Anatomy of pisiform blood supply and feasibility of vascularized pisiform transfer for avascular necrosis of lunate based on digital technique

Abstract

To provide anatomical basis for vascularized pisiform transfer in the treatment of advanced avascular necrosis of the lunate (Kienböck's disease) by studying its morphology and blood supply pattern based on digital technique. Twelve adult fresh wrist joint specimens were selected and treated with gelatin-lead oxide solution from ulnar or radial artery. Then the three-dimensional (3D) images of the pisiform and lunate were reconstructed by micro-CT scanning and Mimics software. The morphologies of pisiform and lunate were observed and the longitudinal diameter, transverse diameter, and thickness of pisiform and lunate were measured. The main blood supply sources of pisiform were observed. The number, diameter, and distribution of nutrient foramina at proximal, distal, radial, and ulnar sides of pisiform were recorded. The anatomic parameters of the pedicles (branch of trunk of ulnar artery, carpal epithelial branch, descending branch of carpal epithelial branch, recurrent branch of deep palmar branch) were measured, including the outer diameter of pedicle initiation, distance of pedicle from pisiform, and distance of pedicle from lunate. There were significant differences in the longitudinal and transverse diameters between pisiform and lunate ( t=6.653, P=0.000; t=6.265, P=0.000), but there was no significant difference in thickness ( t= 1.269, P=0.109). The distal, proximal, radial, and ulnar sides of pisiform had nutrient vessels. The nutrient foramina at proximal side were significantly more than that at distal side ( P<0.05), but there was no significant difference in the diameter of nutrient foramina between different sides ( P>0.05). The outer diameter of pedicle initiation of the recurrent branch of deep palmar branch was significantly smaller than the carpal epithelial branch and descending branch of carpal epithelial branch ( P<0.05). There was no significant difference in the distance of pedicle from pisiform/lunate between branch of trunk of ulnar artery and recurrent branch of deep palmar branch ( P>0.05), and between carpal epithelial branch and descending branch of carpal epithelial branch ( P>0.05). But the differences between the other vascular pedicles were significant ( P<0.05). There are abundant nutrient vessels at the proximal and ulnar sides of pisiform, so excessive stripping of the proximal and ulnar soft tissues should be avoided during the vascularized pisiform transfer. It is feasible to treat advanced Kienböck's disease by pisiform transfer with the carpal epithelial branch of ulnar artery and the descending branch.