What are the treatment options for osteoarthritis in the knee?

Treatment of Knee Osteoarthritis

Start with a combination of regular exercise, weight loss if BMI ≥25, and topical NSAIDs for the knee, adding oral acetaminophen or NSAIDs as needed for pain control. 1, 2

Initial Core Treatment Approach

Begin all patients with knee osteoarthritis on the following non-pharmacological interventions simultaneously:

Exercise Program

• Implement regular strengthening exercises, low-impact aerobic activity, and neuromuscular education as the foundation of treatment. 2
• Prescribe 30-60 minutes of moderate-intensity aerobic activity most days of the week 2
• Focus specifically on quadriceps strengthening exercises, which show significant improvements in both pain and function 2
• Low-impact aerobic exercises demonstrate substantial effects with effect sizes of 0.52 for pain relief and 0.46 for disability reduction 2
• Exercise programs should run 8-12 weeks, with 3-5 sessions per week, each lasting approximately 1 hour 3
• Both aquatic and land-based programs show comparable positive effects 3

Weight Management

• Mandate weight loss for any patient with BMI ≥25 kg/m², targeting a minimum 5% reduction in body weight. 2
• Combine dietary modification with exercise for optimal results 2
• Refer to comprehensive lifestyle intervention programs for weight reduction 1

Self-Management Education

• Enroll patients in self-management educational programs to learn coping skills and activity modifications 2
• Consider early referral to physical therapy based on pain severity and functional limitations 1

Assistive Devices

• Prescribe walking sticks, knee braces, or insoles to decrease weight burden and provide stability 1, 2
• Do not use lateral wedge insoles—they are not recommended. 2

Pharmacological Treatment Algorithm

First-Line Medications

Start with topical NSAIDs for the knee combined with acetaminophen for mild-to-moderate pain. 1, 2

• Topical NSAIDs and capsaicin have clinical efficacy and are safe for knee osteoarthritis 2
• Acetaminophen shows substantial benefits in reducing pain in patients with mild-to-moderate symptoms 1
• Acetaminophen can be dosed up to 4,000 mg/day 4

Second-Line: Oral NSAIDs or COX-2 Inhibitors

If pain persists despite acetaminophen, escalate to oral NSAIDs or COX-2 inhibitors. 1, 2

• Oral NSAIDs demonstrate superiority over acetaminophen in moderate-to-severe osteoarthritis pain 1
• For patients with increased gastrointestinal risk, use either non-selective NSAIDs with gastroprotective agents or selective COX-2 inhibitors 2
• Naproxen at 375 mg twice daily (750 mg/day) causes statistically significantly less gastric bleeding and erosion than aspirin, with fewer adverse events than higher doses 5
• Patients tolerate oral NSAIDs well, though they carry increased cardiovascular risks in certain populations 6

Third-Line: Duloxetine

For patients with inadequate response to NSAIDs, add duloxetine. 1

• Duloxetine achieves significant reductions in pain and statistically significant improvements in physical function 1
• Initiate at 30 mg/day and increase to a goal of 60 mg/day 1
• Educate patients that duloxetine must be taken daily (not as needed) and requires tapering over at least 2-4 weeks when discontinuing after more than 3 weeks of therapy 1

Intra-Articular Injections

Use intra-articular corticosteroid injections for acute flares of knee pain, especially when accompanied by effusion. 2

• Corticosteroid injections provide inexpensive, short-term relief lasting 4-8 weeks 7
• Hyaluronic acid injections may have symptomatic effects and can maintain symptom improvement for longer periods than corticosteroids, though the American Academy of Orthopaedic Surgeons does not recommend them 2, 7

Medications to Avoid

Do not use opioids, including tramadol, for osteoarthritis pain management. 1

• Current evidence does not support opioid use for managing osteoarthritis pain 1
• Opioids lead to higher risk for adverse events (relative risk 1.28-1.69) compared to placebo 1
• Tramadol has a poor trade-off between risks and benefits 8

Reassessment and Escalation

After Initial Treatment (4-8 weeks)

If pain or functional limitation has not improved:

• Consider combination pharmacotherapy using multiple agents from different classes 1
• Refer for additional physical therapy 1

If Conservative Management Fails

Obtain weight-bearing plain radiographs before surgical referral. 1

• Refer for surgical consultation when patients have radiographic evidence of knee osteoarthritis with refractory pain and disability despite maximal conservative management 2
• Total joint arthroplasty should be considered for chronic pain and disability unresponsive to conservative symptomatic management 8
• Do not refer for arthroscopic surgery—it has been shown to have no benefit in knee osteoarthritis. 8

Common Pitfalls to Avoid

• Do not combine NSAIDs with aspirin, as aspirin increases the rate of naproxen excretion and the combination results in higher frequency of adverse events without additional benefit 5
• Do not use lateral wedge insoles despite their historical use 2
• Avoid prescribing opioids as they lack supporting evidence and carry significant adverse event risks 1
• Do not delay weight loss interventions—they are as important as pharmacological treatments 2
• Reassess patients annually or as needed rather than continuing unchanged therapy indefinitely 1