close

Вход

Забыли?

вход по аккаунту

?

Effects of maceration and drying upon the vertebral column.

код для вставкиСкачать
E F F E C T S O F MACERATION AND DRYING UPON
THE V E R T E B R A L COLUMN
T. W I N G A T E TODD AND S. I D E L L PYLE
Anatomical Laboratory, Western. Beserve University, Cleveland, Ohio
ONE CHART
CONTENTS
Introduction and methods ............................................
Material and the vertebral curves ......................................
Precision of measurement ............................................
The shrinkage of cancellous tissue on drying ............................
The analysis of vertebral shrinkage ...................................
Final statement of the problem .......................................
Summary ...........................................................
Literature cited .....................................................
303
306
308
311
313
315
318
319
INTRODUCTION AND METHODS
Detailed and accurate measurement of defect is more important in dealing with disability in the vertebral column
than in treatment of any other p a r t of the skeleton. But as
the bones of the column are, f o r the most part, deeply placed
in the body, the only practicable method of obtaining information is the roentgenogram. To derive dimensions of
the actual vertebral bodies from measurements on the roentgenogram is our chief aim. But since we may study the
column itself, as a rule, only upon the dried macerated skeleton it is equally necessary to discover the relation of the
macerated dimensioiis to those of the fresh or ‘green’ bones.
The senior author has already set forth in detail the shrinkage in skull dimensions consequent on maceration and drying(2). Ingalls has dealt in similar manner with the femur
as a representative of the long bones, arid also with the ribs,
scapula and other bones(1). The vertebrae form a class by
303
AMERICAN JOURNAL O F PHYSICAL .4YTHROPOLOOY. VOL. XII, NO. 2
OCTOBEU-DECEMBER. 1928
304
T. WINGATE TODD A R D S. IDELL PYLE
themselves and must be separately and intensively studied.
To this end we have applied ourselves and our results a r e
presented in this communication.
Since the vertebral bodies a r e largely composed of cancellous tissue the problem differs somewhat from those previously undertaken and the period of shrinkage is greatly
lessened.
To assure ourselves of technical precision it is necessary
to provide check determinations and hence we have adopted
four methods of measurement. All are vertical dimensions
and are comprised in the following.
Method I. Ventral vertical diameter. This is measured
by sliding calipers directly upon the thoracic and lumbar
bodies but on the cervical bodies it is necessary to place the
limbs of the instrument in contact with upper and lower surfaces of the body. Hence the height is a projected measurement and is less than the direct determination.
Nethod 11. Mid-centrum vertical diameter. The instrument used is the bow calipers of the Flower craniometer type
though spreading calipers would do. We have chosen the
former f o r greater ease in determining fractions of a millimeter for on the Flower instrument the divisions a r e actual
millimeters and not progressively changing fractions of a
millimeter a s they must be on spreading calipers. Moreover, spreading calipers except those manufactured in this
laboratory, appear to have the fractions determined by a kind
of interpolation of assumed value and hence cannot be depended upon throughout the range of the instrument. The
R,eserve spreading calipers a r e calibrated by mathematical
computation upon a lead screw. Although this instrument is
accurate i n all parts of its range the divisions are too small
to enable fractions of a millimeter to be sufficiently accurately
judged for our present purpose. There is frequently an ifregularity in the upper surface of the thoracic and lumbar
vertebral bodies, either an elevation or a depression, about
the center of the surface. Method IT avoids this irregularity
and the measurement in practice is usually made immediately
dorsal t o the uneven area.
EFFECTS OF MACERATION A N D DRYING
305
Method I11 was intended as a determination of postcentral
vertical height. It was taken by sliding calipers one limb
of which was laid along the upper surface of the vertebral
body. The lower limb was then drawn u p to contact with the
point on under surface most distant from the upper surface.
The scheme was planned to measure the maximum height of
centrum wherever found. I n practice the method proved uiireliable since true maximum height is often vitiated by a
raised irregular ar ea on upper surface of body and by temporary irregularities occurring on the cancellous surfaces
during drying. Method I11 was therefore given up and the
records eliminated from this report.
Method IV. Dorsal vertical height. Flower’s craniometer.
