The Size of the Articular Surfaces of the Long Bones As Characteristic of Sex; an Anthropological Study

THE SIZE OF THE ARTICULAR SURFACES OF THE LONG BONES AS CHARACTERISTIC OF SEX; AN ANTHROPOLOGICAL STUDY. BY THOMAS DWIGHT, M. D., LL. D., Parkman Professor of Anatomy at the Harvard Medical School. WITH 6 PLATES. The pelvis has long been recognized as a reliable guide to the sex of the skeleton and still longer as the greatest peculiarity of the female figure. From twenty to thirty years ago several papers appeared on the means of determining the sex of the skull. It is, I think, now generally admitted that the skull is of value in the hands of an expert; but the late Professor Brinton very near the end of his life declared that apart from the pelvis there is no guide to the sex among the bones. Hyrtl (1) long ago wrote : " I find the difference between the male and female sternum so clearly expressed by the proportion of the manubrium to the body that it is hardly possible to err in determining the sex. The manubrium of the female sternum exceeds in length that of half the body; while in the male sternum it is at least twice as long as the manubrium. I (2) was able to show on sufficiently large series that while this was true of the average male and female sterna, it was not true of about 40 per cent of the individual instances, so that it was very possible indeed to err in determining the sex by that means. Prob- ably the rule applies to well-formed bodies, but not to a large proportion of those that we meet with. The femur again is a bone that is to the expert of much value. A typical male and a typical female femur can hardly be mistaken; but practically there are a great many thigh bones, perhaps 75 per cent, on which an expert would be unwilling to give an opinion by methods hitherto in use. Without going so far as Professor Brinton, we may say that with our present methods, excepting the pelvis, and even this is not always conclusive, in the great majority of cases the expert must form his opinion of the sex of bones from their general appearance, and that comparatively rarely can he speak (still excluding the pelvis) with any great certainty. AMBIRICANJOURNAL OF ANATOMY.-VOL.IP. 20 Size of Articular Surfaces of Long Bones The purpose of this paper is to present a new method, which indeed J have suggested before, but which I had not established by a sufficient series of observations ; namely, the relatively small size of the articular surfaces of the long bones in the female. If this be true it clJrtainly deserves a place among the laws of anthropology. While I believe that this applies to the long bones in general, I have limited the demon- stration of the principle to the heads of the humerus and femur. In the Shattuck lecture on the Range and Significance of T7ariation in the Human Skeleton, which I had the honor of giving before the Massachusetts Medical Society in 1894 (3), I advanced the opinion that the size of the articular surfaces of the limbs has an important sexual significance. I mentioned that I had studied the dimensions and propor- tions of the glenoid cavity of the scapula on 63 male and 27 female bones. Its average length in the male bones was 3.92 em. and in those of the female 3.36 em. Very few male ones were less than 3.6 cm. and very few female as long. Though I had made observations on the bones of the arm and forearm I had no series large enough to quote; but I spoke more in detail of the observations on 64 femora on which many measurements had been taken, and which came from bodies that had been measured before dissection. After discussing some of the more common features as guides to determine the sex, I said: “ Some other measurements seem to throw more light on this matter. They tend to establish the theory that the small size of joints is characteristic of woman. They are the greatest diameter of the head of the femur and the greatest transverse breadth through the condyles. The average diameter of the male head is 4.8 em., that of the female 4.15. My tables show one marked difference between the sexes; namely, that in the women there is a fairly regular increase in the size of the head cor- responding with the increase in length of the femur. Among men this is not so. While it is true that most of the largest heads are found in the longer half of the bones and most of the smallest in the shorter half, the correpondence is far less evident. I find, moreover, that but two male heads have a diameter of less than 4.5 em., and but two of the female a greater. Both these female bones were among the longest, but the two male were but little below the average. Thus it would seem that the actual measurement of the head of the femur is a pretty good criterion of the sex. The measurements of the knee are less conclusive. The average difference is just under one centimeter (8.3 and 7.3), but there are more that overlap.” Dr. Hepburn (4) published jn 1896 measurements of femora of many races, one of the measurements hejng that of the head. He did not, Thomas Dwight 21 however, make any attempt to consider the sexual significance of the head. In fact, there were but few females among the bodies of Europeans from which the bones were taken. He mentions, however, incidentally, that the diameter of the head of the male femur was never below 40 mm., except among the Andamans; and also that a diameter below 40 was found in several female bones of various races. Dr. Dofsey (5) published in 1897 a paper recording observations on the long bones of American aborigines in which he tested the accuracy of my views, taking the greatest diameter of the head of the humerus and of the femur and also the breadth of the upper end of the tibia. The sex was first decided from the .pelvis. His results from the heads of the bones of 135 skeletons of various races of both North and South America were very strikingly in confirmation of the value of the size of the joints as a sexual characteristic. “ Thus, if the maximum diameter of the head of the humerus of any American skeleton measure 44 mm., the chances are extremely great that it is a male; if it measure 45 mm.. it is a male to a practical certainty. The inference to be drawn from the measurements of the femur seem almost, if not quite, equally valuable; and it would almost seem that we could determine the sex from the femur alone with a great deal more certainty than we could from the skull. After Professor Jwight’s disparaging remarks about his results from measurements through the condyles of the femur, I was quite unpre- rared for the results which have been derived from the tibia. The range of variation is, to be sure, greater than it is for either the humerus or the femur; and this, it may be repeated, is largely due to the discrepancy in stature between the North and South American skeletons, but the dividing line for the two sexes, between 71 mm. and 72 mm., is almost as sharp as it is for the femur, and makes the tibia a valuable aid for the determination of sex.” Although I was satisfied that the principle that the small size of ioints is characteristic of woman is correct, I felt that it should be established by a series of measurements large enough to be beyond question. Accord- ingly, I undertook to make the measurements of the head of one humerus and one femur of 100 male and as many female bodies. Those of white adults only were used. The head of the humerus was measured in both the vertical and the transverse diameter, .the object being to get the greatest diameter for each, even if it deviated somewhat from the strictly vertical or transverse plane. In the femdr the greatest possible diameter was carefully sought for. The measurements were made with blunt calipers. The bodies were those used for anatomy and surgery in the Harvard Medical School. I took the measurements when the cartilage was still 22 Size of Articular Surfaces of Long Bones fresh. This is certainly proper for the purpose of an anthropological study as it represents the size of the joints as they are in life. Moreover, on many dried bones, the cartilage remains as a very thin layer, which, though amounting to little, causes a discrepancy between those bones and others in which it has been quite removed. The question of what deduction from diameters thus obtained should be made in comparing them with those from dry bones shall be considered later. When I had obtained these measurements on 100 male and 100 female bones I tabulated the results and drew the curves. While the results seemed to establish the law, the curves were so irregular that it seemed certain that they could hardly show a true mean. I then made 50 more examinations in each sex, and again was dissatisfied with the curves, and undertook 50 more. Thus I have now the measurements of 400 bones equally divided between the sexes.

Load more