studies on the femur. v. the femur at birth

STUDIES ON THE FEMUR V. THE FEMUR AT BIRTH

N. WILLIAM INGALLS Department of A n a t o m y , Wes tern Reserve Univel-sity, Cleveland, Ohio

THREE FIGURES

I n the course of our investigations on the femur there has been brought together a certain amount of material from male white fetuses at term. Although the series is very short, 10 pairs of femora, 20 bones in all, it has seemed advisable to put on record at this time some of the more general points of interest, while certain other special features will be con- sidered in the future. Another reason for offering this material at present is that we have recently (1926) published the results of measurements upon the fresh femur, with all cartilage intact, and it is naturally in this condition that the fetal femur must be studied. We are therefore able to compare the bones in what is practically their natural, living condition.

The methods employed are throughout the same as those used on previous occasions (1924,1926). The preparation of the bones consists simply in the careful removal of both the periosteum and perichondrium without damage to the free articular surfaces.

It does not seem necessary to enter upon any formal de- scription of the fetal femur. Its characteristic features will be brought out sufficiently by contrasting it with the adult bone, more especially with the adult bone with its cartilage fresh and in place. Figure 1 represents the adult and fetal femur in ventral view, reduced to corresponding oblique lengths. In table 1 there have been brought together the

107 hMERICAI? JOURNAL Ol? PHYSICAL ANTIIROPOLOGY, YOL. XI, NO. 1

OCTOBER-DECENBEB, 1927

108 N. WILLIAM INQALLS

02.702.57 02.35f.58 93.562.50

9.3 2 . 0 5 8.67f.06 6.762.06 7.05f.03 9.54f.12

31.65f.22 17.57f.13 16.97rt.13 28.72336 27.67f.21 21.142.19 21.64-t.20 19.82f.14 20.89+.15

principal dimensions, in their mean values, for combined right and left sides, together with the standard deviation, coefficient of variation and the range. The mean measurements of the fetal femur will be taken up later as indices, and it is only necessary here t o call attention to the coefficients of variation and contrast them with our results on the adult femur. Not- withstanding the small measurements and the shortness of the

TABLE 1 Data 0% male white fetal femora. Right and left combined

3.77k.40 3.672f.392 3.84f.41 3.7572.401 3.302.35 3.529k.376

.37k.04 3.9361.420

.38-C.04 4.346f.463

.38+.04 5.571f.594

.19&.02 2.710f.289

.80&.08 8.395f.895 1.462.16 6.7812.723 .85&.09 4.8452.517 .87k.O9 5.1232.546

1.042.11 3.621+.386 1.422.15 5.1411.548 1.292.14 6.1332.654 1.302.14 6.000f.640

.92&.10 4.6582.497

. 9 9 t . l l 4.731-t.505

NO.

1 2 3 4 5 6 7 8 9

10 11 12 13 1 4 15 16 1 7

MEASUREMENT

Kaximum length 3blique length Oiaphyseal length Platymeric sagittal Platpmeric transverse Pilasteric sagittal Pilasterie transverse Least sag. inf. diaph. rrans. same level Zead, vertical Bead, horizontal Epieoiidylar breadth [nf. articular breadth Lat. condyle, projected ;at. condyle, maximum Heed. condyle, projected Ned. condyle, maximuE

110.5 110 100

1 0 9.5 7.5 7.5

11 24 19 18.5 30.5 29.5 24.5 25 22 23

dinimum

98 97 88

8.5 8 6 7 8

18 16 16 25 24 19.5 20 18.5 1 9

series, the variability is much lower than was expected, rang- ing from 2.710 for the pilasteric transverse diameter to 8.395 for the least sagittal diameter of the lower end of the diaphysis. The mean variability for the 17 dimensions tabulated is only 4.879. In our 100 adult bones the range for combined right and left was from 4.691 for the epicondylar breadth to 10.2 fo r the least sagittal diameter of the lower end of the diaphysis. The mean variability for the corresponding 17 measurements was 6.438.

STUDIES ON THE FEMUR. V 109

I n a more recent series where the bones were fresh and all cartilage is intact, series A, the variability is a little higher than for the series of 100 which were macerated and dried. The mean variability for 5 measurements, right and left combined, nos. 2, 10, 11, 14 and 16 of table 1 are as follows: fetal, 4.903, 100 series, 5.388, series A, 5.965.

