The morphologic and morphometric features of the triquetrum.

Fractures of the triquetrum are the second most common form of isolated carpal bone fracture after the scaphoid. However, data on triquetrum morphology and morphometry are sparse. The aim of this study was to describe the morphology of triquetrum using anatomical landmarks, evaluate its morphometric features, and determine its vascular entry points. The morphological and morphometrical features of 87 adult dry triquetral bones (39 left, 48 right) were determined by measuring length, width and thickness. The number and locations of nutrient foramina wider than 0.5 mm were recorded. Mean length, width and thickness were 17.37 mm (range, 14.26-22.13), 12.65 mm (range, 10.37-15.85) and 11.41 mm (range, 8.98-18.23), respectively. The facet articulating with the pisiform was oval in 40 bones, round in 8 and amorphous (neither round nor oval) in 39. The mean length of the interarticular ridge was 7.09 ± 0.9 mm. The mean number of nutrient foramina was significantly greater on the dorsal than on the other aspects. The dorsal predominance of nutrient foramina makes the bone weaker in the dorsal region, which could explain why fractures are more common in this region. Also, the dorsal aspect is rich in blood supply, which could explain why avascular necrosis is less common in triquetral fractures. As most of the vascularization is on the dorsal side, there is need for caution when performing triquetrum surgery. LEVEL OF EVIDENCE: Level 2.