In the
article, the author raises the question of the function of the ligamentum
capitis femoris (LCF). The researcher develops the views of Professor William
Turner outlined in «Human Anatomy and Physiology» (1857TurnerW). An important
point of the work presented below is the view that LCF «...is especially called
into action whenever the weight of the body is thrown upon one leg».
ON THE USE OF THE LIGAMENTUM TERES OF THE HIP-JOINT
What is the
function of the Ligamentum Teres? Many authors who describe this structure are
silent on the question, while of those who answer it the general conclusion is
that it has, for its chief function, to limit adduction of the thigh, or when
the thigh is fixed, to limit lateral movement of the pelvis on the femur — to
prevent the pelvis from rolling toward the opposite side; Authors, of course,
are not fully agreed in explanation of its use, and other less prominent
functions are by many assigned to it, such as to limit rotation of the thigh;
but the conclusion substantially arrived at is the one given above. I cannot,
and need not, here quote from the several authors who are entitled to speak
with authority on the subject, but neither in them nor elsewhere can I find any
allusion to what appears to me to be the prime purpose of this ligament*. Its strength
is very great; its attachments are remarkable; its situation is peculiar. I
submit the following explanation of its use.
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* Since this paper has been in type I have learnt that Prof. Partridge
in his lectures on anatomy at King's College was accustomed to compare the
Ligamentum Teres, in its function, to the leathern straps by which the body of
a carriage is suspended on springs ; and my attention has been called to the
following passages published by Prof. Turner in 1857 (Human Anatomy and
Physiology, Edinburgh): «In the interior of the joint (hip) is a strong band of
fibres called the inter-articular or suspensory ligament. When a person is
standing erect or with the body slightly bent, a portion of the weight of the
trunk is borne directly by the heads of both thigh-bones, or of one thigh-bone,
according as he stands upon one or both legs, owing to the direct pressure of
the acetabulum upon the heads of those bones. Now as the end of this ligament,
which is connected to the lower margin of the acetabulum, is much lower than
the end connected to the thigh-bone, it of necessity suspends that portion of
the weight of the body which is thrown upon it. The effect of this is to
distribute over the head of the thigh-bone that weight which, supposing the
suspensory ligament had not been present, would have been sustained by that
portion merely which is in direct contact with the upper part of the
acetabulum.» (p. 42.)
------------
When the
person is erect the ligament is vertical and tight. This statement, although
generally accepted, has been challenged. I am satisfied of its accuracy.
By removing the bottom of the
acetabulum fi-om the pelvis with a trephine the state of the ligament may be
demonstrated. But I think the discrepancy of observation is due to the fact
that the degree of tension of the ligament is dependent on the line of
direction of the femur. The ligament is moderately tight when a person stands evenly
upon both legs. It is tighter when the femur is slightly flexed as it more
usually is. But when resting upon one leg, inasmuch as the pelvis is then
raised on that side, which of course affects the ligament in the same way as
adduction of the femur would do, then the ligament becomes extremely tense. In
other words, it becomes tightest when the hip-joint has to sustain the greatest
weight.
When
therefore the pelvis is borne down upon the femur, or when the femur is forced
upwards — that is, when the pressure would be greatest between the upper part
of the acetabulum and the opposite surface of the head of the femur — it is put
directly on the stretch. More precisely, its great purpose is to prevent undue
pressure between the upper portion of the acetabulum, just within the margin,
and the corresponding part of the head of the femur. But for this ligament such
undue pressure must inevitably occur. Suppose the Ligamentum Teres absent, and
the person standing upright : owing to the obliquity of the acetabulum and the
head of the femur — of the axis of the joint— pressure between the two could
not be equally, or nearly equally, diffused over their opposing surfaces, but
it would be concentrated on a spot in the upper part of the socket through which
a line drawn down the body, through the joint into the leg, would pass. When
the thigh is straight, when the femur is in a line with the body, as when one
stands upright, then is the Ligamentum Teres in the same line too, and
consequently any force which drives the femur and pelvis together must tell at once
upon the ligament, and be directly checked by it.
Owing,
therefore, to the shape and obliquity of the hip-joint, and the weight of the
body, the Ligamentum Teres is necessary to prevent concentration of pressure at
a particular point above it.
The line
through which the weight or force acts between the upper part of the acetabulum
and the opposed surface of the head of the femur forms, with the line of weight
or force which passes through the Ligamentum Teres, an obtuse angle; and the resultant
of these forces is in a line which passes through the long axis of the head of
the femur.
