The fabella is a sesamoid bone located in the posterolateral aspect of the knee, embedded in the muscular and tendon fibers of the lateral head of the gastrocnemius muscle. It articulates anteriorly with the posterior surface of the lateral condyle, and is bordered posteriorly by the oblique popliteal ligament. The presence of the fabella in humans is a variant and is reported to range from 20% to 87%. When the fabella is present, an additional ligament called the fabello-fibular ligament (ligament of Vallois), which runs from the fabella to the fibular head, can be found.
The presence of the fabella is usually asymptomatic; however, it can be a source of posterolateral knee pain. The pain is usually periodic and is accentuated with the knee in extension, because of the compression of the fabella against the lateral femoral condyle in this position. Irritation of the common peroneal nerve resulting in neurologic symptoms, such as numbness or pain, may be present in some patients.
Conservative treatment can be an effective way to reduce painful symptoms and increase activities involving extension, flexion, and rotation of the knee. However, in patients who do not respond to nonoperative treatment, surgical treatment may be performed. A fabella excision can be successfully performed either as an open or arthroscopic procedure.
The aim of this Technical Note is to describe an arthroscopy-assisted fabella excision, which can be challenging because of the position of the fabella to key structures of the posterolateral side of the knee.