Distribution of Scaphoid Nutrient Foramina

Abstract

Avascular necrosis (AVN) is a frequent complication of scaphoid fractures especially those involving the proximal segment of the bone. This has been attributed to its precarious blood supply which is further compromised by the fracture and surgery. Knowledge of the distribution of scaphoid nutrient foramina, which show variation across populations, is thus important in estimating the risk of vascular damage during surgical approaches and hence the likelihood of AVN. It may also be useful in determining techniques to mitigate this risk. The purpose of this study was to describe the distribution of scaphoid nutrient foramina in adult Kenyans. Methods: One hundred and four human scaphoids were studied. Each was divided into 3 segments: proximal, middle and distal, and the nutrient foramina in each segment counted and categorized into type I (no foramina), type II (1-2 foramina) and type III (>2 foramina). The number of nutrient foramina on the dorsal and volar aspects of the bone was also compared. Results: Type I nutrient foramina were most common (54%) in the proximal segment of the bone while the middle and distal segments had predominantly type III and type II foramina respectively. More foramina were present on the dorsal aspect with a dorsal-volar ratio of 4.23:1. Conclusion: The dorsal approach may result in more damage to nutrient foramina heightening the risk of avascular necrosis. Non-unions in the proximal segment may require vascularized bone grafts.