134 
On the Sesamoids of the Knee- Joint 
Before we can properly talk about our subject it is really needful to have some 
terminology. The sesamoid may be a true ossification of hyaline cartilage, or it 
may be a thickening or nodule of cartilage without ossification. In the young 
it is open to us to consider the latter as a stage of growth towards the former. In 
the adult this is not possible. We can, of course, assert, as many anatomists have 
done, that all sesamoids are produced by intensive stress acting on cartilage, but 
we shall then have to account for the absence of sesamoids in regions where such 
stress undoubted!}^ exists. Or we may look upon the non-ossified nodule as an 
attempted sesamoid, or better still as a vestige or trace in the species of where a 
sesamoid once has been. Whatever accoimt of the matter we choose to accept, it is 
needful to distinguish between the two cases. Pfitzner proposed to call the bone a 
sesamum and the nodule a sesamoid. This upsets the historic origin of the word, for 
the Greeks most probably knew only the sesamum and called it a sesamoid, and the 
name sesamoid remained as a name for the bone through many centuries. We 
might speak of sesamoid bone and sesamoid nodule or cartilaginous sesamoid, but 
the terms are cumbersome. We shall accordingly reserve the term sesamoid or 
orthosesamoid for a true bone and adopt an independent term for the thickened 
but unossified element of cartilage, calling it a hemisesamoid. Further we shall 
term all pathological ossifications, exostoses, or again, broken off and not reunited 
portions of bone occurring in or near the positions of sesamoids i^s^udosesamoids. 
In the knee-joint itself we have come across no less than ten sesamoids, some 
of which are, however, more frequent or better established than others. To these 
sesamoids we have given the following distinctive names : 
We retain the names of lateral fahella and mesial fahella for the sesamoids 
found in the tendons of M. gastrocnemius above the lateral and mesial condyles 
respectively. 
We introduce the term ci/amella* for the sesamoid which is to be found in the 
tendon of M. ■popUteus. It may be termed the lateral ci/aniella, to distinguish it 
from a mesial cyamella which Pfitzner asserts he observed in two catsf. Gruber, 
notwithstanding his wide knowledge, seems to us to have confused the lateral 
cyamella in man with an unusual position of the lateral fahella. The existence in 
the cat of both lateral /a6e/^a and lateral cyamella ought to have warned him that 
both might appear in man. 
Lastly a number of sesamoids occur in the borders of the semi-lunar cartilages. 
We term these lunidael. They may occur in six positions which we describe as 
follows: antero-lateral, antero-sagittal, antero-mesial, postero-lateral, postero-sagittal, 
and postero-mesial. Of these the sagittal are doubtful and may be anomalous in 
all species. Thus we have two fahellae, two cyamellae and possibly six lunulae as 
sesamoids of the knee-joint. In most cases some only of these will be present; in 
certain species some will always be present as true sesamoids, or will be present as 
* CijameUa, a small bean, the bean-stone, an ornament worn by Roman women. 
f Pfitzner, S. 584, without identification of an association with any particular muscle. 
X Lunula, a little moon, a crescent, or crescent form of ornament worn by Roman women. 
