I get the impression that you want to make an arm that flexes without the geometry near the joints moving at all. If this is the case, rigid binding might work. You would probably have to tweak the setting to get exactly what you wanted, though. What will work is this: Each segment of the arm would have to be a seperate object. You make the skeleton.
Consider that as two cubes side by side. The +'s are the skeleton, while the <> is the middle joint. The skeleton was created from LEFT to RIGHT. Click the skeleton portion on the left. It highlites both the portion you clicked on as well as the right skeleton due to the hierarchy (sp) of it all. Anyway, after you select the left skeleton, select the left box. Go to Skin>Bind>Smooth or Rigid Bind. Now select the rightmost skeleton. Select the right box. Choose Skin>Bind>whatever. Now both segments of geometry move independantly with the skeleton part it was attached to. This won't work unless the segments are two different objects, though, unless you can select individual faces to bind to skins.
If it is all one big piece of geometry, look into rigid binding.
Anyone else have a take on this?