment resected includes the condyle; these are the most frequent. The others are "su~btotal", i. e. the segment of bone resected leaves two bony margins. It may be :in the region of the symphysis or in the horizontal ramus. They are rarer than "terminal" resections. These resections affect the mandible adversely and have severe functional and aesthetic consequences. They have been well documented by Cantor and Curtis (1971). The aim of the implant or bony reconstruction is to restore immediately the movements and equi- librium of the mandible. It then becomes possible to fix the muscles to a rigid support and the planes which maintain the floor of the mouth and the tongue, may then be reconstituted anatomi- cally. Almost normal feeding becomes possible the day after the operation, and normal respiration is restored, without any risk of peri-laryngeal oedema or ha&ward displacement of the tongue. Later, the absence of aesthetic deformity and the recovery of effective masticatory function have, psychologically, a favourable effect on the course of the .disease and the social reintegration of the patient.

Material and Methods

Aetiology

The aetiology of diseases, liable to be treated by resection and reconstruction of the mandible, is various. We consider that this technique may be used in three cases: For benign tumours of relaps- ing type; for malignant tumours of the jaw bones or their immediate vicinity; for sequelae of trauma which has caused a considerable loss of vital substance. Table I indicates the aetiotogies which we have noted in our series of 220 cases. I t may be ob- served that benign and malignant tumours consti- tute by far the largest number of cases treated (benign tumours 38 o/0, malignant tumours 560/@ The traumatic aetiologies, on the other hand, are much rarer, which is not surprising as their early treatment generally avoids a large loss of bony substance.

Table 1 Conditions requiring mandibular reconstruction.

Ameloblastomas 38O/o

Epitheliomas 44O/o

Osteosarcomas 5o/0

Fibrosareomas 4o/o

Chondrosarcomas 3%

Facial injuries 6°/0

Total 100%

Types of Implant

In order to avoid the functional and aesthetic consequences of mandibular resection, we use two types of implant: The first are metallo-plastic structures, constructed to replace the resected bony segment, and they have exactly the same dimensions. They are placed in position permanently and are used when reconstitution by a bone graft is not advisable (Fig. l a + b). The others are metallic trays, shaped like the previous protheses, but designed to receive a bone graft and maintain the latter in good position. They are temporary and are removed when consolidation of the bone graft has been obtained (Fig. 2a + b). The ad- vantage of these two types of implant is that they permit the reconstitution of the muscle layer of the floor of the mouth and ensure stability of the tongue. Intermaxillary fixation is avoided and feeding may be started immediately after operation (Cernea et al. 1966). Later, these implants restore the normal shape of the face and avoid the unaesthetic consequences of the resection.

Construction of the Implant

The dimensions of the implant are determined in relation to the resection envisaged. Pre-operative tele-radiographs, in lateral and vertical views, give information, which, in our opinion, is too ap- proximate. We prefer to proceed in the following way: the limits of the resection are marked on the skin with a pencil. When the resection is "terminal", which is the most common, one may note: the T.M.J. interspace, situated 1 cm in front of the median part of the tragus, the mandibular angle, the anterior line of section. The latter is determined Jntra-orally and marked on the skin.

42 M. Benoist

Fig. 1 a Fig. 1 b

Fig, l a + b Metallo-plastic implants, a) Standard implant used to reconstruct half the mandible, b) The variants employed in the method described.

Fig. 2 a Fig. 2 b

Fig. 2a+b Different types of metallic splints used to maintain a bone graft.

A model, consisting of a large malleable wire, (20/10 ram) is then used to determine the shape of the 'implant. It is modelled to follow the bony outlines, which are detected by palpation, taking into consideration the thi&ness of the soft tissues (Fig. 3a). If a very large tumour modifies the normal outline of the mandible, the measurements are made on the opposite side adjusting the shape of the model and taking care to place the wire in the inverse position (Fig. 3 b). This clinical deter- ruination o.f the dimensions of the implant should be carried out strictly and precisely, in order to avoid joint disorders after the insertion of the implant.

