close

Вход

Забыли?

вход по аккаунту

?

Anatomical differences in the femur and tibia between Negroids and Caucasoids and their effects upon locomotion.

код для вставкиСкачать
Anatomical Differences in the Femur and
Tibia between Negroids and Caucasoids
and Their Effects upon Locomotion
M. R. FARRALLY AND W. J. MOORE
Departments of Physical Education and
Leeds, England
KEY WORDS Patellarligament
Caucasoid . Negroid.
2
Anatomy, University of Leeds,
. Locomotion . Femur . Tibia .
ABSTRACT
Nine variables of length, width and circumference of the femur
and tibia were measured on post-cranial remains of 28 Caucasoids and 45 Negroids. The distance from the point of tibial attachment of the patellar ligament
to the head of the tibia (PLID) was also determined.
I t was found that the Negroid has a significantly longer and narrower femur
and tibia than the Caucasoid, although PLID did not vary between the two
groups. Thus PLID, relative to the length of the tibia, was less in Negroids than
Caucasoids.
A factor analysis was carried out in order to examine the relation between
PLID and the other variables. It appeared that the same three factors governed
the ten variables in both races. I n Caucasoids, PLID did not load on either the
“length” or “width” factors and appeared unique. In Negroids, PLID loaded on
Factor I11 with two width measures, and this factor correlated positively with
the “width” factor. It is suggested that in Caucasoids PLID does not relate to
length or width dimensions of the leg but in Negroids it is related to width rather
than length.
It is well documented that the inferior
limbs of Negroids tend, on average, to be
longer than those of Caucasoids, both in
absolute terms and relative to total body
stature (Dupertuis and Hadden, ’51; Trotter and Gleser, ’58; Graham and Yarbrough, ’68). Assuming that the mechanical characteristics of the human limb are
similar to those in other animals, a n increase i n its linear dimensions will give
greater potential for jumping and speed of
movement (Howell, ’44; Alexander, ’68)
provided that the increase in limb segment
lengths does not adversely affect leverage
about the joint axes.
Extension of the knee is brought about
by the action of the quadriceps femoris
muscle developing tension in the patellar
ligament. In this movement, the tibia behaves as a third class lever, rotation occurring about the joint centre in the knee with
the point of application of the effort being
located at the tibial tuberosity and that of
Ann. J. PHYS.ANTHROP., 43: 63-70.
the load a t the distal extremity. The centre
of rotation is instantaneous (i.e., its position varies with different angles of flexion)
since the articular surfaces of the joint are
not spherical (Kapandji, ’70). Thus, the
effort moment arm (FMA) changes its
length during extension.
For any particular knee angle the instantaneous centre can be located radiographically and FMA measured (Smidt, ’73) but
to do this throughout the range of movement occurring in locomotion would demand a prohibitively large exposure to
X-irradiation. Even the radiographic measurement of FMA at a fixed knee angle
presents difficulties in the recruitment of
suitable subjects (see DISCUSSION). Accordingly, a search was made for a simple
measurement on skeletal remains to indicate the magnitude of FMA suitable for
comparisons between individuals or groups
of individuals. An examination of the morphology of the head of the tibia suggested
63
64
M. R. FARRALLY AND W. J. MOORE
that the distance from the point of application of the force generated in the patellar
ligament to the most proximal point on the
tibia (PLID) would provide such an indication (fig. 1 ) . If the point of application
were to be moved distally, for example,
FMA would increase because of the sloping anterior face of the head of the tibia.
Conversely, movement of the point of application proximally would lead to a reduction of FMA. PLID will not change with
the angle of flexion and cannot be used
to quantify FMA at various positions of the
joint. It should, however, provide an indication of the overall magnitude of FMA
suitable for comparative purposes.
It might be expected, a priori, that an
overall increase in tibia1 length, and therefore in load moment arm, as evidenced in
Negroids, will be compensated for by a
related increase in PLID, but this expectation involves two assumptions: first, that
the Negroid tibia is a scaled-up version of
the Caucasoid bone so that an increase in
Fig. 1 The knee joint, showing the line of action of the force in the patellar ligament ( F ) , effort moment arm (FMA) and distance from point
of application of force generated in patellar ligament to most proximal point in the tibia (PLID)
in relation to the instantaneous centre of rotation ( X ) .
length will be accompanied by a corresponding increase in PLID and secondly,
that increasing the load arm increases the
load moment. In this study, these two assumptions have been investigated by an
examination of the relationship between
PLID and length and width variables of
the femur and tibia in male Negroid and
Caucasoid skeletal remains.
