The purpose of this study is to evaluate the safety, efficacy and pharmacokinetics of FX005 for the treatment of pain in patients with osteoarthritis of the knee.

The objectives of the study are to assess FX005, as compared to placebo control, for:

• Safety and tolerability
• Analgesic effect
• Pharmacokinetics

Analgesic effect will be assessed using the Western Ontario & McMaster University Osteoarthritis Index (WOMAC), the Measure of Intermittent and Constant Osteoarthritis Pain (ICOAP) questionnaire, and patient and clinical observer global assessments.

Inclusion Criteria:

• Male or female ≥40 years of age
• Diagnosis of unilateral or bilateral osteoarthritis of the knee for at least 6 months; confirmation of osteoarthritis according to American College of Rheumatology Criteria (clinical and radiological)
• Kellgren-Lawrence grades II or III
• Mean score for the WOMAC A subscale (pain) between 2.0 and 3.5 for the index knee
• Score of 2-3 for the WOMAC A1 score (pain on walking) for the index knee
• Body mass index ≤ 40 kg/m2
• Willingness to abstain from use of restricted medications during the study
• Willingness and ability to comply with the study procedures and visit schedule

Exclusion Criteria:

• Kellgren-Lawrence Grade 0, I or IV radiographic stage of the index knee
• Clinically apparent tense effusion in index knee
• Presence of surgical hardware or other foreign body in the index knee
• Clinical signs and symptoms of active knee infection or crystal disease
• Intra-articular corticosteroid within 3 months of Screening
• Intra-articular hyaluronic acid within 6 months of Screening
• Other intra-articular therapy within 3 months of Screening
• Prior arthroscopic or open surgery of the index knee within 12 months of Screening
• Planned/anticipated surgery of the index knee during the study period
• History of malignancy or other serious, non-malignant, significant, acute or chronic medical (e.g.. uncontrolled diabetes) or active psychiatric illness
• Skin breakdown at the knee where the injection would take place
• Women who are pregnant, nursing or likely to become pregnant during the time of the study
• Women of child-bearing potential (not surgically sterile or post-menopausal for at least 1 year) not using effective contraception