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Stability of the Le Fort I osteotomy in patients with cleft lip and palate
htt. J. Oral Maxillofiw. Surg. 1995; 24:201-207 Printed fit Demnark . All r(~hts reserved
Copyright © M u n k s g a a r d 1995
lnr,-m,~io,a/Joumalof
Oral Madllofacial Surgery I S S N 0901-5027
Stability of the Le Fort l osteotomy in patients with cleft
P. R. Ayliffe, P. Banks, h C. Martin Department of Oral and Maxillofacial Surgery, Queen Victoria Hospital, East Grinstead, West Sussex, UK
lip and palate P. R. Ayliffe, P. Banks, L C. Marthu Stabili O" o f the Le Fort I osteoton O' hz patients w#h cleft lip and palate, htt. J. Oral Maxillofac. Surg. 1995; 24: 201-207. © Munksgaard, 1995 Abstract. Relapse of the maxilla was studied retrospectively in a group of 61 patients with previously repaired cleft lip and palate who had undergone Le Fort I ostcotomy. The extent of surgical move and relapse over a mean period of 28 months was measured witl~ reference to the cranial base, and found to be similar to those in other studies. The use of direct bone plates for fixation of the maxilla is associated with a significantly more stable postoperative result.
The stability of maxillary osteotomies in patients with cleft lip and palate is known to be unpredictable. There is a much higher tendency for cleft patients to relapse than nonclcft patients with maxillary hypoplasia7,14J9,'°. Furthermore, the extent of the relapse tends to be higher s.ts,2o. The study of postoperative relapse has posed technical problems largely because of the difficulty in comparing serial radiographs where the normal cephalometric markers are absent or distorted by the primary cleft deformity, or by subsequent corrective surgery. Most previous studies have demonstrated a wide variation in relapse rates, but the small numbers invoh'ed have not allowed any clearly definable causes to be identified. In 1987, HousToY et al. L' described a technique for the accurate comparison of standard cephalometric radiographs to record changes in maxillary position following orthognathic surgery. A further study 13 by the same authors demonstrated that the method could be applied to the analysis of postoperative changes in cleft cases. A previous paper from this department I used
the same technique to analyse data from 27 cleft lip and palate patients who had undergone maxillary osteotomies including Le Fort II procedures. In this study, a small subgroup of six patients, w h o had fixation by direct bone plating, were found to be more stable postoperatively than patients who were fixed by craniomaxillary suspension. Subsequent studies, albeit on relatively small series of cleft patientss'lkj6, also suggested that miniplate fixation of maxillary osteotomies improved stability. The present study of Le Fort I osteotomies in two groups of patients with previously repaired cleft lip and palate is substantially larger than those previously published and was designed to compare the use of bone plates and craniomaxillary fixation in achieving postoperative long-term stability.
Material a n d m e t h o d s Patient selection and characteristics The records of 131 patients with cleft lip and palate who had undergone maxillary osteotomy at the Queen Victoria Hospital, East Grinstead (UK), between 1982 and 1991
Key words: cleft lip and palate; maxillary osteotomy; maxillary advancement; stability. Accepted for publication 8 February 1995
were examined. Within this group, 85 patients had undergone osteotomy at the Le Fort I level. Those patients treated with Le Fort II, Le Fort Ili, or complex combinations of osteotomies were excluded from the study. Twenty-fourof the patients treated by Le Fort I alone had to be excluded (Table 1), leaving a study sample of 61 patients (34 male and 27 female). Within this sample, there were 46 unilateral and 15 bilateral clefts with a mean age of 19 )'ears, 5 months, and the period of follow-up ranged from 1 year, 2 months, to 4 )ears with a mean of 28 months. All patients were derived from a joint surgical orthodontic clinic. Fifty-six patients (92%) were treated pre- and postoperatively by means of fixed orthodontic appliances to achieve preoperativecoordination of the dental arches and provide postoperative retention. The other variables are listed in Tables 2 and 3, and the surgical variables are detailed below under surgical technique.
Table 1. Reasons for exclusion from study Cases Reason 2 14 4 4
Insufficientclinical records One or more radiographs inadequate Patient lost to follow-up No radiograph in fixation
202
A y l i f f e et aL
Tdbh" 2. Characteristics of two subgroups
series to facilitate later superimposition of the tracings. This excluded all teeth and dental restorations. 4. A reference line was next drawn to the observed palatal plane, and a point (P3) was defined as the perpendicular projection of the posterior bony point of the maxilla. A point (P4) was established 40 mm anterior to P3 upon the maxillary reference line (Fig. I). 5. All tracings were repeated 1 week later to assess the accuracy of the initial measurement.
Plated (n=36)
Craniomaxillary fixation (n=25)
Age
Mean Range
20 yr, 1 mth 15 yr, il mth-32 yr, 10 mth
21 yr, 2 mth 15 yr, 1 ruth-31 yr
Sex
Male Female Unilateral Bilateral
20 16 27 9
14 1! 19 6
VSS Sagittal split Total
6 9 15
7 4 i1
22
13
Registrations of surgical move and
6
17
relapse
Two-stage procedure with alveolar bone graft at first stage 30
8
Cleft Bimaxillary
Bone grafted One-stage osteotomy
Surgical technique In all cases included in the study, Le Fort I osteotomy was carried out by a down-fracture technique via a full upper buccal sulcus incision. On 26 occasions, a bimaxillary osteotomy was performed, the mandible being set back or the occlusal plane adjusted by means of a sagittal split 9r intraoral vertical subsigmoid osteotomy (~SS). In 25 cases, fixation was indirect, utilizing an extraoral frame supplemented by intermaxillary wiring (IMF) which was maintained for up to 3 months. In 36 patients, fixation was by direct osteosynthesis across the osteotomy site, using noncompression miniplates (Table 3). In 35 cases, autogenous iliac crest bone grafts were used over the lateral antral walls to fill defects produced by vertical repositioning. Those cases which had not had intermediate alveolar bone grafts at the time of eruption of the permanent canine tooth, and in which the maxillary alveolus was still cleft, were treated in two stages, the osteotomy being carried out 1 year after repair of the alveolar defect with a bone graft and alignment of the maxillary arch with fixed orthodontic appliances2'3,17.
