Paper - The epiphysis of the head of the femur (1915)
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The Epiphysis of the Head of the Femur
By Tuomas Walmsley, M.B.,
Demonstrator of Anatomy, Glusgow University.
So far as the writer is aware, there is on record no detailed description of the epiphysis of the head of the femur—that separate centre of ossification in the continuity of the cartilaginous “Anlage” — apart from the usual statement that the margin of the articular cartilage of the head represents the position of the epiphyseal cartilage.
At birth, as is well known, the femur is ossifying in its diaphyseal portion, the lower epiphyseal centre is usually present, but the whole of the upper extremity of the femur is as yet one undivided mass of cartilage —the tri-epiphyseal cartilage (fig. 1). In this upper cartilage appear ossific centres, for the head towards the end of the first year, and subsequently for the trochanters. In the consideration of that centre which ossifies as the articular portion of the head of the femur, there will fall for study the shape and change of shape of the epiphysis, the position and change of position of the epiphyseal cartilage, the effects of these changes in addition to their causation, and of this especial epiphysis its blood supply.
Fig, 1. — The proximal extremity of the Fig. 2. — The ossific centre for the epiphysis femur, at birth. of the head, at eleven months.
The ossific centre for the head, often surrounded by a number of small osseous granules, appears then a little earlier or a little later towards the end of the first year,! and the position of its earliest occurrence is above and medial to the centre point of the whole head (fig. 2). After the appearance of this ossific centre, the head, yet mainly cartilaginous, is still connected with the great trochanter by a thick mass of epiphyseal cartilage ; but after differentiation of the trochanter as a separate ossification, these two epiphyses are gradually separated from one another by the growing diaphyseal neck, and subsequently increase in size quite independently of one another. By the end of the fourth year nearly the whole of the epiphysis of the head is osseous, the cartilage now consisting only of the thin dentate epiphyseal cartilage separating the head from the neck. At seventeen years the epiphysis is fully ossified, and finally joins the diaphysis about nineteen to twenty years, though a line of separation often persists at the circumference, especially at the lower part, even with margin, at twelve years.
1 This centre may appear at the tenth month, or may be absent at the thirteenth month.
Fig. 3. — Section through head of femur, Fig. 4. — Vertical section of femur, at medial and parallel to the articular twelve vears,
firm osseous union at the centre. On section, a line of dense bone persists for some years, indicating the line of cartilaginous union. Taking, however, a section through the head parallel to the articular margin but medially distant about one centimetre, such as is represented in fig. 3, at about twelve years of age, there is clearly shown the large part taken by the diaphyseal neck in the formation of the central core of the head, and the peculiarity of the manner in which it does so. This peculiarity consists of the greater proportional representation of the diaphysis at the under part of the head as compared with the upper. An examination of the upper surface of the diaphysis is explanatory of this peculiarity, for on reference to fig. 4 it is clearly shown that the inner end of the neck projects above the general plane of the rest of this diaphyseal surface. At this age (twelve years) the diaphysis of the neck forms a central core down over which the articular surface of the epiphyseal head extends: not in a regular fashion, however, but yet so as to embrace the upper end of the neck in a circularly complete manner. While the under surface of the epiphysis of the head is thus concave in all directions, it is most deeply excavated at its application to the medial process of the neck, and the extension of the epiphysis over the diaphysis is in this situation the most limited. (Macalister has already pointed out how the thin irregular rim from the head extends outwards over the upper part of the neck, and assists in the transmission of weight from the head above to the calcar femorale of the neck below.) From a morphological point of view, however, it is more important to recognise that the lower aspect of the epiphyseal rim extends to the least extent over the diaphyseal neck, that it is the thinnest part of the whole epiphysis, and that it is the last portion to become osseous. It will also be noted, and more especially at the period immediately previous to the bony union of the epiphysis with the diaphysis, that both ossifying surfaces are irregular; and the irregularities are so arranged and of such a shape, that small hemispherical nodosities of the upper surface of the neck are occupying small concavities of the under surface of the head.
Fig. 5. — Head of femur of seal—diagrammatic.
