The work is dedicated to the experimental study of the function of the ligamentum capitis femoris (LCF). According to J. Struthers, «the position of combined rotation outwards with flexion is the only one in which the round ligament is employed as a checking structure». In 1848, the author proposed an original method of trepanation of the acetabulum floor for visualization of the LCF. A similar article was published in the Edinburgh Medical Journal, as well as in a separate monograph titled «In Anatomical and Physiological Observations» (see 1858StruthersJ).
CONTRIBUTIONS TO
ANATOMY.
By JOHN STRUTHERS,
M.D., F.R.C.S.,
LECTURER ON ANATOMY IN THE EDINBUBGH SCHOOL OF
MEDICINE.
No. II.
ON THE TRUE FUNCTION OF THE ROUND LIGAMENT OF THE HIP-JOINT.
It may seem
strange that the use of a great ligament in an important joint in the human
body should not be generally understood. That anatomists so able as Barclay,
Mayo, Knox, and G. and E. Weber should have come to different conclusions, and
that all of them should have missed the true one, could arise only from their
having adopted fallacious methods, or having merely theorized. By removing more
or less of the capsular ligament, they destroyed a structure which naturally prevents
several motions from going so far as to put the round ligament on the stretch.
They have thus assigned it uses which it has not, while, from not seeing it in
its natural position, they have unavoidably failed to discover its true
function. Reflecting on this, it occurred to me that the ligament might be seen
in its natural position, and its funetion discovered, by exposing it from
behind by the removal of the floor of the acetabulum. The capsular ligament
would thus be left entire, and, by putting the limb through its movements, the
state of the ligament in each would become a matter of simple demonstration. By
this method I was able to prove what is not and what is the function of the
ligamentum teres.
Method of
exposing the ligament. — In thus exposing the ligament a trephine may be used,
but it is better to begin at once with a gouge and mallet. The whole of the
floor of the acetabulum should be dug and scooped away, sloping the cut; as the
hone becomes thicker, so as to expose freely the ligament and the end of the
femur, as seen in Fig. 8. In approaching to within a fourth of an inch of the
upper or anterior half of the obturator foramen, care should be taken not to injure
either of the attachments of the round ligament to the edges of the cotyloid
notch. The fatty and synovial tissues of the Haversian cushion being now picked
away, the ligament will be exposed down near to its origin. The synovial
covering and any fatty tissue on the ligament should also be removed so as to
expose the fibres of the ligament proper. It is now seen that the ligament is
directed vertically upwards in the extended position of the limb, as in
standing, or as the body lies upon the table. Also that the ligament, in the
greater part of its length, is rounded, soft or pulpy, and more or less
twisted, except in that position which tightens it, when it assumes the form of
a straight-fibred, thick belt.
In order to avoid all source of fallacy, I have repeated the following observations, with the same result, on the subject after merely opening the abdomen and removing the viscera, and then putting the entire undissected limb through its motions; but the demonstration is most conveniently made on a moist ligamentous preparation of the half pelvis and upper third of the thigh-bone, the capsular ligament being dissected but entire. If such a preparation be preserved wet, the means of demonstrating the function of the ligament will always be at hand in the anatomical school. I have still in my possession the one on which I first employed, in 1848, this method to demonstrate the use of the ligament.
Fig. 1.
Typical form, size, and direction of cushioned recess in acetabulum.
Fig. 2.
Situation, form, and direction of the pit and groove on the head of the femur.
Figs. 3 to
6 show the direction and condition of the round ligament, and its relation to
the groove, in different movements. The pit is larger than the average, but not
larger than in the specimen from which the diagrams were made.
3. As in
rotation inwards.
4. Rotation
outwards.
5.
Adduction.
6. Rotation
outwards with flexion. Ligament tense, as in Fig. 8.
Fig. 7.
Diagram showing vertical position of ligament, and how, theoretically, it might
be expected to check adduction. But Fig. 5 shows its condition in extreme adduction.
Fig. 8. The round ligament is seen, exposed from behind, by removing the floor of the acetabulum. The femur is flexed and rotated outwards, carrying the ligament upwards, until it becomes tense, and checks the movement.
It will
render the demonstration more satisfactory if preceded by a clear comprehension
of the connexions and functions of the special bands of the capsular ligament.