operatively, immediately postoperatively, and at least 1 year postoperativel3: All radiographs were taken with the same cephalostat. The cephalometric tracing procedure was as follows: 1. Cranial base reference points were established on the preoperative radiograph by tracing the structures recommended by D~: COSTEa6. An arbitrary cranial base reference line was then drawn roughly parallel and close to the sella-nasion line. 2. A point (PI) was then defined at the perpendicular projection of the sella to the chosen reference line, and a second point (P2) was defined 60 mm anterior to PI. 3. A maxillary reference line was similarly established on the tracing of the preoperative radiograph. The outline of the maxilla was traced using bony landmarks consistently identified in all radiographs in the
3
Cephalometric analysis
The first postoperative radiograph was placed on a viewing screen, and the cranial base tracing from the preoperative film was carefully superimposed, using the common cranial base landmarks. Points PI and P2 ~-ere reproduced. The maxillary tracing from the preoperative film was then independently superimposed on the first postoperative radiograph, and the new points P3 and P4 were reproduced. This procedure was then repeated on the third radiograph, which represented the latest postoperative position. The procedure was repeated 1 week later to check for error. The movement of points P3 (posterior maxilla) and P4 (anterior maxilla), either relative to the preoperative radiograph or relative to the immediately postoperative radiograph was measured with an overlay grid. These t~vo comparisons represent the amount of surgical movement and the amount of further growth or relapse in both the horizontal plane (x-axis) and vertical plane (y-axis). The principle of the method is illustrated diagrammatically in Fig. 1.
4
All cases in the study had lateral cephalometric radiographs taken immediately pre-
Tabh, 3. Procedural characteristics Total number of patients Le Fort I alone Bimaxillary Le Fort I with vertical subsigmoid Le Fort I with sagittal split One-stage osteotomy Two-stage osteotomy (first stage reconstruction of alveolar continuity and bone graft) Plated Craniomaxillary fixation
61 35 26 13 13 23
38 36 25
B C A Fig. 1. Diagrammatic representation of method of cephalometric analysis. A shows preoperatire tracing with two reference lines marked. In B, reference lines have been transposed to immediately post6pcrati~.'e radiograph using independent best fit for both cranial base and maxilla. Movement of maxilla in relation to preoperative maxillary reference line can be measured in both horizontal and vertical dimensions. C shows same method applied to most recent postoperative radiograph. In practice, only preoperative radiograph is actually traced. Postoperative points P3 and P4 are determined by superimposition of relevant parts of preoperative tracing.
203
Le Fort t osteolooO'
P4X Craniomaxillary Fixation
V2(n- 1)
15.0 ~
1 250.0
Fig. 2. Dahlberg's formula for method error. lO.O 1-
Errors of the method The mean error represents the difference between the ftrst and second measurements from each radiograph. The method error, which is the standard deviation of errors in individual cases, was tested with Dahlberg's formula (Fig. 2), where d is the difference between measurements and/1 is the number of cases. Errors of radiographic technique were minimized by using the same cephalostat for all radiographs.
.
mm t,
.
.
15o.o
! I i i i i I I I I, t I._, I~,~,~,~]~ 50.0~0
,oo
L P4X Plated
Data analysis and statistical methods This was a retrospective study to examine the effect of the method of fixation of the maxilla on postoperative stability. Although the final osteotomy of the maxilla in each case was complete at the Le Fort I level, there ~'ere several variables within the total sample. For this reason, statistical expertise was invoked before any data ~ere analysed,,~s it ~ s important to examine the influence of possible confounding variables which could have affected the outcome. Initially, correlational analysis using the Pearson product moment correlation coefficient for all the variables was applied. These statistical tests were performed using the Microsoft Excel Version 4 spreadsheet. Next, distribution analyses were performed to determine whether the data conformed to the requirements for parametric statistical tests, i,e., that the variables were normally distributed around the mean. The data were found not to be normally distributed. This can clearly be seen by referring to the graphed data (Figs. 3-6). Therefore, subsequent analyses were performed with nonparametric tests, The conventional chi-square test examines the null hypothesis that there is no relationship between an independent and a dependent variable. This study was designed to test whether one independent method of fixation was associated with greater stability than another. It was therefore better to apply the chisquare test for trend, as this allows the direction of effect to be predicted, increasing the sensitivity of the analysis in terms of statistical significance.
Results
ii i T
150.0 50.0
ilil
mil 1
-50.0 -t 50.0 -250.0
Surgical M o v e
~
Relapse
----¢----- Percentage Relapse
Fig. 3. Graph to show surgical movement and postsurgical change in each individual case. P4X represents horizontal movement of anterior maxilla.
All variables were correlated against measured relapse using the statistical correlation tools o f a c o m p u t e r spreadsheet (Microsoft Excel Version 4). The method o f fixation was found to be more significant by a factor o f 10, in terms of correlation with relapse, than any other variable. The two methods o f fixation used were either craniomaxillary extraoral immobilization or direct osteosynthesis with miniplates. The total sample was tfierefore divided into two subgroups based on fixation method. The subgroups were found to
be evenly matched for all variables apart from tile pattern o f osteotomy (one-stage or two-stage) (Table 2). Staging was accordingly tested separately against relapse, and a much weaker correlation was found (see below). After examination o f the associations between variables with the spreadsheet, it became necessary to test the a priori hypothesis that "fixation method affected the stability of the o s t e o t o m y " , as this appeared to be the most significant controllable variable to affect the eventual surgical outcome.
Table 4. Changes in maxillary position Surgical change
The mean surgical change, postsurgical change, and percentage o f relapse for the whole sample of 61 patients are shown in Table 4, and the mean error for each of the recorded points is shown in Table 5.
250.0
,
P3X P3Y P4X P4Y
mm mm mm mm
Mean
SD
Range
6.4 -3.7 6.1 -5.7
3.4 3.0 3.3 3.7
1.0-14.5 -12.5-1.5 0.5-15 -14.5-0.0
Postsurgieal change Range Mean SD -0.4 1.1 -0.3 1.2
1.5 2.0 1.8 2.0
-4.0-10.0 -2.0-6.0 -4.5-4.5 -3.0-6.5
Mean percentage of surgical change 6.3% 29% 5% 21%
204
Ayliffe et aL
P4Y Craniomaxillary Fixation 250.0
15.0 T
iii
150.0 50.0
m
o
-50.o g. -150.0
-250.0
P4Y Plate d 250.0
15.0 1
150.0
-i-i I
g
• -~0.0
~.
