lever arm

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rositakay

Senior Member
Arabic
Hi,
Position of the patient (movement against the gravity): sited on the edge of the bed

Movement: the patient does the internal rotation (foot goes outside) and the external rotation (the foot goesinside)

Resistance: the PT resists pushing the foot inside (internal rotation) or outside (external rotation). The resistance is done at the level of the ankle (the lower as possible to increase the lever arm and decrease the resistance needed)
What is meant by "lever arm" in this context please?
Source: Rehabilitation Assessment - HI
Thanks,
 
  • Edinburgher

    Senior Member
    German/English bilingual
    The same as in any other context. It is the distance from a lever's fulcrum to where a force is applied by or to that lever.
    If you have copied this out correctly, then your book seems to be a translation from some other language into English by a non-native speaker. It is full of mistakes, and it also appears to have mixed up "inside" and "outside" in the "Movement:" section.
     

    Andygc

    Senior Member
    British English
    This is not written in English, and the descriptions make no sense whatsoever. At least I know what the abbreviation "PT" means (my wife is one, albeit retired), although you haven't told us.

    You haven't told us what part of the body is being examined. "Sited on the edge of the bed" makes no sense. Internal and external rotation of which joint? Is the leg straight or bent? Even when you know what a "lever arm" is, the text is still meaningless.
     

    rositakay

    Senior Member
    Arabic
    Actually this is how I got the text. You're right it's written in a very bad way! Andygc they are talking here about the
    Internal and external rotators of the hip and "Sited on the edge of the bed" means that the patient will sit on the edge of the bed to do the test!
     

    Andygc

    Senior Member
    British English
    Right. Sitting on the edge of the bed with the thigh horizontal and the knee flexed to 90 degrees.

    Internal rotation - foot moves away from the centreline. (Outwards)
    External rotation - foot moves towards the centreline. (Inwards)

    Resistance applied at the ankle. The axis of rotation is along the centreline of the thigh. The lever arm is the distance from the knee joint to the ankle joint.
     

    rositakay

    Senior Member
    Arabic
    Thank you Andygc. So the lever arm (the distance from the knee joint to the ankle joint) is the part on which the force is applied?
     

    Andygc

    Senior Member
    British English
    Not quite. The force is applied at the end of the lever. The arm of a lever is the distance between the applied force and the pivot point (post #2). The longer the lever arm, the further from the pivot point the force is applied. The longer the lever arm, the less force that is needed to achieve the same resistance to rotation.

    |< force applied here (ankle joint)
    |
    |
    |
    |
    * pivot point (knee joint)
     
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