The frequencies and types of adverse events were comparable between Synvisc-One® and HYAJOINT Plus® groups. The majority of adverse events were mild or moderate, lasted 1 to 3 days, and resolved spontaneously or responded well to simple analgesics. The adverse events reported in each group were joint pain, joint swelling, joint stiffness, limb weakness, back pain. Twelve patients ( 9 treated with Synvisc-One® and 3 treated with HYAJOINT Plus®) developed joint effusion within 1 week after the injection, all infections revolved except for 2 patients treated with Synvisc-One® who required arthrocentesis for pain relief. No allergies, pseudosepsis or serious adverse events occurred during the study in either group.2