Looking at the course of these arteries it appears that when we sit on hard seats the pressure is sustained by the bones; when we recline on soft seats the pressure is sustained more by the soft parts, and reaches the arteries; hence the tendency of modern modes of reposing to drive the blood into the interior of the pelvis and favour the production of piles and uterine disorders. A celebrated French accoucheur used to say that the fashion of high waists, tight lacing, and easy chairs brought him many thousands a year.
THE KNEE.
107. Bony points.—The patella; the tuberosities of the two condyles; the tubercle of the tibia for the attachment of the ligamentum patellæ; another (the lateral) tubercle, on the outer side of the head of the tibia; and the head of the fibula are the chief bony landmarks of the knee.
Observe that the head of the fibula lies at the outer and back part of the tibia, and that it is pretty nearly on a level with the tubercle for the attachment of the ligamentum patellæ.
We can also feel the adductor tubercle or spur-like projection of bone above the internal condyle which gives attachment to the tendon of the adductor magnus. This spur-like projection corresponds with the level of the epiphysis of the lower end of the femur, and also with the level of the highest part of the trochlea for the patella: facts worth notice in performing excision of the knee.
‘In reducing a dislocation of the hip, it is important to bear in mind that the inner aspect of the internal condyle in every position of the limb faces nearly in the direction of the head of the femur.’ ([100])
The tubercle on the outer side of the head of the tibia gives attachment to the broad and strong aponeurosis (tendon of the tensor fasciæ), which, acting like a brace for the support of the pelvis, is well seen in emaciated persons down the outer side of the thigh. This tubercle indicates the level to which the condyles of the femur descend, and the lower level of the synovial membrane.
The patella, in extension of the knee, is nearly all above the condyles; in flexion, it lies in the inter-condyloid fossa (more on the external condyle), and thus protects the joint in kneeling. Its inner border is thicker and more prominent than the outer, which slopes down towards its condyle.
108. Ligamentum patellæ.—The line of the ligamentum patellæ is vertical. Hence any deviation from this line, one way or the other, indicates more or less dislocation of the tibia. There is a pellet of fat under the ligament, which answers a ‘packing’ purpose—sinking in when the knee is bent; rising when the knee is extended, and bulging on either side of the tendon, almost enough to give the feel of fluctuation.
In a well-formed leg the ligamentum patellæ, the tubercle of the tibia, and the middle of the ankle should be in the same straight line. A useful point in the adjustment of fractures.