- At Baseline, after all analgesic/anti-inflammatory medications have been discontinued for 2 weeks (withdrawal from acetaminophen rescue medication for at least 24 hours prior to Baseline assessment), patients should have a VAS pain score of > 40 mm but < 90 mm immediately after the 50-foot walk on a flat surface. Again, if bilateral knee pain is present, the investigator will select the more painful knee and the contralateral knee must have a VAS pain score of < 30 mm.