 [ Symptoms ] i have had a knee replaced twice and revised once in 17 months my sed rate is 50 should i be worried about infection i have alos been expering pain when i got my knee drained today the doc said it looked like there was blood in it and described it as cloudy should i be concerned [ Disease ] i am glad to hear you are under the care of a physician who is watching this carefully any joint replacement carries a risk of infection it sounds like your doctor has things under control in general an elevated sed rate indicates inflammation somewhere within the body an elevated sed rate alone would not be enough to say your prosthetic knee is infected cloudy bloody drainage does not necessarily indicate infection presumably your doctor will culture the drainage which can take several days or even weeks to see if any bacteria grow out  if there are bacteria in the drainage the culture will identify the strain so your doctor can treat the infection i think instead of worrying or being concerned  you should be proactive about monitoring your symptoms get a thermometer and take your temperature every day at the same time not when you first wake up in the morning you can expect some variation but if you start running a fever over 101f then it is time to call your doctor if you do not get a same day call back call again before the office closes also be alert for other symptoms of infection such as loss of appetite feeling weak and general malaise feeling like you are getting the flu for example if these symptoms develop call your doctor i hope your knee problem turns out to be something very simple wishing you well