When the
person is erect the body partly hangs upon the Ligamentum Teres.
I submit
that this is the prime function of the Ligamentum Teres. Other purposes I do
not deny, but would maintain that they only occasionally come into play, and
are altogether subordinate to this one, which is especially called into action
whenever the weight of the body is thrown upon one leg.
Now this
view may be tested by the facts of comparative anatomy.
It has
often been remarked that the Ligamentum Teres is apparently distributed among
animals in a very arbitrary manner.
In most of
the mammalia it is present, e.g. in ruminants, rodents, and terrestrial
carnivora. In many other absent, e.g. in the elephant, sloth, seal, walrus,
sea-otter, ornithorhynchus, and echidna.
It exists
in animals with the utmost diversity of form and habits.
It is
sometimes present in one animal, e.g. the chimpanzee, and absent in another
very closely related to it, e.g. the ourang-outang**.
------------
** There is great difference in the degree to which the Ligamentum Teres
is developed in Birds. In some it hardly appears, while in many it is very
strong. The great depth of the groove in the head of the femur of the Ostrich
shews the size it occasionally attains. In several birds in which I have
dissected this ligament I have always found its pelvic attachment to be, not to
the border of the acetabulum, but to the lower margin of the large foramen or
foramina which exist at the bottom; this, so far as its action is concerned,
comes to the same thing.
------------
Now is it
possible to discern the conditions under which it is present or absent?
When the cavity
of the acetabulum looks downward and the head of the femur upward, in other
words, when the direction of the hip-joint is nearly vertical, and the weight
of the body falls through the centre of the joint, then the Ligamentum Teres is
absent, e.g. elephant.
When the
acetabulum looks outward and the head of the femur is inclined inward, in other
words, when the hip-joint is placed obliquely, so that there would otherwise be
undue pressure at a particular part, then the Ligamentum Teres is present, e.g.
horse.
The
exceptions to this occur in those animals in whom, although it is an instrument
of progression, the posterior extremity does but little in supporting the
weight of the body, e.g. seals, and the ourang-outang.
These
facts, that while the Ligamentum Teres is found in the chimpanzee and other
monkeys, it is almost or entirely wanting in the ourang-outang, at first sight
apparently so capricious, are very suggestive. It is easy, I think, to understand
why it is generally present in monkeys, inasmuch as in them the hip is placed
obliquely, and the posterior extremity can support the trunk. But the hip-joint
is oblique also in thei ourang-outang. The conformation of the foot, however,
is the; key ta the explanation of its absence here. It is clear that in the
ourang-outang the posterior extremity cannot be such an instrument of support
to the trunk raised upon it, as in the chimpanzee, and consequently the
Ligamentum Teres is not needed to counteract undue pressure at a particular
point.
Again, it
may be said that when an animal stands, in proportion as the long axis of the
head of the femur approaches to a vertical line, so does the Ligamentum Teres
become weak until it disappears. On the contrary, it is strongest where the head
of the femur has a direction farthest from the vertical, and has to support the
greatest weight.
In
conclusion, I should like to call attention, without attempting to lay too much
stress on it, to a specimen (2. 43) in the pathological series of the museum of
St Bartholomew's Hospital, which is thus described in the catalogue.
«Two
hip-joints from the same person. In each joint the Ligamentum Teres is
completely wanting. The capsule of each is perfect and exhibited no appearance
of disease. In the usual situation of the attachment of the Ligamentum Teres
there is a
deep depression
in the head of the femur, and just above this the cartilage of each femur is
slightly absorbed.»
It may be
observed that the cartilaginous shell on the head of the femur is naturally
thickest on the upper and inner aspect.
The above
Paper was read at a Meeting of the Cambridge Philosophical Society, in April,
1874.
In discussions which followed Professor Humphry, after expressing his
obligation to Mr Savory for affording the opportunity of discussing the subject
with him, observed that the suggestions made with reference to the function of
the ligament by Mr Savory rested entirely upon the view that the ligament is
tight in the erect posture. Professor Humphry was one of those who had
challenged this view, of the accuracy of which Mr Savory had expressed himself
to be satisfied. He referred to his work On the Human Skeleton including the
Joints, in which he had stated as the result of careful observation that
the ligament is not tense and cannot be rendered tense in the
erect posture. He had lately reconsidered the question and re-examined
the specimens, or some of them, upon which his statement had been based, as
well as other recent specimens made for the purpose, and he was convinced that
it was correct. In the first place, the dimple in the head of the femur for the
ligament is more or less oblong or pear-shaped, and is directed from above
downwards and backwards with such obliquity that the ligament can lie in it, as
it must do when it is in a state of tension, only in the semifiexed position of
the hip, the thigh being inclined from the vertical to an angle of about 45°.
