Biology Reference
In-Depth Information
It is important to understand howbones grow in order tomeaningfullymeasure the skeleton
of subadults. Endochondral bone growth is the manner in which the long bones of the limbs
grow from an original cartilage model. The bone first begins to develop
in utero
as a cartilage
template of the bone. Primary centers of ossification begin at midshaft, with secondary miner-
alizationoccurring at the epiphyses (
White andFolkens, 2000
). Growth rates are extremely rapid
in the first year after birth, decelerate gradually from1 to 6 years and then are slow and uniform
from 6 to 10 years (
Bogin, 1988
). Rates speed up again during puberty and then growth halts at
adulthoodwhen the long bones epiphyses fully fuse (any time between 19 and 25 years) (
Bogin,
1988; Scheuer and Black, 2000
). See also Uhl (Chapter 3), this volume.
When measuring subadults, the problem of stature estimation is similar to that brought
up in the section above on fragmentary bones: What proportion of the whole bone length is
the diaphysis versus the epiphysis? In the humerus, the proximal epiphysis is 1.3
e
2.2% of
the total bone length (
Seitz, 1923
). In the tibia, the proximal epiphysis is 2.4
e
3.9% of the total
bone length and the distal epiphysis makes up 1.8
e
2.9% of total length (
Seitz, 1923
).
Balth-
azard and Dervieux (1921)
and
Smith and Moritz (1939)
estimated fetal skeletal stature
along with age.
Olivier and Pineau (1958, 1960)
recalculated these measurements and found
that the estimates by Balthazard and Dervieux only worked postnatally, which is not neces-
sarily a problem because we would only be interested in calculating stature or length for
babies who have been born. This study also found that all the major long bones worked
equally well and that the combining of two or more bones did not improve accuracy (Oliv-
ier and Pineau, 1958,
1960
).
Olivier (1969)
estimated stature using the femoral diaphysis,
with no account of population or sex.
Telkk¨ et al. (1962)
used radiographs of 3848 Finnish
children (up to 15 years old) to measure the diaphyseal lengths. They realized the need to
create separate age groups, as allometric growth is not consistent in each age group.
For children 10
e
15 years old, stature correlates linearly with all six long bones (humerus,
radius, ulna, femur, tibia, fibula). For children aged 1
e
9 years, the correlation is linear with
all of the bones, except for the femur, which requires a logarithmic transformation. The
femur appears to be the exception (perhaps due to the evolutionary significance of biped-
alism in our species) and does not scale isometrically to (at the same rate as) the other bones.
If the regression of a bone length to stature is more of a curved line, transforming the line
logarithmically can improve the correlation. For children under one year, all of the bones
must be log transformed.
Himes et al. (1977)
found that the metacarpals correlate well
with stature in children from rural Guatemala, using a least-squares regression method. In
this study, 1597 radiographs of the left hand and wrist were studied longitudinally. Surpris-
ingly (and fortunately), the growth of the metacarpals seemed to be unaffected by the envi-
ronment, even when severe malnutrition had occurred.
18
The more common use for long bone length in juveniles is to assess age (
I¸can, 1988
),
which has been extensively studied in fetuses and subadults by
Fazekas and K´sa (1966,
1978)
and later by
Scheuer and Black (2000, 2004)
. Fazekas and K´ sa (1966, 1978) measured
the remains of 138 Hungarian fetal skeletons of known age, sex, and height, 3
e
10 lunar
months. They developed regression formulae for body height to bone length.
Mehta and
18
With chronic malnutrition, stature is significantly shorter from one generation to the next (
Himes et al.,
1977; Bogin, 1988
).
