Ped
iulrics
VOLUME 33 MAY 1964 NUMBER 5, PART
I
COMMENTARY
DR. PARK AND
THE GROWTH
OF BONE
I
N THE PREFACE to his monograph “BoneGrowth in Health and Disease” Harris’
concluded with the following paragraph:
“The romance of bone growth is not yet
exhausted. The manifestations of disease
in bone, the registration of lines of arrested
growth in long bones, the phenomenal
re-sponse of certain deficiency diseases to
vita-mins, the age changes in bone, and the
ex-tent to which the child can ‘grow out of’
disease conditions still present
fundamen-tal problems in clinical research and
bi-ology. Gradually, but surely, we are passing
from the vitalism of Ecclesiastes: ‘As thou
knowest not what is the way of the wind,
nor how the bones do grow in the womb
of her that is with child’ to the clinical
cer-tainty of Job: ‘His bones bear witness to
the sins of his youth.’” The distinguished
author of the supplement to the current
number of PEDIATRICS, Dr. Edwards A. Park, would certainly agree with at least
the first sentence of this quotation.
How-ever, the material Dr. Park now reports,
which constituted the Joseph Goidherger
Lecture in Clinical Nutrition at the 111th
Annual Meeting of the American Medical
Association in June, 1962, would appear to
have shifted the problems related to “the
registration of lines of arrested growth in
the long bones” to a level even more
funda-mental than Harris envisaged.
Transverse lines iii the ends of shafts of
growing long bones were recognized
an-atomically in 18742 and
roentgenographi-cally in 1903. Stettner’ first called attention
to these as lines of arrested growth,
accord-ing to Harris, who subsequently adopted this
concept. Radiologists in particular have
been intrigued by the presence of
trans-verse lines of increased density in the bones
of growing children, both healthy and
dis-eased. My own interest was so much aroused in 1946, while I was studying with l)r. John Caffey, that a challenge was prepared
against the concept of arrested growth as a
basis for the formation of the lines. My
argument rested upon clinical and
radio-graphic observations of a single patient.
In a carefully worded, critical, yet warm
and kind letter Dr. Park explained why he
disagreed with my thesis and offered very
sage advice to the young investigator, to
wit: “I should think that you could
ap-proach your problem experimentally and
that is what I think you ought to do. Your
clinical case has given you a lead. Before you publish, prove that you are right
through experiment.”
It may be fortunate that the young
in-vestigator did not attempt the
experimen-tal approach to his problem. Otherwise Dr.
Park, entering into his retirement from the
professorship of Pediatrics at Johns
Hop-kins University School of Medicine that
same year, might not have undertaken the
experimental study himself, extending and
amplifying research reported twenty ‘ears
earlier with Eliot and Souther. For
al-most two decades of that “retirement,”
dur-ing the years when he might have been content to rest upon his laurels, this teacher,
who has never ceased to be a student and
whose young mind accepted the advice
640
GROWTH
OF
BONE
given a younger colleague, continued the
studies which so much extend our
under-standing
of
bone
growth
and
reaction
to
disease. These are summarized andevalu-ated
inthe
Goldberger Lecture which thisjournal
is privileged
to
publish.
Itcan
be
predicted
safely
that
this
article
will
pro-vide the secure base upon which future
investigators can build our knowledge of
normal bone growth and its aberrations for
many years to come.
Disagreement
among
students
of
trans-verse
lines
(growth
arrest
lines)
arose
from
several factors. Harris attributed their
for-mation to a disturbance of proliferative
cartilage
which
subsequently
calcified
ab-normally
so that
the
bone
formed
from
and
on
it wouldbe
abnormal with respect tothat
formed
before
and
after
the
disturb-ance.
Lines
originating
from
exposure
of
growingbone
to
heavy
metals
and
other
noxious
substances
were
considered
similar,
in that the dense trabeculae responsible
for
the
radiographic
appearance
were
thought to result from resistence of
ab-normal
calcified
cartilage
to erosive
actions
of
endosteal
vessels
and
cells.
Dr.
Park,
noting
the
transverse
orientation of thetrabeculae in histologic sections of bones
with transverse lines, considered the lines
to be the consequence of osteoblastic
ac-tivity spreading laterally on the shaftward
side
of
epiphyseal
cartilage
which
had
ceased its normal proliferation-calcification
sequence,
had
lost
its calcified component,and
was,
therefore,
resistant
to
capillary
invasion
from
the shaft.
The varying concepts came into conflict
especially when a transverse line was found
to be thicker and more remote from the
epiphyseal line where it had been
gener-ated than its counterpart in the same region
of the contralateral extremity. The
in-took
place
during
the
generation
of
the
line.
Did
not
such
lines
then
mean
accelera-tion rather than arrest of growth? If the
lines were generated by changes in
car-tilage, subsequently reflected in the bone
to which it became transformed, this
con-clusion would be reasonable.
It is here that Dr. Park’s experimental
approach has been so valuable. Dr. Park
has
demonstrated
unequivocally
that
the
line
is
generated
not
by
the
cartilage
as
suggested in Harris’s short-term
experi-ments, but on the undersurface of the
epi-physeal cartilage whose calcified portions
have been eroded. The osteoblasts,
de-prived of a longitudinally oriented
tem-plate of calcified cartilage matrix, continue
their activities on the horizontally disposed
template produced by the undersurface of
the epiphyseal cartilage. This line is too
thin to cast a radiographic shadow, but
with the recovery from the condition
in-hibiting cartilage growth, osteoblastic
ac-tivity, first on the shaftward side and
sub-sequently on the epiphyseal side of this thin
line, produces a distinct widening of the
primary or basic bony stratum of the
sub-epiphyseal line making it susceptible to
radiographic demonstration. Should
accel-erated growth take place at this time, the
increased osteoblastic activity of the cells
coating the basic stratum will result in a
line not only thicker than that in the
oppo-site extremity, but also more remote from
the epiphyseal plate upon which it was in-itially formed. This sequence of growth
ar-rest and recovery, clearly documented by
Dr. Park, resolves the conflict and
consti-tutes one of the basic contributions of his
studies. It is interesting that Dr. Park joins
with those who objected to the term “lines
of arrested growth” and proposes still
COMMENTARY
641fled
cartilage
at the
cartilage-shaft
junction
from
inhibition
of destructive
cellular
activi-ties
normally
so pronounced
there.”
Just as the transverse lines of bones
rep-resent marks upon the bones of nutritional
disturbances in the growing organism
which, according to Dr. Park “become
petri-fied in situ,” the significance of the studies
reported in this supplement, both explicit
and
implied,
will
remain
a durable
guide
to professional and personal endeavor.
The
Board
of
Editors
of
PEDIATRICS ispleased that our journal is the vehicle for
so excellent
an
example
of medical
schol-arship by so distinguished an author.
FREDERIC N. SILVERMAN,
M.D.
Cincinnati, Ohio
REFERENCES
1.Harris, H. A.: Bone Growth in Health and Dis-ease. London: Oxford Medical Publishers, 1933.
2. Wegner, C.: tYber das normale und patholo-gische Wachsthum der R#{246}hrenknochen. Arch. f. Path. Anat., 61:44, 1874.
3. Ludloff, K.: lYber Wachstum und Architektur der unteren Femurepiphysere und oberen Tibiaepiphysere. Beitr. Kim. Chir., 38:64, 1903. 4. Stettner, E.: lYber die Beziehungen der
Ossifi-kation des Handskeletts zu Alter und L#{228}nger-wachstum bei gesunden und kranken Kindern von der Geburt his zu Pubert#{228}t. Arch. Kinder-heilk, 69:27, 1921.
