The post-condylar cartilage graft in the treatment of distocclusion — A preliminary report

British Journal of Oral Surgery (1980) l&17-33 @ The British Association of Oral Surgeons

THE POST-CONDYLAR CARTILAGE GRAFT IN THE TREATMENT OF DISTOCCLUSION - A PRELIMINARY REPORT

PETER BANKS, M.B., B.S., F.D.s.~ and DENNIS G. ARDOUIN, F.D.s.R.c.s.~

1 Department of Oral and Maxilla-facial Surgery, Queen Victoria Hospital, East Grinstead, Sussex; 2 Department of Orthodontics, Royal East Sussex Hospital, Hastings,

Sussex

Summary. The use of the post-condylar cartilage graft appears to have been little used for the treatment of retrograthia. A preliminary report of nine cases is presented with an evaluation of the post- operative results, the period ranging from one month to 24 months.

Introduction

Trauner (1954) described a surgical method for advancing the mandible by inserting a cartilage autograft of appropriate size between the bony external auditory canal and the back of the mandibular condyle. The technique was mentioned in subsequent papers (Trauner & Dupuis, 1967; Trauner, 1969) and a total of 30 cases reported. Very little attempt appears to have been made to evaluate the stability of the method which was however claimed to be simple and to give good results. Trauner & Dupuis (1967) observed that no inter-maxillary fixation was necessary and that modification of the articular fossa eventually occurred. They noted a tendency to transitory posterior open bite after the procedure (something which might be expected from anatomical considerations) and that the method had been used in cases of up to 10 mm distocclusion. Trauner (1969) reported three early cases in which an acrylic block was inserted instead of autogenous cartilage but in each of these the block had to be removed owing to interference with temporomandibular joint function.

Success with the technique was reported by Lenart (1968) who noted that a bone graft in the same site was always resorbed. He had abandoned alloplastic implants after one exfoliated three years after insertion. Lachard & Vitton (1973) described the surgical method in some detail and reported three successful cases. Vitton et al. (1973) considered the technique to be indicated for retrognathia of less than 10 mm and to be useful before the end of growth. These authors noted relapse could occur owing to ‘crushing’ of the cartilage especially when a posterior open bite had been created, but a detailed analysis of their cases was not presented. Poswillo (1968) observed that he had used a similar operation in 16 patients and had been able to achieve a mandibular advance of up to 15 mm. He had also noted slight remodelling of the condylar head and illustrated one instance of considerable remodelling of the articular fossa.

In a recent review of the literature concerned with the surgical treatment of mandibular retrognathia Fox 8z Tilson (1976) observed that the post-condylar cartilage graft has not been widely accepted which indeed the foregoing review of the literature confirms. There is no doubt that the sagittal split osteotomy (Trauner & Obwegeser, 1957) has become the most widely used method. Some authors notably Barton (1977) have thrown doubt on the stability of this operation particularly in retrognathia; in all

(Received 22 September 1979; accepted 17 October 1979) 17

18 BRITISH JOURNAL OF ORAL SURGERY

cases analysed Barton reported a relapse of between 20 and 70 per cent. Personal experience suggests that a careful technique combined with at least eight weeks immobilisation produces an acceptable degree of stability particularly if the mandibular advance is limited to 10 mm.

Surgical advance of the mandible in the treatment of developmental jaw dispro- portion is best carried out in the post-puberty early teen age group. In the extreme Class II division 1 case, surgery can with advantage be carried out before definitive orthodontic treatment with the sole object of correcting the skeletal base relationship. In this group of patients a sagittal split osteotomy carries an appreciable morbidity. There is an established risk to the innervation of the lower lip and a need for prolonged immobilisation. The simplicity of the post condylar cartilage graft and the reported low morbidity prompted the present investigation. The technique appeared to offer another advantage in the younger age group in that it would achieve a correction of the skeletal relationship at an age when residual occlusal problems such as posterior open bite would tend to correct with a minimum of orthodontic intervention.

