Safety and Effectiveness of Monovisc® Injection for Osteoarthritis of the Knee

Main Inclusion Criteria: * Male or Female * Age 35 to 75 years * Body Mass Index (BMI) 20 to 40 kg/m2 * Willing and able to provide informed consent * Willing to limit analgesic use to acetaminophen 7 days prior to and 12 weeks after injection * Not pregnant or lactating * Previous conservative treatment regimen for osteoarthritis (OA) * Diagnosis of idiopathic OA of the index knee * OA symptoms for \>= 6 months * Index knee Kellgren-Lawrence (K-L) grade of II or III * Index knee Baseline Summed WOMAC Pain Score \>= 200mm and \< 400mm after NSAID washout * Contralateral Knee K-L grade 0, I or II * Contralateral Knee Baseline WOMAC Pain Score \< 150mm after NSAID washout Main Exclusion Criteria: * Joint disorders which could interfere with treatment effectiveness * Joint disorders which could interfere with study assessments * Arthroscopy of either knee within 3 months of screening * Open surgery of index knee within 12 months of screening * Open surgery of contralateral knee within 3 months of screening * Injection of Hyaluronic Acid (HA) in either knee within 6 months of screening * Injection of steroid in index knee within 3 months of screening * Any pre-treatment contraindication for injection or aspiration of the index knee, including cutaneous infection, intra-articular infection, knee deformity or condition which may jeopardize sterility or delivery of injection * Synovial fluid aspirate volume \> 20 milliliters (mL) * Visual appearance of synovial fluid that contraindicates injection * Index knee range of motion \< 90 degrees * Subject participation in other research study within 30 days of screening * Subject unwilling to maintain active lifestyle, exercise program and body weight similar to that during 3 months prior to screening for duration of study * Unwilling to maintain constant dosage of oral glucosamine or chondroitin sulfate for duration of study, if applicable * Other medication or treatments that could interfere with study injection or assessments * Allergy to gram positive bacterial products or intolerance of acetaminophen * Active fibromyalgia * Peripheral neuropathy severe enough to interfere with evaluation of either knee * Vascular insufficiency severe enough to interfere with evaluation of the subject * Hemiparesis involving either lower extremity * Systemic bleeding disorder * Other conditions which may adversely affect the success of the procedure