Biostereometric analysis of surgically corrected abnormal faces

Biostereometric analysis of surgicaEZp corrected abnormal faces Samuel

Berkowitz,

D.D.S.,

M.S.,*

and

Jaime

Cuzzi,

B.Sc., Ph.E.**

South Miami, Pla., and Dallas, Texas I believe the day must come when the biologist will, without being a mathematician, not hesitate to use mathematic analysis when he requires it.’

T

he eye alone is not capable of analyzing components of the face and their interrelationship with other parts. The need to measure and record objectively is essential for practical as well as academic reasons. This we have tried to do by comparing presurgically treated faces with faces treated postsurgically. Biostereometrics, the science which permits the three-dimensional measurement of body form, is being used to obtain a full conceptualization of the changing face in order to answer the following questions : (1) Can the soft-tissue contours of the face be accurately measured? (2) To what extent does the geometric relationship of the components of the face change as a result of various surgical procedures on the skeleton of the face? (3) Are there objective measures which delineate specific facial syndromes ? Material Stereophotographs of five patients with various craniofacial were taken prior to reconstructive surgery by Paul Tessier and J. 1972 and again postoperatively in 1973. Some of the patients have ditional surgical treatment for which follow-up stereophotographs

abnormalities W. Curtin in since had adwere not ob-

This research has been sponsored by Mead-Johnson Laboratories, Evansville, Ind., and, in part, by the National Institute of Health (DE-02872) and Maternal and Child Health Services, Department of Health, Education and Welfare. *Director of Craniofacial Anomalies Program, University of Miami School of Medicine. **Associate Director of Biostereometric Laboratory, Baylor College of Medicine.

526

Biosteremnetric

Fig. 1. cameras.

Subject Note

sitting in head the latex skullcap

reference as the

frame with head covering.

three

sets

of

oriented

analysis

527

stereometric

tained. The patients are part of the longitudinal facial growth studies conducted at the Center for Craniofacial Anomalies, The Abraham Lincoln School of Medicine, Chicago, Illinois. Method

The application of this technology to the study of heads and bodies has been developed by the Biostereometric Laboratory at Baylor College of Medicine.2-6 For a better understanding of its application to the study of faces, the method will be reviewed. Biostereometrics is the spatial and spatiotemporal analysis of biologic form and function, based on the principles of analytic geometry. The primary tool of biostereometrics is stereophotogrammetry, which uses stereoscopic equipment and methods. Stereoimages provide a means of creating a spatial model of the object, a face which can be measured in three dimensions. A stereometric camera is used to take overlapping photographs or stereopairs (Fig. 1). The images comprising a stereopair are suitably oriented in a stereoplotting instrument. The operator sees a three-dimensional optical model, the two photographs. A contour map, or Cartesian coordinates (x, y, z) , of a point on the object can be compiled by varying the elevation to correspond with the contour interval. Stereometric

equipment

and

requirements

Each stereometric camera (Fig. 1) consisted of a specially designed pair of individual metric cameras and a surface contrast optical projector unit. The stereopictures were taken with glass plates to ensure flatness of the emulsion.

528

Berkowitz

Fig. 2. Patient form of skull.

sitting

Am. J. Orthod. November 1977

and Cuzzi

in head

reference

frame

wearing

an

elastic

head

covering

to expose

Electromechanical shutter releases assured simultaneous firing of the camera’s shutters. The contrast optical projector not only illuminates the subject, but it also provides contrast and detail to the otherwise unvaried surface of the skin through projection of a fine-line random pattern. Synchronized with the camera shutters, power for the three units comes from five power supplies located under the examination chair. The three stereometric camera systems are positioned around the reference frame at a distance of 24 inches (60.96 mm.) from the nearest part of the face. To compress the hair uniformly, a thin elastic cap (Fig. 2) was cut to fit around the ears, where four cords were attached to form a harness or bridle which the subject pulled to stretch the cap and compress the hair. Although this technique adequately modeled the head surface in almost all cases except those in which subjects had thick, very dense hair and longer hair styles, it was still decided not to include the cranial area in the analyses, as the measurements were not reliable. The head reference frame (Fig. 2) consists of five rectangular frames joined orthogonally to form a cube whose sixth side is open. The seated subject’s head was introduced through this opening. Completely enclosing the head, the frame defines a three-dimensional system of coordinates which can be referenced from five views. The head frame can be raised and lowered for proper seating of the subject. At the bottom of each face of the frame, a set of electromechanical digital counters advances with each picture. The subject is viewed from the side and then from the front to ensure that

Biostereometric

fig.

