Intra-articular hyaluronic acid injections are used in TMJ disorders. What is a main contraindication?

• A. Age over 65
• B. Prior hyaluronic acid injections in other joints
• C. Active infection of the TMJ or systemic infection, or known allergy to hyaluronic acid
• D. History of osteoarthritis

Answer: (C)

The main idea is that intra-articular hyaluronic acid injections should not be given when there is an active infection. Injecting into a joint that is infected can drive bacteria into the joint space, leading to septic arthritis and spreading the infection, which is dangerous. If there is a known allergy to hyaluronic acid, that also makes the injection inappropriate due to the risk of a hypersensitivity reaction.

In contrast, factors like age over 65, having had injections in other joints before, or a history of osteoarthritis do not by themselves contraindicate the procedure. These elements may influence overall management or risk but do not inherently prohibit the use of hyaluronic acid when there is no infection or allergy.

So the best answer is that an active TMJ infection or any systemic infection, or a known allergy to hyaluronic acid, are the main contraindications.