On the structural symmetry of human femurs.

The distribution of transverse and longitudinal lamellae from osteons and interstitial bone of the two femurs from a woman aged between 25 and 30 was investigated. Exactly plane parallel cross-sections (100 micron) were prepared from the upper, middle and lower thirds of the two bones. The distributions of transverse and longitudinal lamellae was determined for both osteonic and interstitial bone, using circularly polarised light. The results show that (a) as in the male femur, the transverse and longitudinal lamellae in these female femurs have a characteristic rotational distribution along the shaft consistent with the distribution of the bending strains normally operative in bone; and (b) the rotational distribution of the two types of lamellae is slightly asymmetrical in the two female bones, probably because of imperfectly symmetrical use of the lower limbs.