• -150.0
-250.0
-15.0 I
• 50.0
surgical Move
I
I Relapse
" m e - " - - Percentage Relapse
Fig. 4. Graph to show surgical movement and postsurgical change in each individual case. P4Y represents vertical movement of anterior maxilla.
The data were analysed for the two subgroups delineated in Table 2 (36 cases fixed by miniplates and 25 cases in which craniomaxillary fixation and I M F were employed). The surgical and postsurgical changes for P4 (anterior maxilla) and P3 (posterior maxilla) are shown in Table 6. Movements in the horizontal (X) dimension are shown positively for an anterior move, and
negatively for a posterior move. Movements in the vertical (Y) dimension are shown as negative values for an increase and as positive values for a decrease. The surgical change, relapse, and percentage of relapse for each of the patients in both groups are illustrated in Figs. 3-6. The graphs have been arranged so that the patients with the maximum percentage of relapse are
Table 5. Mean error and error of method
glean error Method error (mm) (mm) Surgical change
P3X P3Y P4X P4Y
0.65+-.0.54 0.504-0.3 0.62+-0.5 0.64_+_0.5
0.5 0.52 0.6 0.54
Postsurgical change
P3X P3Y P4X P4Y
0.54+-_0.46 0.60+-_0.6 0.74+-_0.62 0.62_-.0.5
0..75 0.74 0.7 0.76
grouped to the left, and those in whom complete stability or actual increase in "growth" occurred are grouped to the right. As can be seen from the graphs, the results are nonorthogonal for both the absolute relapse and the percentage of relapse. The data are skewed by individual cases that show high percentages of relapse, often associated with very small surgical moves. It is not possible (and probably of little clinical relevance) to try to analyse the data using statistical transformations in order to apply parametric statistical methods. For these reasons, the data were analysed using grouping criteria applied to the measurements of absolute relapse. The grouping criteria applied were related to perceived clinical significance. Three groups were defined for each of the points analysed (anterior maxilla. P4 and posterior maxilla P3). Group 1 were those patients with complete postoperative stability, group 2 were those patients in whom postoperative change was less than 2.5 mm vertically or 1.5 mm horizontally, and group 3 comprised the patients in whom relapse was more than these values (Table 7). Examination of chi-square values calculated from these data (Table 7) revealed a trend in relapse related to the use of fixation by direct bone plating. The chi-square test for trend 4 showed this to be significant. A highly significant difference could also be shown between those patients who had fixation by bone plating and those who had fixation by craniomaxillary fixation. As slated above, the two subgroups were evenly matched as regards all other variables apart from the number of cases having one-stage or two-stage surgery. For historical reasons, more of the earlier cases which constituted the majority treated with extraoral fixation had a one-stage procedure. Accordingly, this variable was tested separately against relapse using the same statistical tool. The two-stage procedure appears to produce more stability in the vertical dimension (P=0.01) and to a lesser extent in the horizontal dimension (P=0.09). These values are not highly significant and would appear to exert only a marginal effect on the highly significant effect of different fixation. No significant difference could be demonstrated when bimaxillary procedures were compared with maxillary (P=0.5) or when VSS was compared
Le Fort 1 osteotono'
P3X Craniomaxillary Fixation 250.0 150.0 50.0 ~, e.. mm
.:_--
o.o
.:
.:
.
.,,
.,.
.:
u
-50.0
~_
-150.0
-1o.o
-250.0
-15.0
P3X Plated l
15.0 10.0
5.0 mm 0.0
~
~
j
~
250.0
IJ !!!il II I !!
,50.0
-5.0 -150.0
-10.0
-250.0
-15.0 SurgicalMove
~
Relapse
~
PercentageRelapse
Fig. 5. Graph to show surgical movement and postsurgical change in each individual case.
P3X represents horizontal movement of anterior maxilla.
with sagittal split in the bimaxillary group (P=0.6).
the lack of data relating to such surgical procedures in patients with cleft lip and palate deformity. The few available studies at that time all demonstrated considerable relapse, particularly in the vertical dimension, and "~LCH concluded that "a Le Fort I procedure in cleft patients tends to be as unstable as
Discussion In a comprehensive review of the factors affecting stability after orthognathic surgery, WELOd 9 commented on
Table 6. Surgical data for two study samples
Surgical change
Postsurgical change
Mean
SD
Range
Mean
SD
7.5 -4.0 7.0 -6.0
3.5 2.8 3.0 4.0
1.0-14.5 -12.5-1.5 0.5-15 - 14.5-0
0 1.0 -0.l 1.0
2.5 2.0 2.0 1.75
-4.0-10.0 -1.0-4.5 -4.5-4.5 -2.0-6.5
Craniomaxillary'fixation P3X (mm) 5.0 P3Y (mm) -3.5 P4X (mm) 5.0 P4Y (mm) -5.0
3.0 3.5 3.0 4.0
1.5-10.0 -10.5-1.0 0.5-8.5 - 13.5-0.0
- 1.0 1.0 0.5 1.5
2.0 2.0 2.0 2.0
-3.0--4.0 -2.0-6.0 -3.0~1.0 -3.0-6.0
Plated P3X (mm) P3Y (mm) P4X (ram) P4Y (ram)
Range
205
it is in patients with vertical maxillary deficiency". A previous study carried out in this department = suggested that a small subgroup of six patients who had fixation with plates was more stable postoperatively than the majority' who had fixation by craniomaxillary suspension. The numbers were, however, too small to be statistically significant. The present study was designed to investigate further the relationship between the method of fixation and the stability of the maxilla in adult cleft lip and palate patients treated by Le Fort I osteotomy to correct maxillary hypoplasia. The resuits, in a series larger than most previously published, confirm many of the findings reported elsewhere, which all show a large individual disposition for relapse of the maxilla, particularly in the vertical dimension. The method of measurement used in this study produced levels of accuracy within those accepted in other comparable studies. In the anterior maxilla, which is more relevant to the final cosmetic result than the posterior maxilla, the mean horizonta~ relapse of 5% and mean vertical relapse of 21% (Table 4) were similar or better than in other studies s't°'tS,16"2°. Some individual patients shoxxed very high percentages of relapse, sometimes greater than the surgical move. This can be clearly seen from the graphs (Figs. 3-6). Although these high percentages of relapse could be due to postoperative instability, in this study they are often associated with small amounts of surgical move. As GRAVELY & BENZIES9 have suggested, in measuring point differences in individual cases, it is impossibIe to be confident at the 5% level unless the change is greater than twice the method error. For point P3X, two patients demonstrated a percentage of relapse of 233% for a surgical move of only 1.5 mm in this dimension, while the method error for P3X was 0.75 mm (Table 5). This large percentage of change could be due to measurement error, and consequently may well be of little clinical significance. Percentage of relapse would thus appear 1o be an unreliable way of interpreting the data. For these reasons, it was decided to analyse the data within three groups determined by the perceived clinical significance of the relapse measured in absolute rather than percentage values (Table 7). Relapse in the subgroup of patients who had direct osteosynthesis by mini-
Ayliffe et al.
