Fabella

fabella

The fabella is a sesamoid bone in the posterior knee located within the lateral head of the gastrocnemius tendon, present in approximately 10 to 20 percent of people as an ossified sesamoid (and in up to 87 percent as a cartilaginous nodule). It articulates with the posterior lateral femoral condyle and is a landmark for posterolateral corner anatomy. The fabella has gained clinical attention because its presence alters biomechanics after total knee replacement and it can become symptomatic from chondromalacia or impingement.

Region: Knee

Clinical Relevance

Clinical Notes

Fabella syndrome produces posterolateral knee pain that worsens with knee extension, reproduced by direct posterolateral condyle palpation and passive knee extension. The common peroneal nerve runs adjacent to the fabella and can be irritated by an enlarged fabella or by fabella-related osteophytes. Total knee replacement prostheses must account for the fabella to avoid posterior impingement. Fabellectomy relieves symptomatic fabella syndrome when conservative management fails.