He had been waiting, for quite a while, to have a knee surgery and that was the letter of the famous surgery-bank checks. When a person is waiting for a long time, they get a bank check and with that bank check they can have that surgery in the private sector.
Había esperado, mucho tiempo a una cirugía de rodilla y era la carta de un cheques para cirugía; cuando una persona espera mucho tiempo, logra un cheque para hacerse la cirugía en el sector privado.