Paget's disease of bone Paget’s disease affects the way your bone develops and renews itself, causing it to become weaker than normal. Learn about the causes, symptoms and treatments. Palindromic rheumatism Palindromic rheumatism is an inflammatory arthritis causing attacks of joint pain and inflammation which come and go. Learn the causes, symptoms and treatments. Patellofemoral pain syndrome (knee pain in young adults) Patellofemoral pain syndrome causes pain and scratching/grinding in the knee of young adults. Learn about the causes, symptoms and treatments. Plantar fasciitis Plantar fasciitis affects the heel of your foot. Learn the causes, symptoms and treatment. Polyarteritis nodosa (PAN) Polyarteritis nodosa (PAN) is a serious but rare form of vasculitis causing inflammation to medium-sized arteries. Learn more about the symptoms. Polyarthritis Polyarthritis is a type of juvenile idiopathic arthritis (JIA) which affects multiple joints. Learn about the causes, symptoms and diagnosis. Polymyalgia rheumatica (PMR) Polymyalgia rheumatica (PMR) is a condition that causes severe stiffness and pain, mainly in your shoulders and hips. Learn the symptoms, causes and treatment. Psoriatic arthritis Psoriatic arthritis causes painful joint inflammation and is often linked with the skin condition psoriasis. Learn about the causes, symptoms and treatments.