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.

Inclusion Criteria:

• Kellgren-Lawrence (KL) Grade 1-3 knee osteoarthritis
• Symptoms of knee osteoarthritis for at least 3 months before presentation in one knee
• Will be able to attend and perform physical therapy

Exclusion Criteria:

• Received injection therapy for knee osteoarthritis in the past 6 months
• Have severe arthritis diagnosed in ≥1 major joint by radiology criteria
• History of septic arthritis
• Underwent knee surgery for osteoarthritis or osteochondral defects within 1 year before randomization (e.g., autograft or allograft surgery)
• Have had high tibial osteotomy, partial knee replacement, patellar resurfacing, total knee replacement, or have existing surgical hardware in the knee
• Received a platelet-rich plasma injection elsewhere in the body within the past 3 months
• Have a platelet disorder or bleeding disorder
• Have a rheumatologic disease, autoimmune disorder, immunocompromised status, or active history of cancer
• Are taking chemotherapy, require regular prednisone, or require regular anti-inflammatory use
• Are pregnant, breastfeeding, or unwilling to practice birth control during the study
• If both knees have osteoarthritis and the other knee has KL score equal to or greater than 2.
• Have uncontrolled illness, physical disability, or other contraindication to aerobic exercise training