What is the initial management for an elderly patient presenting with acute right knee pain in primary care?

Initial Management of Acute Knee Pain in Elderly Patients in Primary Care

Start with acetaminophen (up to 4 grams daily) as first-line treatment, obtain plain radiographs if the patient meets Ottawa Knee Rule criteria (age ≥55, focal tenderness, isolated patellar tenderness, inability to flex to 90°, inability to bear weight, or cannot take 4 steps), and implement a multimodal approach including activity modification, ice application, and limb immobilization while avoiding NSAIDs unless acetaminophen fails and the patient has no contraindications. 1

Step 1: Initial Assessment and Red Flags

Immediately obtain radiographs if:

• Age ≥55 years with any knee pain 1
• Focal tenderness over the fibula head or isolated patellar tenderness 1
• Inability to flex knee to 90 degrees 1
• Inability to bear weight immediately after injury or cannot take 4 steps 1
• Gross deformity or palpable mass present 1, 2

Consider septic arthritis urgently if:

• Fever, refusal to bear weight, inability to move the joint, or signs of systemic infection 2
• This requires immediate joint aspiration—do not delay 2

Step 2: First-Line Pain Management

Acetaminophen is the primary analgesic:

• Regular dosing of 1 gram every 6 hours (maximum 4 grams per 24 hours) 1
• This provides equivalent pain relief to NSAIDs without gastrointestinal, renal, or cardiovascular risks 1, 3
• The 2024 World Society of Emergency Surgery guidelines specifically recommend intravenous acetaminophen every 6 hours as first-line treatment for acute trauma pain in elderly patients 1

Non-pharmacological measures should be implemented immediately:

• Immobilize the affected limb 1
• Apply ice packs 1
• Advise activity modification and relative rest 1, 4

Step 3: When to Add NSAIDs

Consider NSAIDs only if acetaminophen provides insufficient relief and after careful risk assessment: 1

Before prescribing NSAIDs in elderly patients, evaluate for:

• History of peptic ulcer disease or GI bleeding (10-fold increased risk of GI complications) 1, 5
• Congestive heart failure, hypertension, or cardiovascular disease 1, 5
• Renal insufficiency or hepatic disease 1, 5
• Concurrent anticoagulant, corticosteroid, or aspirin use 1, 5

If NSAIDs are appropriate:

• Use the lowest effective dose for the shortest duration 1, 5, 3
• Ibuprofen 400 mg every 4-6 hours (maximum 3200 mg daily, though doses above 400 mg show no additional benefit for acute pain) 5
• Co-prescribe a proton pump inhibitor in all elderly patients taking NSAIDs 3
• Monitor blood pressure, renal function, and GI symptoms regularly 5, 3

Topical NSAIDs are a safer alternative:

• Topical ibuprofen provides equivalent pain relief to oral formulations over 12 months 6
• Significantly fewer systemic adverse effects (7% respiratory effects vs 17% with oral NSAIDs) 6
• Less treatment discontinuation due to adverse effects (1% vs 16% with oral) 6

Step 4: Imaging Strategy

Plain radiographs (AP and lateral views minimum):

• Obtain if any Ottawa Knee Rule criteria are met 1
• Cross-table lateral view can demonstrate lipohemarthrosis (fat-fluid level), which indicates intra-articular fracture 1, 2
• Joint effusion >10 mm on lateral radiograph warrants further investigation 2

MRI without contrast is the next step if:

• Radiographs are negative but clinical suspicion remains high for internal derangement 1, 7
• Persistent joint effusion or mechanical symptoms suggest meniscal injury 7
• Suspected occult fracture or bone contusion 1, 7
• Do not skip radiographs and go directly to MRI, even if soft tissue injury is suspected 7

Step 5: Additional Interventions for Persistent Pain

If pain persists despite acetaminophen and activity modification:

• Intra-articular corticosteroid injection (e.g., triamcinolone hexacetonide) for acute episodes with evidence of inflammation or effusion 1
• Particularly effective when joint effusion is present 1
• Provides short-term relief with minimal risk of complications 1, 3

Consider referral to physiotherapy:

• Exercise programs focusing on strengthening, flexibility, and balance reduce pain and improve function 1, 4
• Should be implemented early rather than waiting for pain to resolve 4

Critical Pitfalls to Avoid

Do not:

• Prescribe NSAIDs as first-line therapy in elderly patients—acetaminophen is safer and equally effective 1, 3
• Use NSAIDs in high doses for prolonged periods—elderly patients have significantly higher risk of GI bleeding, renal toxicity, and cardiovascular events 1, 5
• Prescribe NSAIDs without co-prescribing a PPI in elderly patients 3
• Skip radiographs in patients ≥55 years with knee pain—age alone is an Ottawa Knee Rule criterion 1
• Delay aspiration if septic arthritis is suspected—this is an orthopedic emergency 2
• Assume negative radiographs exclude significant pathology—occult fractures and soft tissue injuries require MRI if clinical suspicion persists 1, 7, 2

Monitor closely for:

• NSAID-related complications: GI symptoms, elevated creatinine, hypertension, edema 5, 3
• Drug-drug interactions, particularly with anticoagulants, diuretics, ACE inhibitors, and aspirin 1, 5
• Signs of worsening heart failure if NSAIDs are used in patients with cardiac disease 5