Orthodontic considerations Although there have been a number of claims that orthodontic treatment can mar-

kedly affect growth of the jaws and hence the skeletal pattern, these are still quite unsubstantiated (Mills, 1978). In severe skeletal discrepancies therefore it is likely that a surgical approach will usually be more satisfactory but a number of options have to be considered:

(I) To accept the Class II pattern, align the arches and partially reduce the overjet. This is obviously the simplest treatment and will be chosen where the patient and parents are not unduly concerned about the appearance. However, if the upper incisors are prominent it is important that they are well aligned.

(2) To reduce the overjet with complex orthodontic appliances. This may not be technicallv possible in the more severe cases and even where uossible often

(3)

(4)

produces a ;ery unsatisfactory profile as there has been no skeletal change. Indeed the end result can be less pleasing than the original with the upper incisors tucked back in the shadow of a still prominent nose. The most successful results occur where growth has been favourable, but this is unfortunately unpredictable. To correct the discrepancy surgically. Adjunctive orthodontic treatment will often be necessary to align the teeth and improve the axial inclination of the incisors particularly. There are obvious objections to what many parents and children regard as a rather drastic form of treatment. The orthodontist is more inclined to recommend surgery when the procedure is as simple as the post- condylar graft. To use functional appliances particularly in the borderline cases hoping to improve the skeletal profile and therefore make later conventional orthodontic treatment feasible. The proponents of this form of treatment recommend an early start and hence greatly prolong the total time of treatment. There is moreover little evidence to support the rather extravagant claims made for these appliances. A simple procedure such as the post-condylar cartilage graft would seem to offer a more certain prognosis.

Surgical technique

A preauricular incision is made and the cartilaginous portion of the external auditory canal identified. The dissection is carried deeper in this plane until the bony

POST-CONDYLAR CARTILAGE GRAFT 19

part of the meatus is located. At this point a finger can be interposed between the external bony meatus and the posterior aspect of the condylar head indicating the position of the proposed graft. This space is now cleaned by blunt dissection and the posterior attachment of the joint capsule detached from the back of the articular fossa above. Periosteum is elevated from the zygomatic process of the temporal bone to expose the lateral and superior aspects. With the mandible held forward a hole is drilled through the zygomatic process obliquely downwards and in- wards to emerge in the articular fossa behind the anteriorly positioned condylar head.

The cartilage graft is next prepared. The graft may be autogenous cartilage or lyophilised bank cartilage, both varieties having been employed in the series. The antero-posterior dimension of the block corresponds with the planned advance on that side. The graft needs to be about 10 mm deep in the coronal plane and somewhat longer in its vertical axis. Some care is necessary to obtain an accurate fit into the curvature of the articular fossa above. After the graft has been prepared it is wired in place via the single hole in the zygomatic process of the temporal bone. The wire is secured over a small stainless steel washer on top of the zygomatic process. (Fig. 1).

The procedure is repeated on the opposite side and the two wounds closed in layers without drainage. Although other workers have stated that inter-maxillary fixation is unnecessary, there is no doubt that immobilisation for one week by means of eyelet wires enhances the comfort of the patient during the immediate post-operative period. When this regime was adopted it was found that the morbidity of the procedure was minimal and the stay in hospital reduced to three to four days.

FIG. IA. Model indicating position of post-condylar cartilage graft between bony external auditory canal and the posterior aspect of the mandibular condyle.


FIG. IB (top left). Operative view: the condyle is held forward as the trimmed cartilage graft is inserted. In this case autogenous cartilage was used. 1C (top right). Operative view: The graft is in place and held by a double wire secured over a small stainless steel washer above the root of the zygomatic arch. 1D (bottom left and right). Tomogram of same case to show articulation 19 months

after surgery. The graft has become incorporated into a new articulation.

Results

At the time of writing (May, 1979) nine cases of distocclusion have been treated by this technique the follow-up period varying from two years to one month. The results are summarised in Table I.

An orthodontic assessment was made on cases 1-8 (by D.G.A.) prior to surgery. As would be expected, all could be regarded as having fairly severe Class II, division one malocclusions with overjets ranging from 10-18 mm.

Tab

le I

Patie

nt

Sex

Age

at

Ope

ratio

n G

raft

Plan

ned

Adv

ance

Adv

ance

in

Fi

xatio

n

1. K

.P.J.

2.

D.R

. 3.

J.L

. 4.

D.W

. 5.