3A.

H. Dell

Foster

analysis

529

quantitizer.

the chin was raised sufficiently to afford a direct view beneath the chin. The subject is asked to bite on his back teeth while looking straight ahead. Digital data are generated via the steroplotter from three camera stations (front, left, and right sides) and integrate views and convert the coordinates to object scale. The data obtained from each camera station are tied to a common coordinate system with the aid of the head reference frame. The stereoplotter was connected via cable to an H. Dell Foster quantitizer (Fig. 3, A) which digitized the electronic signal, producing coordinates (x, y, z) which were subsequently dumped into a card punch on command from the plotter operator. The resulting data were three sets of coordinates (x, y, z) on punched cards comprising almost a complete head form. Each set represents part of the head surface covered from one of the three stereometric camera stations. The three sets of coordinates are linked by a common reference system defined by the sides of the control cage. An IBM 360/50 computer is programmed to scale each view from model scale to object scale, to perform coordinate axis transformation, to place all coordinates in the same orthogonal system, and to store data in the form of optical (stereopairs) and graphic three-dimensional analogs (contour maps, cross sections) for future review. Andytical

systems

The three following complementary methods (Fig. 4) are used to locate facial landmark points : (1) the orthogonal system (x, y, z) , (2) the polar system of coordinates (P, x, y, z) , and (3) the radius of spherical coordinates system (r x y z) .

530

Berkowitz

and Cuzzi

Am. J. Orthod. November 1977 PROCESS

CRART

ANALYSIS

fig.

36.

Stereometric

measurement

of head

form.

% Fig. 4. Types of spatial analysis: Orthogonal system, two-dimensional (x, y, z). Polar system of coordinates, three-dimensional, measured from (a direction and distance) point called pole (x y z). Radius of spherical coordinates system (three-dimensional); every point in space measured from intersection of x, y, z axis and its distance is the linear measurement along the straight line to that point.

Biosteremetric

analysis

531

Fig. 5. A, and B, Frontal and lateral facial views demonstrating the system of coordinates used for locating landmarks on facial surfaces. All three planes of space intersect at point SN. All numerical values above the X axis and to the left of the Y axis are positive. In the ZY plane those values forward of SN are positive, those behind are negative.

Glossary Code

of

landmarks

(Fig. Landmark

n

Nasion

sn

Subnasale

en al eh t’ spn

Endocanthion Alare. Cheilion ‘(Tragion” Supernasale

sa sba

Superaurale Subaurale

Y axis X axis Z axis

5)

- Line drawn - Line drawn - Perpendicular

Description The point at which a horizontal tangential to the highest points on the superior palpebral sulci intersects the midsagittal plane The point at which the nasal septum merges with the upper cutaneous lip in the midsagittal plane The inner corner of the eye of palpebral opening The most lateral point on the wing of the nose The most lateral point at the corner of the lips The most prominent central point of the tragus A point on the midsagittal plane where the nose begins to project forward, as indicated by the change in direction of the profile. The highest point on the inferior border of the helix The lowest point on the inferior border of the ear lobule

through points SN to SPN through point SN perpendicular to the Y and X axis drawn

to SN-SPN at point SN

532

Pig.

Berkowitz

5 (Cont’d).

and Cuzzi

C, System

of

coordinates

Am. J. Orthod. November 1977

to

locate

a point

in a plane

or in space

by

de-

termining the distance from the measured point to three planes which are perpendicular to each other. D, Polar system of coordinates, location of nasal landmarks: Inferior-superior view of the nose, The angle around Z is defined by the perpendicular from the “point” to the Z axis angle drawn to XZ plane. Angle Y is determined by an angle or a point in space, to make the plane XY rotating around Y. The Y axis is the pole in the diagram. The point of the nose (PN) is 85 degrees from X to Z. AL (right) is 347 degrees in X to Z direction. AL (left] is 191 degrees in X to Z direction. The Y axis runs through point SN perpendicular to the paper’s surface; it connects point SPN. If the angles are greater than 180 degrees, the landmark is behind SN; conversely, if the angle is less than 180 degrees, it is in front of SN. linear

measurements

Total head height Skull height Facial height Upper face height Midface height Lower face height Length of eye Distance between eyes Interpupillary distance Width of mouth Width of nose

SHP-LCP SPN-SHP SPN-LCP SPN-SN SN-CH CH-LCP EX-EN ENI-EN2 PPl-PP2 CH~-CH’J Al&AL2 Angular

measurements

CHI-CH2 to Y axis EX-EN to Y axis EXl-EN1 to EN2 - EX2 (inter-eye Code SHP P.S. PUL PLL

angle IEA)

Landmark Superior head point Prominence of skull in lateral view, in Prominence of upper lip in rest position Prominence of lower lip in rest position

Description Included contribution of hair the area of “glabella”

Biostereonwtric

Rg. 6. Types mouth to the

and angular measurements X, Y, Z coordinates.

