Anatomical And Clinical Research Of The First Metacarpal Artery Metacarpal Neck Ulnar Perforator

Background:The second dorsal metacarpal artery(SDMA)flap is one of the most commonly used methods for repairing finger wounds in clinical practice.Compared with other repair methods,the dorsal palmar artery flap has the advantages of being closer to the recipient area,easy to design in the same field of view of the donor and recipient areas,simple to operate,and highly similar to the recipient area in terms of texture,color and elasticity.The fly in the ointment is that the donor site is located on the exposed part of the back of the hand,which will leave scars on the exposed area after surgery.When the flap survives smoothly,the disadvantage of a linear surgical scar on the back of the hand is negligible compared with the advantages of the flap;When the survival quality of the skin flap is poor or even partially or completely necrotic,the linear scar in the exposed area is increased,but the recipient area does not obtain a satisfactory repair effect,then the advantages of the skin flap do not exist,and compared with other skin flaps,the increase The disadvantage of scarring on the back of the hand is more prominent,and once it occurs,it will pay an irreversible price.The advantages of flap survival are more than other flaps,while flap necrosis is far inferior to other flaps.Therefore,the 2nd dorsal metacarpophalangeal flap must be guaranteed to be "foolproof".However,from time to time,the flap survival quality is not good or even partial or complete necrosis.There are also reports in the literature on the occurrence of dark red,blisters,and partial necrosis after the second dorsal palmar artery flap.Analysis of the causes of necrosis Conclusive evidence is still lacking.We found in clinical operations and specimen anatomy that in some cases or specimens,there was no direct anastomosis between the second dorsal palmar artery and the digital web artery.Careful dissection revealed that there was a dorsal perforator from the palmar artery on the ulnar side of the neck of the second metacarpal bone,and there was anastomosis between the perforator and the second dorsal metacarpal artery and the digital web artery.Some perforators are thickly fitted between the second dorsal palmar artery and the digital web artery,and the second dorsal palmar artery and the digital web arteries are indirectly anastomosed through this perforator.We call this perforator the ulnar side of the metacarpal neck of the first palmar artery.perforator.This is inconsistent with the description of the anatomy of the second dorsal metacarpophalangeal artery in the previous literature(constant course,relatively thick diameter,less variation,reliable flap blood supply,etc.).According to the previous description of the anatomy of the second dorsal metacarpophalangeal artery,the distal pedicle of the second dorsal metacarpophalangeal artery flap is relatively safe,and flap necrosis is unlikely to occur.We speculated that the necrosis of the flap was related to the ulnar perforator of the first palmar artery at the metacarpal neck.When the second dorsal metacarpophalangeal artery is indirectly anastomosed with the webbed artery,if the flap is also cut in the conventional way,the blood supply connection between the second dorsal metacarpal artery and the webbed artery will be destroyed,resulting in the failure of the operation.There is still a lack of understanding of the anatomical location and possible variation of the second dorsal metacarpal artery,even if the proportion of this variation is very low,but for the patient himself,the operation is 100%unsuccessful.To this end,we conducted a clinical anatomical study of this part to reduce the risk of surgical failure,improve the survival rate of the flap,and benefit patients.Purpose:In our study,we investigated different types of anastomosis between the first metacarpal artery metacarpal neck ulnar perforator,SDMA,and the webbed artery in order to provide anatomic basis for the safe design and incision of the distally pedicled flap of SDMA.Methods:There were a total of 39 fresh adult cadaveric hands.All the arteries of those hands were perfused with red latex.Meticulous anatomical observation under the microscope was recorded not only the origin,course,and outer diameter of the first metacarpal artery metacarpal neck ulnar perforator but also the anastomosis between SDMA and the webbed artery.The hand specimens of 2 cases were successively shaped,fixed,perfusion,embedded and frozen,then placed on a CNC vertical milling machine for milling,and the sections were cleaned by a cleaning system and a fan debris collection system.After the cross-section data were collected by a high-resolution camera,the background was processed by Photoshop software.Results:The first metacarpal artery metacarpal neck ulnar perforator started at the second metacarpal neck from the first metacarpal artery,with a diameter of(0.57±0.20)mm at the beginning,and passed to the dorsal side along the gap between the ulnar side of the second metacarpal neck and the interosseous muscles,with an outer diameter of passing through the dorsal interosseous fascia is(0.35±0.26)mm,in which forming an anastomosis with SDMA and the webbed artery.In our study,characteristics of the anastomosis between the dorsal metacarpal artery and the webbed artery are divided into 4 types:Type Ⅰ.Non-anastomosis in 15 cases,accounting for 38.46%,There is no obvious anastomosis with SDMA and the webbed artery after the first metacarpal artery metacarpal neck ulnar perforator pass through the dorsal interosseous fascia;Type Ⅱ."T" type in 13 cases,accounting for 33.33%,the first metacarpal artery metacarpal neck ulnar perforator pass through the dorsal interosseous fascia and merges into the direct anastomosis between SDMA and the webbed artery;Type Ⅲ."Y" type in 10 cases,accounting for 25.64%,Between SDMA and the webbed artery,the ascending and descending branches of the first metacarpal artery metacarpal neck ulnar perforator communicate with each other,and the ascending branch forms anastomosis with SDMA,and the descending branch forms anastomosis with the webbed artery;Type Ⅳ."π" type in 1 case,accounting for 2.56%,SDMA and the webbed artery communicate with each other through the first palmar artery and the two ulnar perforators of the metacarpal neck originating from the first palmar artery.Three communicating branches were found between SDMA and the lateral palmar artery.The first communicating branch is located at the base of the second metacarpal bone and is the origin of SDMA,and communicates with each other through the proximal perforating branches of the deep palmar arch;The second communicating branch is located at the neck of the second metacarpal bone and communicates with each other through the first metacarpal artery metacarpal neck ulnar perforator;The third communicating branch is located at the base of the proximal phalanx and also at the origin of the webbed arteries,and communicates with each other through the webbed arteries.Conclusion:About 28.20%of SDMA and the webbed artery are not directly anastomosed,but indirectly anastomosed through the first metacarpal artery metacarpal neck ulnar perforator("Y" type,"π" type anastomosis).When these two situations are encountered,the continuity of the anastomosis between SDMA and the webbed artery is easily destroyed during the operation,resulting in difficulty or even failure of the second dorsal metacarpal artery flap.Therefore,Type Ⅲ("Y" type)requires dissection of the intramuscular part of the first metacarpal artery metacarpal neck ulnar perforator in order to ensure the blood supply of the retrograde island flap of SDMA pedicled with the webbed artery continuity.Type Ⅳ("π"type)needs to cut off the first palmar artery during the operation to ensure the continuity of the blood supply of the flap,but this is too destructive,and it is recommended to abandon the operation.Type I(Non-anastomosis)and type Ⅱ("T" type):the most common,accounting for 71.79%in this study,when the distal pedicle of SDMA is designed to be transferred to the retrograde island flap to repair the finger wound,the flap can be cut in the usual way.When designing a retrograde island flap of SDMA with the distal pedicle to transfer and repair finger wounds,there are two options for the flap rotation point,one is the distal web of the finger,and the other is the first metacarpal artery metacarpal neck ulnar perforator.Collateral perforators can be selected according to the location of the repaired wound.