T.M

. 6.

A.C

. 7.

D.C

. 8.

D.B

. 9.

M.C

.

M

M

M

F F F F M

M

15 y

rs

13 y

rs 1

1 m

ths

14 y

rs 6

mth

s 12

yrs

15

yrs

3 m

ths

11 y

rs

13 y

rs 7

mth

s 14

yrs

6 m

ths

14 y

rs 1

1 m

ths

9mm

R

.6m

mL.

5mm

12

mm

5m

m

R.5

mm

L.6m

m

10 m

m

R.9

mm

L.8m

m

R.5

mm

L.Sm

m

R.5

mm

L.8m

m

10 m

m

9mm

12

mm

5m

m

8mm

10

mm

8m

m

10 m

m

8mm

SN-M

P

30”

35”

40”

31”

54”

35”

27”

31”

32”

Follo

w-u

p

24 m

ths

20 m

ths

18 m

ths

12 m

ths

12 m

ths

6 m

ths

3 m

ths

1 m

th

1 m

th

Rel

apse

5mm

4m

m

Nil

Nil

3mm

N

il 2m

m

Con

dyle

R

emod

ellin

g

No

Yes

N

o N

o N

o N

o Y

es

Tabl

e II

D.R

. A

ge a

t op

erat

ion

13 y

rs 1

1 m

ths

Adv

ance

R

t. 6

mm

Lt

. 5

mm

Pl

anne

d 9

mm

in

Fixa

tion

(7 d

ays)

Pre-

op.

Post

-op.

3

mth

s 12

mth

s 20

mth

s

SNA

82

.5”

82”

81”

81”

SNB

73

” 79

” 77

” 76

76

” I-

SN

105”

10

6”

95”

99”

I-M

P 97

” 97

” 95

” 94

II

12

5”

126.

5”

134”

13

4”

SN-M

P 35

” 31

” (-4

”)

Rel

apse

N

il (3

mm

) lm

m(4

mm

) 1

mm

(4

mm

) C

ondy

le

Rem

odel

ling

Yes

Y

es

Yes


The skeletal pattern in Case 1, where the upper incisors were very proclined was assessed as only moderately Class II although having the second largest overjet of 14 mm. The others were rated as moderately severe (Cases 6, 7 and 8) and severe (Cases 2, 3, 4 and 5).

Although only two cases (3 and 5) were considered to be untreatable orthodonti- tally, the other six would all have required a long course of orthodontic treatment with complex appliances in order to obtain a Class I incisor relationship. In the six treatable cases both patients and parents were unhappy about the proposed orthodontic treatment and chose surgery as a more satisfactory means of improving the appearance.

Some tooth movement is however usually required either pre-operatively to provide an acceptable occlusion when the mandible is advanced, or post-operatively to obtain good final alignment. Cases 1 and 8 were the only patients who had no orthodontic treatment but in Case 1 there was a spontaneous reduction of the overjet post-operatively presumably resulting from better lip control. Four cases (2,3,6 and 7) underwent a short (3-10 months) course of orthodontic treatment with removable appliances prior to surgery. The objectives were variously, to expand the upper arch laterally, especially the inter-canine width; to reduce the overbite; to improve incisor angulation; and to reduce crowding by extraction of premolars. Case 5 had very crowded arches and was treated pre-operatively over 21 months with upper removable and lower fixed appliances.

Pre-operative cephalometric radiographs have been analysed and compared with cephalometric films taken post-operatively, during intermaxillary fixation and at regular intervals thereafter. The behaviour of the cartilage graft and the pattern of remodelling of the articulation has been investigated by serial standard tomography.

In such a small series it is only possible to emphasise points from individual cases which may give pointers to the long-term effects of the method. These preliminary results are encouraging.

Stability The position of the mandible in all cases has been related to the sella-nasion axis on

the lateral cephalometric radiograph using where possible a lower molar restoration as a marker. The information recorded in each case can be illustrated by one patient’s records (Table II). It was discovered in some cases the position in fixation was further forward than the measured advance to which the cartilage blocks had been trimmed. This situation produced an apparent rather than an actual initial relapse after release of fixation. The ‘planned advance’ column in Table I refers therefore to the antero- posterior dimension of the cartilage blocks which in some cases was larger on one side than on the other. If the ‘planned advance’ is compared with the figure for ‘advance in fixation’ it can be seen that in some cases (2 and 5) the relapse is apparent rather than actual.