206
P 3 Y Craniomaxillary Fixation 15.0
250.0
10.0
.150.0
5.0 mm
50.0
g
==
0.0
.50.0 -5.0 -I 50.0 -10.0 -250.0
-15.0
P 3 Y Plate.d. 15.0
250.0
10.0
150.0
5.0
50.0
o e-
mm
0.0
.50.0 .= -.5.0 ,
-150.0
-10.0
-250.0
-15.0
Surgical Move
~
Relapse
~
Percentage Relapse
Fig. 6. Graph to show surgical movement and postsurgical change in each individual case. P3Y represents vertical movement of anterior maxilla.
when compared with a one-stage operation (P=0.01). N o statistically significant difference was found when bimaxillary procedures were compared with maxillary surgery alone or when the VSS was compared with the sagittal split in the bimaxillary group. Clearly, however, these and other factors could represent compounding influences on t h e results and, ideally, a randomized prospective study would be more suitable. Furthermore, the patients x~ere not randomized to receive either plates o r craniomaxillary fixation. M o s t patients with craniomaxillary fixation were treated earlier in the period of study, and it could be argued that the degree o f surgical expertise, particularly that o f surgical mobilization, was greater when treating the later group of patients. The mean surgical move was, however, greater for the plated subgroup, and yet they were significantly m o r e stable. The highly significant P values do suggest a causal relationship between the use o f direct bone plating and stability of the maxilla. For the g r o u p as a whole, and for the two subgroups, no other single factor was found to have such a level o f significance.
Acknowledgment. We would like to thank Dr M. Bland, Senior Lecturer in Medical Statistics at St George's Hospital, London, for his help with the statistical analysis of the data. References
plates was comparable with Le Fort I osteotomies in noncleft patients. The two test samples were evenly matched for other criteria such as age distribution, cleft type, and incorporation of a mandibular procedure. The one factor which was not reasonably matched was the osteotomy type. This weakness in
the argument is likely in any retrospective study. The relationship between the type o f osteotomy and the degree o f relapse was studied separately, and a much weaker correlation was found. The two-stage procedure was shown to be associated with increased stability in the vertical dimension in particular
Table 7. Chi-square tables P4X Plated Not plated
0 mm 14 5
0.5-1.5 mm 16 7
2-4.5 mm 6 13
P=0.008
P4Y Plated Not plated
0 mm 16 1
0.5-2.5 mm 15 7
3-6.5 mm 5 17
P=0.0001
P3X Plated Not plated
0 mm 13 3
0.5-1.5 mm 16 8
2-4.5 mm 7 14
p=0.006
P3Y Plated Not plated
0 mm 11 0
0.5-2.5 mm 20 16
3-6.5 mm 5 9
P=0.004
1. ADLAMDM, YAU CK, BANKSP. A retrospective study of the stability of midface osteotomies in cleft lip and palate Patients. Br J Oral Maxillofac Surg 1989: 2 7 : 265-76. 2. BaNKs R Orthognathic surgery for the adult with cleft lip and palate. Ann Acad Med Singapore 1986: 15: 346-54. 3. BANKSP. Cleft deformities and their surgical correction. In: HARRIS b,|, REYNOLDS IR, eds.: Fundamentals of orthognathic surgery. London: WB Saunders, 1991: 205-32. 4. BLAND 1~|. An introduction to medical statistics. Oxford: Oxford University Press, 1991: 248-51. 5. B U N D A A R D ~1, MELSEN B, TERP S. Changes during and following total maxillary osteotomy (Le Fort I procedure): a cephalometric stud)'. Eur J Orthod 1986: 8: 21-9. 6. DE COSTERL. A new line of reference for the study of lateral facial teleradiographs. Am J Orthod 1953: 39: 304--6. 7. EPKER BM, ~,XbLrORD , LM. Middle third facial osteotomies: their use in the correc-
Le Fort I osteotono" tion of congenital dentofacial and orofacial deformities. J Oral Surg 1976: 34: 324-42, 8. ESKANAZILB, SCIIENDELSA. An analysis of Le Fort I maxillary advancement in cleft lip and palate patients. Plast Reconstr Surg 1992: 90: 779-86. 9. GRAVELY JF, BENZIES P]~l. The clinical siKnificance of tracing error in cephalomerry. Br J Orthod 1974: 1" 95-101. 10. HEDEMARKA, FREIIIOFERHE The behaviour of the maxilla in vertical movements after Le Fort I osteotomy. J Max-Fac Surg 1978: 6: 244-9. 11. HOClIBAN W, GANSS C, AUSTERMANN KH. Long-term results after maxillary advancement in patients with clefts. Cleft Palate Craniofac J 1993: 30: 237-43. 12. HOUSTON WJB, JOSE.S E, JAMES DR. A method of recording changes in maxillary position following orthognathic surgery. Eur J Orthod 1987: 9: 9-14.
13. HOUSTON WJB, JAMES DR, JO.','ES E, KAVVADIA S. Le Fort I maxillary osteotomies in cleft palate cases. J CranioMax-Fac Surg 1989: 17: 9-15. 14. KUFNER J. Four )ear experience with major maxillary osteotomy for retrnsion. J Oral Surg 1971: 29: 549-53. 15. PERSSON G, HELLEM S, NORD PG. Bone plating for stabilising Le Fort 1 osteotomies. J Max-Fac Surg 1986: 14: 69-73. 16. Pos.xlcK JC, Ewl.XG MR Skeletal stability after Le Fort I maxillary advancement in patients with unilateral cleft lip and palate. Plast Reconstr Surg 1990: 85: 70610. 17. STOELINGA PJ, HAERS PE, LEENEN RJ, SOUBRV R J, BLIJDORP PA, SCI[OENAERS JH. Late management of secondarily grafted clefts. Int J Oral Maxillofac Surg 1990: 19: 97-102. 18. TEUSCHER U, SAILER HE Stability of Le Fort I osteotomy in Class III cases with
207
retropositioned maxillae. J Max-Fac Surg 1982: 10: 80-3. 19. ~3&ecli TB. Stability in the correction of dentofacial deformities: a comprehensive review. J Oral Maxillofac Surg 1989: 47: 1142-9.
