Platelet Rich Plasma Injection clinical trials at University of California Health

The investigators would like to study the differences in the quality of Platelet Rich Plasma (PRP) between two different machines in those with knee osteoarthritis. Knee osteoarthritis means your cartilage has been worn down, and it affects your knee joint. Both machines, the APEX Biologix XCELL PRP System and the Emcyte PurePRP Supraphysiologic Concentrating System, are FDA approved, commercially available, and makes PRP. The investigators will check if the platelets in the PRP have different amounts or work differently. The investigators will also assess participants symptoms after the injection and compare the two different preparation systems.