Vascular Analysis of Radial Artery Perforator Flaps.

Background: Radial forearm free flap with all its present day modifications is the workhorse of soft tissue reconstruction in head & neck. Although there are several advantages, it requires the sacrifice of a major artery of forearm. There are several modifications of harvesting a forearm flap based on perforator principles. A clear understanding of vascular anatomy of individual perforators relative to its vascular territory & flow characteristics is essential for both flap harvest & design. The purpose of this cadaveric observational anatomical study was to determine the location, size & vascular territory of the radial artery cutaneous perforators.

Materials and Methods: 12 fresh human cadavers & 24 cadaveric forearms were dissected to determine the total number, location, size & vascular territory of radial artery adipo-fascio cutaneous perforator. The cutaneous territory of distally dominant perforators was analyzed using methylene blue injections & three-dimensional computed tomographic angiogram.

Results: In the 12 fresh human cadavers & 24 forearm specimens, a total of 222 perforators were dissected for an average of 18.5 radial artery perforators per forearm. Of the total 222 perforators dissected 118 were smaller than 0.5mm in diameter (53.15%) these were not clinically significant. 104 perforators were greater than 0.5mm in diameter (46.84%) these were clinically significant. Of the 222 radial artery perforators dissected, 127 perforators (57.20%) were radially distributed & 95 perforators (42.79%) had ulnar distribution. A total of 90 perforators (40.54%) were identified on distal side (Radial styloid) & 132 perforators (59.45%) were identified on proximal side (Lateral epicondyle). Mean number of perforators on radial side was 10.6 & 7.9 on ulnar side, a comparison of both using student t paired test gives a P value of 0.006, which was statistically significant. Comparison of mean number of perforators on the distal side was 7.5 & proximal side was 11.0, Student Paired t test gives a P value of 0.003, which was statistically significant. Comparison of mean Diameter of perforators between the Distal side (1.11) & Proximal side (0.86) using Student Paired t test gives a P value of 0.01 which was statistically significant. A chi square test was done to compare mean diameter of perforators on distal side, which were more than 1mm (80%) & less than 1mm (20%) & on proximal side more than 1mm (35.6%) & less than 1mm (64.4%). Chi square value of 42.406 was obtained, degree of freedom value was 1& P value of <0.001 was achieved which was found to be highly significant. Methylene blue injections into the proximal part of radial artery demonstrated clusters both in proximal & distal forearm & also cutaneous territory of flap. Three- dimensional computed tomographic angiography reveals a network of linking vessels found to communicate between adjacent perforators & running parallel to radial artery. Large network of linking vessels could be found between fascia & dermis, which also explains the ability to harvest forearm flap at the supra-fascial level.

Conclusion: Increase in knowledge of vascular territory of radial artery perforators with regards to numbers, size, location, and cutaneous territory can lead to expanded use of radial forearm flap based on either distal or proximal perforator alone, without sacrificing the radial artery.