The fabella is a sesamoid bone that is embedded in the tendon of the gastrocnemius muscle where the fibers of the popliteus, arcuate complex and the fibular-fabellar ligament attach.
Fabella syndrome is a painful condition of the posterolateral knee that is exacerbated when the knee is extended. The pain can be exacerbated by palpation of the fabella and if it is compressed against the condyles. The condition is most common in adolescence, but occurs in adults too.
Consider this condition in patients with posterolateral knee pain, which can also be due to tears of the posterior horn of the lateral meniscus, and tendonitis of the lateral head of the gastrocnemius.