Not only is the fetal variability much lower than that of the adult, at least as far as this series is concerned, but there are also rather marked differences in the relative variability of different parts of the bone. As pointed out in an earlier article (1924) the epiphyses are the most con- stant part of the adult femur while the diaphysis is the most variable. In the fetal femur there are only faint indications of this. I n the fetus the least variable and the most variable features are diaphyseal in .character, with the epiphyseal measurements scaitered in betveen. The mean variability f o r the diaphysis however is very slightly higher than for epiphysis, 5.290 €or 6 dimensions as compared with 5.031 f o r 8 dimensions. I n the adult series the corresponding values were 8.824 and 5.204. In the fetal bone the transverse measurements, regardless of whether they are epiphyseal or diaphyseal, are less variable than the sagittal, 4.519 against 5.632. In the adult bone the relations are reversed 7.200 against 6.549. Of the 17 dimensions in question, in both series the least sagittal diameter of the lower end of the diaphysis and the transverse diameter at the same level are the most variable characters, with the difference that in the fetus the sagittal measurement is the variable while in adult it is the transverse. The means of the two f o r the fetus is 7.588, for the adult 9.868.

In the series of 100 the epicondylar breadth is the least variable dimension, but in the fetal series it is third in order while the pilasteric transverse is the least variable. Both of these measurements, however, in both series, are the least variable epiphyseal and diaphyseal measurements. In both series also there is a well defined tendency for closely asso- ciated dimensions to show a similar variability. There are

110 N. WILLIAM INGALLS

I I

I I

Figure 1


two rather conspicuous discrepancies in the two series which should be noted. I n the adult the width of the inferior articular surface is slightly more variable than the epicondylar width just above it, in the fetus the articular surface is very much more variable, a feature which may be correlated with a second difference in the region of the knee. I n the adult, although there is no great differences in the variability of the lengths of the condyles, the lateral shows slightly lower values than the medial. At birth, on the contrary, the lateral condyle is very definitely more variable than the medial. I f the variabilities shown in table 1 are arranged in order of magnitude and if the same be done f o r the corresponding measurements in the adult, it will be found that in both cases the medial condyle will fall in the middle of the series. The lateral condyle, however, will be close to the beginning of the series in the adult, and near the opposite end in the fetus. The greater Variability of the lateral condyle early in life may very well be an expression of the essentially human character of this part of the knee joint. As will be seen later, it is slightly longer, in relation to the medial condyle, than it will be later.

There is, therefore, here as in some other features, the tendency to accentuate the human characteristics. Except for the inferior articular breadth, this is the only feature in which the variability a t birth exceeds that of adult life.

Conditions somewhat analogous to those in the condyles also obtain in the femoral head, where the horizontal diameter is slightly more variable than the vertical, while in the adult the reverse is true, but by a smaller margin.

It should be pointed out that the diaphyseal length, no. 3 in table 1 is not the same as the diaphyseal lengtb used in our first article. In the latter case the length was determined from the point of intersection of the axes of the neck and shaft above, to the intcrcondyloid notch below. This method

Fig. 1 Adult and fetal femur reduced to the same oblique length. The short lines, above and below indicate the position of a vertical plane passing through the center or highest point of thc head.


naturally involved the determination of the axes of the shaft and of the head and neck and this was not done on the fetal material. Instead of this we have measured from the same point below to upper surface of the neck of the femur close to the great trochanter, a minimal measurement in all eases. We have had this determination in mind f o r some time as a possible means of measuring the length of the bone without including the head and neck or great trochanter. I ts relatively low variability is an argument in its favor, as well as the ease and dispatch with which the determination can be made. This new diaphyseal length is 91.41 per cent of the oblique length while the length as determined previously is only 85.74 per cent of the oblique length.

Further details as to the relative variability of different parts of the femur in the fetus and adult may be obtained by comparing table 1 above, with tables 1 and 2 of our first article on the femur.

Within any given series, the end result, as regards variability, may be looked upon as due to the operation of two sets of factors. The one is inherent, or hereditary in nature, while the other is composed of all those forces which tend to mold or alter, more or less successfully, the material or conditions provided by the first. In the case of the fetal femur these latter, extrinsic factors are of secondary importance and there obtains a low and rather uniform variability, with the exceptions being provided by characters which have an intensely human bias, and whose hereditary inertia is correspondingly weak or variable. With the advent of actual use and active functioning, the second set of factors comes into play with a consequent increase in the mean variability and also with changes in the relative variability of different parts of the bone. TVe have called attention elsewhere (1924) to the relatively high variability of the diaphysis as compared with the epiphyses. This is the result of the long operation of various extrinsic factors, the response of the hone to a great variety of environmental conditions, with the resulting changes, adjustments and adaptations, much more

STUDIES O N THE FEMUR. V 113

in evidence in the diaphysis than in the epiphyses. There is practically no difference, in the variability of eight epiphyseal dimensions, between the fetus and the adult, 5.031 as compared with 5.174. Between birth and adult life, however, the diaphyseal variability rises from 5.290 to 9.207 f o r six measurements. Diaphyseal or combined diaphyseal and epiphyseal dimensions are far more closely related to growth, stature,

TABLE 2

Femoral indices. Indices o f weam. Right and left combined. Series A is made up of 36 pairs of male white adult femora, fresh with. cartilage i?ttact

NO.