This is the over-all dimension of the body at the floor of the
vertebral or spinal canal.
I t was expected that Methods I and I V would check each
other and measure the thin shell of compact tissue on ventral
and dorsal surfaces of the body. Methods I1 and I11 were
also planned to check each other and determine the value
of the cancellous tissue dimension of the vertebra. I n practice
this did not happen. Method I11 became obsolete and method
TV turned out to be a check on Method I1 and not on Method
I. Examination of our final results (Table V I ) demonstrates
this quite clearly and indicates that the shell of compacta on
the floor of the spinal canal does no more, in our data, than
act as a regulator of shrinkage of cancellous bone without
affecting its total extent. It is but a glaze upon the cancellous tissue, nothing more.
The senior author and Doctor Ingalls agree that there is
no warping of a bone on drying after maceration comparable
to that which occurs in wood. The warping certainly found
in exhumed bones must be laid to other causes than simple
drying. Nevertheless both authors also agree that compact
tissue shrinks much more slowly than cancellous tissue but
the bones upon which they worked gave no data for determination of the relation between the shrinkages of these two
forms of osseous tissue. One of the secondary issues of the
present work is the elucidation of this subsidiary problem.
306
T. WI NGATE TODD AND S. IDELL PYLE
MATERIAL AND THE VERTEBRAL CURVES
The material upon which our work is based consists of
106 vertebral columns divided into three series. The first
series consists of 10 columns of which flat lateral roentgenograms were taken before maceration. The second series comprises of 71 columns upon which the vertical dimensions of
the discs were determined in the fresh or green stage before
the columns were macerated. There a r e no roentgenograms
of this series. The vertebral bodies, being already macerated
and dried when our work commenced, had to be soaked t o
restore the original green dimensions. That this actually
occurs may be inferred from Todd’s work on the skull(2).
The third series includes 25 columns on which stereoscopic
anteroposterior and lateral roentgenograms were taken before
maceration. These columns were obtained wet from the
macerator and measured during drying.
I n all columns the direct height is known. This determination is made by the Stangenzirkel, one limb of which is
placed on the upper border of the ventral arch of the atlas or
the tip of the odontoid process of the epistropheus, the other
on the ventral upper lip of the sacral promontory. Since the
cervical, thoracic and lumbar curves differ from column t o
column this dimension bears a varying relationship to the
composite measurement which is the sum of all ventral vertebral body heights and disc heights on the specimen.
To illustrate this, Table I has been prepared. The composite column height is obtained by adding together the wet
body heights and green disc heights. From this the atlaspromontory length is subtracted and the difference is expressed as a percentage of the atlas-promontory length. As
a rule this percentage varies between 1 and 3. Examination
of the lateral roentgenogram shows slightly marked curves
in all regions though in No. 1207 it is stated that the thoracic
curve was greater than usual. I n No. 1145 the thoracic curve
was marked and the percentage 8.4; in No. 1210 both thoracic
and lumbar curves were marked yet the percentage amounted
to but 5.4. I n No. 1227 with no marked curves the percentage
307
EFFECTS OF MACERATION A N D DRYING
is 5.3. W e have examined the records to pick out bedridden
cases with their exaggerated thoracic and cervical curves but
this gives us no help. So, f o r the moment, we a r e baffled and
can but state that 011 the average, 3.0 per cent added to the
atlas-promontory length will give the approximate sum of
the composite heights of bodies and discs. It must be very
clearly understood that this refers only to our cadaveric material under observation and must on no account be transferred to living individuals. The curvatures of the column
change with death. Although there is but little difference
TABLE I
Composite column height and atlas-promontory length
Skeleton number
1 1114 11145
I
1
I I 1
11133 1097 1179 1205 1227
__ __
1207
1201
1310
--
1. Sum of heights
of soaked bodies
(method I )
2. Sum of heights
of green discs
3. Total composite
column height
4. Atlas-promontory
stangenzirkel
dimension
5. Difference (3-4)
6. Percentage of
5 011 4
540.0 493.0
147.5 144.5
687.5 637.5
682.0 605.0
5.5 32.5
0.8
5.4
~
between sitting height and stem length in the living there is a
profound distinction between living sitting height and dead
stem length. Since o u r observations a r e certainly inadequate
for transference from the latter to the former we a r e driven
to the only alternative, namely the measurement of actual
dimensions of living vertebrae by roentgenographic methods
and the correlation of these with living sitting height.