The wire is then cut posteriorly at the level of

the joim interspace, and anteriorly, 3 cm beyond the line of resection. This area corresponds to the site of fixation of the implant and indicates the shape which will be necessary. If the resection is situated in the midline of the mandible, one may proceed in the same way; adjusting the model is, in this case, much easier. From this stage onward, the construction of the implant is different, depending on whether one uses a metallo-plastic insert or a splint in asso- ciation with a bone graft.

Metallo-Plastic Implant

If it is a "terminal" insert, it consists of two parts: the body and the fixation part (Fig. 4).

Mandibular Rcconstruction- Experience with 220 Cases 43

Fig. 13 a Fig. 13 b

Fig. a a + b Technique of measuring, a )The dimensions of the implant are determined by means of a model following the bony outlines, b) If a tumour modifies the normal outline, the measurements are made on the opposite side, but the model is in an inverse position.

Fig. 4 Schematic drawing of body and fixation part Fig. 5 The wax model of the implant. of the implant.

The body of the implant consists of a metallic f ramework surrounded by methyl methacrylate. The framework cannot be made using a chrome- cobalt alloy, as it is not possible to obtain a wire of this nature sufficiently malleable owing to the la& of ductility of the alloy. We use a stainless steel rod, such as a Kirschner nail 20/10 mm. Although it is not made of the same metal as the fixation part, there is no risk of electrolytic action as this wire is totally embedded in the acrylic and is never .in contact with the tissues.

This framework is adjusted using forceps to give it the exact shape of the mendel. I t is then covered with a layer of wax, which gives it its final shape. Its thickness is approximately that of a pencil (Fig. 5). The distal extremity is :simply rounded. The shape of the condyle is not reproduced; this

facilitates removal of the prosthesis if this becomes necessary. The medial par t is expanded in order to fit against the broad surface of the bony section of the mandible. I t receives the fixation part.

The fixation part is modelled separately. It is curved in the form of a gutter and includes two sides which are applied on the .internal and external cortices of the mandible. The lateral part is pierced with holes for the passage of the fixing screws. It includes a prolongation designed to fix i,t to the body of the implant. It is first constructed in wax, then cast according to the usual techniquc used for chrome-cobalt alloy prostheses. When this piece is completed, it is united to the body of .the implant by inclusion of its prolongation in the wax. It must be placed in position very

44 M. Benoist

Fig. 6 The distal part of the implant can be adapted Fig. 7 Fixation parts for metallo-plastic implant. to the length of the ramus.

precisely and in conformity with the model which has been prepared. The whole prosthesis is in- vested, and processed in hard acrylic. It should then be thoroughly polished in order to avo,id the presence of particles or irregularities which might impair tolerance.

Although the limits of resection cannot ,be defined precisely before operation, it is possible to con- struct an adaptable implant. The part which corresponds to the ascending ramus may be constructed in two parts (Fig. 6). The distal part is deliberately constructed too long. It may slide along the framework. Whilst placing the prosthesis in position, one should adjust the length of the ascending ramus, the .distal part should be cut to a suitable length and sealed with self-curing acrylic resin.

The fixation part may thus be constructed to be adapted and modified if necessary. For this purpose, it may be constructed with three fixation wires. Each wire is orientated in a ,different direction (Fig. 7). Whilst being placed in position only the wire, which is situated in the right direction, is utilized, the others are cut. The fixation part is then attached to the body of the prosthesis with self-curing resin in a cavity specially designed for this purpose in the body of the implant. The screws used for fixation should be made of the same alloy as the metallic part. One may use prefabricated screws, if not, one may order suitable screws from the prosthesis laboratory. One may use an industrial screw as a model. An alginate mould is made and then a wax model. The latter is then used for making screws in a chrome-cobalt alloy.

Fig. 8 In the case of a metallic splint, the part corresponding to the ascending ramus must be shorter than the bone-graft.

If the resection involves only the horizontal ramus, the implant should be constructed according to the same principle, but it includes two fixation parts situated respectively at each extremity. They are fixed on the extremities of the mandibular fragments using nails or screws.