1 2 3 4 5 6 7 8 9

10 11 1 2 13 1 4 15 1 6 1 7

18 19

XEASUBEMENT

Platyinoric index Pilasteric index Upper gracility index Lower gracility index ltobusticity of femur iiider Direct, oblique length index First eapital index Second eapital index Third capital index Robusticitp of head index Bieondylar width index Condylar index Condylar lengths index Ext. capito-condylar index Int. cnpito-condylar index Condylar, projected index Condylar lengths, projected

Bicondyfar width, obl. iiidex Second capital, obl. inclex

index

FORMULA

4X 100/5 6 X 100/7 7 x 100/5 7 X 100/9

6 + 7 X 100/2 2 x 100/1 11 x 100/10 10 x 1 0 0 / 1

10 x 100/12 10+11x100/2

1 2 x 100/1 15 X 100/12 15 x 100/17 1 0 x 100/14 1OX 100/16 1 4 X 100/12 14X 100/16

1 2 x 100/2 10 x 100/2

FETAL SEIIIES

107.27 95.81 81.31 32.64 13.49 99.57 96.58 17.07 61.18 33.75 27.94 75.35

103.59 83.11 88.65 73.61

106.66

28.06 17.17

SERIES A

98.94

61.27 22.50

74.36 78.70 82.39

105.81

18.46 11.31

00 SERIES

83.52 103.49

87.8 50.00 12.60 99.36 99.44 10.41 58.05 21.10 18.11 78.78

102.36 74.76 78.19 77.64

108.45

18.23 10.58

weight, muscular development, etc., than are any of the purely epiphyseal dimensions.

'The femur at birth is short wit,h massive articular ends, a very short thick neck and a shaft which tapers rapidly from either end toward the center where it presents about the same proportion as in the adult. The angle of obliquity as well as the torsion and collar angles are less than those of the adult bone. In table 2 will be foand some of the more

I X G R I C A N JOCEXAL OF PIIYSICBL ANTITROPOLOGP, VOL. XI, NO. 1


important femoral indices not only f o r the fetal and adult macerated bone but also a few for the adult bone while it is still fresh and its cartilage intact. The numbers used in the formulae refer to the measurements as given in table 1. I n order to make more extended use of series A, for purposes of comparison, we have computed some of the indices on a somewhat different basis, Indices no. 14-19.

The platymeric index (no. 1) is very high in the fetus, 107.27 as compared with 83.52 in the adult, the higher index indicating a flattening from side to side or a greater antero- posterior diameter. I n fact the fetal femur at the platymeric level is roughly triangular with one apex behind. This pe- culiar form, as well as the high index, are due to the thickness and massiveness of the entire trochanteric region. Like the femoral head the trochanteric region is very bulky at birth, especially in its antero-posterior dimensions. Added to this is the conical or pyramidal lesser trochanter which occupies quite a different position in the fetus as compared with the adult. In the former it is higher up, just below the axis of the head and neck, it is also more laterally placed, just inside the center of the bone, looking almost directly backward and therefore not seen ordinarily in a ventral view (fig. 1). It is the ridge running downward from the lesser trochanter which gives rise to the triangular outline of the platymeric cross section. This configuration has made it more difficult to determine the proper level at which to take the platymeric diameters, the point selected being about 5 mm. below what appeared to be the base of the trochanter.

The pilasteric index (no. 2) on the contrary, is much lower in the fetus than in the adult, 95.81 against 103.49. In other words there is an antero-posterior flattening of the femur at its narrowest point at this stage, instead of the typical lateral compression of the adult, but the deviation from a circular cross section is greater in the fetus. Although there is a two- lipped linea aspera early, there is little o r no evidence of a pilaster and consequently there is a low index. I n later stages, under the influence of the weight carried on the head


of the femur, and the pull of the muscles attached to the linea aspera, there will gradually develop a more or less conspicuous pilaster. Related also with the low index, o r absence of pilastering is the very slight ventral bowing of the femur at birth.

