Intraosseous and extraosseous arterial anatomy of the adult navicular.

BACKGROUND The etiology of navicular stress fractures is a topic of interest due to the implications in high-level athletes. Previous studies suggest an avascular zone in the central one-third of the bone as a potential causative factor. This study investigated the extraosseous and intraosseous arterial anatomy of the adult navicular. METHODS Sixty legs from 30 cadavers were amputated below the knee. India Ink and Wards Blue Latex were injected into the anterior tibial, peroneal, and posterior tibial arteries. The specimens were frozen, thawed to room temperature, and the skin was sharply dissected away. The soft tissues were chemically debrided, leaving the bones, interosseous ligaments, and casts of the extraosseous blood vessels. The vascular supply to the navicular was elucidated in 55 specimens. The navicular was then cleared using a modified Spälteholz technique; the intraosseous vascularity was reviewed in 54 specimens. RESULTS Medial tarsal branches of the dorsalis pedis consistently supplied the dorsal navicular (96.4%). Lateral tarsal branches of varying size and distribution patterns also supplied the dorsal navicular. The medial plantar bone received small branches from the superficial branch of the medial plantar artery. Thirty of 54 specimens had a diffuse intraosseous vascular supply throughout the bone. Only six (11.8%) specimens had an avascular zone in the central third of the navicular extending to the dorsal cortex. CONCLUSION The dorsalis pedis and posterior tibial arteries branch to supply blood flow to the navicular. In the majority of these specimens the navicular had a dense intraosseous vascular supply throughout it. CLINICAL RELEVANCE If diminished vascular supply is a contributing factor to navicular stress fracture, our results suggest that a relatively small proportion of individuals is prone to their development. Biomechanical or other clinical factors may play a more prominent role in the development of navicular stress fractures than previously suspected.