To compare the therapeutic effect of single intra-articular injection of hyaluronate with a single intra-articular injection of normal saline (placebo) for osteoarthritis of the ankle.

This study is a randomized, prospective, double-blind (blinded observer) , saline solution-controlled, parallel experimental design. The study device is SUPARTZ (Seikagaku Corporation, Tokyo, Japan) a brand of sodium hyaluronate.

Inclusion Criteria:

• To be eligible, subjects had to be at least 18 years old, not pregnant, and have pain and osteoarthritis of the ankle of at least stage 2 on the Kellgren and Lawrence scale.
• Their AOFAS score had to be 90 points or less out of a possible 100 points.
• Eligible subjects had to be willing to discontinue all pain medications and NSAIDs other than the rescue pain medications provided in the study.

Exclusion Criteria:

• Persons with systemic inflammatory condition or infection of the ankle or nearby soft tissues,
• an injection of steroid or surgery on the involved joint within 6 months,
• local cellulitis, rash, skin condition
• diabetic or neuropathic Charcot arthropathy,
• significant vascular insufficiency,
• current treatment with anticoagulants,
• lower extremity pain syndromes, sciatica, sprains, plantar fasciitis,
• significant ankle instability or malalignment,
• any known allergy to any of the components of either injection, known or suspected allergy to birds or bird products,
• disabling degenerative joint disease of the ipsilateral hip, knee or foot were ineligible for the study.