The post treatment Responder Rate at 39 weeks is determined through a calculation defined by the Outcomes Measures for Rheumatic Arthritis Clinical Trials-Osteoarthritis Research Society International (OMERACT-OARSI) Responder Index. The OMERACT-OARSI Responder Index reports the percentage of subjects that met the criteria to be a good responder. The criteria for response are (1) improvement in pain or physical function ≥50% and an absolute change ≥20 mm; or (2) improvement of ≥20% with an absolute change ≥10 mm in at least two of the following three categories: pain, physical function, and patient's global assessment.

A higher percentage of subjects responding indicates a better outcome.

Intent to Treat population

The change from baseline in knee pain as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain Score at 39 weeks post treatment comparing the Cingal group to the Triamcinolone Hexacetonide group. The WOMAC Pain Score is a validated visual analog scale from 0 to 100 mm, where a higher score is equal to a higher pain level. A negative number for the difference from baseline indicates improvement in pain. A greater negative difference from baseline indicates a better outcome.

Intent to Treat Population

This endpoint compares the change of the WOMAC Physical Function Score from baseline to Week 39 between the Cingal and Triamcinolone Hexacetonide arms. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Physical Function Score is a validated visual analog scale from 0 to 100 mm, where a higher score is equal to a higher degree of functional limitation. A negative number for the change from baseline indicates improvement in physical function.

Intent to Treat Population

The change from baseline in knee stiffness as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Stiffness Score at 39 weeks post treatment comparing the Cingal group to the Triamcinolone Hexacetonide group. The WOMAC Stiffness Score is a validated visual analog scale from 0 to 100 mm, where a higher score is equal to a higher degree of stiffness. A negative number for the change from baseline indicates improvement in knee stiffness.

Intent to Treat Population

The change from baseline as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Total Score at 39 weeks post treatment comparing the Cingal group to the Triamcinolone Hexacetonide group. The Total WOMAC Score is determined from the SUM of the scores from the WOMAC Pain Score, the WOMAC Stiffness Score, and the WOMAC Physical Function Score, resulting in a final range for Total Score from 0 mm to 240 mm. A higher Total WOMAC Score indicates a higher overall degree of pain, stiffness and functional limitations. A negative number for the change from baseline indicates improvement in the Total WOMAC Score.

Intent to Treat Population

Comparison of the change of the Patient Global Assessment from baseline to 39 weeks between the Cingal and Triamcinolone Hexacetonide arms (ITT population). The Patient Global Assessment is done by the subject, and answers the question "Considering all the ways the osteoarthritis in your index knee bothers you, what is your assessment of how much your knee is bothering you today?" The Patient Global Assessment is scored on a 0 to 100 mm visual analog scale, where a higher number means the patient is bothered to a higher degree. A negative number for the change from baseline indicates a reduction (improvement) in the assessment.

Intent to Treat Population

Comparison of the change of the Evaluator Global Assessment from baseline to 39 weeks between the Cingal and Triamcinolone Hexacetonide arms (ITT population). The Evaluator Global Assessment is done by the Blinded Outcomes Assessor, and answers the question "Considering all the ways the osteoarthritis in the patient's index knee bothers him/her, what is your assessment of how much the patient's knee is bothering him/her today?" The Evaluator Global Assessment is scored on a 0 to 100 mm visual analog scale, where a higher number means the Evaluator assesses that the patient is bothered to a higher degree. A negative number for the change from baseline indicates a reduction (improvement) in the assessment.

Intent to Treat Population

The usage of rescue medication (number of pills of acetominophen) at Week 39 weeks post treatment in the Cingal group compared to the Triamcinolone Hexacetonide group.

Intent to Treat Population