Arthrocentesis--specific site code for 20610

I have a question regarding the joint injections. Is it mandatory to use lt or rt modifiers for a single injection? Is this a site specific HCPCS? I know Medicare requires that one be used when a pt receives the Synvics injection due to the type of substance used, but I have been told by some auditors that a site specific modifier is not needed if pt presents for an inj of steroid or anesthesia only. It's very confusing when you are being told different ways of coding this. I don't see it as site specific HCPCS and the only LCD I see is one regarding the Intra-Articular Inj of the Hyaluronan (Synvisc)....

PLEASE HELP!!!!!!