20. WILLMARK K. On Le Fort I osteotomy. Scand J Plast Reconstr Surg 1974: 12 (Suppl): !-64.
Address: Mr P. R. Ayliffe, FRCS (Eng), FDSRCS (Eng) Department of Oral and Maxillofacial Surge O' Queen Victoria Itospital lloloe Road East Grinstead, IVest Sussex RItI9 3DZ UK
Copyright © M u n k s g a a r d 1995
lnr,-m,~io,a/Joumalof
Oral Madllofacial Surgery I S S N 0901-5027
Stability of the Le Fort l osteotomy in patients with cleft
P. R. Ayliffe, P. Banks, h C. Martin Department of Oral and Maxillofacial Surgery, Queen Victoria Hospital, East Grinstead, West Sussex, UK
lip and palate P. R. Ayliffe, P. Banks, L C. Marthu Stabili O" o f the Le Fort I osteoton O' hz patients w#h cleft lip and palate, htt. J. Oral Maxillofac. Surg. 1995; 24: 201-207. © Munksgaard, 1995 Abstract. Relapse of the maxilla was studied retrospectively in a group of 61 patients with previously repaired cleft lip and palate who had undergone Le Fort I ostcotomy. The extent of surgical move and relapse over a mean period of 28 months was measured witl~ reference to the cranial base, and found to be similar to those in other studies. The use of direct bone plates for fixation of the maxilla is associated with a significantly more stable postoperative result.
The stability of maxillary osteotomies in patients with cleft lip and palate is known to be unpredictable. There is a much higher tendency for cleft patients to relapse than nonclcft patients with maxillary hypoplasia7,14J9,'°. Furthermore, the extent of the relapse tends to be higher s.ts,2o. The study of postoperative relapse has posed technical problems largely because of the difficulty in comparing serial radiographs where the normal cephalometric markers are absent or distorted by the primary cleft deformity, or by subsequent corrective surgery. Most previous studies have demonstrated a wide variation in relapse rates, but the small numbers invoh'ed have not allowed any clearly definable causes to be identified. In 1987, HousToY et al. L' described a technique for the accurate comparison of standard cephalometric radiographs to record changes in maxillary position following orthognathic surgery. A further study 13 by the same authors demonstrated that the method could be applied to the analysis of postoperative changes in cleft cases. A previous paper from this department I used
the same technique to analyse data from 27 cleft lip and palate patients who had undergone maxillary osteotomies including Le Fort II procedures. In this study, a small subgroup of six patients, w h o had fixation by direct bone plating, were found to be more stable postoperatively than patients who were fixed by craniomaxillary suspension. Subsequent studies, albeit on relatively small series of cleft patientss'lkj6, also suggested that miniplate fixation of maxillary osteotomies improved stability. The present study of Le Fort I osteotomies in two groups of patients with previously repaired cleft lip and palate is substantially larger than those previously published and was designed to compare the use of bone plates and craniomaxillary fixation in achieving postoperative long-term stability.
Material a n d m e t h o d s Patient selection and characteristics The records of 131 patients with cleft lip and palate who had undergone maxillary osteotomy at the Queen Victoria Hospital, East Grinstead (UK), between 1982 and 1991
Key words: cleft lip and palate; maxillary osteotomy; maxillary advancement; stability. Accepted for publication 8 February 1995
were examined. Within this group, 85 patients had undergone osteotomy at the Le Fort I level. Those patients treated with Le Fort II, Le Fort Ili, or complex combinations of osteotomies were excluded from the study. Twenty-fourof the patients treated by Le Fort I alone had to be excluded (Table 1), leaving a study sample of 61 patients (34 male and 27 female). Within this sample, there were 46 unilateral and 15 bilateral clefts with a mean age of 19 )'ears, 5 months, and the period of follow-up ranged from 1 year, 2 months, to 4 )ears with a mean of 28 months. All patients were derived from a joint surgical orthodontic clinic. Fifty-six patients (92%) were treated pre- and postoperatively by means of fixed orthodontic appliances to achieve preoperativecoordination of the dental arches and provide postoperative retention. The other variables are listed in Tables 2 and 3, and the surgical variables are detailed below under surgical technique.
Table 1. Reasons for exclusion from study Cases Reason 2 14 4 4
Insufficientclinical records One or more radiographs inadequate Patient lost to follow-up No radiograph in fixation
202
A y l i f f e et aL
Tdbh" 2. Characteristics of two subgroups
series to facilitate later superimposition of the tracings. This excluded all teeth and dental restorations. 4. A reference line was next drawn to the observed palatal plane, and a point (P3) was defined as the perpendicular projection of the posterior bony point of the maxilla. A point (P4) was established 40 mm anterior to P3 upon the maxillary reference line (Fig. I). 5. All tracings were repeated 1 week later to assess the accuracy of the initial measurement.
Plated (n=36)
Craniomaxillary fixation (n=25)
Age
Mean Range
20 yr, 1 mth 15 yr, il mth-32 yr, 10 mth
21 yr, 2 mth 15 yr, 1 ruth-31 yr
Sex
Male Female Unilateral Bilateral
20 16 27 9
14 1! 19 6
VSS Sagittal split Total
6 9 15
7 4 i1
22
13
Registrations of surgical move and
6
17
relapse
Two-stage procedure with alveolar bone graft at first stage 30
8
Cleft Bimaxillary
Bone grafted One-stage osteotomy
Surgical technique In all cases included in the study, Le Fort I osteotomy was carried out by a down-fracture technique via a full upper buccal sulcus incision. On 26 occasions, a bimaxillary osteotomy was performed, the mandible being set back or the occlusal plane adjusted by means of a sagittal split 9r intraoral vertical subsigmoid osteotomy (~SS). In 25 cases, fixation was indirect, utilizing an extraoral frame supplemented by intermaxillary wiring (IMF) which was maintained for up to 3 months. In 36 patients, fixation was by direct osteosynthesis across the osteotomy site, using noncompression miniplates (Table 3). In 35 cases, autogenous iliac crest bone grafts were used over the lateral antral walls to fill defects produced by vertical repositioning. Those cases which had not had intermediate alveolar bone grafts at the time of eruption of the permanent canine tooth, and in which the maxillary alveolus was still cleft, were treated in two stages, the osteotomy being carried out 1 year after repair of the alveolar defect with a bone graft and alignment of the maxillary arch with fixed orthodontic appliances2'3,17.
