What is a suitable low-dose topical gel for managing knee pain?

Topical Diclofenac Gel for Knee Pain

For knee pain, use topical diclofenac sodium 1% gel at a dose of 40 mg (2 pump actuations) applied to each painful knee twice daily, which provides equivalent pain relief to oral NSAIDs while causing markedly fewer gastrointestinal adverse events. 1

Recommended Dosing Protocol

• Apply 40 mg of diclofenac sodium (2 pump actuations) to each painful knee, twice daily 2
• Dispense directly onto clean, dry skin of the knee or first into the hand, then spread evenly around the front, back, and sides of the knee 2
• The pump requires priming before first use by fully depressing 4 times (discard this portion) 2
• Wash hands completely after each application 2

Evidence for Efficacy

• Topical diclofenac is superior to placebo and equivalent to oral diclofenac at reducing knee osteoarthritis pain, with patients experiencing a mean reduction of 4.5 points on the WOMAC pain subscale compared to 3.6 points with vehicle control 2
• The effect size is 0.91 compared to placebo, demonstrating clinically meaningful pain relief 3
• Improvements in pain, physical function, and stiffness are maintained for up to 12 months of continuous use, with 39.8% improvement in WOMAC pain scores at 1 year 4

Critical Safety Advantages Over Oral NSAIDs

• Topical diclofenac causes markedly fewer gastrointestinal adverse events compared to oral NSAIDs while maintaining equivalent pain relief 1
• For patients aged ≥75 years, the American Geriatrics Society strongly recommends topical NSAIDs over oral NSAIDs due to substantially greater risk for cardiovascular, gastrointestinal, and renal adverse reactions with oral formulations 3
• The safety profile at 1 year is consistent with 12-week data, with no serious gastrointestinal or renal adverse events reported 1, 5

Common Side Effects and Management

• Application-site dermatitis is the most common treatment-related adverse event, occurring in 4-6% of patients 6, 4
• Local skin dryness or irritation affects approximately 36% of patients but leads to treatment discontinuation in only 6% of cases 5
• Gastrointestinal, renal, hepatic, and cardiovascular adverse events are rare (occurring in ≤3% of patients) 4

Application Precautions

• Avoid showering or bathing for at least 30 minutes after application 2
• Wait until the treated area is completely dry before covering with clothing or applying sunscreen, insect repellent, or other topical products 2
• Avoid skin-to-skin contact between other people and the treated knee until completely dry 2
• Do not apply to open wounds or mucous membranes 2
• Protect treated knees from natural and artificial sunlight 2
• Do not apply external heat or occlusive dressings to treated knees 2

Alternative Topical Option

• Topical capsaicin 0.025% to 0.075% provides moderate pain relief (standard mean difference 0.44) for knee osteoarthritis but requires continuous use for 2-4 weeks before therapeutic effect is experienced 1
• Capsaicin causes frequent burning or stinging at the application site, which may limit tolerability 1

When to Avoid Combination Therapy

• Do not use topical diclofenac in combination with oral NSAIDs unless the benefit outweighs the risk, and conduct periodic laboratory evaluations if combination therapy is necessary 2