SM

Submental

LCP

Lower chin point

PC

Prominence

Facial

foatunr

which

cm

which

the

eyes

and

their

sockets

533

and

the

Deepest depression between lips and chin comparable to skeletal point B Most interior point of chin comparable to skeletal point menton Comparable to skeletal point pogonion

point

of chin

bo evalua@d

relate

an&M

(Fig.

61

(1) Angulation of the eye sockets to each other (IEA), (2) degree of protrusion of the globe of the eye related to the socket, (3) distance of the eye sockets to each other (not a skeletal measurement), and (4) angulation of interpupillary line to x axis. Nose: (1) Length between the tip of the nose (PN) to the bridge (SPN), (2) degree of protrusion relative to subnasale (SN), and (3) width between right and left alare. Mozlth: (1) Length as measured between the commissures, (2) protrusion of the lips relative to subnasale, and (3) angulation of the mouth compared to X axis. CMn: (1) Location of chin point relative to Y axis and (2) protrusion of chin point relative to subnasale. Eyes:

Fclcial Case

changes CCFA

#1955

resulting M (Fig.

from

surgical

intervention

71

The patient, born on June 2, 1954, was seen in 1972 and diagnosed as having mandibulofacial dysostosis. The patient had an anti-mongoloid slant of the eyes, a prominent nasal bridge, and hypoplastic malar bones and zygoma. Also noted were a hypoplastic mandible, bilateral low-set microtic ears, and no visible external auditory canals. Szvrgical history. In 1972 onlay bone grafts were placed on the orbital rims, malar bone, and zygoma. In 1973 the lateral superior corners of the orbits were raised, and the lateral and inferior orbital rim and malar bone were grafted. There was also a bilateral fixation of

534

Berkowitz

and C’uzzi

Fig. 7. Case CCFA #1955. mandibulofacial dysostosis. to the mandible.

Am. J. Orthod. November 1977

A and Most

of

6, Pretreatment and posttreatment the facial change occurred as

a

facial result

of

views of surgery

the lateral canthus and a mandibular osteotomy to elongate the mandible and correct the occlusion. As a result of the surgery, the upper face height increased 6 mm. (12 per cent), while the lower face height showed the greatest change by decreasing 9 mm. (25 per cent). The ratio of lower to total face height decreased 9 per cent, and the distance between the eyes decreased 6 mm. The right eye socket became more acute relative to the x axis, while the left eye socket remained the same. The interpupillary line remained at the same degree of parallelism with the x axis, while the right eyeball became slightly more protrusive. The nose increased 7 mm. in length, with the point of nose moving slightly to the right. The width of the mouth decreased 14 mm. (32 per cent), while the angle of the mouth changed only slightly (2 per cent). The chin became more protrusive, and its distance from the midface point increased 4 mm. The point of the chin moved off center to the left. The point of both lips moved toward the left, while submentale moved 5 mm. to the left. It also moved 3 mm. farther inferiorly. Care

CCFA

# 1909

F (Fig.

8)

The patient, born on Jan. 5, 1955, was diagnosed as having Apert’s syndrome. The physical characteristics included syndactyly of hands and feet, hypertelorism, exophthalmia, more pronounced on the right side, cleft palate, maxillary hypoplasia, nasal deformity, mandibular prognathism, and open-bite. Szlrgioal history. In 1972 the cleft palate was repaired. A LeFort III midfaeial osteotomy with anterior repositioning with bone grafts from ribs and iliac crest to eye area (wire fixed),

Biostereowwtric

Fig. 8. Case CCFA # 1909. A and 6, Pretreatment syndrome. The greatest degree of change occurred

and posttreatment to the orbits

and

analysis

facial views midface.