The index of the upper gracility (no. 3) is lower at birth corresponding to the rapid tapering from the platymeric to the pilasteric level. The lateral flaring of the lower end of the diaphysis is even more marked as indicated by the very low index of lower gracility, (no. 4) 32.64 as compared with 50.00 in the adult. This last index does not correspond ex- actly with Pearson’s index for the reason that the popliteal width is taken at a slightly different point,

The robusticity of the femur (no. 5) varies but little in the fetus and adult since it is based, Pearson’s formula, on characters which undergo relatively little change. According to this the fetal femur is only a trifle more robust than that of the adult, the index being 13.49 f o r the former and 12.60 for the latter. If one employs the platymeric diameters instead of the pilasteric to compare with the oblique length then the fetal index rises to 17.62 but the adult to only 13.00, while the relations of the lower end of the shaft, measurements nos. 8 plus 9, to the oblique length give still higher values for the fetus, 30.58 against 19.07. The center of the shaft, therefore, is very small in the fetus as compared with the ends.

The relation of the oblique to the maximum length (no. 6) differs but little in the two series, 99.57 f o r the fetus and 99.36 for the adult. The maximum length does not at first show the excess over the oblique length which will occur later, due to the increase in the angle of obliquity and changes in certain other features.

The first capital index (no. 7) is a measure of the ellipticity of the head, indices above 100 would indicate a vertical flattening indices below 100 would indicate an antero-posterior flattening. The lower index at birth means a less spherical head, since the vertical axis is longer than the horizontal, the fetal index is 96.58, in series A, 98.94 and in the series of 100 i t

116 h’. WILLIAM INGALLS

is 99.44. In other words the head of the fetal femur is much more definitely flattened from before backwards than is the

+

Fig. 2 Outlines of the femoral head on sagittal section a t right angles to the eapito-collar axis. Outside is a perfect circle, with an index of 100.00. Within this is the form of the head in the male white, adult, cartilage in place, the mean index being 98.94. The innermost ellipse represents the fetal head with a mean index of 96.58. All indices represent combined right and left values. The short lines on the four sides of the figure indicate the location of the major and minor axes of the elliptical head, vertical and horizontal respectively. Actually the upper end of the vertical axis is a little in front of the lower end, and the posterior end of the horizontal axis is above the anterior end.

case in the adult. The actual difference in form is shown in figure 2. The outside line describes a perfect circle or a femoral head with an index of 100.00; then follows the head

STUDIES O X THE FEMUR. V 117

of the male white femur, with cartilage intact, with a mean index of 98.94. The innermost outline is the fetal head with a mean index of 96.58. In view of the fact that the femoral head becomes more nearly spherical later, one would be led to suppose that the acquisition of the definite form is dependent upon normal usage. This, however, says nothing as to why it should be less spherical at birth and it would be necessary to invoke inherent tendencies or in addition assume that the flexed position of the hip joint during development favors growth in the vertical rather than the horizontal diameter.

The relatively large size of the head of the fetal femur is shown by the second and third capital indices (nos. 8 and 9) and by the index of robusticity of the head, (no. 10). The second capital index is the relation of the vertical diameter of the head to the maximum length, the index being 17.07 for the fetus and only 10.41 for the adult. I n no. 19 we have computed the same index on the basis of the oblique length with essentially the same result. Series A shows a somewhat higher index, i.e. a larger head, than the series. of 100. The third capital index is a comparison between the vertical diameter of the head and the epicondylar width. The indices in the fetal series and series A are practically the same, 61.18 and 61.27, indicating that no changes occur during growth in the relative dimensions concerned. This index is lower in the series of 100 since the head has lost its cartilage while there is no corresponding decrease in the epicondylar width. The robusticity of the head, as indicated by index no. 10, gives substantially the same results as the second capital index.

The bicondylar width index, (no. 11) is an expression of the relatively greater distance between the two epicondyles as compared with the maximum length, 27.94 for the fetus and 18.11 for the adult. No. 18 gives the same relations in terms of the oblique length.

The remaining indices have reference to the dimensions of the lateral and medial condyles. The condylar index, (no. 12) is the relation of the maximum length of the lateral condyle to the epicondylar width. I n no. 16 the projected

118 N. WILLIAM INGALLS.

length of the condyle was used instead of the maximum length. This is one of the few indices in which the fetus shows a lower value than the adult, but this is simply the result of the way in which the indices are formulated. This lower index in the fetus, and the same results would have been obtained by using the medial condyle instead of the lateral, is due t o the short antero-posterior dimensions of the knee joint. It is low from before backward, i.e. the condyles are short. The condylar lengths index, (no. 13) shows that there is little difference in the relative lengths of condyles at birth as compared with the adult condition. No. 17, using the projected lengths, gives essentially the same result. As the indices stand they would indicate that the lateral condyle may be relatively a trifle longer in the fetus. There are two indices which we have used on another occasion under the names ex- ternal and internal capito-condylar (nos. 14 and 15) to indicate the relation of the vertical diameter of the head to the projected lengths of the lateral and medial condyles. The very considerably higher values in the fetus are another indi- cation of the relatively short antero-posterior dimensions of the condyles, the shortness being a little more marked for the medial condyle.