A piece of collateral evidence which will be fully presented
in another communication, but is of considerable suggestive
importance in the difficulty here presented, is illustrated by
our measurements of stature in children. Whereas the aver-
308
T. WINGATE TODD AND S. I D E L L P Y L E
age heel height was 10 mm., the difference between the average stature, shod and unshod, was 25 111121. This of course
means that the raising of the heels results i n reduction of
spinal curvature to a relatively high degree.
PRECISION OF MEASUREMENT
I n a problem which involves the summation of many separate measurements of relatively small dimension it is quite
necessary to establish the precision of technique. We need
to know how closely remeasurement of the column will approximate the original figures whether of the same or of
another observer.
Table I1 gives evidence on the former count. Miss Pyle
measured the composite heights of four columns by methods
TABLE I1
(Z.P.) Repeated measurement of column i n millimeters
I
_
_
_
Method I
A. Skeleton
Dried composite column height:
1st observation
2nd observation
Difference
Average difference
B. Skeleton
Dried composite column height:
1st observation
2nd observation
Difference
1
~
1066
___
430.5
432.5
2.0
1188
1215
1080
484.0
483.0
1.0
444.5
446.5
2.0
471.0
472.0
1.0
1215
1080
416.0
418.0
2 .o
439.0
439.5
0.5
i
1066
1
_______-
375.5
373.5
2.0
C. Eight skeletons (see table IIIc) Method I
(i) Measured dry
(G) Soaked: dried 18 days: measured
(iii) Measured 7 days a f te r (ii)
Average differences between i and ii, 6.0 mm.
i and iii, 8.6 mm.
ii and iii, 2.6 mm.
Average of these differences,
5.7 mm.
~
1188
442.5
442.5
0.0
[
EFFECTS O F MACERATION AND DRYING
309
I and 11. Later, after the measurement of some sixty other
columns so that memory might be confused, she remeasured
these four. The average differences are only 1.1mm. and
1.5 mm. respectively on the entire column.
This evidence which looks so satisfactory is precisely the
kind of evidence which gives a false sense of security f o r it
is based on the results of a trained observer consciously
checking herself. Table I I C gives a more truly representative indication of reliability for, as explained in the table,
procedures were carried out between measurements which
threw out of mind all possible conscious relationship of
measurements with the consequence that the true average
difference is about 6.0 mm. Of course, in making Table IIC
we have been careful to utilize measurements made when the
bone dimensions were really comparable. This is explained
in the chapter on shrinkage in drying. The average diffcrence of approximately 6.0 mm. per column indicates an average difference of 0.25 mm. per vertebra. This is the same
observational difference which we shall find characteristic of
the results of successive observers. It is the maximum possible precision of reading unmarked fractions of a millimeter.
The problem of the second observer is of course f a r the
more important and we therefore present a extended check
upon this count. Table I I I A gives the composite column
height in two skeletons measured by Miss Pyle and myself
according to Method I. The average difference amounts to
6.3 mm. Appended to this is Table I I I B, which, by method IV.
gives an average difference of 1.5 mm. We believe that the
former difference of 6.3 mm. is a closer probable value and
that the difference of 1.5 mm. is a fortunate accident. Tables
C and D show the results of measurement of the 17 thoracicolumbar vertebrae and of the 7 cervical vertebrae respectively.
The differences of 4.4 mm. for thoracico-lumbar and 1.7 mm.
f o r cervical, together with the 6.3 mm. of Table I I I A, indicate
that the difference between the determinations of two observers depends upon the number of observations made and
summated rather than upon the absolute values of the dimen-
~
-
-
_
~-
I
I
98.0
95.0
3.0
_ _
1133
_
~
_
1.5
_
1
-
~
364.5
361.0
3.5
__
1207
564.5
563.5
1.o
~
I
1
1201
90.5
89.5
1.0
-
I
~
-
1210
~
Average 1.5 mm.
