Whether or not a urinary catheter is inserted for knee arthroscopy depends on whether or not the patient has postoperative urinary retention, or how likely it is to occur. If the patient has a high likelihood of postoperative urinary retention, a urinary catheter is usually recommended. If the knee arthroscopy is relatively simple and the procedure is short, within 1-2 hours, a urinary catheter can usually be left in place. If the procedure is longer and more complicated, possibly up to 2-3 hours, a urinary catheter is required. However, with or without a urinary catheter, the post-operative effects on the patient are relatively minor, as the catheter can be removed after the anesthetic has worn off, so there is no need to worry.