METHODS
Specimens
The Caucasoid sample was taken from
the Scarbrough Collection of the British
Museum of Natural History, London (B.M.
N.H.). Of the 28 specimens measured, 19
were “complete” - that is, both the femur
and tibia were present and in a condition
which permitted all the measurements to
be recorded. None of the series was sexed.
The Negroid sample was taken from five
collections : the Ibo and East African series
from B.M.N.H. and the Haya, Somali and
Jebel Moyan series from the Duckworth
Laboratory, Cambridge. Of the 45 subjects
measured, 24 were “complete.” All the Negroid specimens were sexed upon excavation except the Jebel Moyan.
Where not previously recorded, sex was
determined by examination of the pelvic
girdle or, if not available, from the characteristics of the femur. In cases of doubt the
bones were discarded.
Anthropomet y
Measurements were recorded using a
Harpendon Survey Set, the instruments
being calibrated against a steel tape. The
measurements taken were as follows:
( 1 ) Maximum length of the f e m u r : the
maximum distance from the head of the
femur to the most distal point on the medial condyle, after Warren (1897).
( 2 ) Bicondylar length of the f e m u r : the
distance from the head of the femur to the
horizontal plane of the condyles, termed by
Warren ( 1897) the “oblique length.”
( 3 ) Bicondylar width of the f e m u r : the
maximum distance across the condyles in
the transverse plane.
( 4 ) Anterior-posterior w i d t h of the f e m oral condyles : the maximum distance between the anterior and posterior surfaces
of the condyles, measured in the anteriorposterior plane.
ETHNIC DIFFERENCES IN FEMUR AND TIBIA
( 5 ) Anterior-posterior w i d t h o f the f e m oral shaft: the minimum width of the shaft
in the anterior-posterior plane.
(6) Transverse width of the femoral
s h a f t : the minimum width of the shaft in
the transverse plane.
( 7 ) Minimum circumference of the
femoral shaft.
( 8 ) M a x i m u m length o f the tibia: the
maximum length of the tibia, from the
most proximal point on the intercondylar
eminences to the most distal point on the
malleolus.
( 9 ) Transverse width o f t h e distal extremity of the tibia: the maximum transverse width of the distal extremity, including the medial malleolus.
(10) PLID: the anterior surface of the
head of the tibia slopes downwards and
forwards (fig. 1 ) . The lower part of this
slope produces an eminence termed the
tibial tuberosity. On the upper part of the
tuberosity is a smooth area which gives attachment to the patellar ligament. PLID
was taken as the mean of two measurements from the most proximal point on the
intercondylar eminences to: ( a ) the most
proximal point on the smooth area of the
tibial tuberosity; (b) the most distal point
on the smooth area of the tibial tuberosity.
Measurements (8) and (10) included
the intercondylar eminences and where
there were any signs of damage to either
of these structures the bone was discarded.
Reliability of measurement was tested
by taking 20 repeated sets of measurements on a femur and tibia from one individual. The largest coefficient of variation
was less than 1.5%.
65
group variability (i.e., between collections)
in the Negroid was surprisingly low, only
five coefficients were less than 0.999, the
lowest being 0.998 recorded between a
Jebel Moyan and a Haya. The variability
between Negroid and Caucasoid was somewhat greater, well over half the coefficients
being below 0.999, the smallest value being 0.996. (2) A one-way ANOVA using
the five Negroid collections as treatment
levels showed there was no significant difference between collections on nine of the
ten variables at the 0.05 level of confidence. On the tenth variable, maximum
length of the tibia, a significant difference
was recorded at a = 0.05 but not at a =
0.01, and an a posteriori investigation of
the difference between means revealed that
this difference was in evidence between
the Ibo and Somali collections. The difference was only just significant (mean difference bl:b2 = 31.192, HSD at a = 0.05
is 31.982).