I l l
_____-__
-~
428.5 384.5
433.5 382.5
5.0
2.0
______
1201
__-
I
-___
Average 6.3 mm.
I
I -1
I
1179
__-
I
I
_
_
108.0
105.5
2.5
~-
~
99.0
98.0
1.0
___
..__.___
1227
_
I
_
-
94.0
97.5
3.5
111.5
110.5
1.0
.__
1205
-
I
1201
107.5
107.5
0.0
93.0
96.0
3.0
87.0
93.0
6.0
- ~ . _ _ _ _
108.0
107.0
1.0
____
1207
92.5
91.0
1.5
___
-
110.0
109.5
0.5
__
_ 1210
__
~ _ ~ _ _ _ _ _ - - . _ _ -
_
_
1227
~
___
385.0
381.5
3.5
_
4.5
467.5
463.0
1133
99.5
120.5 102.5
98.0
119.0 105.0
1.5
--__ _ _ _ 1.5
_ _ 2.5
I -1097
__
1
_
1205
_
375.5
367.5
8.0
_
_
_
1179
_
358.0
360.0
2.0
_
1
I
l l
-___-
~ _ _ - _ _ - _
_
114.5
115.5
1145
_
_
I
_
_
________I
_
96.0
100.5
4.5
_ _ _ _ _ _ _ _ ^ _
-_____
~
I
I
_
1097
____
348.0
340.0
8.0
_
~
_
_
1114
_ _ _ _ _ _ ~
___I__
~~
___
E. Skeleton
Cervical oiily. T.W.T.
Cervical only. I.P.
Difference
Average 2.4 nim.
1
I
388.0
355.0
3.0
-
1145
503.0
505.0
2.0
1179
I _-__
~____
~
I____-__
Cervical only. T.W.T.
Cervical only. I.P.
Difference
Average 1.7 mm.
-_____ _
_
__
D. Skeleton
Average
4.4 mm.
__-____
_
T.W.T.
I.P.
1
1
0. Skeleton
Thoracico-lunibar only.
Thoracico-lumbar only.
Difference
~-
1
~
R. Skeleton
Composite height dried bodies I.P.
Composite height dried bodies T.W.T.
Difference
-____
___-___~
423.0
431.0
8.0
- 1114
- _ _ _ _~
______
_
_
I
_
_
A. Skeleton
Composite height dried bodies I.P.
Composite height dried bodies T.W.T.
Difference
Composite heights
TABLE I11
E F F E C T S O F MACERATION A N D DRYING
311
sions measured. I n other words the difference in column
length is really the difference in reading the fractions of
millimeter which must be estimated on the instrument. A
check of method I1 on method I is set forth in Tables IT1
D, E.
The evidence brought forward enables us to state with
confidence that measurement of vertebral body height can
be made by different observers with sufficient accuracy and
read with precision enough to permit comparison of results.
I n comparing the records of different observers, however, it
is wise to allow a possible individual difference in reading
of 0.25 mm. per observation recorded. I n any anthropometric
data this is, indeed, the maximum accuracy attainable.
THE SHRINKAGE O F CANCELLOUS TISSUE ON DRYING
To investigate shrinkage on drying we adopted the methodfollowed by Todd on the skull, namely the investigation of
successive samples, thereby eliminating discrepancies due to
variations in atmospheric conditions with change of season,
artificial heat in the Institution, and dampness due to forcing
washed air through the building in the absence of artificial
heat. W e took the first series of 10 columns, measured them
dry, soaked them, measured them again, dried them at atmospheric temperature and measured them during drying. Later
we obtained the third series of 25 fresh from the macerating
tank and measured them also during drying.
The first essential is knowledge of the drying period of a
vertebra, during which shrinkage occurs. F o r the skull this
is about 28 days at atmospheric temperature and moisture;
for the femur it may be 18 months. The length of time depends on the absolute thickness of compact tissue. There is
very little compacta in vertebrae, practically none in measurements by method 11. B y method I1 we may therefore investigate the period of shrinkage of cancellous tissue in drying.
