Dynamic External Distraction Device for Proximal Phalangeal Head Intra-articular Fracture.

Dynamic distraction external fixation (DDEF) is commonly used for proximal interphalangeal joint fractures based on the principle of ligamentotaxis. However, this mechanism may be limited when fracture fragments lack soft tissue attachment. We present a 14-year-old girl with a depressed intra-articular fracture of the proximal phalanx head and joint stiffness, treated 5 weeks after injury using DDEF. Despite delayed treatment and minimal ligamentous connection, the fragment was successfully elevated and healed. We propose the so-called "vacuum phenomenon" as a hypothesis-generating concept that may represent a supplementary mechanism in fracture reduction under distraction. This effect may be particularly relevant in cases where ligamentotaxis alone does not fully explain fragment repositioning, and may help broaden the understanding of DDEF in managing such injuries.