Flexion Therapeutics, Inc. is a United States-based specialty pharmaceutical company. The Company is focused on the development and commercialization of local therapies for the treatment of patients with musculoskeletal conditions, beginning with osteoarthritis (OA), a type of degenerative arthritis. The Company's lead product candidate, Zilretta, is a late-stage, injectable, extended-release, intra-articular (IA) investigational steroid. The Company is developing Zilretta as a treatment for patients with moderate to severe OA knee pain. The Company has specifically designed Zilretta to combine a steroid, triamcinolone acetonide (TCA) with poly lactic-co-glycolic acid (PLGA), for providing sustained therapeutic concentrations in the joint and persistent analgesic effect. The Company's other product candidates include FX007 for post-operative pain and FX005 for the treatment of end-stage OA patients. The Company is engaged in conducting a Phase IIb clinical trial of Zilretta.