Graft Carrying Implant

These implants designed to carry a suitably adjusted ,bone graft are entirely metallic. The model is prepared in the same way as metallo-plastic implants. But these implants are modelled in the form of a gutter in such a way that the bone graft may be maintained without any risk of ,displacement from its support (Fig. 2). The appliance is constructed from a wax model,


Fig. 9 a Fig. 9 b Fig. 9 c

Fig. 9a-c Reconstruction with metallo-plastic imp!ant, a+b) X-rays showing a hemi-mandibular reconstruction by means of a metallo-plastic implant, c) Result 6 days after surgery.

the shape o.f which is identical wit'h a model which has ,been drawn on the patient. It is not necessary for the ascending ramus of the implant to pass up into the temporo-mandibular joint. This metallic piece :is only designed to maintain the graft in position and it is only the latter which will arti- culate with the glenoid cavity (Fig. 8). In front, the metallic implant is prolonged directly by a fixation part similar to that of the metallo-plasti c implant.

Placing the hnplant in Position In the case of a metallo-plastic implant, sterili- sation is carried out using ethylene gas. The prosthesis is then washed in sterile normal saline immediately before fixation. If the implant is entirely metallic, :it is sterilized in an oven at 180 o C. As it should occupy exactly the same space as the resected bony segment, it is necessary for it to be adjusted and fixed whilst the dental arches are in occlusion. This is why one must, before operation, place in position some means of .intermaxillary fixation which may, for example, con- sist of two Ivy ligatures on the upper arch and two identical ligatures on the lower arch. Their position will be chosen in relation to the site and extent of the resection. If many teeth have been lost, a palatal prosthesis should be made, permit- ting easy determination of the occlusion. Two wires are passed through the loops of ,the ligatures, to maintain fixation of the dental arches after the

Fig. 10 The illiac graft has the form of an "L".

resection has been carried out. An assistant ensures that the wires are tightened and controls the precision of the fixation under direct vision. These wires will be removed at the end of the operation. The adjustment is reduced to a minimum, if the dimensions and shape have been correctly determined (Fig. 9). One should pay particular atten- tion to two important points: The plane of the section should ~be penpen, dicular to the external cortical bone and the lower border,

46 M. Benoist

Fig. 11 Anterior reconstruction with metallic splint and bone-graft.

Fig. 12a Fig. 12b

Fig. 12c Fig. 12d

Fig, 12a-d Intermediate bone grafting with tray. a) Operative view of bone-graft with metallic splint. b) Result after six months when the metallic splint is removed. c) X-ray of the same case. d) Results after 6 months.

to enable correct adaptation to the extremity of the prosthesis.

The adjustment of the fixation plate should be modelled carefully, has to be applied without tension to the external cortical bone. One should take into consideration the fact that chrome- cobalt alloy is not very malleable, that adjustment may be made at the expense of the bony tissue and not at the expense of the metallic prosthesis.

Origin of the Graft We usually ebtain .the graft from a single cortical area of the external iliac bone. It is possible to cut out the bone graft in one piece the shape of which then corresponds to that of the ascending ramus and of the horizontal ramus. The graft is in the form an "L" of which the horizontal branch is cut out from the region of the iliac crest, the vertical,branch descends below the antero-superior


Fig. 13 a + b Intraoral result after reconstruction. a) Occlusion after reconstruction. b) The alveolar process is favourable for prosthetic reha- bilitation.

Fig. 13a Fig. 13b

iliac spine, near the upper border of the acetabu- lure (Fig. 10). It is very important for the graft to be removed in a single piece. Our experience has shown that when the reconstruction is made in two parts united together at the level of the mandibular angle, the distal graft, which constitutes the ascending ramus, then undergoes marked resorption. It seems to us preferable to obtain the graft from the same side of the iliac bone as the side of the mandible which is going to be reconstructed. Thus, the curve of the horizontal part of the graft is convex outwards which permits symmetrical restoration of the morphology of the face.

A costal graft is definitely thi&er and more resistant, but it is not possible to give it an adequate shape to reconstruct half the mandible. The angle between the horizontal and ascending rami is too acute for the lateral curve of the rib to conform with it. On the other hand, a costal graft may be used in limited resections of the horizontal ramus of the mandible. In these cases, the metallic implant is screwed on two mandibular fragments, situated on each side of the resected portion and the graft i.s inserted between the two margins of the resection (Fig. 11).

