Cystic fibrosis can affect the joints in different ways. 5-10% of people living with CF can get non-destructive inflammation of their joints called arthropathy. It is also associated with a condition called hypertrophic pulmonary osteoarthopathy (HPOA) which is inflammation of a layer of connective tissue called the periosteum that surrounds the bone. This can result in bone pain and swelling especially in the knees, ankles and wrists. People with HPOA also have clubbing of their nails but this can also happen to CF patients who don’t suffer from HPOA.