Gel-200 Extension and Open-Label Study in Osteoarthritis of the Knee

• Improvement From Baseline in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Visual Analog Scale (VAS) (Pain Subscore) [ Time Frame: Baseline and Week 13 ] [ Designated as safety issue: No ]
  Observed WOMAC pain subscore on VAS of 100 mm.; 0 mm meaning no pain; 100 mm meaning extreme pain. Improved score from baseline to week 13 were calculated as baseline minus week 13.
• Improvement From Baseline in WOMAC VAS (Stiffness Subscore) [ Time Frame: Baseline and Week 13 ] [ Designated as safety issue: No ]
  Observed WOMAC stiffness subscore on Visual Analog Scale (VAS) of 100 mm; 0 mm meaning no stiffness; 100 mm meaning extreme stiffness. Improved score from baseline to week 13 were calculated as baseline minus week 13.
• Improvement From Baseline in WOMAC VAS (Physical Function Subscore) [ Time Frame: Baseline and Week 13 ] [ Designated as safety issue: No ]
  Observed WOMAC physical function subscore on Visual Analog Scale (VAS) of 100 mm; 0 mm meaning no difficulty; 100 mm meaning extreme difficulty. Improved score from baseline to week 13 were calculated as baseline minus week 13.
• Improvement From Baseline in WOMAC VAS (Total Score) [ Time Frame: Baseline and Week 13 ] [ Designated as safety issue: No ]
  Observed all WOMAC mean scores on Visual Analog Scale (VAS) of 100 mm; a total of WOMAC pain, stiffness, and physical function subscores. Improved score from baseline to week 13 were calculated as baseline minus week 13.
• Outcome Measures in Rheumatology Artthritis Clinical Trials (OMERACT) - and the Osteoarthritis Research Society International (OARSI) Response [ Time Frame: Weeks 13 ] [ Designated as safety issue: No ]
  Outcome Measures in Rheumatology Clinical Trials and Osteoarthritis Research Society International (OMERACT-OARSI) strict responses defined by improvements from baseline in WOMAC pain or physical function subscore ≥50% with absolute changes ≥20 mm (termed strict responders), or ≥20% with absolute changes ≥10mm in 2 of 3 measures of WOMAC pain or physical function subscore or subject global evaluations (termed responders).
• Improvement From Baseline in Subject Global Evaluations [ Time Frame: Baseline and Week 13 ] [ Designated as safety issue: No ]
  Observed subject evaluations on Visual Analog Scale (VAS) of 100 mm; 0 mm meaning excellent feeling in knee joint; 100 mm meaning poor feeling in knee joint. Improved score from baseline to week 13 were calculated as baseline minus week 13.
• Improvement From Baseline in Physician Global Evaluations [ Time Frame: Baseline and Week 13 ] [ Designated as safety issue: No ]
  Observed physician evaluations on Visual Analog Scale (VAS) of 100 mm; 0 mm meaning excellent feeling in knee joint; 100 mm meaning poor feeling in knee joint. Improved score from baseline to week 13 were calculated as baseline minus week 13.
• Acetaminophen Consumption [ Time Frame: Week 9 to Week 13 ] [ Designated as safety issue: No ]
  Weekly mean acetaminophen consumption between weeks 9 and 13.

• Safety: Examination of the knee, Laboratory tests
• Effectiveness: WOMAC VAS scores (Pain subscore, Stiffness subscore, Physical Function subscore, Total WOMAC score), OMERACT-OARSI Response, SF-36, subject and physician global evaluations, acetaminophen consumption

The purpose of this study is to determine if a single or repeat intra-articular injection of Gel-200 is safe and effective in subjects with symptomatic osteoarthritis of the knee and to determine if original SI-6606/01 Gel-200 therapy is durable beyond the original study.

Inclusion Criteria:

• Previous participation in study SI-6606/01.

Exclusion Criteria:

• Female subjects who are pregnant or lactating.