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challenged: but the author was satisfied ofits accuracy. It could 
be demonstrated by removing the bottom of the acetabulum 
with the trephine. The ligament is moderately tight when a 
person stands evenly upon both legs. It is tighter when the 
femur is slightly flexed, as it usually is. But when resting 
upon one leg, inasmuch as the pelvis is then raised on that 
side, which of course affects the ligament in the same way as 
adduction of the femur would do, then the ligament becomes 
extremely tense. In other words, it becomes tightest when 
the hip-joint has to sustain the greatest weight. When there- 
fore the pelvis is borne down upon the femur, or when the 
femur is forced upwards—that is when the pressure would 
be greatest between the upper part of the acetabulum and 
the opposite surface of the head of the femur—it is put directly 
on the stretch. More precisely, its great purpose is to prevent 
undue pressure between the upper portion of the acetabulum, 
just within the margin, and the corresponding part of the 
head ofthe femur. But for this ligament such undue pressure 
must inevitably occur. Suppose the ligamentum teres absent 
and the person standing upright, owing to the obliquity of the 
acetabulum and the head of the femur, pressure between the 
two could not be equally, or nearly equally, diffused over their 
opposing surfaces, but it would be concentrated on a spot in 
the upper part of the socket through which a line drawn down 
the body, through the joint into the leg, would pass. When 
the thigh is straight, when the femur is in a line with the 
body, as when one stands upright, then is the ligamentum 
teres in the same line too, and consequently any force which 
drives the femur and pelvis together must tell at once upon 
the ligament, and be directly checked by it. Owing therefore 
to the shape and obliquity of the hip-joint, and the weight of 
the body, the ligamentum teres is necessary to prevent con- 
centration of pressure at a particular point above it. The 
line through which the weight or force acts between the upper 