A capsular ligament does not act as a whole, but is functionally made up of a
series of parts, each checking the movement in the direction opposite to it, or
some particular motion; and in joints with every intermediate motion, like the
hip and shoulder, the required intermediate parts come to fill up the spaces so
as to form a continuous bag. That is the true meaning of a capsular ligament. The
capsular ligament of the hip presents three special ligaments, the intervals
being filled up by thinner membrane. These are - 1. The ilio-femoral band, so
well described by G. and E. Weber as one of the greatest ligaments in the body;
proceeding from below the base of the antero-inferior iliac spine, and
broadening as it descends to be fixed to nearly the whole length of the
anterior intertrochanteric line. This ligament, I find, checks extension, adduction,
rotation outwards in the extended position, and assists in checking also
rotation inwards in the extended position. 2. The pubo femoral band, noticed by
some writers, the most slender of the three, proceeding from the horizontal
ramus of the pubes above the cotyloid notch, downwards and outwards to the
lower roughened end of the intertrochanteric line, about half an inch in front
of the trochanter minor. This band checks abduction. 3. A band which I am in
the habit of describing as the ischio-femoral, a strong flattened band,
proceeding from the acetabular margin, just behind the cotyloid notch, winding upwards
and forwards across the back of the neck of the femur, and inserted into the
great trochanter at the upper end of the anterior intertrochanteric line, just
where the outer part of the ilio-femoral band is attached. The direction and
function of this band explain why the capsular ligament has so little attachment
to the back of the neck of the femur. This band checks rotation inwards. It
will be observed that one of these bands proceeds from each of the three
primary bones which form the acetabulum and the haunch of the vertebrate skeleton.
The meaning
of the form of the depression on the head of the femur, and of the recess in
the floor of the acetabulum, are explained by this demonstration. If two lines
are drawn across the middle of the head of the femur, as in Fig. 2, it will be seen
that the depression on the head of the femur is situated in the lower and
posterior quarter, a little behind and below the centre; that it is elongated
backwards, or also a little downwards, and that the hinder end becomes
shallower and rounded off at the edges. Amid some varieties as to size and
depth, this will be found to be the typical form if a series of specimens be
examined, especially before the cartilage is removed or dried. The ligament is
attached only to the anterior end of the pit, the posterior part being a
groove, in the ordinary position as if uselessly directed away backwards from
the ligament, but which, as we shall see, exactly lodges the ligament during its
action. The anterior part may be distinguished as the pit, the posterior part
as the groove.
The form
and size of the cushioned recess in the floor of the acetabulum have relation
to the direction and extent of the sweep of the round ligament in the motions
of the joint. It extends a little beyond the extreme reaches of the ligament, and
the greater or lesser prolongation of its extreme points or angles causes a
good deal of variety in the form, size, and direction of the fovea. The study
of a series of specimens will, however, show that, as seen in Fig. 1, it is
generally somewhat square shaped, with the anterior superior angle as the
highest point (when the pelvis is placed with its natural obliquity) sometimes
considerably prolonged, and that this part is vertically above the cotyloid
notch. A bluntly diamond shape would, perhaps, describe its form better in
relation to its meaning. Whatever the variety may be, the typical form is, that
it broadens above the notch, and tends to throw out three angles, - an
anterior, posterior, and superior, - of which the latter is the most prolonged
or most distant from the notch and origin of the round ligament. The posterior
angle corresponds to the backward sweep of the ligament in rotation inwards, as
in Fig. 3; the anterior to the forward position of the ligament in rotation
outwards, as in Fig. 4, while the upper angle corresponds to the high position
to which the ligament is carried before it becomes tight, as in Figs. 6 and 8.
Thus the form and direction of these recesses in the femur and acetabulum at
once corroborate my view of the functions of the round ligament, and themselves
receive an explanation.