Postoperative Control

The inter-maxillary fixation, which was placed in position during the operation to ensure that the implant is in ~che right position, is removed immediately after the intervention. Liquid feeding may be started on the following day. It will be replaced by normal feeding one week later. Consolidation may be considered effective after 12 weeks. However, the implant is left in position

for at least 6 months, usually we remove it only one year after the grafting (Fig. 12). It is possible to place a removable dental prosthesis 6 months after the operation. The surface of the graft constitutes an alveolar process perfectly usable for the support of a prosthesis provided the latter produces only moderate stresses (Fig. 13).

Discussion

Conditions of Good Tolerance

To be well tolerated, the implant should fulfill certain physical, biological and anatomical conditions (Benoist 1973):

The implant should ,be constructed with a material which produces no reaction in the tissues in which it is embedded. We use only, for the metallic parts, an alloy of molybdenum, chromium, and cobalt (C = 0.50 Ni = 2.50 Cr = 28.30 Mb = 5.10 Fe = 0.67 Co = 60.80). Its most interesting pro- perties are: low electrolytic activity, good physical stability, ease of moulding and perfect polishing. On the other hand, this alloy is not very malleable or ductile. All the metallic pieces which enter into the constitution of the implant and which are used for its fixation are constructed in the same alloy. If this rule is not respected, electrolytic currents may occur between pieces of ,different nature and provoke a series of tissue reactions. The plastic parts of the implants are in pure methyl methacrylate. This material has been shown to be we]l tolerated .by human tissues. It is polymerized very slowly (24 hours) under high pressure and at fairly low temperature (80 °C) using the minimum of monomer,

The volume occupied by the implant should be as small as possible. One should not attempt to recon-

48 M. Benoist

'Fable2 Mandibular reconstruction total number of cases : 220.

Years Plast. Metal Total Implants implants implants removed before

+ bone 3months graft NBR.

The soft tissues which cover the implant should be sufficiently thi& to form an anatomical and bio- logically resistant covering. The sutures should be inserted without tension, in order to avoid secondary breakdown. The intraoral route (Obwegeser 1966) should ,be exceptional (4 cases in our series).

1955 1967 107 45 152 36 (25%)

1968 1974 18 50 68 9 (13%)

Total 125 93 220 45 (21°/0)

Table 3 Causes of failure.

Infection-Fistula (insufficient coverage) Inadequate size (too short or too long) Inadequate orientation (T.M.J. luxation) Insufficient fixation (abnormal mobility)

26 10 6 3

Total 45

stitute the morphology of the bone, .but give the piece the linear dimensions of the reseeted segment. The implant should be as thin as possible and then it is better tolerated.

T:he prosthesis should be perfectly adjusted to the dimensions of the resected bone. An implant, which is too long or too short, will cause occlusion disorders by vestibulo- or linguo-ocelusion of the lower dental arch. The curve of the implant should be such that luxation of the piece into the area of the temporo-mandi'bular joint becomes impossible (Fig. 4). The implant should be solidly fixed to the mandi,bular segment to which it is attached. Any move- ment, even minimal, will cause bony resorption and greater and greater mobility.

The implant should be placed in position under the best possible conditions of asepsis. This is obviously difficult to carry out owing to the pro- ximity of the mouth. It should be carefully dis- infected during the days preceding the operation. During the latter, one should attempt to reconsti- tute rapidly a watertight mucosal surface to isolate the implant. The operative area is irrigated with a solution of normal saline to which antibiotics are added.

Indication

The results experiences they should

During the many more

and Results

are analysed in the table No. 2. Our date from 1955, but we consider that be divided into two periods:

first period (1955 to 1967), we used metallo-plastic implants (700/o) than

bone grafts (30 0/0). Our failures were relatively numerous as they reached the overall figure of 25 °/0 (Table 2). However, it is necessary to explain what is meant by failure. We consider that an implant which is exfoliated spontaneously or is removed surgically less than 3 months after being placed in position, constitutes a failure.

Beyond 3 months, it is exceptional for manifesta- tions of intolerance or infection to cause exfoliation of the implant. Moreover, after this delay, its rejection is much less serious, for the tissues have had time to become organized and the dental articulation is stabilized. The functional consequences are thus not important.

