Anatomical relationship between the vinculum breve derived from the flexor digitorum superficialis tendon and the volar plate in the proximal interphalangeal joint of the hand: variation in the distribution of attachments.

The vinculum breve, a structure connected to the flexor digitorum superficialis tendon, located near the volar plate of the proximal interphalangeal joint. It has traditionally been regarded as a conduit for vascular supply to the tendon and its sheath. However, the detailed morphology of the vinculum breve and its relationship to the volar plate have not been fully elucidated. In this study, we examined the vinculum breve at the proximal interphalangeal joints from the index to little fingers of 20 cadavers (160 fingers in total). Two morphological types of the vinculum breve were identified: cord-like (59.4%) and membranous (40.6%). The membranous vinculum breve attached to the proximal interphalangeal joint tended to be denser proximally than distally. A high proportion (82.5%) of the vinculum breve was found to be attached to the volar plate. Cord-like vinculum breve was significantly more common in the index and middle fingers, where it attached to portions of the volar plate. In contrast, membranous vinculum breve was significantly more frequent in the little finger, often covering a large portion of the volar plate. These findings suggest that during flexion of the proximal interphalangeal joint, the vinculum breve contributes to the proximal sliding of the volar plate in coordination with the flexor digitorum superficialis tendon.