Now of the 10 columns, one, No. 1097, is that of a Negro
male aged 18 years. The partially ossified and as yet ununited epiphyses of this column warped on drying as such
312
T. WINGATE TODD A N D S. I D E L L PYLE
epiphyses always do. This vitiated the shrinkage records
and the specimen is therefore eliminated. No. 1179, a male
IVhite of 35 years, developed, in the third week of drying,
local convexities on the upper surface of the thoracico-lumbar
bodies. Hence it also had to be eliminated. With two columns
discarded the remaining eight are reliable as a series for
use. By Table IV the average shrinkage, per column, during
the first week is 8.0 mm., during the second week 4.3 mm., and
during the third week 0.12 mm. Clearly then the drying
period of cancellous tissue at room summer temperature is
about 14 days. This is confirmed by the oscillatory change
TABLE IV
Shrinkage of cancellow tissue. 8 columns: Method XI
xm.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Total wet length
Total shrinkage 0-6 days
Total shrinkage 7-13 days
Total shrinkage 14-25 days
Expansion between 26 and 50 days
Total dry length 25 days
Total dry length 50 days
Percent of 4 (cumulation) on 6
Percent of 5 (cumulation) on 7
(CUMULATION)
3554.0
444.25
63.5
34.5
1.0
4.0
3455.0
3459.0
2.86
2.74
AMEAOE
8.0
(98.0)
(99.0)
(95.0)
4.3
0.12
0.5
431.9
432.4
setting in during the fourth week, resulting in an average
expansion of 0.5 mm.
Now the total amount of shrinkage equals 2.7% of the final
summated dry length. It greatly exceeds the shrinkage of
the skull and far outdistances that of the femur. On the
average the shrinkage in a bone has been found t o amount
to about 1% of the dried length. It is conceivable that the
greatly increased shrinkage in the vertebrae may be due to
the fact that method I1 measures cancellous tissue shrinkage
alone. One must also make the reservation that the discrepancy might be an artefact due to errors of measurement
and reading. Obviously further investigation is necessary.
EFFECTS O F MACERATION A N D DRYING
313
THE A N A L S S I S O F VERTEBRAL SHRINKAGE
So unexpectedly great was the shrinkage of the trial sample
of mixed columns just recorded that we have taken u p the
problem in greater detail. Series I and I11 together contain
thirty-five columns. But of these fifteen had to be discarded
in this particular phase of the study since readings upon
them were vitiated by the presence of warping epiphyses or
by the occurrence of fusion between successive bodies, or
because of some deficiency in record. Very galling it was to
find, after weeks spent in laborious measurement and remeasurement, that many columns must be disqualified by a
single fusion between two successive vertebrae. The twenty
remaining however constitute a series of quite reliable character. Of these one half were male Whites, one quarter male
Negroes and of the rest two were female Whites and three
were female Negroes.
These four groups were segregated and their shrinkage
studied separately. The total shrinkage in twenty-five days
of drying is set forth in detail in Tables V and V I and the
successive stages in drying are shown in Graphs. There is
an erratic character in the shrinkage especially of the pure
cancellous tissue as demonstrated by method I1 but the final
results, allowing for discrepancies in numbers, a r e unexpectedly harmonious.
Since the number varies so greatly from group to group
it is necessary to weight the average values. This is done
by multiplying the average of each group by the number in
the group, adding the values thus obtained and dividing the
resulting sum by the total number of cases. I n this manner
Table V I has been prepared. The probable shrinkage of the
ventral face of the vertebra averages about 1.5% of the final
dry dimension whereas the shrinkages of both the central part
of the body and the dorsal margin a r e about 2.5% of the
final dr y dimensions.
As a test of these conclusions we investigated certain
columns originally in Series I but eliminated therefrom before
the series was amalgamated with Series I11 f o r the con-
314
T. WINGATE TODD AND S. IDELL PYLE
struction of standard shrinkage tables. Of these columns
there were eight, namely two male White and six male Negro.
Total wet and dry dimensions, summated for the entire eight,
were obtained by methods I, I1 and IV, and from these
figures the differences between wet and dry totals were converted into percentages of the summated d r y totals. The
TABLE V
Percentage on total ?*aktes
Slirinkage b y days.