We believe that the reason for the numerous failures of the implants during the period ,between 1955 and 1967, was mainly due to too wide indications for reconstruction. In fact, during this period, all the surgical resections were reconsti- tufted even when the local conditions were relatively unfavourable. Moreover, the most frequent cause of exfoliation, during this period, was secondary breakdown of the sutures or perforation of the skin or mucosa, by the implant, owing to insufficient covering by skin or mucosa (Table 3). During the second period, from 1968 to 1976, we obtained much better results, only 130/o failures out of a total of 68 implants (Table 2). This seemed to us to be due to two reasons: The first was that the indications were more limited. Re- construction was not attempted if the covering tissues were insufficient, owing to the extent of the resection necessary for removal of the tumour. The second reason was that we used fewer metallo- plastic implants (26.5 0/0) and many more bone


grafts (73.50/@ It is certain that, when local conditions are poor, bone grafts give better results, for the graft which becomes invaded by connective tissue buds, participates in the revascularisation of the covering planes.

In the long-term, the results are roughly the same whether reconstruction is carried out .by graft or by metallo-plastic implants. Certains grafts under- went secondary resorption after one year. Certain metallo-plastic implants fractured or became un- stable after the same period.

On the other hand, we may consider that, after one year, the result obtained is permanent. Some metallo-plastic implants have been replaced after a period of three to ten years by a bone graft for aesthetic reasons. In these cases, although the mandible was stabilized, .this did not always restore the contours of the face satisfactorily.

Conclusion

From this experience, we consider that this double method of reconstruction is valid, that it is always preferable to use implants adapted to each case. Prefabricated implants did not give us the same satisfactory results. Metallo-plastic implants should be reserved for cases where a graft is impossible, either owing to the general condition of the patient, or owing to the nature and malignancy of the tumour. One may without danger, carry out radiotherapy on a metallo-plastic implant. The reconstruction by bone graft maintained by a metallic implant, constitutes the procedure of choice. It should be used whenever the local and general conditions permit. The choice of operative indications and the technical precision of the operations are the major factors ensuring success in this technique.

References

Benoist, M.: Les causes m~caniques d'6chec dans les reconstructions mandibulaires. Rev. fran% Proth&e Maxillo-Faciale 2 (1973) 31

Cantor, R., T. A. Curtis: Prosthetic management of edentulous mandibulectomy patients. I. Anatomic, physiologic, and psychologic considerations. J. Prosth. Dent. 25 (1971) 446

Cantor, R., T. A. Curtis: Prosthetic management of edentulous mandibulectomy patients. II. Clinical procedures. J. Prosth, Dent. 25 (1971) 546

Cantor, R., T. A. Curtis: Prosthetic management of edentulous mandibulectomy patients. III. Clinical evaluation. J. Prosth. Dent. 25 (1971) 670

Cernea, P., C. Crepy, M. Benoist, R. Kuffer, F. Guil- bert: Reconstitution mandibulaire apr& r&ection par greffe osseuse imm6diate, sans blocage bimaxil- hire. Rev. Stomat. 67 (1966) 672

Conley, J. ].: Use of" vitallium prostheses and implants in reconstruction of the mandibular arch. Ptast. reconstr, Surg. 8 (1951) 150

Conley, ]. ].: Technique of immediate bone grafting in

treatment of benign and malignant tumors of the mandible and a review of 17 consecutive cases. Cancer 6 (1953) 568

Martin, Cl.: De la proth&e immediate appliqu~e ~t la r&ection des maxillaires. Masson, Paris 1889

Millard, D. R.: Immediate reconstruction of the lower jaw. Plast. reconstr. Surg. 35 (1965) 60

Millard, D. R.: W . P. Garst, R. C. Campbell, S. P. Stockley: Composite lower jaw reconstruction. Plast. reconstr. Surg. 46 (1970) 22

Obwegeser, H. L.: Simultaneous resection and reconstruction of parts of the mandible via the intraoral route in patients with and without gross infection. Oral Surg. 21 (1966) 568

Michel Benolst, M.D., D.M.D. Service de Stomatologie et de Proth~se Maxillo-Faciale Groape Hospitalier Pitle-Salpetri~re 47, Boulevard de l'H@ital F-75634 Paris Cedex 13

4 J. max.-fac. Surg. 1/78

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Experience with 220 cases of mandibular reconstruction