535

of Apert

temporal muscle advancement, and medial pseudocanthopexies were performed. In 1973 a pharyngeal flap was created, and in 1974 nasal reconstruction and a bilateral medial canthopexy and correction of right eye ptosis were performed. As a result of the surgical procedures, the upper and midface heights increased 5 mm. and 4 mm., respectively, while the lower face height decreased 8 mm. The ratio changes were: upper :total increased 5 per cent, middle:total increased 4 per cent, and lower :total decreased 8 per cent. The distance between the eyes decreased 11 mm. (25 per cent), with the length of eye sockets greatly decreased (approximately 25 per cent). The angle of the left eye socket became more acute, while the intersocket angle became more parallel, with the endocanthi moving superiorly relative to the exocanthi (which remained in the same relative position). Both pupils remained in the same parallel plane, while both eyeballs and eye sockets became less protrusive when compared to the midface. The point of the nose remained in the same place in the X, Y, and Z axis. The length of the mouth increased in length 14 mm. (28 per cent), and t,he corners of the mouth greatly receded relative to midface and moved more inferiorly. The point of the chin moved toward the center and became more recessive. The point of both lips centered and became more recessive.

536

Berkowitz

and Cuzzi

Am. J. Orthod. November 1977

Discussion

Gorlin and associates,7 in a recent two-part monograph, lament the lack of precision in measuring and describing various facial forms. Although they list various anthropometric techniques which have been adapted for the assessment of facial shape, they conclude that none as yet has yielded any useful knowledge. We agree with Go&n and his colleagues that there may be some limitations to the use of soft-tissue measurements in that they may not truly describe the underlying skeletal form. However, three-dimensional analysis by the use of biostereometrics can be of special value, for it has the potential of gaining added insight not available through conventional two-dimensional visualization. Although much of the earlier works, s in the biologic application of stereophotogrammetry originated in European institutions of stereophotogrammetry, in more recent times its application to the study of human form was refined under the impetus of space exploration. Robin Herron, Jaime Cuzzi, and others3-6 from the Biostereometric Laboratory at the Texas Institute for Rehabilitation and Research did extensive research in exploring body form and density changes of the astronauts under the influence of prolonged weightlessness. They also refined the technology, making it practical for this study to be undertaken. Posing error. The recent application of stereophotogrammetry for making facial measurements has been extensively reviewed by Burke.*’ s He and otherslo* I1 criticize the use of two-dimensional photography for making accurate measurements, since it is restricted by the posing error of the subject. Gorlin suggests that errors of interpretation from two-dimensional photographs may arise from the posterior rotation of the head which can make the pinna of the ear appear lowset. Such distortion errors are eliminated in this study since the interpretation is mainly quantitative in nature and is three dimensional in character. The head reference frame which is used to orient the head properly in space does, however, permit the orthographic projection of an irregular threedimensional body and the accurate superimposition of serial two-dimensional photographs for graphic analysis. Surface reference planes. Cartesian and other coordinate systems for the analysis of the skeletal and soft-tissue facial structures have been used extensively in the past.1° In cephalometric roentgenographic analysis, X, Y coordinates are structured, using relatively stable reference landmarks within the neurocranium. Unfortunately, the same relative stability of surface reference landmarks does not exist, because of the growth changes of the underlying skeletal structures as well as that of the soft tissue .I2 Therefore, the task of evaluating positional changes of the eyes, nose, mouth, and chin as well as the transformation in form of the head is made more difficult. In creating a coordinate system, Tidesley,13 Buxton and Mora.nt,*4 and Sollas15 report difficulties in identifying the median plane of the face for measurements, since such a plane does not exist as a true biologic entity but is only an approximation which is convenient for descriptive purposes. Where some investigators15 have used such midline points as soft-tissue pogonion for the chin and point prosthion, which is defined as the lowest point of the intermaxillary suture between the maxillary incisor teeth, for the construction of the midline

plane, we selected reference points around the nose (supernasale and subnasale) since these landmarks were readily discernible. Coordinate reference planes are used here for assessing the relative location of the nose, chin, eyes, and midface to each other. It helps describe relative changes that have occurred in position and not the mechanism which produced the change. Rabey16 has written that organic transformation is continuous and variable in time and space, that nothing is fixed and everything moves. It is also our opinion that the shape of a three-dimensional object, such as a head which has three easily discernible features and transforms into various shapes, can be studied against a coordinate reference frame which is dependent on these two superior and inferior nasal points, even though they are in the object that is changing form. We had originally tried to use reference points involving the ear, such as the tragus or external meati, since these landmarks were further removed from the operative site, but unfortunately they were not always discernible because of the overlaping of hair. Biostereometrics has been used successfully in this study to assess both shape and relative changes in position of facial features incident to corrective surgical procedures. Plans are now underway to expand the use of this technology further for the improvement in classification of oral-facial anomalies based on a better understanding of the geometric relationship of facial features in a normal growing child population. Ultimately, it is our aim to determine what it is that distinguishes the unusual-looking child from the range of variation that constitutes the norm. Where it is now possible to recognize a classic case of a syndrome, in many cases the presence or absence of one or more typical features may open the diagnosis to argument because of the lack of definitive objective criteria. We have reached that point in time when it is essential to redefine syndrome recognition and classification by the addition of quantitative measurements of abnormal features, distinguishable from the range of normal variation. Although the state of the art does not make the technique widely available or economical for common use, the mensurative resource of biostereometrics coupled with advanced mathematical analysis merits further application in seleetive problem solving. Summary

