Posterior Knee Pain Diagnosis and Management

Primary Posterior Knee Pathologies

The American College of Radiology recommends MRI as the preferred imaging modality for detecting popliteal cysts when radiographs are normal but symptoms persist 1
MRI accurately depicts the presence or rupture of a popliteal cyst, and these cysts often communicate with the knee joint and may be associated with underlying intra-articular pathology 1
Ultrasound can detect popliteal cysts, particularly when loose bodies might be within the cyst, and is useful for detecting synovial pathology 3

The American College of Radiology suggests that in patients with chronic knee pain, referred pain from the lower back must be considered, especially if knee radiographs are unremarkable and there is clinical evidence or concern for lumbar spine pathology 1, 2
Referred pain from the hip must be considered, especially if knee radiographs are unremarkable and there is clinical evidence or concern for hip pathology 1

Radiography is the initial imaging study for chronic knee pain and should include frontal projection, tangential patellar view, and lateral view 1, 4
MRI without IV contrast is the next indicated examination when initial radiographs are normal or reveal a joint effusion but pain persists 1
MRI accurately depicts the extent of effusion, presence of synovitis, and presence or rupture of popliteal cysts 1

The American College of Radiology advises against overlooking referred pain from hip or lumbar spine pathology before attributing all symptoms to knee pathology 5
A thorough clinical examination, including assessment of lumbar spine and hip, should be completed before rushing to imaging 5
Premature MRI use should be avoided, as approximately 20% of patients with chronic knee pain have had MRI performed without recent radiographs 1
Not all meniscal tears seen on imaging are symptomatic, particularly in patients over 45 years 1

In patients over 70 years of age, bilateral structural abnormalities can be present with primarily unilateral symptoms, limiting the ability to discriminate painful from nonpainful knees 1