Why is Bill’s knee swollen?

A retired police inspector is diagnosed with a common inherited disorder

Bill is 65 and a retired police inspector. He has been experiencing pain and occasional swelling in his right knee.

The knee has been painful intermittently for a couple of months, with episodes of increased pain and associated swelling lasting for a few days. 

An ex-smoker and a social drinker, Bill is in otherwise good health. He has no history of knee injury, and apart from occasional paracetamol, is not using long-term medications.

He is not aware of any family history of any significant illnesses.

Bill is lean and well