What are the treatment options for knee pain?

Treatment of Knee Pain

Start with acetaminophen up to 4,000 mg/day as first-line oral analgesic combined with quadriceps strengthening exercises, as this combination provides the safest and most effective initial approach for knee pain. 1, 2

First-Line Treatment Approach

Pharmacological Management

• Acetaminophen (up to 4,000 mg/day) is the preferred initial oral analgesic due to its favorable safety profile with adverse events occurring in only 1.5% of patients 3, 1
• Topical NSAIDs should be considered as an alternative first-line option, particularly in patients ≥75 years old, as they provide comparable efficacy with significantly better safety profiles than oral NSAIDs 1, 2
• Patients must be counseled to avoid other acetaminophen-containing products to prevent exceeding the maximum daily dose of 4,000 mg, which can cause hepatotoxicity 2
• A full dosage trial of acetaminophen should be completed (2-4 weeks) before considering it ineffective 2

Non-Pharmacological Interventions (Equally Important)

• Quadriceps strengthening exercises are strongly recommended as primary treatment, with closed kinetic chain exercises being more effective than open kinetic chain exercises 2
• Both land-based and aquatic exercises are effective, with the choice depending on patient preference and ability 2
• Exercise programs should be progressive, starting at lower intensity and gradually increasing as tolerated 2
• Weight reduction is strongly recommended for overweight patients, as even modest weight loss significantly improves symptoms and function 3, 2
• Patient education about self-management strategies should be provided at the initial visit 2

Second-Line Treatment Options

When First-Line Fails After 2-4 Weeks

• Oral NSAIDs (such as ibuprofen up to 2400 mg/day) should be considered for patients unresponsive to acetaminophen, particularly if there is evidence of inflammation 3, 1, 4
• For patients with increased gastrointestinal risk requiring oral NSAIDs, use either COX-2 selective inhibitors or non-selective NSAIDs with gastroprotective agents 3, 2
• Supportive devices such as walking sticks, medially wedged insoles for lateral compartment involvement, or laterally wedged subtalar strapped insoles for medial compartment involvement should be implemented 1, 2
• Manual therapy in combination with supervised exercise may provide additional benefit beyond exercise alone 2
• Thermal agents (heat or cold) can be used for symptomatic relief 2

Important Safety Considerations for NSAIDs

• NSAIDs inhibit platelet aggregation and prolong bleeding time, requiring careful monitoring in patients with coagulation disorders or those receiving anticoagulants 4
• Borderline elevations of liver tests occur in up to 15% of patients taking NSAIDs, with notable elevations (≥3x upper limit of normal) in approximately 1% 4
• Long-term NSAID use increases risk of gastrointestinal, cardiovascular, and renal adverse effects 2
• Anemia may develop due to fluid retention or occult GI blood loss; hemoglobin should be monitored in patients on long-term NSAIDs 4

Advanced Treatment Options

For Acute Exacerbations

• Intra-articular corticosteroid injections are indicated for acute flares of knee pain, especially if accompanied by effusion, providing short-term pain relief 3, 1, 2
• These injections should not be used as routine maintenance therapy but reserved for acute inflammatory episodes 3

Alternative Pharmacological Options

• Opioid analgesics, with or without acetaminophen, are useful alternatives in patients in whom NSAIDs are contraindicated, ineffective, or poorly tolerated 3
• Duloxetine 60 mg daily may be considered for chronic musculoskeletal pain, as it demonstrated significant pain reduction in osteoarthritis trials, though this is not typically first-line 5
• Hyaluronic acid infiltrations are conditionally recommended when other treatments fail 6

What NOT to Use

• Nutritional supplements such as glucosamine and chondroitin sulfate are NOT recommended due to lack of evidence for efficacy 2
• Platelet-rich plasma infiltrations and chemical ablation of genicular nerves do not have enough evidence and should only be considered in research settings 6

Treatment Algorithm

Step 1 (Weeks 0-4):

• Initiate acetaminophen up to 4,000 mg/day 1, 2
• Begin quadriceps strengthening exercises (progressive program) 2
• Implement weight reduction strategies for overweight patients 3, 2
• Provide patient education on self-management 2

Step 2 (If inadequate response after 2-4 weeks):

• Add or switch to topical NSAIDs 1, 2
• Consider supportive devices (insoles, walking aids) 1, 2
• Intensify exercise program with professional supervision 2

Step 3 (If still inadequate response):

• Consider oral NSAIDs with gastroprotection if indicated 3, 1, 2
• Continue exercise therapy (critical for long-term success) 2

Step 4 (For acute flares with effusion):

• Use intra-articular corticosteroid injections 3, 1, 2

Step 5 (Refractory cases):

• Consider radiofrequency ablation of genicular nerves (conventional or cooled) 6
• Evaluate for joint replacement in patients with radiographic evidence and refractory pain/disability 3

Critical Pitfalls to Avoid

• Relying solely on pharmacological management without implementing exercise therapy significantly reduces treatment effectiveness 2, 7
• Failing to complete a full trial of acetaminophen at adequate doses before declaring it ineffective 2
• Exceeding 4,000 mg/day of acetaminophen, which can lead to hepatotoxicity 2
• Using NSAIDs without gastroprotection in high-risk patients (history of GI bleeding, age >65, concurrent corticosteroid use) 3, 2
• Prescribing glucosamine or chondroitin, which lack evidence and waste patient resources 2
• Neglecting to address weight reduction in overweight patients, which is one of the most effective interventions 3, 2
• Discontinuing exercise therapy after initial improvement, as adherence to long-term exercise is needed to maintain benefits 7

Tailoring Treatment

Treatment intensity should be adjusted based on:

• Knee risk factors (obesity, adverse mechanical factors, physical activity level) 3
• General risk factors (age, comorbidities, polypharmacy) 3
• Level of pain intensity and disability 3
• Signs of inflammation such as effusion 3
• Location and degree of structural damage on imaging 3