Case 1 is of particular interest (Fig. 2). In this patient, the first of the series, the positioning and fixation of the cartilage blocks was less secure than later cases and on the right side the block displaced laterally during the post-operative period. Here the relapse is due entirely to unilateral reversion of the condyle to its original position. Fortunately the clinical result has been entirely satisfactory without any orthodontic intervention. The relapse occurred in the first three months after surgery and SNB has remained unchanged (82 “) since then. SNA post-operatively was 87 ’ and remained the same at two years. The actual advance was suflicient for the upper incisors to lie behind the influence of the lower lip and the upper incisor angulation to sella-nasion


FIG. 2A. Cephalometric tracing of Case 1 illustrating amount of skeletal relapse. K.P.-J. Age at operation 15 yrs 0 mths. Relapse due to unilateral displacement of cartilage. - - pre-op.; . . ..‘.post-

op.; - 2 yrs post-op.

FIG. 2B. Tomogram of right temporomandibular joint 28.3.77 immediately post-operation showing satisfactory position of cartilage graft.

decreased from 115 ’ post-operatively to 106 ’ at two-year follow-up. The displaced cartilage block has caused no problem apart from narrowing of the external auditory meatus.

The stability of Case 5 is still in doubt. This was the only patient with a really high SN-mandibular plane angle (54 “) and she has been kept in retention as a precaution in view of the relationship of the lower lip to the tips of the upper incisors.


FIG. 2C. Tomogram of same joint 25.7.77 showing that cartilage graft has been displaced and the condyle has reverted to its original position.

Case 3 was advanced more than 10 mm in fact to the limit of available space between the maxillary tuberosity and the anterior border of the mandibular ramus (Fig. 3). A monobloc post-operatively was used as a stabilising appliance for six months during which time the upper incisor angle to sella-nasion decreased from 105 ’ to 100 a with no change in the lower incisor angle to the mandibular plane. The skeletal stability in this case is impressive. Post-operative orthodontics has only been used in two other cases, in one of these for retention only. An upper removable appliance was used in

FIG. 3A. Case 3. Cephalometric tracing. J.L. Pre-op. 158.77. SNA 82”; SNB 72”; SN-MP 40”; inter-incisal angle 136.5”.


3B (top left). Case 3. Pre-operative profile. 3C (top right). Case 3. 11 months post-operation cephalometric radiograph. 3D (bottom left). Case 3. Profile appearance 19 months post-operation.

3E (bottom right). Case 3. 19 months post-operation cephalometric radiograph.


Case 4 for retraction of the upper canines and alignment of upper incisors. This has achieved a 10 ’ reduction in the upper incisor angulation without any recorded change in the skeletal base relationship.

Remodelling of condyle and articular fossa Two of the cases (2 and 7) have shown early and dramatic changes in the shape of

the condylar head. In each instance flattening of the posterior aspect of the condyle occurred which in Case 7 could be measured in terms of a 2 mm relapse of mandibular position. Case 2 has been followed up for nearly two years during which time the condyle shape has recovered dramatically while there has been associated remodelling of the articular fossa (Fig. 4).

The cartilage grafts used in Cases 2 and 3 appear to have become calcified and incorporated in to a new functioning articulation (Fig. Id). At this stage in the investigation there does not appear to be any difference between the behaviour of lyophilised and autogenous cartilage. The use of autogenous grafts in three of the nine cases increased the duration of surgery and the post-operative morbidity. There is some evidence that lyophilised cartilage is less stable in the long term when compared with an autogenous graft (Sailer, 1976) but this has not been a feature in any of these reported cases so far.

Function All the cases have been recently examined in order to evaluate the function of the

new articulation. No restriction of mandibular opening has been noted in any of the cases after the first few weeks, but during the first three months protrusive and lateral

FIG. 4A. Composite cephalometric tracing of Case 2 in which the remodelling of the mandibular condyle was more dramatic than in any other case. D.R. Age at operation 13 yrs 11 mths. - - pre-op.;

. . . . . post-op.; - 2 yrs post-op.


