Diagnosing snapping popliteus tendon is not a snap in lateral knee symptoms

Although snapping sensation that causes pain in the lateral aspect of the knee is a common symptom, snapping of the popliteus tendon (PT) over the lateral femoral condyle rarely presents as the cause. Anatomy, function, and ruptures of the PT have been studied extensively and are well documented in the literature.[1-3] However, clinical and radiological diagnosis of snapping is still challenging, resulting in an increased risk of incorrect diagnosis and eventually inadequate treatment. It can be easily missed among other symptoms of the lateral knee, such as iliotibial band friction syndrome, lateral meniscus tear, discoid lateral meniscus, cartilage injury or loose bodies in the knee joint. Painful snapping located at lateral aspect of the knee is common; however, snapping popliteus tendon syndrome (SPTS) rarely presents as the cause and may be misdiagnosed even by the most experienced surgeons. A 36-year-old male patient was admitted with lateral knee pain and snapping sensation for two years. Snapping was palpated at the lateral knee when flexed at 30° and the patient described intense pain beyond 80°. Arthroscopy revealed thickening of intra-articular portion of the popliteus tendon (PT). Surrounding synovium had extensive inflammation. During flexion, PT snapped back and forth into the popliteal sulcus. The inflamed tissue was debrided with no additional intervention to the PT. Postoperative physical therapy was recommended. The patient was relieved of his symptoms by the end of the first year. In conclusion, surgeons should be aware of SPTS during evaluation of the lateral compartment for optimal management of patients presenting with lateral knee pain and snapping sensation.