A 68-year-old client with moderate osteoarthritis of the knee reports inadequate pain relief with acetaminophen taken regularly for the past 3 months. The client also has a history of mild hypertension and prefers to avoid systemic medications if possible. The primary health care provider is considering a topical agent for localized pain management. Which medication would be most appropriate to recommend for this client's knee pain?
- Intra-articular corticosteroid injection to the knee
- Oral colchicine 0.6 mg twice daily
- Oral tramadol 50 mg every 6 hours as needed
- Topical diclofenac sodium gel applied to the affected knee