Acute Knee Pain Evaluation and Management

Initial Imaging Approach

Radiographs are the mandatory first-line imaging for any patient with acute knee trauma who has focal joint line tenderness, regardless of ability to bear weight 1, 2
Obtain minimum two views: anteroposterior and lateral (with knee at 25-30 degrees flexion) 1
The lateral view allows evaluation for joint effusion and lipohemarthrosis, which frequently indicates intra-articular fracture 1
Osteopenia significantly increases fracture risk after falls due to decreased bone mineral density, making imaging even more critical in this population 3

The American College of Radiology recommends radiographs for patients with palpable joint line tenderness after acute trauma 2, 3
Fracture risk increases with age and decreased bone mineral density, making clinical examination alone unreliable 3
Physician judgment should supersede clinical guidelines only when radiographs are more indicated, not less 1

MRI is superior to CT for detecting bone marrow edema, occult fractures, meniscal tears, and ligament injuries 4
CT should be reserved specifically for better characterizing fractures already visible on radiographs or when MRI is contraindicated 1
CT shows 100% sensitivity for tibial plateau fractures versus 83% for radiographs alone, but MRI provides more comprehensive soft tissue evaluation 1

Orthopedic consultation is recommended for definitive management of fractures identified on radiographs 3
Tibial plateau fractures may require surgical fixation depending on displacement and stability 1
Non-displaced fractures may be managed conservatively with protected weight-bearing 3
Grade III MCL injuries may require surgical repair if unstable 4
Complete ACL tears typically require surgical reconstruction in younger, active patients 4
PCL injuries may need surgical intervention for multi-ligament injuries or persistent instability 4

Do not defer imaging based on ability to bear weight alone, as the Ottawa Knee Rule requires radiographs if any criterion is met—joint line tenderness is sufficient indication regardless of weight-bearing status 1, 2, 3