AP-011 Study to Evaluate the Safety of a Single Intra-articular Injection of Ampion™ for Arthritis of the Basal Thumb Joint

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. Radiographic evidence of Basal joint arthritis (Eaton-Littler classification, stages 1 through 4). 5. Pain associated with basal joint arthritis, defined as a score ≥ 4 as evaluated by the Australian-Canadian OA Index (AUSCAN)-numeric rating score (NRS, 0-10). Exclusion Criteria: 1. As a result of medical review and screening investigation, the Principal Investigator considers the subject unfit for the study. 2. Previous Ampion™ injection. 3. A history of allergic reactions to human albumin (reaction to non-human albumin such as egg albumin is not an exclusion criterion). 4. A history of allergic reactions to excipients in 5% human albumin (N-acetyltryptophan, sodium caprylate). 5. Women who are currently pregnant or who could become pregnant. 6. Inflammatory or crystal arthropathies, acute fractures, history of aseptic necrosis, as assessed locally by the Principal Investigator. 7. Any other disease or condition interfering with the free use and evaluation of the index thumb for the duration of the trial (e.g., congenital defects, stricture). 8. Major injury to the index thumb within the 12 months prior to screening. 9. 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. 10. Use of the following medications are exclusionary: * IA injected pain medications in the study thumb during the study; * Analgesics containing opioids; * NSAIDs (including but not limited to ibuprofen, aspirin, naproxen, diclofenac) acetaminophen is available as a rescue medication during the study from the provided supply; * Topical prescription treatment on osteoarthritis index thumb during the study; * Significant anticoagulant therapy (e.g., Heparin or Lovenox) during the study (treatment such as Aspirin in the cardio-protective dose (81mg) and Plavix are allowed); * Systemic treatments that may interfere with safety or efficacy assessments during the study; * Immunosuppressants; * Use of corticosteroids \> 10 mg prednisolone equivalent per day (if ≤ 10 mg prednisolone, the dose must be stable, defined as chronic use of the same dose for at least 1 month). 11. Any human albumin treatment in the 3 months before randomization.