The high degree of homogeneity revealed by these analyses is in agreement
with the findings of Nutter (’58) who found
a similarly high level of homogeneity in a
large number of measurements taken on
both the upper and lower limbs of the Ibo,
Haya, Somali and Jebel Moyan series. (See
also Mukherjee, Rao and Trevor, ’55.)
Differences between Negroids and
Caucasoids o n t h e measured
variables
Mean values for the two samples together with their standard deviations, determined for each variable, are shown in
table 1. Homogeneity of variance was tested by an F test and in each of the ten
variables the samples were homoscedastic.
RESULTS
The significance of the difference between
Variability within the Negroid sample
the two samples was tested by the pooled
Since the Negroid sample included sev- variance model of “t.” Significant differeral tribal groups of widely separated geo- ences were recorded at the 0.05 level of
graphic location, it was necessary to test its confidence in eight of the ten variables and
homogeneity. Two statistical techniques of these only maximum and bicondylar
were employed. ( 1 ) A correlation matrix femoral lengths were not significant at a =
was drawn up using the Negroid subjects’ 0.01 (table 1). The two variables not exscores on the ten variables in a Pearson’s hibiting significant differences were the
Product Moment design. The Caucasoid anterior-posterior width of the femoral consampIe was included to assist the evalu- dyles and PLID.
ation of any Negroid between group variT h e relationship o f PLID to
ability. The Ibo series contained no “comother measures
plete” specimens and consequently could
not be included in this analysis. Between
In an attempt to discover what factors
66
M. R. FARRALLY AND W. J. MOORE
TABLE 1
Numbers, means and standard deviations, homogeneity of variance ( F ) , and student’s t
value of the Negroid and Caucasoid samples on the measured variables
Negroid
Measure
Caucasoid
N
Mean
S.D.
N
Mean
S.D.
F
value
Student’s
t value
34
476.44
23.95
27
461.42
20.21
1.41
2.56 *
3 Bicondylar width
of femur
32
79.50
4.63
27
83.05
4.11
1.27
3.04**
4 Ant.-post. width of
femoral condyles
33
62.36
3.89
27
62.88
3.12
1.55
0.55
5 Ant.-post. width
of femoral shaft
32
25.84
2.02
26
27.81
2.22
1.20
3.46 **
6 Transverse width
of femoral shaft
32
25.95
1.95
27
28.95
1.53
1.62
6.37**
7 Minimum circumference of
femoral shaft
33
84.44
5.62
27
93.61
4.40
1.63
6.80**
8 Maximum length
of tibia
33
408.00
24.45
24
373.42
24.56
1.01
5.17* *
9 Transverse width
of distal head
of tibia
33
47.07
4.48
23
53.23
3.41
1.73
5.47**
35
45.69
5.98
22
45.36
4.96
1.46
0.22
1 Maximumlength of
femur
2 Bicondylar length
of f emnr
10 PLID
*, P 5 0.05.
**, PL-0.01.
might influence PLID a factor analysis of
the ten variables was carried out on the
data from the “complete” subjects of both
samples (table 2). The variables were subjected to three analyses - principal components, varimax and promax - and factors were extracted separately for each
race. The significance level for loadings on
each factor was calculated using the BurtBanks Formula (Burt and Banks, ’47). The
extraction of factors was terminated at an
eigenvalue of 1.OO. Correlation coefficients
between factors I and I1 in the promax solution were - 0.54 and - 0.46 respectively
for the Negroid and Caucasoid samples
(P f0.05 in both cases). In table 2 , factor
I1 in the Negroid sample accounts for more
percentage variance than factor I and
would usually be extracted first. However,
in the orthogonal solutions factor I accounted for far more percentage variance
than factor I1 and the order of factors thus
established was maintained.
DISCUSSION
The greater length of the Negroid inferior limbs, widely reported by previous
authors, was apparent in this study. In
width measures, the Negroid exhibited significantly smaller values in all cases except
the anterior-posterior width of the femoral
condyles. Du Toit (’55) previously reported
racial differences in width in the geometry
of the knee joint and suggested that the
wider distal extremity of the European femur, compared to the Bantu, was due to
a splaying of the condyles. This would certainly account for a greater transverse diameter without a corresponding increase
in the anterior-posterior width, as recorded
in the present data.