On tracing the ontogeny of this epiphysis, the diaphyseal spur at the medial extremity of the neck will be found to be best developed towards the age of puberty; and though in the process of formation it may be recognised at an earlier period of life, till the age of four years it is certainly non-existent. The advantage gained by such a process is in preventing any undue tendency to luxation of the epiphysis, a tendency, as may be shown, at its greatest degree of mechanical possibility when this natural means of prevention arrives at its maximum of development. A comparison with the femur of the seal is instructive not only as regards the phylogeny of the medial process of the neck, but also in assisting to a . decision of the morphology of the ligamentum teres of the hip-joint. In the Ross seal the articular head of the femur is incomplete, so that the medial process of the neck is entirely a superficial structure (1) (fig. 5). That the ligamentum teres is isolated by the development of the head of the femur as a wing expansion on each side of the ligament, with subsequent fusion of the wings under the ligament at the lower part of the head, as stated by Keith, seems strongly substantiated by the mode of development of the epiphysis.
The axis of the head and neck of the femur in the fcetus is, in respect to that of the shaft, vertical, or perhaps spiral, so that the angles of inclination and declination are both of large size (150° and 45° respectively), and till the end of the first year there is little alteration of the femur in these respects. The epiphyseal cartilage will thus be found horizontal in position even as late as the third year. After this period, however, the cartilage comes more and more to occupy an oblique position, so that before its final absorption it slopes downwards and inwards at an angle of at least 30°. As causative of this change there is the interaction of the developmental and mechanical forces. For, on to the almost vertically growing femoral neck of the young subject there is transmitted, more on its medial than on its lateral side, a shearing force acting vertically, tending to produce an angle between the two components of the femur, and as a result there is, not a bending of the cartilaginous tissue of the head or of the osseous tissue of the neck, but a change in the plane of the epiphyseal cartilage. This cartilage is horizontal in the young bone, and to assume the adult obliquity there is, as it were, a greater amount of growth at its outer end than at its inner end. Asa direct result of this change in position there are two alterations in the form of the femur. Firstly there is the progressive decrease in the angle of inclination of the neck, and secondly there is the alteration in position of the axis of the head. The head, transmitting the same vertical force as before, becomes “tilted over” to the oblique adult position, so that at that period of life, ten to fourteen years, while the cartilage is in the adult obliquity yet still cartilaginous, there is the greatest tendency to the occurrence of the condition of “traumatic slipped epiphysis.”
The blood-vessels which enter the hip-joint by passing under the transverse ligament of the acetabulum have been defined by all observers as arising from the external branch of the a. obturator and from the medial . circumflex branch of the a. profunda femoris. The work of Ssawwin (2) is the most detailed. He demonstrated by means of very fluid injections that the obturator branch anastomosed with that of the medial circumflex to form two main vessels, one, the a. acetabuli, constant, which formed a rich vascular network in the Haversian fat, the other not at all constant, the a. ligamenti teretis, which ran through the ligamentum teres to the head of the femur. In some cases he found no vessel in the round ligament at all, in most a fairly well-marked channel, and in a few specimens a double artery.
The method adopted by the writer was one of differential injection with very fluid media, the posterior division of the internal iliac artery being injected with one colouring matter, and the rest of the body with a differently coloured preparation. By this means it was determined that running underneath the transverse acetabular ligament there is a large branch from the external division of the a. obturator, and a smaller branch from the internal circumflex artery. These two vessels united in the floor of the acetabulum and formed a network, exactly as described by Ssawwin, and from this network a small branch proceeded to the ligamentum teres.
Many authors hold, of course, that this is the sole function of the ligamentum teres, to lead vessels to the head of the femur.! After a most careful inquiry Welcher (3) came to opposite conclusions. On an analysis of 30 cases he found that
in 9, there were no vascular markings on the floor of the teres fossa ; in 11, only one or two small pits ;
in 8, there were three to six foramina;
in 1 ten, and in 1 twenty-five small openings.
