From the Research
The fabella is a small, round sesamoid bone located behind the lateral femoral condyle of the knee joint, embedded within the tendon of the lateral head of the gastrocnemius muscle, and is present in approximately 10-30% of the general population, with a higher prevalence in certain ethnic groups, particularly those of Asian descent, as reported in the most recent study 1.
Definition and Prevalence
The fabella is a normal anatomical variant, typically measuring about 5-15 mm in diameter when present, and functions as a stabilizing structure that may help reduce friction in the knee joint and potentially provides a mechanical advantage to the gastrocnemius muscle during knee flexion.
- The fabella can lead to various pathologies, such as fabella pain syndrome and common fibular nerve palsy, as described in 2 and 1.
- While usually asymptomatic, the fabella can occasionally cause pain in a condition called "fabella syndrome," which involves posterior knee pain that worsens with full knee extension, as noted in 3 and 4.
Clinical Significance
The bone's presence is considered a normal anatomical variant rather than a pathology, though it should be noted during radiological examinations to avoid confusion with loose bodies or other abnormalities in the knee joint.
- Conservative treatment involves physical therapy or injecting local anesthetics or steroids around this bone, however, if symptoms persist, then a fabellectomy can be performed, as recommended in 3 and 2.
- Early decompressive surgery was performed and the fabella was excised in a case of common fibular nerve palsy related to fabella compression, resulting in an almost complete recovery, as reported in 1.
Management
In cases where the fabella causes symptoms, fabellectomy is a recommended treatment option, as it has been shown to provide immediate resolution of symptoms and improve quality of life, as demonstrated in the most recent study 1.