4B (top). Tomograms right and left temporomandibular joints 21.7.77 immediately post-operation. 4C (bottom). Same views 14.9.77 showing condylar resorption.


4D (top). Same views 17.7.78. There is now some restoration of the condylar shape and evidence of calcification of the cartilage graft. The graft was lyophilised bank cartilage. 4E (bottom). Same views 23.4.79. At this stage a normally functioning joint was observed clinically. The cartilage graft has become incorporated into the new joint. The original articular eminence is considerably shallower.


movements are noticeably reduced. Lateral excursion seems to recover earlier than protrusion especially where the mandibular advance approaches 10 mm. Case 6 for example at six months had excellent occlusion, profile and opening, but protrusion was limited to 3 mm (Fig. 5).

Posterior open bite The amount of inclination of the posterior aspect of the articular eminence influ-

ences the amount of open bite produced by the operation. Experience with surgical advance of the mandible suggests that when a posterior open bite is produced it will not always correct spontaneously particularly after the end of the growth period. Part of the theoretical rationale for post-condylar grafts is that by doing the operation in the post-pubertal period of development a posterior open bite if produced would correct spontaneously. This has certainly been observed where it has occurred in this small number of cases. (Figs 5 and 6).

Distortion of the external auditory canal As has been previously noted marked narrowing of the external auditory canal

occurred in Case 1 on the right side. As a result of this all subsequent cases were carefully examined with an auroscope at regular intervals to make sure the ear drum could be visualised and that excessive waxing was not occurring. The distortion observed in the first case seemed to be entirely the result of displacement of the cartilage block on that side as in no other case has there been any significant or observable change in the lumen of the canal. The patient (Case 3) in whom the largest graft was placed observed that there had been a marginal increase in the prominence of the pinnae.

f\ i

FIG. 5A. Composite cephalometric tracing of Case 6 illustrating early stability and closure of posterior lateral open bite. A.C. Age at operation 11 yrs 0 mths. - - pre-op.; . . . . . post-op.; - 4 mths post-op.


5B (top left). Case 6. Pre-operative profile. 5C (top right). Case 6. Four months post-operation. 5D (bottom left). Case 6. Mandibular opening four months post-operation. Protrusion at this stage

was restricted.


FIG. 6A, BAND c. b dodels of Case 4 showing the speed of spontaneous closure

18/1-c

of lateral open bite.


Discussion

A preliminary report such as this can do no more than make pertinent observations on the cases treated and suggest guidelines for further investigation. The previous literature on this operation is scant and there have been no short or long-term attempts at evaluation. The short-term objectives in orthognathic surgery are chiefly cosmetic but significantly functional. With such objectives operative morbidity is extremely important. Advancing the mandible by a post-condylar graft is theoretically an unlikely sort of operation for which a maxillofacial surgeon might reasonably have an instinctive opposition. For example, there is a deliberate distortion of an important joint, the operation cannot achieve definitive correction of the occlusion and furthermore there is no built-in compensation for changes in the lines of action of the mandibular musculature. For these reasons it was felt from a theoretical standpoint the operation should be confined to the developing adolescent where growth potential could compensate for these apparent disadvantages, if the graft itself was stable. These expectations appear to have been realised in the short term in that the articulation has remained functional and adapted favourably. The grafts have appeared to be stable both in position and dimension and the occlusion where disturbed has been corrected with a minimum of post-operative orthodontic intervention. Furthermore the operative morbidity of the procedure is significantly less than the alternatives, notably the sagittal split osteotomy.

It is self-evident that an essential long-term objective of orthognathic surgery is stability and in this respect it is too early to judge the post-condylar graft. McNeil (1973) has delineated three reasons for skeletal relapse after surgical mandibular advancement by conventional methods, distraction of the mandibular condyle at surgery, distraction of the mandibular condyle during healing by remodelling at the osteotomy site and posterior migration of the distal fragment under the influence of the soft tissues.

After a post-condylar graft there can be no distraction of the condyle and there is no distal ‘fragment’. Relapse can theoretically only occur as a result of resorption of the graft, remodelling of the condylar head or mandibular remodelling under the influence of the changed alignment of the musculature.

