Morphological variants of lateral meniscus of the knee: a cadaveric study in South Indian human fetuses

Abstract

In the present study, the objectives were to study the morphology of the lateral menisci (LMs) in human fetuses from a South Indian population and to verify the developmental etiology of the discoid lateral meniscus (DLM). The study included 106 fetal knee joints which were fixed in 10% formalin. After dissecting the joints, the morphological variants of the shapes of the LMs were macroscopically noted and classified as discoid and nondiscoid. The nondiscoids were subdivided into C-shaped and crescentic. The discoid lateral menisci (DLMs) were divided into complete and incomplete discoid. From our observations, 82.1% of the LMs were found to be nondiscoid. Among them, 62.3% were C-shaped and 19.8% were crescentic. The remaining 17.9% of the LMs had a discoid shape, and among these, 14.1% were incomplete discoid and 3.8% were completely discoid. Bilaterality of the discoid shape was observed in 26.6% of the cases. There was a female preponderance (11:8) among LMs with discoid morphology. In conclusion, the prevalence of DLM according to the present study was estimated as 17.9%. Our findings favor Kaplan's theory, as the majority of the fetuses of various gestational ages had nondiscoid LMs. Even the youngest fetus (CRL 88 mm, 14 weeks of gestation) exhibited a lateral tibial plateau that was incompletely covered by the meniscus, which did not exhibit a discoid shape. We believe that the DLM is anomalous and arises through variant morphogenesis.

The Morphological Anatomy of the Menisci of the Knee Joint in Human Fetuses

“…Structural incompatibility between the femur and tibia may be the reason for many clinical problems, particularly MM injury. In adults, the shape, size and thickness of the LM are different to those of the MM ( 9 , 10 ). At the same time, it has been reported that the LM of the tibia in the adult surface footprint of the MM is larger than the area covered by the tibial surface.…”

“…The most common developmental anomaly is discoid meniscus ( 4 , 7 ). A number of researchers have reported a relation between meniscal injuries and discoid meniscus ( 4 , 8 , 9 ). During the foetal period, discoid meniscus is more commonly observed in the lateral meniscus (LM) ( 9 ).…”

“…A number of researchers have reported a relation between meniscal injuries and discoid meniscus ( 4 , 8 , 9 ). During the foetal period, discoid meniscus is more commonly observed in the lateral meniscus (LM) ( 9 ). Different theories have been proposed about the formation of discoid meniscus.…”

“…Different theories have been proposed about the formation of discoid meniscus. Some researchers mentioned that discoid meniscus occurs due to failure of central resorption during the foetal period ( 4 , 9 ), and others noted that no discoid meniscus occurred in the foetal period ( 7 , 8 ).…”

“…Secondary to the increase in the use of CT and MRI in research, there has been a surge in studies on the anatomy of and variations in the menisci in adults ( 9 ). However, there are very few studies on the normal anatomy and anomalies of the menisci in new-borns ( 3 , 7 , 8 ).…”