All patients had arthroscopy at a knee surgery clinic and returned home the same day. On that day, they were randomly assigned to receive a daily injection of LMWH for either 7 days or 14 days or to wear special support hose (a graduated compression stocking) on the operated leg for 7 days. The surgeons followed patients for several days to check for any bleeding problems. At the end of treatment, patients had leg scans (ultrasounds) on both legs to check for blood clots and answered questions about symptoms that might be related to blood clots. The researchers then followed patients with normal scans for 3 months of treatment to see if any developed symptoms or clots or died. Finally, the researchers compared the numbers of patients in each group who had died or had any of the following: pulmonary embolism, clots in the proximal deep veins of the legs, or clots in the distal deep veins of the legs that caused symptoms.