~
I
~~
0.6
1
7-13
1'
14-18
IMethod I
Male White average
Male Negro
Female White
Female Negro
0.92
1
1
19-25
I
0-25
\
l____l
'
0.29
0.78
0.10
0.19
0.17
0.04
1'
j
1.40
1.50
1.58
1.80
1
2.38
2.34
3.26
2.66
Method I1
Male White average
Male Kegro
Female White
Female Negro
--
Male White average
Male Negro
Female White
Female Negro
-_
1
0.68
1.67
1.47
1.73
I
I
!
1
1.64
1.65
I +0.14
0.38
:::; 1
0.43
I
0.16
0.95
0.25
0.09
0.94
0.39
1
___--
I
I
0.55
0.67
0.28
I
:::: 1
0.19
1
_.
1
0.05
0.08
0.17
+0.19
2.44
2.76
2.53
2.29
-
results a r e : method I, 1.59% ; method 11, 2.87% ; method IV,
2.38% (See Table V I I ) . These figures approximate our
st,andard shrinkage results closely enough to give us confidence in applying our standard figures to vertebral shrinkage in general. It must be understood that these eight
columns a re the initial samples used in Table I V but eliminated from the standard series because there is no record
of their being measured on the eighteenth day of drying.
315
EFFECTS OF MACERATION A N D DRYING
F I N A L STATEMENT OF THE PROBLEM
I n this study of shrinkage on drying after maceration the
problem has been complicated by the fact that we a r e not
TABLE VI
Summary of Series I and 111
RACE A N D SEX
NUMBER
i
PERCIINTAQE O? BHEINXAQE
IN 25 DAYS
I
_
I
_
i
WEXOHTED AVERAQE
I N PERCENT
I
Method I
Male White
Male Negro
Female White
Female Negro
-_
I
10
5
i
1.4020
1.5005
1.5801
1.8008
t
14.02
7.50
3.16
5.40
_____I_____
Total
Average
20
-I__.__
___
hlale White
Male Negro
Female White
Female Negro
Total
Average
Method I1
10
j
2
3
I
20
I
30.08
1.50
-
__I
2.3800
2.3378
3.2602
2.6564
~
-1
23.80
11.69
6.52
7.97
49.98
2.50
Method I V
Male White
Male Negro
Female White
Female Negro
-_Total
Average
1
, .-
i
I
-.
20
..-__
24.49
13.82
5.06
2.4492
2.7631
2.5309
2.2936
10
5
2
3
I-
--- -
-1
50.25
2.51
__ _.
I
_
_
I
measuring the shrinkage of a single bone but of a series
of bones. Further, owing to the flexibility of the column,
summation of measnrements bears no constant relation to the
articulated column length. It has been necessary therefore
to embark upon a long and careful investigation of the simple
MYSO
18
25
482
4.2
Y
460
4SB
467
467
u7
445
444
444
4 s
415
4x5
45
429
429
423
420
419
u?
492
492
6
13
METHOD ONE
WW
404
p
METHOD TWO
F W 412
METHOD FOUR
493
r w 456
DAYS 0
44s
444.
4
4%
435
436
13
6
18
25
Chart 1 Shrinkage on drying of vertebral columns. Shrinkage completed in
three weeks, almost completed in fourteen days a t room temperature. There
is a humidity oscillation as in other bones. Method I, ventral body height.
Method 11, mid-centrum diameter. Method IV, dorsal body height.
316
317
EFFECTS OF MACERATION AND DRYINQ
technique of measurement before we could proceed to our
proper object. The results of this iiivestigatioii a r e set forth
above.
Next, the observatioiis on duration and extent of shrinkage
show that the vertebral column requires treatment by itself,
for, unlike the majority of the skeleton, its constituent bones
are built almost solely of cancellous tissue. The ventral face,
with its average shrinkage of 1.5% of the dried measurement,
TABLE VII
Percentage shrinking of the 8 columns
Method I
i'1
Method I1
)RY 25 DAYS
WET
Method I V
DRY 25 DAY
WET
)RY 25 DAYS
_ _ ~ - _ _
1114
coL.