Condition
of the ligament in the various movements. - In proceeding to determine
experimentally the use of the round ligament, care must be taken that the
movements be not confused, especially that the femur be not rotated or flexed
unintentionally. From not attending carefully to this, erroneous conclusions
are apt to be drawn. To prevent mistake as to the position of the bones, the
half pelvis may be held as in the subject after lying on the table. It will be
granted that a ligament is not limb in use until it is tight, and if the
ligament can be made tense in one movement only, that this is conclusive
demonstration of its function. The condition of the ligament in several
movements might lead a careless observer to conclude that it is in use when it
is merely carried to nearly its full length, hut is not really tight. Let the
observer begin at once by rotating outwards in the flexed position, and he will
understand what tight really is. In order to judge of the degree of looseness
in different positions pass a loop of string round the ligament, and try
whether it can be pulled into an angle off the head of the bone, and feel with
the finger whether it is pulpy and round or flat and firm. The following is the
state of the ligament in the different motions of the joint. Each movement is
understood to be carried to the extreme, and to commence from the position of extension,
the ordinary position in standing, and as the subject lies on the table.
1.
Extension. - Ligament directed vertically upwarls, and loose. Groove directed
downwards and backwards from it.
2. Flexion.
- Carries groove forwards and ligament backwards and downwards, rendering it
more loose.
3. Abduction. - Brings upper attachment of
ligament down towards lower, and renders it very loose.
4. Adduction. - Ligament, as seen in Fig. 5,
is carried up, but is not made tense; is round, twisted, pulpy, and may be
pulled by the string away from the hall into an angle. It does not lie in the
groove, which is directed downwards and backwards from the ligament. Adduction
is checked by the ilio femoral band, in the extended position by the lower or
inner part of the band, in moderate flexion by the upper or outer part, while,
in extreme flexion, adduction is checked by the cervix coming against the pubic
part of the acetabular edge. The theory of the Webers [see 1836WeberW_WeberE] is,
that by checking adduction, the ligament serves, in standing on one leg, to
prevent the trunk from falling over to the opposite side, and thus to sustain
the trunk in the erect posture. This seems plausible as a mere theory from
regarding the position of the ligament, as seen in Fig. 7; but that it is not
tight in this position is readily shown by the fact that the movement of
adduction can be carried considerably farther, as by bending the body over to the
opposite side, or by carrying inwards the limb, the other limb having been
removed out of its way. And even then adduction is not checked by the round
ligament, as my demonstration shows, but by the ilio-femoral band. The dotted lines
in Figs. 6 and 8 show how far it must be carried up before it can be made
tight. If those who still teach the Webers’ view will make a preparation such
as that which I have recommended above, they will see that the theory of these
distinguished anatomists is not correct. The trunk is balanced in the erect
posture on the ball of the femur by muscular action, the ligaments coming into
use only in the extreme of each motion.
5. In rotation inwards the ligament is carried
backwards, as in Fig. 3, is nearer tight than in adduction, but is pulpy,
twisted, and round, bears no strain, and is not the checking structure. Groove
quite away back from ligament.
6. In rotation outwards. - Ligament, as in
Fig. 4, carried forwards, and is in much the same state as to tightness, feel,
and form, as in rotation inwards, but lies nearly, though not quite, in the
groove.
7. Adduction with rotation, inwards or
outwards. – The ligament is more nearly tight than in either rotation simply,
but is soft and round, and bears no strain.
8. Adduction with flexion. - Ligament not
tight, and less so in the extreme than in the moderate degree of this combined movement.
Groove a way obliquely backward from the ligament.
9. Rotation inwards with flexion. - Ligament
looser than in simple rotation in wards.
10. Rotation outwards with flexion. - The
ligament is carried directly upwards, is flat, straight fibred, occupies the
groove, is quite tense, and is evidently in use as a checking structure. This
is seen in Figs. 6 and 8, in which the position of the dotted line shows how
much farther up the ligament is carried than in extreme adduction.
The reason
why the flexed position now enables rotation outwards to put the ligament on
the stretch is evident. Flexion so relaxes the front of the capsular ligament
that the latter now allows rotation outwards to go much further, until it is
checked by the round ligament. The amount of flexion necessary to allow the
round ligament to be brought into use need not be so great as represented in
Fig. 8. Flexion to the extent of one-third of the way to bringing the femur to
form a right angle with the pelvis is enough, and in all degrees of flexion after
this the ligament remains on the stretch so long as the limb is also rotated
out. In this position the limb may now be abducted and adducted, the round
ligament still bearing the strain. The position of combined rotation outwards
with flexion is the only one in which the round ligament is employed as a checking
structure. Next to this, the positions in which it approaches the tight are,
adduction with flexion, adduction with rotation inwards, adduction with
rotation outwards, but in none of these positions does it bear any strain.
