when replacing wiper linkage parts

Should just the two linkage arms be replaced, or also replace the units they attach to, ie, the wiper arm units? I recently had the passenger side linkage arm drop off due to a small bit of ice, and when I reattached it, it didn't seem to me to have much holding it, possibly worn. I located a thread from a few years back that gave great instructions on repairing my problem. I think I should replace the linkage so it does not pop off so easily. I want to make sure I replace all the nessesary parts. Thanks for any information on this. Jim