[The development of the wrist joint in the fetal period]

This study was designed to investigate the development and anatomical features of the wrist joint, particularly the scapholunate ligament and triangular disc in the fetal period and to identify possible congenital variations.

The study included 16 wrist joints of eight fetuses aborted at ages 8 to 14 weeks. The samples had no macroscopically discernible anomalies. Tissue specimens were fixed in 10% formalin solution, embedded in paraffin, and mounted on a microtome to obtain 5-micron sections in the coronal plane. Following staining with hematoxylin and eosin, conventional light microscopic examinations were performed.

Organization of the carpal ligaments in the wrist joint began on the radial side in the 9th week. In the 10th week, the scapholunate ligament was formed; a membranous structure was observed, which lied from the interfacet prominence of the radius to the scapholunate ligament and divided the wrist joint into two cavities. The triangular disc formation began to appear at this stage. During the 11th and 12th weeks, the membranous structure underwent regression from the dorsal to the volar aspects, and at the end of the 14th week, the wrist joint became a single cavity. Also noted was the development of fibrous appearance of the scapholunate ligament and the triangular disc into fibrocartilage. Vascular areas were identified on the radial rather than the ulnar side of the scapholunate ligament, but vice versa for the triangular disc. Bicompartmental structure seemed to persist in the wrist joint of a 14-week-old fetus.

In this study, we demonstrated that the scapholunate ligament and the triangular disc were not homogeneous in the fetal period in terms of vascularity and cellularity. We speculate that a plica-like membranous structure may persist in the wrist joint as a remnant of the fetal life. An accurate knowledge of the anatomy is necessary for the treatment planning and arthroscopic interpretation of the wrist joint.