6 projections available • Largest joint in the body • Meniscus and ligament evaluation
The knee is a complex hinge-type joint (ginglymus) that supports weight and allows flexion-extension. Composed of femur, tibia, patella, menisci, and ligament complex.
In acute trauma, look for: tibial plateau fractures, avulsion fractures (second patella), Hoffa fractures, and signs of joint effusion (suprapatellar fat pad line).
AP weight-bearing: Perform with patient standing to evaluate real joint space. Lateral in 30° flexion: To visualize patella and trochlear groove.
Joint space: Measure femorotibial space (normal 3-5mm). Alignment: Evaluate mechanical axis. Patella: Measure Insall-Salvati index.
Indirect signs: Joint effusion, osteochondral fractures, calcifications (Pellegrini-Stieda).