Some clinical cases of knee disorder caused by fabella have been reported. We report an unusual cause of posterolateral knee pain and gait disturbance originating from an enlarged fabella in two clinical cases. Furthermore, we report the incidence of fabello-femoral arthritis from the dissection of 150 aged cadaveric knees.
Case 1: A 69-year-old man presented with a 4-year history of sharp pain and catching localized to the posterolateral aspect of the right knee. These symptoms made walking difficult. He underwent excision of an enlarged fabella without spur formation. Postoperatively his symptoms subsided.
Case 2: An 86-year-old man presented with a 4-year history of sharp, intermittent pain localized to the posterolateral aspect of the left knee. Magnetic resonance imaging showed no meniscal tear. A computed tomography scan showed an enlarged fabella located laterally. The patient underwent excision of the enlarged fabella (17×12 mm) without spur formation. An arthroscopic view showed the fabella articulating the lateral femoral condyle in the knee joint. Postoperatively, this patient's symptoms also subsided.
Aged cadavers (average age 81 years) were dissected. The incidence of fabella was 81%. The incidence of fabello-femoral osteoarthritis was 17%. In conclusion, it is clear that we have to take fabello-femoral osteoarthritis into consideration during examination of symptomatic knees.
