What are the treatment options for a patient with knee pain, possibly with osteoarthritis?

Treatment of Knee Pain and Osteoarthritis

First-Line Treatment: Start with Non-Pharmacologic Interventions and Acetaminophen

Begin immediately with land-based cardiovascular and/or resistance exercise programs, as these are as critical as medications for reducing pain and improving function in knee osteoarthritis. 1

Non-Pharmacologic Core Interventions (Start These First)

• Exercise therapy should begin on day one - prescribe structured land-based cardiovascular and resistance training programs, with the principle of "small amounts often" and gradual progression 1, 2
• Aquatic exercise programs are particularly useful for aerobically deconditioned patients who can later transition to land-based programs 1
• Weight loss counseling is mandatory for all overweight patients (BMI ≥25), as reducing joint load directly improves outcomes 3, 1, 2
• Provide patient education addressing the degenerative nature of OA, realistic expectations, and self-management strategies 3, 2
• Consider assistive devices including walking aids, appropriate footwear with cushioned soles, and medially-directed patellar taping 1, 2

Initial Pharmacologic Management

• Acetaminophen up to 4,000 mg/day is the first-line oral medication due to its favorable safety profile and effectiveness for mild-to-moderate pain 3, 1, 2
• Topical NSAIDs (particularly diclofenac) are equally effective as first-line therapy and superior to placebo, with fewer gastrointestinal adverse events than oral NSAIDs 3, 1
• Oral NSAIDs can be used as first-line therapy but require screening for contraindications including history of GI ulcers, cardiovascular disease, renal impairment, and concurrent anticoagulation 3, 1

Second-Line Treatment: Escalation for Inadequate Response

If acetaminophen fails after an adequate trial, escalate to oral NSAIDs or intra-articular corticosteroid injections, particularly when knee effusion is present. 3, 1

Oral NSAID Considerations

• For patients at increased GI risk (age ≥60, history of peptic ulcer disease, concurrent corticosteroids/anticoagulants), use either topical NSAIDs, oral NSAIDs plus gastroprotective agents, or COX-2 selective inhibitors 3
• NSAIDs should be avoided in patients with heart failure due to fluid retention and cardiovascular risks 2
• All NSAIDs must be avoided in patients with impaired renal function 2

Intra-Articular Corticosteroid Injections

Intra-articular corticosteroid injections provide clinically meaningful short-term pain relief (1-24 weeks) and are particularly effective for acute flares with effusion. 3

Specific Injection Protocol:

• For knee injections: Use triamcinolone acetonide 10-40 mg intra-articularly 4, 5
• Recent evidence demonstrates that 10 mg triamcinolone acetonide is non-inferior to 40 mg for pain relief, potentially reducing systemic exposure 5
• Triamcinolone hexacetonide offers advantages over triamcinolone acetonide when available and should be the steroid of choice 6
• Knee injections do not require image guidance, unlike hip injections which must be image-guided 3
• Inject 2.5-5 mg for smaller joints and 5-15 mg for larger joints; doses up to 40 mg for larger areas have been sufficient 4
• Use strict aseptic technique and inject deeply into the joint space after aspirating excessive synovial fluid if present 4

Critical Corticosteroid Injection Pitfalls:

• Avoid corticosteroid injections within 3 months prior to knee replacement surgery due to increased infection risk 3, 1
• Monitor diabetic patients for 1-3 days after injection due to transient hyperglycemia risk 1
• Avoid repeat injections too frequently, as multiple corticosteroid administrations may have negative effects on bone health, joint structure, and meniscal thickness 3
• Ensure injection into the joint space, not surrounding tissues, to prevent tissue atrophy 4

Alternative Second-Line Option: Duloxetine

• Consider adding duloxetine 30-60 mg daily as an alternative or adjunct to initial treatments for patients with persistent pain 3
• Duloxetine must be taken daily (not as needed) and tapered over 2-4 weeks when discontinuing after >3 weeks of therapy 3

Third-Line Treatment: Viscosupplementation

Hyaluronic acid (viscosupplementation) injections have inconsistent evidence and should only be considered for patients with inadequate response to core pharmacological and non-pharmacological treatments. 3

• The 2022 AAOS guideline found inconsistent support from 17 high-quality and 11 moderate-quality studies, with a number needed to treat of 17 patients 3
• The 2021 VA/DoD guideline suggests considering viscosupplementation only after failure of core treatments 3
• Evidence is more favorable for mild-to-moderate disease rather than severe osteoarthritis 3
• Avoid hyaluronic acid injections within 3 months prior to knee replacement surgery 1

What NOT to Use

Opioids, including tramadol, should NOT be used for knee osteoarthritis management due to limited benefit and high risk of adverse effects. 3, 1

• Opioids led to 1.28-1.69 times higher risk of adverse events compared to placebo, with significantly worse withdrawal symptoms and serious adverse events 3
• Do not use chondroitin sulfate or glucosamine, as evidence does not support their effectiveness 1
• Avoid topical capsaicin due to insufficient evidence of benefit 1

Surgical Referral Criteria

Refer for total knee arthroplasty when patients have radiographic evidence of knee OA with refractory pain and disability despite maximal medical therapy that significantly impacts quality of life. 3, 2

• Joint replacement should be considered only after exhausting non-surgical options including exercise, weight loss, pharmacotherapy, and intra-articular injections 3, 2
• For meniscal tears in the setting of knee OA, arthroscopic partial meniscectomy should only be considered for truly obstructing displaced tears causing mechanical symptoms after failing conservative therapy 3