BACKGROUND: The fabella is an ossified structure located within the tendon of the lateral head of the gastrocnemius muscle. Although typically asymptomatic, it can lead to fabella syndrome under certain conditions. Due to its rarity and nonspecific symptoms, fabella syndrome is often underdiagnosed, leading to prolonged patient discomfort. CASE PRESENTATION: This article presents a case involving a 66-year-old female patient who experienced posterolateral knee pain with snapping six weeks after TKA. A dynamic ultrasound examination revealed friction between the fabella and the prosthesis, confirming the diagnosis of fabella syndrome. The patient underwent arthroscopic fabella resection, which completely resolved her symptoms. CONCLUSION: As a minimally invasive procedure, all-arthroscopic removal offers significant advantages for managing post-TKA fabella syndrome. Notably, this is the first report of all-arthroscopic fabella removal for post-TKA fabella syndrome in the English literature. We document this approach to provide a reference for similar cases.