1145
1133
1205
1227
1307
1201
1210
Total
1
1
1
1
420.0
WET
501.5
460.5
475.5
495.0
469.5
540.0
493.0
3855.0
Difference
Percent on dry
418.5
493.0
456.5
468.5
489.0
460.0
524.0
485.0
384.0
484.5
404.0
479.0
444.5
426.5
498.5
433.0
3794.5
3554.0
--
378.0
4i7.0
397.0
452.0
436.5
410.5
484.5
419.5
447.5
532.0
474.0
492.0
515.0
483.5
566.5
513.0
429.0
522.0
466.5
480.0
504.5
472.0
556.5
499.5
3455.0
4023.5
3930.0
--
60.5
99.0
93.5
1.5944
2.8654
2.3791
-~
_
_
I
_
Pu'one of above by methods I, 11, I V included in the standard series of shrinkage
made up from series I, 111.
approximates most closely to the general rough average for
bones, namely 1.0%. But measurement of the mid-centrum
diameter and of the dorsal face shows in each a shrinkage
of 2.5% of the dried dimension.
Because of the extraordinary and complex change on drying, dimensions on the dried column cannot be used uncorrected as a basis for consideration of the vertebral column
during life. But this difficulty fades into insignificance compared with the greater complexities of inter-vertebral discs
and spinal curves. These must be treated separately in a
AMERICAN J O U R N A L O F PIfYSICAL ANTHROPOLOOY. VOL. SKI, NO.
2
318
T. WINGATE TODD AND S. IDELL PPLE
further communication. Since our preliminary experiments
indicate that there can be no simple solution of the problems
of discs and curves, and since the very measurement of the
dried vertebrae is attended by exceptional difficulty we believe
it more hopeful to attack the problem of vertebral dimensions
from the roentgenographic standpoint.
Naturally the foregoing strictures have reference only to
the problem of the vert,ebral centrum. So far as articular
processes a r e concerned there is no necessary confusion between living and dried values and inter-relationships since
changes on drying must be extremely slight and there is no
warping during drying.
SU M MA RP
1. Determination of changes in the vertebral column produced by maceration and drying is attended with difficulty
inasmuch as the column is a series of small bones, each of
which must be measured separately.
2. Ileasurements and remeasurements, whether by one or
more observers, cannot have a greater precision than the
nearest 0.25 mm. which is the error of observation on a millimeter scale. I n a presacral column of twenty-four vertebrae
this observational leeway is 6.0 mm.
3. Shrinkage determinations, preferably carried out by a
single observer, show that there is very slight shrinkage of
vertebral bodies after fourteen days drying and that a period
of three weeks covers the entire process of shrinkage.
4. Shrinkage of the vertebral centrum is unequal. It
amounts to 1.5% of the dried dimension in the ventral body
height, 2.5% of the dried dimension in the mid-centrum diameter and the dorsal body height. These discrepancies a r e apt
to result in temporary irregularities of upper and lower surfaces although as in other bones, no evidence of warping can
be found.
5. The unequal amounts of shrinkage in the several parts
of the centrum, together with the difficulties introduced by
intervertebral discs and spinal curves indicate that actual
EFFECTS O F M A C E R A T I O N A N D D R Y I N G
319
dimensions of the vertebral column in life can probably be
more precisely determined from the lateral roentgenogram.
6. The results of shrinkage, a s exemplified in different
small samples, a r e harmonious enough to justify the application of our standard figures to vertebrae in general.
LITERATURE CITED
1 INGALLS,N. W. 1927 Studies on t h e femur. 111. Effects of maceration
a n d d r y i n g i n t h e W h i t e and Negro. Am. J. Phys. Anthrop., X.
29 7-32 1.
2 TODD,T. W. 1923 T h e effect o f maceration a n d d r y i n g upon t h e linear
dimensions of t h e green skull. J. Anat., L V I I , 336-356.
1925 The n a t u r e of mummification a n d maceration illustrated
by t h e male W h i t e skull. J. Anat., L I X , 180-187.
1926 The n a t u r e of mummification a n d maceration. 11. Female
and N e g r o skulls. J. Anat., L X , 309-328.
Документ
Категория
Без категории
Просмотров
0
Размер файла
759 Кб
Теги
upon, effect, vertebrate, drying, column, maceration
1/--страниц
Пожаловаться на содержимое документа