These problems are based on a patient standing on one limb. For the following se

Question

These problems are based on a patient standing on one limb. For the following set of problems, determine:

            i. The torque that the abductor muscles must provide in order to maintain the body position.

            ii. The abductor muscle force that was required to produce this torque

            iii. The magnitude of the net hip joint reaction force.

The abductor muscles are assumed to absorb the entire adducting torque produced by the body weight on the hip joint of the stance leg. The following table and figure contain the relevant parameters.

a) Patient standing on one leg (Trendelenburg Test).

            b) Patient carries one suitcase (25 kg ~= 250 N) in the hand opposite the stance leg

     (moment arm = 0.31 m).

            c) Patient carries a suitcase in each hand (moment arm in hand on side of standing leg = 0.14 m).

Explanation / Answer

b) The net moment that will be created by this arrangement is: 250*0.31+ mass of man * 0.155

This moment needs to be balanced off by the abductor muscles, so, 77.5 + mass of man * 0.155 = F X 0.31

c) In this case, the net moment created by the suitcases cancel off, so the man just needs to balance his own weight creating a moment, so F X 0.31 = mass of man * 0.155

Hope it helps. :)

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