Management of Left Knee Pain
Begin with plain radiographs (anteroposterior, lateral, and tangential patellar views) as the mandatory first-line imaging study for any patient with chronic knee pain, then initiate a combined treatment approach of acetaminophen (up to 4000 mg daily), quadriceps strengthening exercises (2 days per week at moderate-to-vigorous intensity for 8-12 repetitions), and weight reduction if BMI ≥25 kg/m². 1, 2, 1
Initial Diagnostic Workup
Obtain plain radiographs immediately as the first imaging study regardless of suspected etiology, including at minimum anteroposterior, lateral (at 25-30 degrees flexion), and tangential patellar views. 1, 2 This serves to exclude fracture, assess degenerative changes, identify loose bodies, evaluate alignment, and detect osteochondritis dissecans or chondrocalcinosis. 1
Key clinical features to assess during examination:
- Age-specific patterns: Teenage girls/young women more likely have patellar tracking problems (subluxation, patellofemoral pain syndrome); teenage boys/young men more likely have extensor mechanism problems (Osgood-Schlatter, patellar tendonitis); adults >45 years most likely have osteoarthritis (95% sensitivity with activity-related pain and <30 minutes morning stiffness). 3, 4
- Pain location and quality: Anterior knee pain during squatting suggests patellofemoral pain (91% sensitivity); joint line tenderness suggests meniscal pathology (83% sensitivity, 83% specificity). 4
- Mechanical symptoms: True locking from displaced meniscal tissue versus pseudo-locking from pain/stiffness; McMurray test (concurrent knee rotation and extension) has 61% sensitivity and 84% specificity for meniscal tears. 4
- Effusion presence: Indicates need for intra-articular steroid consideration if acute exacerbation. 1
- Red flags requiring urgent referral: Fever with swelling/erythema/limited range of motion (septic arthritis); severe pain with instability and inability to bear weight after acute trauma; gross deformity. 5, 6
Consider referred pain sources if knee radiographs are unremarkable: obtain hip radiographs if clinical concern for hip pathology exists; consider lumbar spine imaging if lower back pathology suspected. 1
Advance to MRI without IV contrast only when initial radiographs are normal or show only joint effusion AND pain persists after conservative management, as MRI accurately depicts effusions, synovitis, popliteal cysts, subchondral cysts, articular cartilage abnormalities, and meniscal tears. 1 However, recognize that meniscal tears are often incidental findings in older patients (majority of people >70 years have asymptomatic tears), and the likelihood of meniscal tears in painful versus asymptomatic knees is not significantly different in patients 45-55 years. 1
First-Line Pharmacological Management
Start with acetaminophen (paracetamol) up to 4000 mg per 24 hours as the preferred first-line oral analgesic for long-term use, as it provides significant pain improvement with the best safety profile. 1, 6, 7
Add topical NSAIDs before considering oral NSAIDs, particularly in patients ≥75 years old, due to superior safety profile. 8, 6
Prescribe oral NSAIDs (such as ibuprofen 1200-3200 mg daily in divided doses) only if acetaminophen provides insufficient relief, using the lowest effective dose for the shortest duration. 1, 7 For patients with effusion unresponsive to acetaminophen, NSAIDs are specifically indicated. 1 Administer with meals or milk if gastrointestinal complaints occur. 7
Critical NSAID safety considerations:
- Use lowest effective dose (ibuprofen 400 mg every 4-6 hours for mild-moderate pain; 1200-3200 mg daily divided tid or qid for osteoarthritis). 7
- Co-prescribe proton pump inhibitor in elderly patients due to significantly elevated gastrointestinal bleeding risk. 6, 7
- Monitor for anemia (check hemoglobin/hematocrit if signs/symptoms develop), as decrease of ≥1 gram hemoglobin observed in 17-22% of patients on chronic NSAID therapy. 7
- Avoid in patients with aspirin-sensitive asthma due to cross-reactivity causing severe bronchospasm. 7
- Monitor liver function tests, as borderline elevations occur in up to 15% of patients; discontinue if clinical signs of liver disease develop. 7
Consider intra-articular corticosteroid injection for acute exacerbations of knee pain, especially if accompanied by effusion, but space injections appropriately (typically not more frequently than every 3 months) to avoid potential cartilage damage. 1, 2
Do NOT prescribe glucosamine, chondroitin, or hyaluronic acid injections, as they have no clinically important benefit despite small effect sizes reported in some studies. 6, 1
Essential Non-Pharmacological Interventions
Prescribe structured quadriceps strengthening exercises 2 days per week at moderate-to-vigorous intensity for 8-12 repetitions, which produces effect sizes of 0.57-1.0 for pain reduction. 2 Exercises directed toward increasing quadriceps strength and preserving normal knee mobility are strongly recommended. 1
Refer to physical therapy for 12+ directly supervised sessions, as programs lasting 8-12 weeks with 3-5 sessions weekly produce significant pain reduction. 2 Do not withhold exercise therapy based on age or severity, as elderly patients achieve similar gains as younger adults. 2, 6
Add aerobic exercise (walking or cycling) 30-60 minutes daily at moderate intensity as part of comprehensive management. 2
Implement weight-loss program if BMI ≥25 kg/m², targeting mean reductions of 4.0 kg, as obesity is a major modifiable risk factor. 2
Enroll patient in structured education and self-management program, which reduces healthcare costs by up to 80% within one year and empowers patients to better manage their condition. 2, 4
Consider realignment knee bracing as adjunctive treatment, which can reduce the external knee adduction moment by 10-20% and provides pain reduction at 6-12 month follow-up. 2
Prescribe full-length wedged insoles with 6°-8° wedge angle to optimally balance efficacy and patient tolerance, as combination of wedged insoles with oral NSAIDs shows significant improvement in pain reduction (effect size 0.5). 2, 1
Provide walking sticks or other appliances to reduce pressure on the affected knee. 1, 8
Surgical Considerations
Reserve arthroscopic lavage/debridement only for clear mechanical locking from loose bodies or displaced meniscal tissue (bucket-handle tears), not for degenerative meniscal tears even in presence of mechanical symptoms. 6, 4
Consider total knee arthroplasty only for end-stage disease (grade 3-4 osteoarthritis with minimal joint space) with refractory pain and significant disability after 6+ months of comprehensive conservative management. 1, 2, 4
Consider infra-tubercle tibial de-rotation osteotomy for patients with severe external tibial torsion (≥37°) and refractory anterior knee pain after exhausting conservative management for at least 3 months. 2
Critical Pitfalls to Avoid
Never skip initial radiographs, as approximately 20% of patients with chronic knee pain have MRI performed without recent (within prior year) radiographs, leading to premature and unnecessary advanced imaging. 1
Never refer for arthroscopic surgery for degenerative meniscal tears, as exercise therapy is first-line treatment and surgery is not indicated even with mechanical symptoms. 4
Avoid prolonged NSAID monotherapy without gastroprotection in elderly patients who have significantly elevated gastrointestinal bleeding risk. 6
Do not prescribe opioids unless NSAIDs are contraindicated or ineffective. 6
Recognize that optimal management requires combination of pharmacological and non-pharmacological treatment modalities rather than relying on single interventions, with evidence showing home exercise programs, physiotherapy, and education offer additional benefit when used in addition to analgesic regimens. 1, 8