Table 3 Subject eligibility criteria

Inclusion criteria

1. Males or females in the age range 40–70 years (both inclusive)

2. Radiographic evidence of grade 2 to 3 osteoarthritis (OA) based on the Kellgren and Lawrence radiographic entry criteria*

3. History of primary idiopathic OA of the knee characterized by pain which required intake of analgesics

4. Self-reported difficulty in at least one of the following activities attributed to knee pain: lifting and carrying groceries, walking 400 meters, getting in and out of a chair, or going up and down stairs

5. Patients who had been on stable medication, including non-steroidal anti-inflammatory drugs (NSAIDs)/opioid or opiate analgesics, for the past 3 months

6. Female patients of childbearing age who agreed to use accepted methods of contraception during the course of the study

7. Ability to provide written informed consent

Exclusion criteria

1. Prior or ongoing medical conditions (e.g., concomitant illness, psychiatric condition, alcoholism, drug abuse), medical history, physical findings, electrocardiogram (ECG) findings, or laboratory abnormality that, in the investigator’s opinion, could adversely affect the safety of the subject, makes it unlikely that the course of treatment or follow-up would be completed or could impair the assessment of study results

2. History of surgery or major trauma to the study joint

3. Arthroscopy on the study joint in the previous 12 months

4. Signs of active study joint inflammation including redness, warmth, and/or, if qualifying with OA of the knee, a large, bulging effusion of the study knee joint with the loss of normal contour of the joint at the screening visit or at the baseline examination

5. Patients who received intra-articular steroids or hyaluronan within the last 3 months

6. Infections in or around the knee

7. Patients awaiting a replacement knee or hip joint

8. Patients with other conditions that caused pain

9. Patients with deformity of the knee joint

10. Significantly incapacitated or disabled and would be categorized as ACR Functional Class IV (largely or wholly incapacitated) or unable to walk without assistive devices

11. Patients with other known rheumatic or inflammatory disease such as rheumatoid arthritis

12. Other pathologic lesions on X-rays of knee

13. Positive hepatitis B surface antigen, hepatitis C antibody test, anti-HIV antibody test, or Rapid Plasma Reagin (RPR)

14. History of bleeding disorders

15. Known hypersensitivity to hyaluronan or animal sera

16. For women of child-bearing potential: positive pregnancy test or lactating (females who were planning pregnancy within the next year were excluded)