A Comparative Study of Tramadol Hydrochloride Plus Acetaminophen Tablets Maintenance Versus Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) Maintenance in Participants With Knee Osteoarthritis

Inclusion Criteria: * Participants who have suffered from knee osteoarthritis at least for one year and meet the criteria of American College of Rheumatology * Participants who are taking stable dose of meloxicam 7.5 milligram (mg) or 15 mg daily or aceclofenac 100 mg twice a day at least for four weeks * Participants whose mean pain intensity has been 5 or higher on the numeric rating scale (NRS) for the last 48 hours * Participants whose general health conditions are favorable, according to the criteria below: Medical and medication history, Physical examination before the study medication administration, Vital signs: Blood pressure, pulse, Clinical laboratory tests: Serum glutamic oxaloacetic transaminase (SGOT)/serum glutamic pyruvate transaminase (SGPT) less-than or equal to (=\<) 2 X normal range, Renal function: Creatinine less than (\<) 2.0 milligrams per deciliter (mg/dl) * Female participants of childbearing potential to use the proper contraceptive methods during the study period (Urine pregnancy test prior to the study participation should be negative) Exclusion Criteria: * Participants who are applicable to Kellgren and Lawrence grade * Participants who had failed tramadol treatment before or stopped taking tramadol due to adverse event(s) * Participants who are applicable to one of the following conditions: Rheumatoid arthritis, Ankylosing spondylitis, Active gout or active pseudo-gout, Diagnosis of fibromyalgia (according to ACR Criteria), Anserine bursitis, Major trauma of the target joint within six months prior to the study medication administration, Infection of the target joint within six months prior to the study medication administration, Apparent avascular necrosis of the target joint within six months prior to the study medication administration, Anatomical deformities of the target joint, which may interfere with assessment of the target joint, Surgical procedures associated with the target joint within one year prior to the study medication administration, Arthroscopic procedures associated with the target joint within six months prior to the study medication administration * Participants who have one of the following diseases: Significantly unstable diseases such as sleep disorder (e.g., sleep apnea or narcolepsy) or dementia, Functional damage or disease which may cause malabsorption, excessive accumulation, or metabolism or excretion disorder * Participants who are pregnant or breast-feeding