A Study to Evaluate Safety of Three Intra-articular Injections of Ampion in the Knee of Adults With Osteoarthritis Pain

Inclusion Criteria: 1. Able to provide written informed consent to participate in the study 2. Willing and able to comply with all study requirements and instructions of the site study staff 3. Male or female, 40 years to 85 years old (inclusive) 4. Ambulatory 5. Index knee must have been symptomatic for greater than 6 months with a clinical diagnosis of OA and supported by radiological evidence (Kellgren Lawrence Grade II-IV) acquired at Screening 6. Moderate to moderately severe OA pain in the index knee (rating of at least 1.5 on the WOMAC Pain Subscale) assessed at Screening and confirmed at randomization 7. Moderate to moderately severe OA pain in the index knee (even if chronic doses of nonsteroidal anti-inflammatory drugs \[NSAIDs\], which have not changed in the 4 weeks prior to Screening, had been used) 8. No analgesia taken 24 hours before efficacy measure Exclusion Criteria: 1. As a result of medical review and screening investigation, the Principal Investigator considered the subject unfit for the study 2. Previous Ampion injection 3. Known clinically significant liver abnormality (eg, cirrhosis, transplant, etc.) 4. History of allergic reactions to human albumin (reaction to non-human albumin such as egg albumin was not an exclusion criterion) 5. History of allergic reactions to excipients in 5% human albumin (N-acetyltryptophan, sodium caprylate) 6. Presence of tense effusions in the index knee 7. Inflammatory or crystal arthropathies, acute fractures, history of aseptic necrosis or joint replacement in the index knee, as assessed locally by the Principal Investigator 8. Isolated patella femoral syndrome, also known as chondromalacia in the index knee 9. Any other disease or condition interfering with the free use and evaluation of the index knee for the duration of the trial (eg, cancer, congenital defects, spine OA) 10. Major injury to the index knee within the 12 months prior to Screening 11. Severe hip OA ipsilateral to the index knee 12. Any pain that could interfere with the assessment of index knee pain (eg, pain in any other part of the lower extremities, pain radiating to the knee) 13. Any pharmacological or non-pharmacological treatment targeting OA started or changed during the 4 weeks prior to treatment or likely to be changed during the duration of the study 14. Use of any of the following medications: * IA-injected pain medications in the index knee during the study * Analgesics containing opioids (NSAIDs were allowed at the levels preceding the study and acetaminophen was available as rescue medication during the study from the provided supply) * Topical prescription treatment on the index knee during the study * Significant anticoagulant therapy (eg, heparin or enoxaparin) during the study (aspirin and clopidogrel were allowed) * Systemic treatments that could interfere with safety or efficacy assessments during the study * Immunosuppressants * Corticosteroids \>10 mg prednisolone equivalent per day or corticosteroids at doses ≤10 mg prednisolone equivalent that had been changed during the study 15. Any human albumin treatment in the 3 months before randomization