operatively, immediately postoperatively, and at least 1 year postoperativel3: All radiographs were taken with the same cephalostat. The cephalometric tracing procedure was as follows: 1. Cranial base reference points were established on the preoperative radiograph by tracing the structures recommended by D~: COSTEa6. An arbitrary cranial base reference line was then drawn roughly parallel and close to the sella-nasion line. 2. A point (PI) was then defined at the perpendicular projection of the sella to the chosen reference line, and a second point (P2) was defined 60 mm anterior to PI. 3. A maxillary reference line was similarly established on the tracing of the preoperative radiograph. The outline of the maxilla was traced using bony landmarks consistently identified in all radiographs in the
3
Cephalometric analysis
The first postoperative radiograph was placed on a viewing screen, and the cranial base tracing from the preoperative film was carefully superimposed, using the common cranial base landmarks. Points PI and P2 ~-ere reproduced. The maxillary tracing from the preoperative film was then independently superimposed on the first postoperative radiograph, and the new points P3 and P4 were reproduced. This procedure was then repeated on the third radiograph, which represented the latest postoperative position. The procedure was repeated 1 week later to check for error. The movement of points P3 (posterior maxilla) and P4 (anterior maxilla), either relative to the preoperative radiograph or relative to the immediately postoperative radiograph was measured with an overlay grid. These t~vo comparisons represent the amount of surgical movement and the amount of further growth or relapse in both the horizontal plane (x-axis) and vertical plane (y-axis). The principle of the method is illustrated diagrammatically in Fig. 1.
4
All cases in the study had lateral cephalometric radiographs taken immediately pre-
Tabh, 3. Procedural characteristics Total number of patients Le Fort I alone Bimaxillary Le Fort I with vertical subsigmoid Le Fort I with sagittal split One-stage osteotomy Two-stage osteotomy (first stage reconstruction of alveolar continuity and bone graft) Plated Craniomaxillary fixation
61 35 26 13 13 23
38 36 25
B C A Fig. 1. Diagrammatic representation of method of cephalometric analysis. A shows preoperatire tracing with two reference lines marked. In B, reference lines have been transposed to immediately post6pcrati~.'e radiograph using independent best fit for both cranial base and maxilla. Movement of maxilla in relation to preoperative maxillary reference line can be measured in both horizontal and vertical dimensions. C shows same method applied to most recent postoperative radiograph. In practice, only preoperative radiograph is actually traced. Postoperative points P3 and P4 are determined by superimposition of relevant parts of preoperative tracing.
203
Le Fort t osteolooO'
P4X Craniomaxillary Fixation
V2(n- 1)
15.0 ~
1 250.0
Fig. 2. Dahlberg's formula for method error. lO.O 1-
Errors of the method The mean error represents the difference between the ftrst and second measurements from each radiograph. The method error, which is the standard deviation of errors in individual cases, was tested with Dahlberg's formula (Fig. 2), where d is the difference between measurements and/1 is the number of cases. Errors of radiographic technique were minimized by using the same cephalostat for all radiographs.
.
mm t,
.
.
15o.o
! I i i i i I I I I, t I._, I~,~,~,~]~ 50.0~0
,oo
L P4X Plated
Data analysis and statistical methods This was a retrospective study to examine the effect of the method of fixation of the maxilla on postoperative stability. Although the final osteotomy of the maxilla in each case was complete at the Le Fort I level, there ~'ere several variables within the total sample. For this reason, statistical expertise was invoked before any data ~ere analysed,,~s it ~ s important to examine the influence of possible confounding variables which could have affected the outcome. Initially, correlational analysis using the Pearson product moment correlation coefficient for all the variables was applied. These statistical tests were performed using the Microsoft Excel Version 4 spreadsheet. Next, distribution analyses were performed to determine whether the data conformed to the requirements for parametric statistical tests, i,e., that the variables were normally distributed around the mean. The data were found not to be normally distributed. This can clearly be seen by referring to the graphed data (Figs. 3-6). Therefore, subsequent analyses were performed with nonparametric tests, The conventional chi-square test examines the null hypothesis that there is no relationship between an independent and a dependent variable. This study was designed to test whether one independent method of fixation was associated with greater stability than another. It was therefore better to apply the chisquare test for trend, as this allows the direction of effect to be predicted, increasing the sensitivity of the analysis in terms of statistical significance.
Results
ii i T
150.0 50.0
ilil
mil 1
-50.0 -t 50.0 -250.0
Surgical M o v e
~
Relapse
----¢----- Percentage Relapse
Fig. 3. Graph to show surgical movement and postsurgical change in each individual case. P4X represents horizontal movement of anterior maxilla.
All variables were correlated against measured relapse using the statistical correlation tools o f a c o m p u t e r spreadsheet (Microsoft Excel Version 4). The method o f fixation was found to be more significant by a factor o f 10, in terms of correlation with relapse, than any other variable. The two methods o f fixation used were either craniomaxillary extraoral immobilization or direct osteosynthesis with miniplates. The total sample was tfierefore divided into two subgroups based on fixation method. The subgroups were found to
be evenly matched for all variables apart from tile pattern o f osteotomy (one-stage or two-stage) (Table 2). Staging was accordingly tested separately against relapse, and a much weaker correlation was found (see below). After examination o f the associations between variables with the spreadsheet, it became necessary to test the a priori hypothesis that "fixation method affected the stability of the o s t e o t o m y " , as this appeared to be the most significant controllable variable to affect the eventual surgical outcome.
Table 4. Changes in maxillary position Surgical change
The mean surgical change, postsurgical change, and percentage o f relapse for the whole sample of 61 patients are shown in Table 4, and the mean error for each of the recorded points is shown in Table 5.
250.0
,
P3X P3Y P4X P4Y
mm mm mm mm
Mean
SD
Range
6.4 -3.7 6.1 -5.7
3.4 3.0 3.3 3.7
1.0-14.5 -12.5-1.5 0.5-15 -14.5-0.0
Postsurgieal change Range Mean SD -0.4 1.1 -0.3 1.2
1.5 2.0 1.8 2.0
-4.0-10.0 -2.0-6.0 -4.5-4.5 -3.0-6.5
Mean percentage of surgical change 6.3% 29% 5% 21%
204
Ayliffe et aL
P4Y Craniomaxillary Fixation 250.0
15.0 T
iii
150.0 50.0
m
o
-50.o g. -150.0
-250.0
P4Y Plate d 250.0
15.0 1
150.0
-i-i I
g
• -~0.0
~.