The
function, then, and the only function, of the ligamentum teres is to check
rotation outwards in the flexed position.
It is assisted in doing so by the outer, or
ilio-trochanteric, part of the ilio-femoral band, which, although at first
relaxed by the flexion, is soon made tense by the farther rotation outwards.
This part of the band may be seen to be quite tense at the same time as the
round ligament is so; and if the round ligament be suddenly divided when on the
stretch, any sudden yielding or jerk is prevented by this part of the
ilio-femoral band bearing the strain. These two ligaments, when tense, embrace
the head of the bone in nearly the same circular line the round ligament on its
lower and inner side, the outer part of the ilio-femoral band on its upper and
outer aspect, and both become tense at -the same time. As the force to be
resisted in this position is very considerable, we are not surprised, strong as
the round ligament is, to find another structure placed so as to assist it in
bearing the strain.
Dislocation
of the hip. - It is not difficult to explain why such special provision should
be made to check rotation outwards in the flexed position. A glance at the
skeleton will show that the acetabulum and femur are so directed that the head
of the latter has a natural tendency to be dislocated forwards by the outward
rolling of the limb, as in standing or walking with the toes, as they usually
are, more or less everted. Indeed, unless in the rotated inward position, part
of the ball lies naturally out of the socket, pressing forwards against the front
of the capsular ligament. The natural tendency, then, of the hip joint, from
its mechanism, is to dislocate forwards, although the fact is that the
dislocations forwards are comparatively rare. Very various notions are probably
entertained as to the way in which the direction that the dislocation of the hip
shall take is determined. The backward dislocations are not the most frequent
because the back of the capsular ligament is comparatively thin, but, rather,
the back of the capsule is thin because the ball does not tend by the natural
motions of the limb to throw itself out backwards, and because the front of the
capsule, in the extended position, checks inward as well as outward rotation.
My idea of the matter is, that the ordinary backward and upward direction of
dislocation is determined simply by the obliquity of the shaft of the femur,
the force driving the bone out in that direction; and we would expect the dislocation
as all the more likely to occur if the limb was caught in the rotated inward
position. Dislocation forward, on the other hand, whether pubic or obturator,
we would expect to happen from the limb being wrenched in the rotated outward position,
carrying the natural motion so unnaturally far as to rupture the strong
ligaments which check rotation outwards.
But whatever may be the explanation of the direction of the different dislocations, it is evident that the natural tendency is for the bone to throw itself out of the socket forwards Now to prevent this, there are two strong ligaments. In the extended position, as in standing with the toes turned more or less out, it is checked by the whole front of the capsular ligament, including the entire ilio-femoral band. But by flexion the front of the capsule is relaxed, allowing the outward rotation to go farther, until it is checked by the round ligament and by the outer part of the ilio femoral band. The limb is in this position when it is lifted and advanced in walking, or in stepping up with the toes everted, in sitting with the knees apart, or with one leg laid across the other knee, or in the tailor posture, or on horseback. In all these and similar positions the hip joint is flexed and rotated outwards, and the ligament is called into play to prevent the ball starting forward from the socket.
External links
Struthers, J. (1863). Contribution to anatomy. № II. On the true function of the round ligament of the hip join. The Lancet. 1863;Feb.81(2059)172-4. [archive.org , scholar.archive.org(PDF)]
Authors & Affiliations
John
Struthers (1823-1899) M.D., F.R.C.S., between 1845 and 1847 was Handyside’s Assistant
Demonstrator, Lecturer on Anatomy of Extra-mural School in Edinburgh since 1847,
Professor of Anatomy in the University of Aberdeen (1863–1889), President of
the Royal College of Surgeons of Edinburgh (1895–1897). journals.sagepub.com
.jpg) |
| Portraits of John Struthers (1850, age 27; 1885, age 62) From work: Keith A. Anatomy in Scotland during the Lifetime of Sir John Struthers (1823-1899): Being the First Sir John Struthers Anatomical Lecture Delivered at the Royal College of Surgeons of Edinburgh, 17th November 1911. Edinburgh Medical Journal. 1912;8(1)7-33. [ncbi.nlm.nih.gov] |
ligamentum
capitis femoris, ligamentum teres, ligament of head of femur, role, experiment,
significance
.
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EXPERIMENTS AND OBSERVATIONS
ROLE AND SIGNIFICANCE
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