So far in these few cases no evidence of resorption of the graft has been found. Remodelling of the condylar head and articular fossa has occurred but this has been transitory and eventually the fossa and articulation have stabilised without overall skeletal relapse. The third factor is impossible at this stage to evaluate. It does, however, appear that in this age group where some active growth potential remains it is possible for the forward position of the mandible to be maintained with a minimum of orthodontic intervention. An evident limitation of the technique is that it is mainly applicable to cases with a Class 11 division 1 malocclusion requiring a small mandibular advance. All the patients in this series had an upper incisor angulation to sella-nasion around 105” and only one case could be classified as having a high mandibular angle. All apart from two could have been treated probably by prolonged fixed appliance therapy. It is noteworthy that similar results have been obtained in this department in some comparable patients treated with functional appliances (Thorn, 1979). Further investigation and comparisons are necessary and are indeed proceeding.

What has emerged from this small series is that the post-condylar cartilage graft is a viable operation for some cases requiring mandibular advancement. It cannot be rejected out of hand on theoretical premises and indeed the advantages in terms of simplicity and minimal morbidity must appeal to patient and surgeon alike.


Acknowledgements

The authors would like to acknowledge the assistance received in the preparation of this paper from the Department of Photography and Medical Illustration at the Queen Victoria Hospital, East Grinstead, and in particular Mr Trevor Hill. Mr A. E. Brown, M.B., B.S., F.D.S., prepared most of the cephalometric tracings for publication. We would like to thank Mr A. R. Thorn, Consultant Orthodontist, for permission to include Case 9.

References

Barton, P. R. (1977). Assessment of stability folllowing corrective orthodontic surgery. Proceedings of the Royal Society of Medicine, 70, 432.

Fox, G. L. & Tilson, H. B. (1976). Mandibular Retrognathia - A review of the literature and selected cases. Journal of Oral Surgery, 34, 53.

Lachard, J. & Vitton, J. (1973). Traitement des Retrognathies mandibulaires par greffe cartilagineuse retrocondylienne. Annales de Chirurgie Plastique, 18, 50.

Lenart, V. (1968). Reflexions sur le traitement operatoire des retrognathies. Revue de Stomatologie, 69, 608.

McNeil, R. W. (1973). Skeletal relapse following intermaxillary fixation surgical mandibular advancement. Transactions of the European Orthodontic Society, pp. 361-368.

Mills, J. R. E. (1978). The effect of orthodontic treatment on the skeletal pattern. British Journal of Orthodontics, 5, 133.

Poswillo, D. E. (1968). The aetiology and surgery of cleft palate with micrognathia. Annals of the Royal College of Surgeons in England, 43, 61.

Sailer, H. F. (1976).Experiences with the use oflyophilised bank cartilage for facial contour correction. Journal of Maxillo-Facial Surgery, 4, 149.

Thorn, A. R. (1979). Personal communication. Trauner, R. (1954). Die retrokondylare Implantation; eine Operationsmethode zum Vorbringen des

Unterkiefers beim Distalbik. Deutsche Zahn-, Mund- und Kieferheilkunde mit Zentralblatt fiir die Gesamte Zahn-, Mund- und Kieferheilkunde, Bd 20 H 9 p. 10. 391.

Trauner, R. & Obwegeser, H. (1957). Surgical correction of mandibular prognathism and retrognathia with consideration of genioplasty 11. Operating methods for micrognathia and distocclusion. Oral Surgery, Oral Medicine and Oral Pathology, 10, 677.

Trauner, R. & Dupuis, A. (1967). Le Traitement chirurgical de la Prognathie mandibulaire et de Prognathie superieure. Annales d’Oto-laryngologie et de Chirurgie Cervico-Faciale (Paris), 84, 855.

Trauner, R. (1969). Planning osteotomies for jaw deformity. British Journal of Plasfic Surgery, 22,99. Vitton, J., Gola, R., Blanc, J. L. & Lachard, J. (1973). L’OpCration de Trauner. Revue de Stomatologie

et de Chirurgie Maxillo-Faciale, 74, 633.

Documents

The post-condylar cartilage graft in the treatment of distocclusion — A preliminary report