What is the most appropriate initial management for a 39-year-old patient with left knee pain, difficulty walking, and weight-bearing issues following a traumatic injury, with a history of hypovitaminosis D, and currently taking vitamin D supplements and paracetamol?

Immediate Management of Acute Traumatic Knee Injury with Effusion and Meniscal Pathology

This patient requires urgent MRI without contrast to evaluate for meniscal tear, ligamentous injury, and occult fracture, along with orthopedic referral within 1-2 weeks, while initiating conservative management with NSAIDs (ibuprofen 400-800mg every 6-8 hours), protected weight-bearing with crutches, and structured physical therapy. 1, 2, 3

Imaging Strategy

Obtain plain radiographs immediately (AP and lateral views minimum) despite the negative X-ray from the previous facility visit. 4, 2

• This patient meets multiple Ottawa Knee Rule criteria: lateral joint line tenderness and inability to fully weight bear, which mandates radiographic evaluation 4, 1
• The lateral view is critical for detecting joint effusion and lipohemarthrosis (fat-fluid level), which indicates intra-articular fracture 2
• The positive sweep test confirms significant effusion, and new varicose veins post-injury raise concern for vascular compromise 2

If radiographs are negative but clinical suspicion remains high (as in this case with positive McMurray test, effusion, and mechanical symptoms), proceed directly to MRI without contrast. 2, 3, 5

• MRI is superior for detecting bone marrow edema, occult fractures, meniscal tears, and ligament injuries that are invisible on plain films 2, 5
• The positive McMurray test with lateral meniscus discomfort, inability to fully flex, sensation of knee instability, and persistent effusion 2+ weeks post-injury strongly suggest internal derangement requiring MRI evaluation 3, 5
• Do not delay MRI waiting for "failed conservative management"—the mechanical symptoms (locking, instability, inability to flex fully) indicate structural damage requiring definitive diagnosis 6, 3

Pain Management and Anti-Inflammatory Treatment

Discontinue paracetamol monotherapy and initiate ibuprofen 400-800mg every 6-8 hours with food (maximum 3200mg daily) for combined analgesic and anti-inflammatory effects. 7, 8

• NSAIDs are superior to acetaminophen alone for acute traumatic knee injuries with inflammation and effusion 8
• The FDA-approved dosing for acute pain is 400mg every 4-6 hours, but doses up to 800mg may be used for more severe pain 7
• Administer with meals or milk to minimize gastrointestinal side effects 7
• At age 39 without contraindications mentioned, NSAIDs are appropriate first-line therapy (unlike elderly patients where acetaminophen is preferred) 9, 8

Functional Management

Prescribe protected weight-bearing with bilateral crutches and knee brace continuation until orthopedic evaluation. 1, 8

• The patient's current use of a knee brace for stability is appropriate and should continue 1
• Avoid complete immobilization—early controlled mobilization improves outcomes without compromising stability 1
• Implement RICE protocol: relative rest (not complete immobilization), ice 15-20 minutes every 2-3 hours, compression with brace, and elevation when resting 1, 8

Refer to physical therapy immediately for structured exercise program focusing on quadriceps strengthening and range of motion within pain-free limits. 8

• Physical therapy with strengthening and flexibility exercises reduces pain and improves function in knee injuries 9, 8
• The inability to sit on the floor or pray properly indicates significant functional limitation requiring rehabilitation 8

Orthopedic Referral and Follow-Up

Arrange orthopedic consultation within 1-2 weeks (not emergent but expedited) for definitive management based on MRI findings. 2, 3

• Meniscal tears may require arthroscopic repair or partial meniscectomy depending on tear pattern, location, and patient factors 3, 5
• The "pop" sound at injury, persistent effusion, mechanical symptoms (locking, instability), and positive McMurray test create high pretest probability for meniscal pathology requiring surgical evaluation 6, 3
• Complete ligament tears (if identified on MRI) typically require surgical reconstruction in younger, active patients 2

Critical Pitfalls to Avoid

Do not assume the previous negative X-ray from the other facility excludes significant pathology—radiographs miss meniscal tears, ligament injuries, and occult fractures. 2, 6, 3

• A 21-year-old basketball player with similar presentation (pop, immediate pain, inability to bear weight) had negative initial radiographs but MRI revealed complete patellar tendon rupture 6
• The patient's inability to actively fully extend (if present) would suggest extensor mechanism disruption requiring urgent surgical repair 6

Do not delay MRI based on "trial of conservative management"—the mechanical symptoms and functional limitations indicate structural damage requiring definitive diagnosis now, not in 6 weeks. 3, 5

Address the hypovitaminosis D aggressively as it increases fracture risk and impairs healing—ensure adequate supplementation (typically 1000-2000 IU daily minimum) and check 25-hydroxyvitamin D levels. 10

• Vitamin D deficiency is a major risk factor for bone loss and fracture, and 42-57% of general medical patients are vitamin D deficient even with supplementation 10