Causes of Popping Sounds in Ligaments at the Back of the Knee
Common Causes
- Popping sounds in the back of the knee are most commonly caused by soft tissue structures moving across bony prominences, with common causes including meniscal tears, ligament injuries, and popliteal cysts, as recommended by the American College of Radiology 1, 2
- Popliteal cysts (Baker's cysts) can cause popping sensations during movement due to fluid accumulation in the bursa of the gastrocnemius or semimembranosus muscles, according to the European League Against Rheumatism 3
- Ligamentous injuries, such as those to the posterior cruciate ligament or posterolateral corner structures, can cause popping sounds when these structures move abnormally across bony prominences, as stated by the American College of Radiology 4, 5
Diagnostic Approach
- MRI is the gold standard for evaluating soft tissue structures in the posterior knee, with high sensitivity and specificity for detecting meniscal tears and ligamentous injuries, as recommended by the American College of Radiology 6, 7
- Ultrasound can be useful for evaluating popliteal cysts, ganglion cysts, and some ligamentous injuries in the posterior knee, with reported sensitivity of 90% and specificity of 97% for ACL injuries, according to the American College of Radiology 1, 2
- CT scans may be helpful if bony abnormalities are suspected, but MRI is superior for evaluating soft tissue structures and bone marrow lesions, as stated by the American College of Radiology 8, 7