(Chapter 31) Footnote 51:

Beginning at this point, the 1555 edition substitutes the following chapter ending: “the joints provide even better reasons for giving further thought to all the joints of the leg together: in the hip, the knee, and the connection of the ankle with adjacent bones. For one joint surpasses another so that they need not all perform the same number of motions. This is why it was possible for certain joints to be more strongly constructed and less exposed to dislocation.”