Patient case (clinical description): A 47-year-old woman comes to the office complaining of pain in the calf and knee when she bends down. The pain limits her activity. Her medical history is significant for osteoarthritis, for which she uses nonsteroidal anti-inflammatory drugs (NSAIDs) for the past two years. She is living with her husband and has 3 children. She doesn't smoke but drinks alcohol occasionally. Her vital signs are normal. On physical examination, there is a small effusion in the right knee. The effusion grew a little larger and she developed a tender swelling in the popliteal fossa and calf. Both the pain and swelling worsened as she bent and straightened her knee.

Patient's own account: I'm a 47-year-old woman, married with 3 kids. I don't smoke and I drink occasionally. I went to the doctor because of pain in my calf and knee when I was bending down. This has been limiting my daily activities. I have been diagnosed with osteoarthritis for which I have taken anti-inflammatory drugs for the past 2 years. The doctor saw a small fluid buildup in my right knee. This buildup became a bit bigger and I have a swollen calf. The pain is worse when I bend and straighten my knee.

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

Eligibility criteria:
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
No condition on gender to be admitted to the trial.
No healthy subjects accepted to join the trial.
Subject must be at least 40 Years old.
Subject must be at most 75 Years

Eligibility (NLI label): Entailment