The lack of a statistically significant difference between the two samples in PLID
confounds the initial expectation that a
greater tibia1 length would be associated
with a related increase in this measure.
The findings show that the point of inser-
67
ETHNIC DIFFERENCES IN FEMUR AND TIBIA
TABLE 2
Promax analysis of the te n measures. Loadings, significant at p L 0.05 as defined by the
Burt-Banks Formula, are indicated by an asterisk
Negroid
Caucasoid
Factor loadings
Measurement
Factor loadings
I
I1
I11
Communality
I
I1
I11
Communality
1 Maximum length of
femur
08
103"
01
1.07
10
92"
04
0.86
2 Bicondylar length
of femur
08
102'
00
1.05
11
91
'
05
0.85
3 Bicondylar width
of femur
109"
00
29
1.26
99"
10
05
0.99
4 Ant.-post. width of
femoral condyles
34
35
16
0.26
81"
11
19
0.71
5 Ant.-post. width of
femoral shaft
22
26
49'
0.35
80'
02
33
0.74
6 Transverse width of
femoral shaft
42'
04
58"
0.52
54"
25
15
0.38
65*
03
40'
0.59
82'
20
07
0.71
08
95'
18
0.95
11
91'
07
0.85
10
16
1.13
97'
27
12
1.03
100'
19.1
1.05
06
42.1
00
27.1
99'
11.7
0.98
7 Minimum circumference of femoral
shaft
8 Maximum length of
tibia
9 Transverse width of
104"
distal head of
tibia
10 PLID
% variance
20
31.0
12
32.4
tion of the patellar ligament, relative to
tibial length, is more proximal in Negroids
than Caucasoids. If PLID is an indicator
of FMA, as has been assumed, it would appear that FMA for any given angle of knee
flexion is similar in both ethnic groups and
therefore smaller as a ratio of tibial length
in the Negroid. Initial observations in a
radiographic study that we are carrying
out for a fixed knee angle support our assumption. Subjects for this type of study
are not readily available but so far seven
Caucasoids and 12 Negroids have been examined and the mean values of FMA are
4.75 and 4.65 cm respectively ( P > 0.2).
This study is being extended as further
subjects become available and will form
the basis of a subsequent publication.
From Newton's second law of motion it
can be shown that in knee extension
F x FMA =I;
where F is the force in the patellar ligament,
Of the leg and
I is the moment of inertia
foot about the
& is the angular acceleration
knee
therefore = F x FMA
}
I
If F and I are the same for both ethnic
groups, a decrease in FMA would be associated with a decrease in G. It would thus
appear that the greater length of the inferior limb in the Negroid may be at the
expense of cadence (i.e., the rate at which
the leg can be rotated about the knee). The
fact that tibial length is greater in the Negroid suggests not only a greater mass of
the leg but also a larger radius of gyration
and a greater value of I (since I is a function of mass and radius of gyration, where
the radius of gyration is a measure of how
far the mass is distributed from the centre
68
M. R. FARRALLY AND W. J. MOORE
of rotation). I n contrast, the measures of
width are less for Negroids, possibly an
indication of a compensating mechanism
operating to keep any increase in I as small
as possible. This possibility is further s u p
ported by the results of the factor analysis (table 2). Length and width variables
loaded on separate factors inversely related.
The use of three factor analyses was
found necessary because neither the direct
solution (principal components) nor the
orthogonal rotation (varimax) provided
factors easy to interpret. I n the principal
components analysis some factors were bipolar and some variables loaded on more
than one factor. Orthogonal rotation was
found to give higher loadings but only
oblique rotation of the factors (promax)
reduced the number of marginally significant loadings considerably, thus assisting
interpretation,
In both samples three factors were extracted and the pattern of loadings of the
variables in all the analyses was very similar. It would seem not only are these three
factors of importance within each sample,
but also that the same three factors may
be operating in both samples.