The most characteristic feature of the condylar region at birth is the antero-posterior flattening, in about the same plane as the flattening of the head, but much more conspicuous. The ventral prominences of both condyles and the slightly broader trochlear surface between them, are also a little internal to the adult position, a condition which may be asso- ciated with the smaller angle of obliquity. I n figure 3 lower

Fig. 3 Outlines of the femoral head and condylar region as seen from above, in projection on the standard horizontal plane. Right side represented on basis of mean values for combined right and left sides. The retrocondylar and internal epicondylar planes coincide, cartilage intact in all cases. In the upper half there have been superimposed, to scale, male white, continuous line, 36 pairs of femora; male, colored, interrupted line, 10 pairs; dotted line, female colored, 7 pairs. The small circles indicate the position of the center of the head. The lower half represents the same 36 pairs of male white femora, and 10 pairs of male white, fetal femora, on the basis of the same epicondylar breadth.


Figure 3

120 N. WILLIAM IXGALLS

half, the outline of the condyles and head in the fetus and adult have been superimposed on the same epicondylar breadth. The right bone is represented as seen from above, in projection on the standard horizontal plane. Values for both right and left sides are combined, the continuous line indicates the adult condition. The striking similarity of the condylar region a t birth and at the end of growth and development, is but an expression of the finely balanced forces which are capable of producing in cartilage an accurately modeled joint surface, not only in the absence of functional stimula- tion but also in an extreme position. Although the relative lengths of the condyles change but very little, later development will bring out another essentially human feature, viz., the great antero-posterior dimension of the knee joint. The fact that one of these human characters appears much later than the other need not assume undue importance. As sug- gested in regard to the form of the femoral head, so for the condyles, the development in extreme flexion might favor increase in size in lateral dimensions rather than in a plane at right angles, in antero-posterior dimensions.

The relations of the femoral head to the condyles, as shown in figure 3 are quite different from those in the adult. The center or highest point of the head in the fetus falls just inside the midline of the knee while in the adult it is frankly over the lateral condyle. It is also very much nearer the ventral limits of the joint. The reasons for these different relations are t o be found chiefly in the smaller angle of obliquity, in spite of a shorter capito-collar length, in the larger trochanteric region and broader proximal part of the shaft, and in smaller sagittal dimension of the knee joint.

In the upper half of figure 3 the same relations are represented for the male white and the colored male and female, the interrupted line indicating the male colored, the dotted line the female colored. Disregarding the female colored, where the sexual bias may be much stronger than the racial, and comparing the upper and lower figures it will be seen that the male white occupies an intermediate position between


the fctal wliite and the male colored. Passing from the fetal condition through the male white to the male, colored, there is to be noted an increase in condylar length and a shifting outward and backward of the center of the head. On the other hand the colored is more like the fetus in the smaller femoral head, as compared with the epicondylar breadth, and in the broader and more medially placed trochlear surface. It will be noted that the comparison here is between adult colored and fetal white, fetal colored would naturally have been the ideal material.

SUMMARY

The femur at birth is short, with massive articular ends, a bulky trochanteric region, a very short thick neck and a shaft which tapers rapidly from either end towards the center where it presents about the same proportion as in the adult. The angle of obliquity and also the torsion and collo-diaphyseal angles are lower than in the adult.

The mean variability for 17 femoral characters is definitely lower than in the adult, since the selective and adaptive influence of use and environment are not yet in operation and individual characters, therefore, have not yet been developed.

Among the more conspicuous details, there may be noted, as compared with the adult, the greater ellipticity of the head, the relatively short condyles, the high platymeric and low pilasteric indices and the location of the head far forward over the center of the knee joint.

LITERATURE CITED

INGALLS, N. W. 1924 Studies on the femur. I. General eharacters of the femur in the male white. Am. J. Phys. Anthrop., VII .

1926 Studies on the femur. 11. The cartilage of the femur in the white and negro.

PEARSON, KARL, AND JULIA BELL 1919 A study of the long bones of the English skeleton. Part I. The femur. Drapers’ Co. Research Mem., Biometrie Series X, London.

Id., IX.

studies on the femur. v. the femur at birth

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