• -150.0
-250.0
-15.0 I
• 50.0
surgical Move
I
I Relapse
" m e - " - - Percentage Relapse
Fig. 4. Graph to show surgical movement and postsurgical change in each individual case. P4Y represents vertical movement of anterior maxilla.
The data were analysed for the two subgroups delineated in Table 2 (36 cases fixed by miniplates and 25 cases in which craniomaxillary fixation and I M F were employed). The surgical and postsurgical changes for P4 (anterior maxilla) and P3 (posterior maxilla) are shown in Table 6. Movements in the horizontal (X) dimension are shown positively for an anterior move, and
negatively for a posterior move. Movements in the vertical (Y) dimension are shown as negative values for an increase and as positive values for a decrease. The surgical change, relapse, and percentage of relapse for each of the patients in both groups are illustrated in Figs. 3-6. The graphs have been arranged so that the patients with the maximum percentage of relapse are
Table 5. Mean error and error of method
glean error Method error (mm) (mm) Surgical change
P3X P3Y P4X P4Y
0.65+-.0.54 0.504-0.3 0.62+-0.5 0.64_+_0.5
0.5 0.52 0.6 0.54
Postsurgical change
P3X P3Y P4X P4Y
0.54+-_0.46 0.60+-_0.6 0.74+-_0.62 0.62_-.0.5
0..75 0.74 0.7 0.76
grouped to the left, and those in whom complete stability or actual increase in "growth" occurred are grouped to the right. As can be seen from the graphs, the results are nonorthogonal for both the absolute relapse and the percentage of relapse. The data are skewed by individual cases that show high percentages of relapse, often associated with very small surgical moves. It is not possible (and probably of little clinical relevance) to try to analyse the data using statistical transformations in order to apply parametric statistical methods. For these reasons, the data were analysed using grouping criteria applied to the measurements of absolute relapse. The grouping criteria applied were related to perceived clinical significance. Three groups were defined for each of the points analysed (anterior maxilla. P4 and posterior maxilla P3). Group 1 were those patients with complete postoperative stability, group 2 were those patients in whom postoperative change was less than 2.5 mm vertically or 1.5 mm horizontally, and group 3 comprised the patients in whom relapse was more than these values (Table 7). Examination of chi-square values calculated from these data (Table 7) revealed a trend in relapse related to the use of fixation by direct bone plating. The chi-square test for trend 4 showed this to be significant. A highly significant difference could also be shown between those patients who had fixation by bone plating and those who had fixation by craniomaxillary fixation. As slated above, the two subgroups were evenly matched as regards all other variables apart from the number of cases having one-stage or two-stage surgery. For historical reasons, more of the earlier cases which constituted the majority treated with extraoral fixation had a one-stage procedure. Accordingly, this variable was tested separately against relapse using the same statistical tool. The two-stage procedure appears to produce more stability in the vertical dimension (P=0.01) and to a lesser extent in the horizontal dimension (P=0.09). These values are not highly significant and would appear to exert only a marginal effect on the highly significant effect of different fixation. No significant difference could be demonstrated when bimaxillary procedures were compared with maxillary (P=0.5) or when VSS was compared
Le Fort 1 osteotono'
P3X Craniomaxillary Fixation 250.0 150.0 50.0 ~, e.. mm
.:_--
o.o
.:
.:
.
.,,
.,.
.:
u
-50.0
~_
-150.0
-1o.o
-250.0
-15.0
P3X Plated l
15.0 10.0
5.0 mm 0.0
~
~
j
~
250.0
IJ !!!il II I !!
,50.0
-5.0 -150.0
-10.0
-250.0
-15.0 SurgicalMove
~
Relapse
~
PercentageRelapse
Fig. 5. Graph to show surgical movement and postsurgical change in each individual case.
P3X represents horizontal movement of anterior maxilla.
with sagittal split in the bimaxillary group (P=0.6).
the lack of data relating to such surgical procedures in patients with cleft lip and palate deformity. The few available studies at that time all demonstrated considerable relapse, particularly in the vertical dimension, and "~LCH concluded that "a Le Fort I procedure in cleft patients tends to be as unstable as
Discussion In a comprehensive review of the factors affecting stability after orthognathic surgery, WELOd 9 commented on
Table 6. Surgical data for two study samples
Surgical change
Postsurgical change
Mean
SD
Range
Mean
SD
7.5 -4.0 7.0 -6.0
3.5 2.8 3.0 4.0
1.0-14.5 -12.5-1.5 0.5-15 - 14.5-0
0 1.0 -0.l 1.0
2.5 2.0 2.0 1.75
-4.0-10.0 -1.0-4.5 -4.5-4.5 -2.0-6.5
Craniomaxillary'fixation P3X (mm) 5.0 P3Y (mm) -3.5 P4X (mm) 5.0 P4Y (mm) -5.0
3.0 3.5 3.0 4.0
1.5-10.0 -10.5-1.0 0.5-8.5 - 13.5-0.0
- 1.0 1.0 0.5 1.5
2.0 2.0 2.0 2.0
-3.0--4.0 -2.0-6.0 -3.0~1.0 -3.0-6.0
Plated P3X (mm) P3Y (mm) P4X (ram) P4Y (ram)
Range
205
it is in patients with vertical maxillary deficiency". A previous study carried out in this department = suggested that a small subgroup of six patients who had fixation with plates was more stable postoperatively than the majority' who had fixation by craniomaxillary suspension. The numbers were, however, too small to be statistically significant. The present study was designed to investigate further the relationship between the method of fixation and the stability of the maxilla in adult cleft lip and palate patients treated by Le Fort I osteotomy to correct maxillary hypoplasia. The resuits, in a series larger than most previously published, confirm many of the findings reported elsewhere, which all show a large individual disposition for relapse of the maxilla, particularly in the vertical dimension. The method of measurement used in this study produced levels of accuracy within those accepted in other comparable studies. In the anterior maxilla, which is more relevant to the final cosmetic result than the posterior maxilla, the mean horizonta~ relapse of 5% and mean vertical relapse of 21% (Table 4) were similar or better than in other studies s't°'tS,16"2°. Some individual patients shoxxed very high percentages of relapse, sometimes greater than the surgical move. This can be clearly seen from the graphs (Figs. 3-6). Although these high percentages of relapse could be due to postoperative instability, in this study they are often associated with small amounts of surgical move. As GRAVELY & BENZIES9 have suggested, in measuring point differences in individual cases, it is impossibIe to be confident at the 5% level unless the change is greater than twice the method error. For point P3X, two patients demonstrated a percentage of relapse of 233% for a surgical move of only 1.5 mm in this dimension, while the method error for P3X was 0.75 mm (Table 5). This large percentage of change could be due to measurement error, and consequently may well be of little clinical significance. Percentage of relapse would thus appear 1o be an unreliable way of interpreting the data. For these reasons, it was decided to analyse the data within three groups determined by the perceived clinical significance of the relapse measured in absolute rather than percentage values (Table 7). Relapse in the subgroup of patients who had direct osteosynthesis by mini-
Ayliffe et al.
