Author(s)

Mohammed H. Karrar Alsharif^1,2,3*, Juman M. Almasaad^2,4, Nagi M. Bakhit^2,4, Khalid M. Taha^5,6, Mohammed I. Eltahir^2,3,7, Mamoun A. Alfaki^1,3, Abubaker Y. Elamin^2,3, Mohammed A. Noureddin⁸

¹Department of Basic Medical Science, College of Medicine, Prince Sattam Bin Abdulaziz University, Al Kharj, KSA.
²Department of Histology & Embryology, Medical Faculty, Ondukuz Mayis University, Samsun, Turkey.
³Department of Anatomy, Faculty of Medicine, National University, Khartoum, Sudan.
⁴College of Medicine, King Saud Bin Abdulaziz for Health Sciences University, Jeddah, KSA.
⁵Department of Anatomy, Faculty of Medicine, El Deain University, El Deain, Sudan.
⁶Department of Anatomy, Faculty of Medicine, University of Science and Technology, Khartoum, Sudan.
⁷Department of Anatomy, Faculty of Medicine, University of Bahri, Khartoum, Sudan.
⁸Department of Medicine, College of Medicine, Prince Sattam Bin Abdulaziz University, Al Kharj, KSA.

Background: Fabella is a natural occurring sesamoid bone, cartilage or a mixture of both that is usually located at the posterolateral corner (PLC) of the knee [1]. Recently the PLC of the knee has been extensively investigated because it is a common site of injuries and diseases [2] [3]. The complexity of PLC anatomy needs to be fully understood because the fabella could be missed diagnosis as an osteochondral defect, osteochondritis dissecans (OCD), calcific tendinitis, or foreign body. We present a case report of fabella syndrome triggered by trauma and also performed a review of literature for the various diagnoses that might be confused with fabella syndrome. Case presentation: A 29-year-old, Sudanese male presented to the trauma center in King Khalid Hospital in KSA, complaining of pain and partial swelling in his left knee joint due to trauma. Fabella was detected in the posterior lateral corner (PLC) of the knee joint embedded in the lateral head of the gastrocnemius muscle. All other pathological conditions were excluded. Conclusion: Fabella is sesamoid bone with variable size, found in the PLC. Commonly if present it causes periodic pain especially in the fully extended knee or it remains asymptomatic. Trauma, surgery, sports or heavy extreme activities may trigger the pain of asymptomatic fabella. Clinicians should consider that pain in the PLC of the knee can result from the presence of the fabella in a condition called fabella syndrome.

Fabella Syndrome, Sesamoid Bone, Osteochondral Defect, Osteochondritis Dissecans, Calcific Tendinitis, Foreign Body

Alsharif, M. , Almasaad, J. , Bakhit, N. , Taha, K. , Eltahir, M. , Alfaki, M. , Elamin, A. and Noureddin, M. (2019) Fabella Syndrome: A Typical Case of Misdiagnosis and Discussion. Case Reports in Clinical Medicine, 8, 258-273. doi: 10.4236/crcm.2019.89032.