Biostereometrics is an accurate anthropometric system for quantifying geometric changes of facial form and the relationship of features as they are influenced by growth and by surgery. Facial features distant from the site of surgical intervention are influenced in their geometric relationship to each other by changes in the soft-tissue drape brought about by manipulation of skeletal tissues. The most accurate coordinate system should be elsewhere than on the surface of the face, but if this is not possible it should be in an area farthest removed from the surgical site.

538

Berkowitz

and Cuzzi

Am.

J. Orthod.

November 1977

This investigation demonstrates that a usable coordinate transformation system can be created by connecting points superraasale and szlbnasale for establishing the Y Z plane and the construction of the X 2 plane at subnasale. Accurate comparative numerical measurements can be made by using softtissue landmarks. Although this investigation represents the combined efforts of many persons, special thanks must be given to Samuel Pruzansky, D.D.S., Director of the Craniofacial Anomalies Center, the Abraham Lincoln School of Medicine, for supplying the patients and encouraging the project to be undertaken, and to Robin Herron, Ph.D., for permitting the use of the Biostereometric Laboratory for the photography, data reduction, and analysis. Paul Tessier, M.D., of Paris, France, operated on five of the six cases. J. W. Curtin, M.D., performed the surgical procedures on the remaining case. We are indebted to John Hugg and Ken Rouk for taking the stereophotographs and to Donna Pruzansky for organizing the photographic sessions. REFERENCES

1. Joseph, M., and Dawbarn, C.: Measurement of the facies, S.I.M.P. Research Monograph No. 3, 1970. 2. Herron, R. E., Cuzzi, J. R., Hugg, J. E., and Rouk, K. R.: Stereometric measurement of body and limb volume changes during extended space missions, Bull. Soe. Fr. Photogram. 40: 45, 1970. 3. Herron, R. E., and Cuzzi, J. R.: Stereometric body volume measurement, Apollo 16 Experiment A-14.0, Texas Institute for Rehabilitation and Research. 4. Herron, R. E., Cuzzi, J. R., Hugg, J. E., and Rouk, K. R.: Stereometric measurement of body and limb volume changes during extended space missions, final report, NAS-g-10567, National Aeronautics and Space Administration, March, 1971. 5. Herron, R. E.: Stereophotogrammetry in biology and medicine, XIIth Congress International Society of photogrammetry, July, 1972. 6. Herron, R. E.: Biostereometric measurement of body form. 1% Yearbook of physical anthropology, vol. 6, p. 80, 1972. 7. Gorlin, R. J., Sedano, H. O., and Boggs, W. S.: The face in diagnosis. I. Pediatr.~Ann. 4: 11, 1975. 8. Burke, P. H. : Stereophotogrammetric measurement of normal facial asymmetry in children, Hum. Biol. 43: 536, 1971. 9. Burke, P. H., and Beard, F. H.: Stereophotogrammetry, Aaa. J. ORTHOD. 53: 769, 773, 1967. 10. Howells, W. W.: The designation of the principal anthropometric landmarks on the head and skull, Am. J. Phys. Anthropol. 22: 477-494, 1937. 11. Macgregor, A. R., Newton, I., and Gilder, R. S.: A stereophotogrammetric method of investigating facial changes following the loss of teeth, Med. Biol. 1111.1s.71: 75-82, 1971. 12. Fishman, L.: Longitudinal eephalometric study of normal craniofacial profile, utilizing a proportional analysis of skeletal, soft tissue and dental structures. Int. Dent. J. 19: 351, 1969. 13. Tidesley, M. L.: A first study of the Burmese skull, Biometrika 13: 176-262, 1921. 14. Buxton, L. H. D., and Morant, G. M.: The essential craniological technique. Part I. Definition of points and planes. J. R. Anthrop. Inst. 03: 47, 1933. 15. Sollas, W. J.: The Sagittal section of the human skull, J. R. Anthrop. Inst. 63: 389-431, 1933. 16. Rabey, G.: Morphanalysis, London, 1968, H. K. Lewis, Co. Ltd. 6601

S. W. 80th

St.

(88143)