Incidence and radiological characteristics of fabellae in an Asian population

Abstract

RESUlTSThe incidence of fabellae was 31.25% in our study cohort. The median length, thickness, width and distance of the fabella from the lateral femoral condyle were 7.06 mm, 4.89 mm, 6.12 mm and 33.19 mm, respectively. The fabella was consistently bony and located in the lateral head of the gastrocnemius, with 52% of the fabellae having an articulating facet. Fabellae in men were found to be larger than in women, although the difference was not statistically significant. The presence of an articulating groove was associated with increased size of the fabella, but not with the distance between the fabella and its insertion onto the lateral head of the gastrocnemius. CONClUSIONThe incidence of fabellae in our population was lower than that in regional studies. They were consistently bony and not all had articulating grooves on the lateral femoral condyle. We found that the larger the fabella, the higher the chances of it having an articulating groove. By defining the radiological characteristics of the fabella, we provide objective parameters to help differentiate the fabella from other loose bodies or calcifications in the knee.

Presencia, Localización y Biometría de la Fabela en Individuos Chilenos: Estudio Radiológico

“…Se ha encontrado en 22,8 % (bilateral en 15,2 % y unilateral en 7,6 %); Egerci et al); Iborra et al analizando 200 radiografías de individuos Españoles, lo localizó en 23% (bilateral en 85 %); Lencina en 2007 estudió un grupo de individuos Argentinos en 22 articulaciones de cadáveres y lo encontró en 18,2 % y en una serie radiológica de 214 pacientes (434 radiografías) visualizó su presencia en 20,73 %. Se ha encontrado también en mayor porcentaje, 31,25 % en un grupo Asiático (Chew et al, 2014), así como en 27,8 % en cadáveres de un grupo de individuos Sudafricanos (Phukubye & Oyedele). Los resultados obtenidos en nuestro estudio radiológico han mostrado valores más altos, 37,5% de los casos.…”

Prevalence and distribution of the fabella: a radiographic study in Turkish subjects

“…On the other hand, Tabira et al [35] observed 46 out of 75 fabellae to be osseous and 24 cartilaginous in terms of their structure. In another study conducted in Far East, Chew et al [2] investigated the combination of MRI and radiography and established the prevalence of the fabella to be 31.25% and reported that all of these cases had an osseous structure (cartilaginous cases can be detected in MRI). This study originates from Singapore and identified the prevalence of the fabella to be lower than those specified in South-Eastern Asian studies.…”

A new insight into the fabella at knee: the foetal development and evolution

“…Why did they show no contact? In adults, almost half of fabellae do not carry a facet for articulation to the lateral femoral condyle [3]. Thus, also in foetuses, there were likely to be two types of fabellae: 1) a real sesamoid facing the joint cavity and 2) a false sesamoid without facet.…”

“…The incidence and bony nature of fabellae in human adults has been found to vary, with studies showing incidence rates of 66.6% (44% bony) [8]; 23.5% (72% bony) [13]; 86.9% (56% bony) [24]; and 31% (100% bony) [3]. Almost half of fabellae carry a facet for articulation to the lateral femoral condyle [3]. A bony, but not an elastic-textured, fabella has been found to correlate with thickening of the fabellofibular ligament to strengthen the posterolateral corner of the knee [11].…”