Factor I would appear to be a width factor. The value to be reached for significance was exceeded by all width variables
in the Caucasoid sample, and by all width
variables except the anterior-posterior diameters in the Negroid. The low communality (Le., the total amount of common
variance shared between the three factors)
associated with these two variables in the
Negroid suggests a n unreliable measure.
Factor I1 seems to be a length factor,
significant loadings appearing on the three
length measures in each sample. As length
and width measures did not load on the
same factor in such a way as to make it
bipolar, it cannot be directly concluded
that length and width are inversely related.
However, promax analysis allows oblique
rotation of factors such that the factors
themselves may be correlated. The correlation coefficients between Factors I and I1
were - 0.54 and - 0.46, respectively, for
the Caucasoid and Negroid samples. Both
these values are statistically significant ( P
0.05), thus enabling the conclusion to be
drawn that the two factors are inversely
related. It seems likely that the adaptive mechanisms determining morphological changes to accommodate differences in
environmental temperature will have had
a profound effect upon both these factors.
The above results are in accordance with
Allen’s Rule, the long and thin inferior
limbs of the Negroid facilitating heat loss.
Examination of the loadings on Factor
I11 does not evoke a simple explanation of
the observed relationships. In the Caucasoid this factor seems unique, although
over 11% of the variance was attributed
to this factor alone. Also, there was no significant correlation (r < 0.2) with either
of the other two factors. It would appear
that PLID i n the Caucasoid has little in
common with either length or width measures.
In the Negroid the same trend was not
apparent. Factor I11 accounted for 19%
of the variance. It correlated significantly
with both Factor I and Factor I1 and was
not unique. The presence of loadings from
the two width variables of the femoral
shaft as well as PLID, and the correlation
of r = 0.53 between Factor I and Factor
111, suggests a close link between PLID
and width variables.
ACKNOWLEDGMENTS
We should like to thank Dr. D. Brothwell
of the Sub-Department of Physical Anthropology, British Museum (Natural History)
and Dr. J. Garlick of the Duckworth Laboratory, Cambridge for permission to examine specimens in their charge.
LITERATURE CITED
Alexander, R. McNeill 1968 Animal Mechanics. Sidgwick and Jackson, London.
Burt, C., and C. Banks 1947 A factor analysis
of body measurements for British adult males.
Ann. Eugen., 13: 238-256.
Child, F. 1973 The Essentials of Factor Analysis. Holt, Rinehart and Winston, New York.
Du Toit, G. T. 1955 Internal derangement of
the knee. American Academy of Orthopaedic
Surgeons, Instructional Course Lectures, Vol.
XII, pp. 9-34.
Dupertuis, C. W., and J. A. Haddon 1951 On
the reconstruction of stature from long bones.
Am. J. Phys. Anthrop., 9: 15-53.
Graham, T. M., and J. D. Yarbrough 1968 Anthrouometric studies of the lone bones of the
‘‘Shill Mound” Indians. Am. J. Phys. Anthrop.,
28: 85-92.
ETHNIC DIFFERENCES IN FEMUR AND TIBIA
Howell, A. B. 1944 Speed in Animals. University of Chicago Press, Chicago.
Kapandji, I. A.
1970 The Physiology of the
Joints. Vol. 2 , Lower Limb. E. and S. Livingstone, London.
Mukherjee, R., C. R. Rao and J. C. Trevor 1955
The Ancient Inhabitants of Jebel Moya. Cambridge University Press, Cambridge.
Nutter, M. C. 1958 A n osteological study of the
Hominoidea. Doctoral dissertation, University
of Cambridge.
69
Smidt, G. L. 1973 Biomechanical analysis of
knee flexion and extension. J. Biomechanics,
6: 79-92.
Trotter, M., and G. C. Gleser 1958 A re-evaluation of estimation of stature taken during life
and of long bones after death. Am. J. Phys.
Anthrop., 16: 79-123.
Warren, E. 1897 An investigation on the variability of the human skeleton, with special reference to the Naqada race. Phil. Trans. R. SOC.
Ser. B, 189: 135-227.
Документ
Категория
Без категории
Просмотров
3
Размер файла
476 Кб
Теги
upon, negroids, femur, caucasoids, effect, locomotive, differences, tibial, anatomical
1/--страниц
Пожаловаться на содержимое документа