Lower limb interosseous membrane in foetuses.

Background: The leg interosseous membrane (LIM) stabilises the tibia and the fibula. These two bones articulate at the proximal and distal tibiofibular joints. In addition, the LIM is the place of attachment of tibialis anterior muscle, extensor digitorum longus muscle, fibularis tertius muscle (anatomical variant), tibialis posterior muscle and flexor hallucis longus muscle. The specific structure of the collagen fibre network of the LIM provides durability comprising collagenous fibres that are predominately projected longitudinally, obliquely, and often transversely.

Materials and methods: 222 human foetuses (Male: 120, Female: 102) between 117 and 197 (median 177) days of foetal life were available for the study. The material derived from the foetal collection is stored in the Department of Human Morphology and Embryology, Division of Anatomy of the Medical University of Wroclaw. In this study, we assessed the variability of the foetal LIM using a novel dyeing technique to identify the LIM syndesmotic structure.

Results: Overall, the study of the three types of interosseous fibres (transverse, oblique, longitudinal) of the right/left leg revealed that the fibres run in all three directions with frequencies approximating 60-70%. However, there were differences in the frequency of fibre directions and in the size of LIM between sexes.

Conclusions: After consideration of the directions and size of fibres of LIM, parts of it can be used for reconstruction of the upper limb interosseous membrane. Sexually dimorphic features of the LIM in the studied material confirm the different dynamics of lower limb growth in each sex.