3D investigation of the vascular anatomy of triquetrum by micro-computed tomography

Aim: The aim of this study is to determine which part of the bone is most prone to avascular necrosis by identifying the intraosseous pattern of the nutrient vessels of the triquetrum. These results will be associated with the part of bone which has more nutrient vessels as well as fracture patterns and will create a suggestion for surgical treatment after fracture. Materials and Methods: Ulnar and radial arteries of 7 fresh frozen cadavers were filled with Microfil MV-117. Afterwards, the triquetral bones were removed by dissection and examined by micro-computed tomography. Then, 3D modeling was done and the number of main artery branches entering the triquetrum, the regions from which these branches entered the bone, their diameters at the bone entrances, the cross-sectional areas of the foramen where they entered the bone, whether they anastomose after entering the bone were recorded. Afterwards, the bone was divided into quadrants from certain reference points and the vessel volumes and vessel densities in the dorsal, palmar, proximal and distal parts were measured and the difference between the nutrition patterns of these regions was defined. Based on the bone tunnel and screwing procedures applied to the bone, 3 axes were determined in the bone and the vessel volumes in these axes were calculated. Results: A total of 50 nutrient vessels entered the bone. While the number of vessels entering the bone from the dorsal region was 36, those entering from the palmar region were 14. Two of the vessels in the palmar region entered the bone between the faces of the pisiform and the hamate, and 12 of them entered the bone just proximal to the articular surface with the pisiform. The mean number of vessels entering a bone was 7.14±4.18. Of these vessels; 5.14 of them were entering the bone from the dorsal and 2 of them from the palmar region. The vessels entering from the dorsal showed a palmar-proximal course. The mean vessel volume in one bone was 0.61±0.36 mm3. The vessel volume in the dorsal half of the triquetrum was 0.40±0.22 mm3, while it was 0.21±0.15 mm3 in the palmar half. The vessel volume in the dorsal region was significantly higher than in the palmar region (p<0.05). The mean bone volume of the triquetral bones was 317.62±115.63. The mean diameter of the vessels entering the triquetrum at the entrance was 0.09 mm. The total diameter of the arteries was 0.63±0.32mm on average. The diameters of the vessels in the dorsal region were 0.46±0.26 mm, while those in the palmar region were 0.17±0.87 mm. The vessels in the dorsal region were significantly wider than those in the palmar region (p<0.05). There were anastomoses between intraosseous vessels in 57% of the bones. In all of the bones, vessels were detected at the attachment point of the lunotriquetral ligament. Conclusion: Triquetrum is supplied from two regions, dorsal and palmar, and there is anastomosis between the vessels entering from these regions. The conservative treatment after fractures is possible due to compensated blood flow provided by these anastomotic branches of the dorsal and palmar sided blood vessels. The results of our study showed that the intraosseous blood supply of the triquetrum is rich, thus, complications such as avascular necrosis and nonunion has low incidence. In addition, in our study 3 axes were defined that can be used in screw applications and reconstruction of the lunotriquetral ligament by opening bone tunnels. Since the lateral axis contains fewer intraosseous vessels, it is the most appropriate axis to be applied in these operations. Knowing the intraosseous blood supply pattern and the most appropriate axes for bone-invasive interventions of the os triquetrum, which plays an important role in wrist biomechanics, may guide the surgeon when performing these procedures.