A pilot, open, randomised, controlled, add-on study evaluating the duration of efficacy of one intra articular injection of sodium hyaluronate 2.0% in patients with painful osteoarthritis of the knee

Inclusion Criteria:

1. Patients of both genders between 40 and 70 years of age;
2. Primary tibiofemoral osteoarthritis of the knee according to American College of Rheumatology criteria;
3. Pain ≥ 4 on a 10 point scale for at least two out of five subscores of the WOMAC Section A at baseline;
4. Radiologically ascertained grade II or III severity knee osteoarthritis on the Kellgren-Lawrence scale;
5. Having given signed informed consent.

Exclusion Criteria:

1. Secondary knee osteoarthritis, including:

   • septic arthritis;
   • inflammatory joint disease;
   • gout;
   • recurrent episodes of pseudogout;
   • Paget's disease of bone;
   • articular fracture;
   • ochronosis;
   • acromegaly;
   • haemochromatosis;
   • Wilson's disease;
   • primary osteochondromatosis.

2. Clinical signs of acute flare (pain, warm, erythema, effusion of signal knee) at baseline;

3. Axial deviation > 15 degrees in valgus or varus on a standing X-ray;

4. Clinically significant medio-lateral or antero-posterior instability;

5. Rapid destructive arthritis, evolving arthritis requiring surgery within the coming year;

6. Significant injury to the signal knee within 6 months prior to baseline;

7. Complete loss of range of motion;

8. Painful knee conditions other than osteoarthritis (e.g., Sudeck's atrophy, intra-articular neoplasm, villonodular synovitis);

9. Necrosis of one of the femur condyles;

10. History or evidence of gout, chondrocalcinosis;

11. Peripheral neuropathy;

12. Concomitant rheumatic disease:

    • fibromyalgia;
    • rheumatoid arthritis;
    • collagen diseases;
    • psoriatic arthritis and other seronegative spondylarthropathies (e.g., ankylosing spondylitis);
    • metabolic and crystal-induced arthropathies;
    • other osteopathies.

13. Contraindications to intra-articular injection according to investigator's judgement (e.g., local infection at injection site, generalised infection with possible bacteraemia);

14. Skin disease in the area of injection;

15. Severe coagulopathy, ongoing anticoagulation therapy;

16. Accompanying OA of the hip of sufficient severity to interfere with the assessment of the signal knee;

17. Disease of spine, hip or other lower extremity joints of sufficient degree to affect assessment of the signal knee;

18. Poor general health interfering with compliance or assessment;

19. Concomitant disease/ailment other than knee OA requiring the regular use of the patient's normal analgesic medicine;

20. Initiation of chronic treatment with antihistaminics, glucocorticoids, antidepressants or tranquilisers, within less than 3 months prior to baseline;

21. Use of assistive devices other than a cane (walking stick);

22. Surgery of the signal knee other than arthroscopy;

23. Arthroscopy of the signal knee within one year prior to baseline;

24. Treatment with symptomatic slow acting drug for OA (SYSADOA, i.e., chondroitin sulfate, diacerein, glucosamine, piascledine), unless the patient has been on a stable dose for at least 4 months prior to baseline;

25. Intra-articular depocorticosteroid injection into the signal knee within 3 months prior to baseline;

26. Intra-articular SH injection into the signal knee within 6 months prior to baseline;

27. Ascertained hypersensitivity to any product used in the study (SH, paracetamol, diclofenac, omeprazole) or to similar compounds;

28. Pregnant or lactating female;

29. Female of childbearing potential without adequate contraceptive methods;

30. Participation in a drug clinical trial within 3 months prior screening;

31. Patients who, in the judgement of the investigator, will not comply with the protocol.