206
P 3 Y Craniomaxillary Fixation 15.0
250.0
10.0
.150.0
5.0 mm
50.0
g
==
0.0
.50.0 -5.0 -I 50.0 -10.0 -250.0
-15.0
P 3 Y Plate.d. 15.0
250.0
10.0
150.0
5.0
50.0
o e-
mm
0.0
.50.0 .= -.5.0 ,
-150.0
-10.0
-250.0
-15.0
Surgical Move
~
Relapse
~
Percentage Relapse
Fig. 6. Graph to show surgical movement and postsurgical change in each individual case. P3Y represents vertical movement of anterior maxilla.
when compared with a one-stage operation (P=0.01). N o statistically significant difference was found when bimaxillary procedures were compared with maxillary surgery alone or when the VSS was compared with the sagittal split in the bimaxillary group. Clearly, however, these and other factors could represent compounding influences on t h e results and, ideally, a randomized prospective study would be more suitable. Furthermore, the patients x~ere not randomized to receive either plates o r craniomaxillary fixation. M o s t patients with craniomaxillary fixation were treated earlier in the period of study, and it could be argued that the degree o f surgical expertise, particularly that o f surgical mobilization, was greater when treating the later group of patients. The mean surgical move was, however, greater for the plated subgroup, and yet they were significantly m o r e stable. The highly significant P values do suggest a causal relationship between the use o f direct bone plating and stability of the maxilla. For the g r o u p as a whole, and for the two subgroups, no other single factor was found to have such a level o f significance.
Acknowledgment. We would like to thank Dr M. Bland, Senior Lecturer in Medical Statistics at St George's Hospital, London, for his help with the statistical analysis of the data. References
plates was comparable with Le Fort I osteotomies in noncleft patients. The two test samples were evenly matched for other criteria such as age distribution, cleft type, and incorporation of a mandibular procedure. The one factor which was not reasonably matched was the osteotomy type. This weakness in
the argument is likely in any retrospective study. The relationship between the type o f osteotomy and the degree o f relapse was studied separately, and a much weaker correlation was found. The two-stage procedure was shown to be associated with increased stability in the vertical dimension in particular
Table 7. Chi-square tables P4X Plated Not plated
0 mm 14 5
0.5-1.5 mm 16 7
2-4.5 mm 6 13
P=0.008
P4Y Plated Not plated
0 mm 16 1
0.5-2.5 mm 15 7
3-6.5 mm 5 17
P=0.0001
P3X Plated Not plated
0 mm 13 3
0.5-1.5 mm 16 8
2-4.5 mm 7 14
p=0.006
P3Y Plated Not plated
0 mm 11 0
0.5-2.5 mm 20 16
3-6.5 mm 5 9
P=0.004
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Le Fort I osteotono" tion of congenital dentofacial and orofacial deformities. J Oral Surg 1976: 34: 324-42, 8. ESKANAZILB, SCIIENDELSA. An analysis of Le Fort I maxillary advancement in cleft lip and palate patients. Plast Reconstr Surg 1992: 90: 779-86. 9. GRAVELY JF, BENZIES P]~l. The clinical siKnificance of tracing error in cephalomerry. Br J Orthod 1974: 1" 95-101. 10. HEDEMARKA, FREIIIOFERHE The behaviour of the maxilla in vertical movements after Le Fort I osteotomy. J Max-Fac Surg 1978: 6: 244-9. 11. HOClIBAN W, GANSS C, AUSTERMANN KH. Long-term results after maxillary advancement in patients with clefts. Cleft Palate Craniofac J 1993: 30: 237-43. 12. HOUSTON WJB, JOSE.S E, JAMES DR. A method of recording changes in maxillary position following orthognathic surgery. Eur J Orthod 1987: 9: 9-14.
13. HOUSTON WJB, JAMES DR, JO.','ES E, KAVVADIA S. Le Fort I maxillary osteotomies in cleft palate cases. J CranioMax-Fac Surg 1989: 17: 9-15. 14. KUFNER J. Four )ear experience with major maxillary osteotomy for retrnsion. J Oral Surg 1971: 29: 549-53. 15. PERSSON G, HELLEM S, NORD PG. Bone plating for stabilising Le Fort 1 osteotomies. J Max-Fac Surg 1986: 14: 69-73. 16. Pos.xlcK JC, Ewl.XG MR Skeletal stability after Le Fort I maxillary advancement in patients with unilateral cleft lip and palate. Plast Reconstr Surg 1990: 85: 70610. 17. STOELINGA PJ, HAERS PE, LEENEN RJ, SOUBRV R J, BLIJDORP PA, SCI[OENAERS JH. Late management of secondarily grafted clefts. Int J Oral Maxillofac Surg 1990: 19: 97-102. 18. TEUSCHER U, SAILER HE Stability of Le Fort I osteotomy in Class III cases with
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retropositioned maxillae. J Max-Fac Surg 1982: 10: 80-3. 19. ~3&ecli TB. Stability in the correction of dentofacial deformities: a comprehensive review. J Oral Maxillofac Surg 1989: 47: 1142-9.
20. WILLMARK K. On Le Fort I osteotomy. Scand J Plast Reconstr Surg 1974: 12 (Suppl): !-64.
Address: Mr P. R. Ayliffe, FRCS (Eng), FDSRCS (Eng) Department of Oral and Maxillofacial Surge O' Queen Victoria Itospital lloloe Road East Grinstead, IVest Sussex RItI9 3DZ UK