Recommended X-ray Views for Knee Pain

Standard Initial Radiographic Series

The American College of Radiology recommends obtaining at minimum two views—anteroposterior (AP) and lateral—with the lateral taken at 25-30 degrees of knee flexion, and adding a tangential patellar view to complete a standard three-view series for initial evaluation of knee pain 1, 2
The anteroposterior (AP) view is essential for evaluating the tibiofemoral joint, fractures, and alignment, according to the American College of Radiology 1, 3
The lateral view must be obtained with the knee at 25-30 degrees of flexion in the lateral decubitus position, demonstrating the patella in profile, as recommended by the American College of Radiology 1
The lateral view allows evaluation for joint effusion and, when obtained as a cross-table lateral with horizontal beam, can visualize lipohemarthrosis (indicating intra-articular fracture), according to the American College of Radiology 1

The American College of Radiology recommends including a tangential patellar view (sunrise/skyline view) as part of the standard knee series to evaluate the patellofemoral joint 2

For chronic knee pain or suspected osteoarthritis, weight-bearing views significantly improve diagnostic accuracy, with the weight-bearing AP view being standard for chronic pain evaluation, according to the American College of Radiology 2

The American College of Radiology recommends a patellofemoral view when patellar fracture, subluxation, or dislocation is suspected 1
Internal and external oblique views are commonly performed as supplemental projections in acute knee trauma, according to the American College of Radiology 1

The American College of Radiology indicates that radiographs are suggested if ANY of the following Ottawa Knee Rules are present: age >55 years, isolated tenderness of the patella, tenderness at the head of the fibula, inability to flex knee to 90 degrees, or inability to bear weight both immediately after injury and in the emergency department 1, 3, 4
The Pittsburgh Rules suggest three criteria: inability to bear weight, inability to flex the knee to 90 degrees, and presence of bony tenderness, according to the American College of Radiology 1

The American College of Radiology advises never skipping radiographs even when effusion is clinically obvious, as plain films are essential to rule out fractures, prosthetic complications, or chronic changes before proceeding to advanced imaging 3
The American College of Radiology recommends not ordering MRI without recent radiographs first, as approximately 20% of patients with chronic knee pain inappropriately receive MRI without radiographs within the prior year 2, 5
Clinical judgment supersedes decision rules, and the American College of Radiology advises not applying Ottawa or Pittsburgh rules in patients with gross deformity, palpable mass, penetrating injury, prosthetic hardware, unreliable examination due to multiple injuries, altered mental status, or neuropathy 1

For acute trauma with positive Ottawa/Pittsburgh criteria, the American College of Radiology recommends AP + lateral (25-30° flexion) + consider patellofemoral view 1, 3
For chronic knee pain (initial evaluation), the American College of Radiology suggests weight-bearing AP (or tunnel view) + lateral + tangential patellar view 2
For suspected patellar pathology, the American College of Radiology recommends standard views + dedicated patellofemoral/skyline view 1
For suspected arthritis, the American College of Radiology advises weight-bearing AP + weight-bearing tunnel view + lateral + tangential patellar 2