Knee
Page Index: Tips | Anatomy |Joint effusion|
Tips:
Check for joint effusion
Frontal
1 Medial femoral condyle. 2 Tibial spine. 3 Femorotibial joint - Medial compartment. 4 Tibia. 5 Fibula. 6 Fibular head. 7 Proximal tibiofibular joint. 8 Femorotibial joint - Lateral compartment. 9 Lateral femoral condyle. 10 Patella. 11 Femur. 12 Fabella. 13 Tibial tuberosity. 14 Femoropatellar joint. 15 Medial patellar joint. 16 Lateral patellar joint.
Sunrise
10 Patella. 15 Medial patellar joint. 16 Lateral patellar joint.
Lateral
1 Medial femoral condyle. 2 Tibial spine. 3 Femorotibial joint - Medial compartment. 4 Tibia. 5 Fibula. 6 Fibular head. 7 Proximal tibiofibular joint. 8 Femorotibial joint - Lateral compartment. 9 Lateral femoral condyle. 10 Patella. 11 Femur. 12 Fabella. 13 Tibial tuberosity. 14 Femoropatellar joint. 15 Medial patellar joint. 16 Lateral patellar joint.
Joint Effusion
Red lines highlights the position of peri-articular fat pads.
Yellow line indicates the base of the suprapatellar bursa (i.e. fat pad separation sign - see discussion for further detail). Red arrow indicates loss of normal crisp outline of the posterior aspect of the quadriceps tendon
Small knee joint effusion separating periarticular fat pads in >10 mm.
Knee joint effusions are only reliably seen on lateral projections. A knee joint effusion appears as well-defined rounded homogeneous soft tissue density within the suprapatellar recess on a lateral radiograph.
Kellgren and Lawrence system for classification of osteoarthritis
Typical osteoarthritis with cartilage loss on the medial side, subchondral sclerosis and osteophytes.
There is uniform cartilage loss.
There are no osteophytes.
In such a case your first thought should be inflammatory joint disease.
Calcium pyrophosphate dihydrate deposition disease
Chondrocalcinosis of the knee, with prominent calcification of the menisci.
Extensive degenerative changes, chondrocalcinosis in both menisci, predominant patellofemoral joint osteoarthritis, and calcification of the gastrocnemius tendon origin.
Calcium pyrophosphate dihydrate deposition (CPPD) disease, also known as pyrophosphate arthropathy or pseudogout, is defined by the co-occurrence of arthritis with evidence of CPPD deposition within the articular cartilage.
The terminology regarding CPPD disease has been confusing, with chondrocalcinosis, CPPD, and pseudogout often used synonymously. Indeed, although initially described as chondrocalcinosis articularis, it is now understood that imaging findings of chondrocalcinosis do not always indicate CPPD disease
Modified Insall-Salvati ratio
A: distance from the inferior margin of the patellar articular surface (as opposed to the lower pole of the patella itself) to the patellar tendon insertion
B: length of the patellar articular surface
Interpretation
normal: 1.25 (range 1.2-2.1) 2
patella alta: >2
