Polymyalgia rheumatica is an infrequently occurring, inflammatory condition that causes pain or aching in the large muscle groups, especially around the shoulders and hips.Polymyalgia literally means many muscle pains. Rheumatica means changing or in flux..n this article. Polymyalgia rheumatica is an infrequently occurring, inflammatory condition that causes pain or aching in the large muscle groups, especially around the shoulders and hips. Polymyalgia literally means many muscle pains. Rheumatica means changing or in flux..