Lubrication of Joints - Biofluidmechanics: An Introduction to Fluid Mechanics Macrocirculation and Microcirculation - page 311

tendon, and the joint reaction force (F J ). Figure 11.7 depicts the location and directions
that the forces act on the ankle joint. The angle that the Achilles tendon makes in this
position is 40 and the angle that the joint reaction force acts on the ankle is 75 . Calculate
the muscle force and the joint reaction force needed to maintain this position. Ignore the
weight of the foot.

11.10 Calculate the stress on the cartilage and the change in length of cartilage, assuming that

the force on the cartilage is 9875 N and that the diameter of the cartilage is 2 cm (assume
that it is circular). The cartilage has a thickness of 1.5 mm and an elastic modulus of
250 MPa.

*11.11 Using the results from the previous example, calculate the change in molecular volume of

synovial fluid if all of the criteria are the same as in homework problem 11.7, except that
the formation of synovial

fluid from cartilage now includes 142 ng/hr/mm from

compression.

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