The shoulder is a complex joint with nerves and muscles interacting with bones and a squishy cushion (lubricating sac called the bursa). When you have an impingement, trapped nerve, bone spur, or the like, these elements rub together in ways they are not meant to and become irritated and inflamed. There’s less room to move freely, so your range of movement shrinks. Taking anti-inflammatory painkillers act on inflammation and reduce it, which creates more space in and around the joint and returns some range of motion. The pain is reduced because the bones are no longer rubbing against tender, swollen flesh. The inflammation itself is an response to direct your immune system to a problem or threat in your body and work to resolve it.
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