Hyrtl also upholds the view that the ligament does not convey bloodvessels to the head of the femur, and claims to have proved that at the femoral extremity of the ligament the arterial vessel forms a capillary loop and runs back as the vein. For the present work about 100 round ligaments were examined for the contained vessel by means of a hand lens, yet a vessel of any size was never found; therefore it was concluded that not only is this vessel not the sole supply, but that it can convey only a very trifling amount of blood to the head of the bone. On minute examination of the “ differentiated” specimen numerous vessels were found ascending to the head from the articular margin, but not the slightest evidence of any vascular channel from the ligamentum teres into the neighbouring bone could be determined; that is, in the adult at least, the blood-vessels of the ligament are not destined for the supply of the head of the femur. In support of this anatomical fact there is the finding of pathology, first in regard to dislocation of the hip, and secondly in fracture of the neck of the femur. For the full development of the former condition there must be of necessity a complete rupture of the round ligament, yet after reduction of the dislocation it is never held that the head of the femur is defective in nutrition. A considerable amount of detailed work is available in regard to fracture of the neck of the femur, and here the consensus of reliable opinion is that the condition of the ligament is absolutely immaterial, the rupture or non-rupture of the synovial and fibrous connexions between the neck and the head with the contained vessels determining the future state of the head.
- 1 Henle and Sappy both held this view.
It is in the child, however, it is by some writers held, that the ligamentum teres as a means of leading vessels to the femoral head is in the fullest degree active, and after that period the blood supply is derived from the blood-vessels of the diaphysis at the articular margin (Lange). Against this view there are the very dogmatic statements of Fick and of Welcher. The former (4) definitely states: “In the young subject the blood supply is not through the round ligament, but through the vessels which enter the large foramina at the articular margin of the head”; while the latter is equally certain of this view in the determined absence of vascular foramina in the teres fossa of the embryo and of young children.
Fig. 6. - Blood supply of centre of ossification, at two years of age.
Fig, 7. - Blood-vessels of head, at six years of age.
For the present work two male children, aged two years and six years respectively, were prepared by the differential injection method already described. In the child of two years—that is, at a period when the ossification of the head is not to any extent advanced—the blood-vessels which passed to the osseous nucleus were derived in no part from those of the ligamentum teres, but entirely from vessels entering the neck of the femur at the articular margin of the head. These vessels are distinctly seen in their course to the centre of ossification, lying in the lower part of the cartilage of the head, but a small area of the superficial cartilage above this centre and in the immediate proximity of the attachment of the ligamentum teres did seem to be vascularised from the a. ligamentum teretis (fig. 6). The specimen obtained from the child of six years (fig. 7) also gave emphatic evidence that for purposes of ossification the blood supply is obtained, not from the vessels of the ligamentum teres, but from those which enter at the articular margin of the head and pass thence proximal to the epiphyseal plate to ramify in the osseous substance of the head. And when in addition it is determined in those cases of congenital dislocation of the hip that the head of the femur undergoes no especial atrophy in the absence of the ligamentum teres, it may no longer be held that “the round ligament conveys a blood supply to the head of the femur.”
As regards the foramina in the floor of the teres fossa, the following alternative view as to their causation is advanced. From a detailed examination of these foramina there is made evident not only the inconstancy in number as described by Welcher, but that the sectional area of the average number is out of all proportion to that which could possibly result from a subdivision of the a. ligamenti teretis: that is, all of these openings could not possibly be intended as vascular channels. Now, from a study of the method of attachment of the ligamentum teres to the head of the femur in the foetus and in the adult, it may be shown that, while the marginal parts of this ligament may become continuous with the superficial layers of the articular cartilage, the central parts are in direct continuity first with the cartilaginous and subsequently with the osseous substance of the head. And the foramina, found only in the adult, represent such channels of communication.
(1) THompson, “Osteology of Antarctic Seals,” Edin. Phil. Trans., vol. xlvii. p- 187,
(2) Ssawwin, “Die Blutversorung des Hiiftgelenks,” Cherurgya, Bad. ii. S. 461.
(3) Wetcuer, “ Das Hiiftgelenk,” Zettschr. f. Anat. u. Entwick., Bd. i. S. 41.
(4) Fick, Handb. d. Anat. u, Mech. d, Gelenke, Bd. i. S. 480,
Cite this page: Hill, M.A. (2020, October 19) Embryology Paper - The epiphysis of the head of the femur (1915). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_The_epiphysis_of_the_head_of_the_femur_(1915)
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