SIR - We are regularly told we should get our bikes out and not use the car. I would love to. I used to cycle a lot until I had a hip replacement in 1994. It was at the time they had problems with a hip replacement called a Castle "M." The cement used had a fault. The metal component worked loose in the femur bone due to the faulty cement.

They were replaced by the makers free of charge to the NHS. But unfortunately in mine, it was the plastic cup that moved out of place restricting movement. But this was not covered and I was told I would have to put up with it until the pain became unbearable.

JOHN NORWOOD,

Worcester.