that's a very interesting question. i certainly think this warrants an investigation. my initial reaction is that a pin in the bone shouldn't cause any problems no matter how long it stays in. but my second reaction was that i don't know (and you may not either) exactly what type of "pin" was inserted. was it a screw into the bone? a rod running the length of the bone? we know for example that screws used to repair hip fractures can cause pain years later either from irritation to the surrounding tissues or due to arthritis. it's not impossible the same could be true with your arm. so i'd suggest you make an appointment with your primary care provider. he or she can do an initial evaluation and if necessary refer you to a specialist. hope you feel better soon!
had a pin inserted into by broken arm in 1974. could it cause pain and weakness after all those years?