What is the suitable dose of Platelet-rich plasma (PRP) to use alongside intraarticular corticosteroids, such as triamcinolone acetonide (Kenacort), for knee pain?

PRP Should Not Be Combined with Intraarticular Corticosteroids for Knee Osteoarthritis

Current clinical guidelines do not support the combined use of PRP and corticosteroids, and these therapies should be used as separate treatment options rather than simultaneously. The evidence base addresses these as distinct therapeutic alternatives, not as combination therapy.

Why Combination Therapy Is Not Recommended

Lack of Evidence for Combined Use

• No major clinical guidelines from the American Academy of Orthopaedic Surgeons (AAOS), European League Against Rheumatism (EULAR), or VA/DoD address combining PRP with corticosteroids 1.
• The available research studies compare PRP versus corticosteroids as competing interventions, not as complementary treatments 2, 3, 4, 5, 6.
• Corticosteroids may theoretically interfere with the regenerative mechanisms of PRP by suppressing the inflammatory cascade that PRP relies on for tissue healing 1.

Guidelines Position These as Alternative Therapies

• The 2022 AAOS guidelines present corticosteroids and PRP as separate intra-articular injection options, with corticosteroids having stronger evidence (19 high-quality studies) compared to PRP (2 high-quality studies) 1.
• The 2021 VA/DoD guidelines found insufficient evidence to recommend for or against PRP, while supporting corticosteroid use for both hip and knee osteoarthritis 1.

Individual Dosing When Used Separately

Corticosteroid Dosing (When Used Alone)

• 40 mg of corticosteroid is recommended for maximal short-term benefit, particularly for acute flares with significant effusion 7.
• Repeat injections should occur at 3-4 month intervals based on duration of relief 7.
• Benefits typically last 1-12 weeks, with most evidence showing effectiveness for 1-4 weeks 1.

PRP Dosing (When Used Alone)

• Standard PRP protocols use 5 mL of platelet-rich plasma per injection 6.
• Most studies employ 2 injections at 4-week intervals 2.
• Some protocols use a single injection, which has shown effectiveness in late-stage osteoarthritis 4.

Clinical Decision Algorithm

First-Line: Corticosteroid Injection

• Use 40 mg corticosteroid for acute flares, especially with effusion 7.
• Expect 1-12 weeks of benefit 1, 8.
• Monitor glucose for 1-3 days post-injection in diabetic patients 7.
• Advise avoiding joint overuse for 24 hours following injection 7.

Second-Line: Consider PRP If Corticosteroids Fail

• PRP may be considered after corticosteroid failure, not in combination with it 1.
• PRP shows inconsistent results, with worse outcomes in severe osteoarthritis (Kellgren-Lawrence grade 3-4) 1.
• Evidence suggests PRP provides longer-lasting benefits (up to 6-12 months) compared to corticosteroids, though with slower onset 2, 3, 5, 6.

Important Caveats

PRP Limitations

• The 2022 AAOS guidelines note concerns about PRP cost and safety profile 1.
• PRP effectiveness decreases with disease severity—patients with grade 2 osteoarthritis show better responses than those with grade 3-4 2, 3.
• PRP is not FDA-approved for osteoarthritis, which limits recommendation strength 1.

Corticosteroid Concerns

• Repeated corticosteroid injections (40 mg every 3 months for 2 years) may cause cartilage loss, though this was not associated with worsening pain or function 7.
• Benefits are short-lived, typically requiring repeat injections every 3-4 months 1, 7.

Sequential vs. Simultaneous Use

• If both therapies are to be used in the same patient, they should be administered sequentially (corticosteroid first, then PRP if inadequate response), not simultaneously 1.
• Allow adequate washout period between therapies—at least 3-4 months after corticosteroid before considering PRP 7.