Clinical Anatomical Study On The Cutaneous Branches Of The Digital Arteries And Its Clinical Significance

Background :Science the digital artery island flap was first introduced by Littler in 1956, the flap has become one of the most popular flaps for reconstruction of fingers. Rasing of the digital artery island flap without proper palmar digital artery ,as described by Rose EH in 1983. preserves the donor digit sensibility. However , seperation of the digital arteries from the digital nervers would affect the blood supply of the flap. To aquire excellent reconstruction by preserving more cutaneous branches, we provide a surgical procedure for detaching the proper palmar digital neurovascular bundles according to the anatomical research .The dorsal incision should be initially performed to find and preserve the cutaneous branches which course laterally through the trunk of the proper palmar digital nerves, the palmar incision is then made to dissect the proper palmar digital neurovascular bundles.Patient and Methods:Anatomy study1 materials and method40 fresh fingers from 5 adult cadaver hands were studied .(the pollicis are not included ), the hands were perfuse with red latex from both the radial arteries and ulnar arteries. (the injection pressure was about 90mmHg).The fingers were dissected under 4 microscope magnification. The origin, course, branches, external diameter and distribution of the cutaneous branches of the proper palmar digital arteries, were observed . The small branches (the external diameter of original part is less than 0.3mm), which contribute little to the survival of the flap , were not inculded. 1 hand was perfused with lead oxid,and scaned with digital roentgenology.2 ResultThe proper palmar digital arteries are the main blood supply of the fingers,and the dorsal digital arteries arising from metacarpal arteries contribute little to digital supply because they are minute. As is shown in Figure 1,2 . The arteries lie dorsal to the nerves , each proper palmar digital artery gives off several dorsal and palmar cutaneous branches ,and the cutaneous branches run medially or laterally through the trunk of the proper palmar digital nerves to the digit skin .As is shown in the figure 3,4. There is a obvious difference between the numbers of the medial cutaneous branches and the lateral cutaneous branches. As the result listed in Table 1,2Flap elevation:The flap is designed not extending the dorsal and palmar median line of the finger , as far as the persveration of the function of the fingers is concerned, reduce the designed area on the palmar skin. The radial aspect of the index finger and the ulnar aspect of the little finger are not the good donor site,because of their important location.Incision is initially performed proximally on the dorsal skin of the finger , dissect the superficial layer to find the neurovacular bundles . elavate the flap on the surface of the tendon , and confirm the cutaneous branches which course laterally through the trunk of the proper palmar digital nerves .palmar incision is then made to find the cutaneous branches traveling medially over the trunk of the proper palmar digital nerves . In most of the specimens , according to our anatomy basis, more cutaneous branches running laterally through the trunk of the proper palmar digital nerves than running medially. Transect the meidal cutaneous branches to detach the proper palmar digital nerves. This flap can be harvested containing the cutaneous branches of the proper palmar digital nerves , but as described by Han SK , there is no obvious different outcomes in sensation recovery after a long follow-up between flaps with and without nerves. Skin graft is required for the covery of the defect at the donor site . Primary suture can be easily achieved if the defect area is small or part of the flap is designed at the fingerweb region.The operation procedure is performed on a fresh specimen perfused with red latex in its arteries. As is shown in the Figure 20, 21, 22.Patient summary:Between 2000 and 2006 June , 25 fingers from 23 patients with defects of phalangeal areas were reconstructed using this flap. The size of the skin defect varied from 1.7×1.2 cm to 3.8 x 1.7 cm. All flaps survived well. Patient age ranged from 17 to 50 years (average age, 32.5 years). Long-term follow-up for more than 6 months was possible in 10 fingers from 9 patients. Light touch and temperature sensation could be detected in all the flaps evaluated. The mean value of the static two-point discrimination test was 4.2 mm.DiscusionThe modified Little vascular island flap ,as described by Rose EH, not including the digital nerves, preserves the sensation of the donor digit , However ,the surgical procedure of dissecting the proper palmar neurovacular bundles , meanwhile preserving more cutaneous branches to acqurie good reconstruction for the fingers is seldom described. The digital island flap is perfused from the cutaneous branches of the proper digital artery and is drained through the accompanying tiny venules and capillaries contained in the perivascular soft tissue. To aquire excellent reconstruction , more perforator branches should be contained in the flap . We suggest to sacrifice the cutaneous branches which traveling medially over the nerves when dissecting the neurovascular bundles, preserve the reliable lateral branches. There is a great variation of the number of cutaneous branches which running medially through the trunk of the proper palmar digital nerves .In the 40 fingers ,we observed 11 proper palmar digital arteries do not give off any cutaneous branches running medially through the trunk of the proper palmar digital arteries at middle phalanx, and 8 proper palmar digital arteries give off no medial branches at proximal phalanx. In the contrary, according to our anatomy study , more cutaneus branches of the proper palmar digital arteries course laterally to the trunk of the proper palmar digital nerves . As described in many materials , there are 2 constant branches in the proximal and middle phalanx from each proper digital artery running to the dorsal skin. In addition, the maximum distance between the oringinal point of 2 neighbour cutaneous branches which coursing medially through the nerves is over 2cm , if the designed area of the flap is small, there will no perforater branches perfusing the flap .