Distribution of Scaphoid Nutrient Foramina

Abstract

Introduction: 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.

Study of Morphometry of Scaphoid and Its Vascular Foramina

“…Number of vascular foramina is more on the dorsal surface (1 -24) than volar surface (3 -7). This finding is consistent with Dubey et al [4] and Owira et al [8] who reported that dorsal to volar ratio is 4:1 and 4.23:1 respectively. In the present study it is 3.42:1.…”

“…There is no foramen proximal to the mid waist in 6% scaphoid bones as reported by Dubey et al [4], in 13% scaphoids as observed by Obletz [3] and in 3% bones in the present study. Owira [8] observed type I (no foramina) scaphoids in 54% cases. It can be stated that in such cases when there is a fracture of waist, there will be diminished blood supply to the proximal fragment leading to nonunion or avascular necrosis.…”

“…Number of vascular foramina is noted on both volar and dorsal surfaces of scaphoid. Owira et al [8] classified scaphoids into type I (no foramina), type II (1 -2 foramina) and type III (more than 2 foramina). There is no foramen proximal to the mid waist in 6% scaphoid bones as reported by Dubey et al [4], in 13% scaphoids as observed by Obletz [3] and in 3% bones in the present study.…”