Arthrocentesis of the knee

Arthrocentesis of the knee

The knee and connecting suprapatellar pouch can be punctured while the patient is supine and the knee is extended. The needle, 18- or 20-gauge, can be inserted anteromedially, under the cephalad half or third of the patella. Alternatively, the needle can be inserted laterally, just under the cephalad edge of the patella (shown in drawing).