This can be seen in the dry bone, and still better in recent specimens in which
the direction of the insertion of the fibres of the ligament are seen to
correspond with this view. Secondly, the trephine hole through the bottom of the
acetabulum shews clearly that it is at about this angle only, and when the
thigh is adducted, that the ligament is really tense. In the erect posture, and
by the erect posture he meant when the thigh descends vertically from the
pelvis and the capsular ligament, more particularly the anterior part of it, is
tight, neither adduction, nor rotation, nor any other movement will throw it
into a state of full tension. If this is so, which the several specimens
examined by the Professor proved to be the case, then it is quite certain that
the body cannot hang upon the Ligamentum Teres when the person is erect, and
the inferences based upon such a view fall to the ground.
When resting upon one leg the body is tilted a little over to that side
so as to throw the line of gravity more directly over that limb, the opposite
side of the pelvis is slightly raised, the movement being equivalent to that of
adduction of the limb upon which the weight is borne, and the Ligamentum Teres
is not stretched, but is still more relaxed than in the erect posture. Even in
the position of 'stand at ease,' when the weight is borne upon one limb and the
opposite side of the pelvis is lowered, the other limb being placed upon the
ground slightly flexed, the movement now being equivalent to that of adduction
of the weight-bearing limb, though the Ligamentum Teres is less relaxed than in
the former position, and is also less relaxed than in the erect posture, still
it is not tight; and the body is slung, not upon the Ligamentum Teres, but upon
the thick and strongly resisting upper portion of the anterior ligament of the
hip. The use of the ligament the Professor believed to be, as he had stated in
his work, to assist in bearing weight when the limb is placed upon the ground partially
flexed and adducted, when the capsule of the hip is comparatively relaxed, and
when, if the body be overweighted, dislocation is most likely to occur. In
estimating, however, its value, even in this position, it must not be forgotten
that several instances have occurred, some of which are noted in Meckel's Archiv,
vi. 341, in which the ligament was wanting without its being known that any inconvenience
had resulted from its absence. In dislocation, too, it must be severed, and it
is highly improbable that it ever unites. It has been found indeed ununited.
Still the loss of it does not appear to be much felt.
With regard to other mammals the ligament as stated in the paper is
commonly absent when the lower limbs do not bear much weight, and also when
they descend vertically from the pelvis. The Professor had, however, pointed
out in the Journal of Anatomy, Vol. iii. p. 312, that it is present in the
Bats. In most mammals in which it exists the dimple or furrow or angular
depression which it occupies in the head of the femur is oblique, as in Man,
indicating its tension in them, as in him, to occur in the semiflexed position
of the joint.
There were other points to which the Professor took exception, but the
important one was this of the position of the joint in which the tension of the
ligament takes place.
Mr Savory, in reply, remarked that he quite agreed with Professor Humphry that, if he were wrong as to the assumption of the tension of the ligament in the erect posture, his view fell to the ground, but he could not agree with the Professor as to what really is the erect posture. The skeletons in museums are commonly articulated wrong, and give too much inclination to the pelvis, and he thought Professor Humphry was in error on this point, and that if the ligament be examined in the strictly erect posture it will be found tight, or more nearly so than the Professor admitted. He added that by applying his view he had generally been able to judge from the direction of the limbs in well-articulated specimens of animals whether the ligament had been present during life or not. Still there were some exceptions, among the most notable of which was the difference between the ostrich and the emeu. In the former it is large, whereas in the emeu it is absent. Yet, though he had visited the latter animal in the Zoological Gardens, and examined its posture and movements with reference to this question, he had been unable to make out why it should thus differ from the ostrich.
References
Savory WS.
On the use of the ligamentum teres of the hip joint. J Anat Physiol. 1874;8(2)291-6.
[ncbi.nlm.nih.gov , archive.org]
Authors & Affiliations
William Scovell Savory (1826-1895), F.R.S., Surgeon and Lecturer on Surgery, St Bartholomew's Hospital, late Professor of Comp. Anat & Physiol., R.G.S.E. wikipedia.org
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William Scovell Savory, 1st Baronet (unknown date) Unknown author, original in the wikimedia.org collection (CC0 – Public Domain, color correction) |
Keywords
ligamentum capitis femoris, ligamentum teres, ligament of head of femur, anatomy, role, significance, biomechanics, pathology, absents
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