Once the cartilage lining begins to thicken and thin, tendons and ligaments must work harder. This can cause swelling and spur formation, called osteophytes. Unhygienic sexual practices can lead to pathologic conditions like urinary tract infection. Rheumatic polymyalgia - a condition that almost always affects people over 50 years of age, in which case the immune system can cause muscle pain and stiffness, often across the shoulders and upper legs. It can also cause joint inflammation.