Best X-ray Views for Evaluating Knee Arthritis
The optimal radiographic examination for evaluating knee arthritis should include weight-bearing anteroposterior (AP), lateral, and tangential patellar views, with the AP view preferably obtained during weight bearing. 1
Standard Radiographic Protocol for Knee Arthritis
- Knee radiographs should include at least one frontal projection (anteroposterior, Rosenberg, or tunnel view), a tangential patellar view, and a lateral view of the affected knee 1
- Weight-bearing views are essential for proper evaluation of joint space narrowing, which is a key radiographic finding in arthritis 1
- Standing AP views allow for assessment of alignment and measurement of the tibiofemoral angle 1
Specific Views and Their Value
Weight-bearing AP View
- Provides visualization of the tibiofemoral joint space in the coronal plane 1
- Allows assessment of joint space narrowing, osteophytes, subchondral sclerosis, and cysts 1
- Should be obtained with the patient standing to properly evaluate weight-bearing surfaces 1, 2
Rosenberg/PA Flexion View (45° flexion)
- More sensitive than conventional AP views for detecting joint space narrowing, particularly in the medial compartment 3
- Shows narrowing that may not be apparent on standard AP views 4, 3
- The PA weight-bearing view in 45° of flexion (Rosenberg view) significantly increases detection of joint space narrowing compared to AP view alone 4, 3
Lateral View
- Essential for evaluating the patellofemoral joint and posterior knee compartment 1, 5
- Helps detect osteophytes, joint effusion, and loose bodies 1
- May be easier to acquire with high quality than the skyline view 5
Tangential Patellar View (Skyline/Merchant View)
- Specifically evaluates the patellofemoral joint 1, 5
- Allows assessment of patellar alignment, tilt, and patellofemoral joint space 1
- Important for detecting patellofemoral arthritis which may be missed on other views 5
Enhancing Diagnostic Accuracy
- The combination of weight-bearing AP and tunnel views significantly increases detection of joint space narrowing in both lateral (p<0.001) and medial (p=0.006) compartments over the AP view alone 4
- Combined views improve identification of subchondral cysts, sclerosis, and osteophytes 4
- Poor standardization of knee positioning in serial radiographs can obscure the true rate of joint space narrowing 6
- Adding either a lateral or skyline view to an AP view yields high sensitivity (94-97%) for detecting radiographic knee osteoarthritis 5
Pitfalls and Considerations
- Failure to obtain weight-bearing views may lead to underestimation of joint space narrowing 1, 2
- Misalignment of the medial tibial plateau and x-ray beam can affect the apparent progression of osteoarthritis in serial radiographs 6
- Only 14% of serial radiographs exhibit proper alignment of the medial tibial plateau in both images, which can affect assessment of disease progression 6
- Technical quality of skyline views can be challenging; lateral views may be a reasonable alternative for evaluating the patellofemoral joint 5