TreatMent Of Knee osTeoarthritis wIth chONdroitin Sulfate - the OA MOTION Study (MOTION)

Inclusion Criteria: Subject has provided written informed consent for participation in the clinical study. Subject is outpatient of either sex, aged ≥50 years. Subjects with a diagnosis of OA (osteoarthritis) according to the ACR (American College of Rheumatology) criteria. Subject has a radiographic diagnosis (confirmed by a central reader) of knee OA classified Kellgren-Lawrence Grade of 2 or 3 on standing anterior-posterior X-ray of the index knee based on an x ray assessment of both knees available <6 months from Screening or performed during Screening. Subject has a history of knee OA for >6 months (including regular pain and functional impairment) as confirmed by the investigator, based on available written documentation and/or subject reporting. Subject meets the following requirements: Has a mean score of ≥5 to ≤9 on the 24-hour average daily pain score in the index knee (0-10 Numerical Rating Scale-NRS), where the mean is calculated over all values that are available in the 7 days prior to randomization (Day 1), and it is required that at least 5 pain score values will be available during that period. Subject has an individual index knee 24-hour average daily pain score ≥1 and ≤9 for all values that are available in the 7 days prior to randomization (Day 1). Subject has rated the pain in the non index knee consistently lower than the pain in the index knee at both the Screening and Baseline Visits in case of bilateral knee OA. Subject, if of childbearing potential, is nonlactating and nonpregnant (has negative serum pregnancy test results at Screening and negative urine pregnancy test result at the start of IP administration prior to dosing). Subject, if female, is either not of childbearing potential (defined as postmenopausal for at least 1 year or surgically sterile [bilateral tubal ligation, bilateral oophorectomy, or hysterectomy]) or practicing 1 of the following medically acceptable methods of birth control: Hormonal methods such as oral, implantable, injectable, or transdermal contraceptives for a minimum of 1 full cycle (based on the subject's usual menstrual cycle period) before IP administration. Agrees to abstain from heterosexual intercourse during study participation and to use a highly effective contraceptive (as described above) as backup if they become sexually active during the study. Abstinence is only acceptable if this is the subject's usual lifestyle. Periodic abstinence (calendar, symptothermal, postovulation methods), withdrawal (coitus interruptus), spermicides only, and lactational amenorrhea method are not acceptable methods of contraception. Intrauterine device. Double barrier method (condoms, sponge, diaphragm, with spermicidal jellies, or cream). Subject able to understand and follow the study requirements. Exclusion Criteria: Subject with an allergy or hypersensitivity to the active substance or to any other ingredient of the IP (i.e., chondroitin sulfate tablets or placebo) or has a vegan lifestyle. Subject presenting with lactose intolerance. Subject with ≥1 pain score reported as 10 on the NRS during the 7 days prior to randomization (Day 1). Subject with New York Heart Association Grade III-IV with an ongoing treatment. Subject with severe renal or hepatic impairment (Child-Pugh Stage C) with renal and liver function assessment based on laboratory results. Subject with any other clinically severe or significant uncontrolled concurrent illness. Subject with any other concurrent illness requiring chronic use of analgesics/NSAIDs (nonsteroidal anti-inflammatory drug). Subject has a body mass index ≥40 kg/m2. Subject has predominantly patellofemoral osteoarthritis based on clinical diagnosis and/or x-ray. Subject had surgery of the index knee in the past 6 months (for arthroscopic surgery) or 12 months (for osteotomy or other surgery) or significant injuries in the past 6 months prior to Screening, or has planned knee surgery during the study. Subject with presence of clinical effusion of the knee requiring arthrocentesis or active infection of the index knee. Subject has any important genu varum or valgum >8°(physiological angle including) or any other axial disorder justifying an osteotomy as assessed by central reading. Subject had viscosupplementation, tidal lavage, platelet-rich plasma, or stem cell injection within the last 6 months before Screening. Subject has systemic inflammatory arthropathies (rheumatic disease, inflammatory, infective, or metabolic joint diseases; recurrent clinical chondrocalcinosis; crystal arthropathies; osteo-articular pathologies differing from arthrosis; ochronosis; acromegaly; heritable disorders; or collagen gene mutations), metabolic arthropathies, or Paget's illness. History of acquired or congenital immunodeficiency diseases or positive test results for human immunodeficiency virus, hepatitis B virus, or hepatitis C virus current infection at Screening. Subject has received any of the following: Basic treatment of arthritis with food supplements for joint care (chondroitin sulfate, glucosamine sulfates, diacerein, hyaluronic acid etc.) within the last 3 months. Treatment with oral or parental corticoids during the last month or corticosteroid joint injection within the last 3 months; treatment with inhaled corticosteroids is allowed. Any medication having an influence on pain: NSAIDs (washout period begins ≥5 half-lives of the drug prior to Day 7 and needs to be completed prior to Day 7); Hypnotics, muscle relaxants, anxiolytics, if intake has started <8 days before Screening to be completed prior to Day -7; Use of cannabinoids needs to be stopped ≥2 weeks before the Screening Visit; Acetaminophen or other analgesics (washout period begins ≥5 half-lives of the drug prior to Day 7 and needs to be completed prior to Day -7). Subject has foreseen physiotherapy or alternative medicine (mesotherapy, acupuncture) within the next 12 months (study period). Subject is presenting with clinically relevant psychiatric illness hindering the protocol compliance. Subject is presenting with alcoholism or substance use disorder according to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, criteria, or has a positive drug screen result at the Screening or the Baseline Visit. The use of tricyclic antidepressants at low doses for sleep is allowed. Subject has participated in any other clinical study in the month prior to Screening. Subject is noncompliant with eDiary use as determined at the Baseline Visit (i.e., has a compliance <70% throughout the entire Screening Period). -