Anatomical Study Of Superior Ulnar Collateral Artery Perforator Flap

【Objective】It is possible to injury the ulnar nerve whenobtaining a medial arm flap, because the superior ulnar collateralartery must be contained in it. To introduce the anatomical study ofsuperior ulnar collateral artery perforator flap based on the medial armflap, in order to simplify the conventional operating method. 【Methods】Microsurgical anatomical study was carried out on14 fresh upper limbs of human cadavers, which had been injected withred latex. The internal condyle of humerus is the anatomic landmark.The study was focused on the origin, numbers, diameter, position andvascular anastomosis of perforator artery (diameter ≥ 0.50mm)origiated from superior ulnar collateral artery. The nonconventionalflap was designed according to the proximal and distal perforatingvessels and the rotational point, vessel axis, donor area and incisionlevel are involved. 【Results】 1. Anatomical basis of superior ulnar collateral artery perforatorflap Superior ulnar collateral artery originates from brachial artery ordeep brachial artery at 16.62±1.90cm proximal to internal condyle ofhumerus, and it occures in 100% individuals. The diameter of superiorulnar collateral artery is 1.55±0.19mm at the original site. In 93%cadavers, about 2-4 fasciocutaneous perforators could be found withcaliber of 0.66mm -0.97mm and the positions of the proximal anddistal perforators are comparatively constant. The original diameter ofthe proximal perforator is 0.66±0.10mm and its original point is14.52±2.51cm above the internal condyle of humerus. The originaldiameter of the distal perforator artery is 0.97±0.13mm and its originalpoint is 3.31±1.20cm above the internal condyle of humerus. Afterthese perforator vessels perforate through the deep fascia, 3-5 radiatebranches are divided. The vascular anastomosis constantly emergesbetween ascending branch and descending branch of adjacent radiatebranches. So the chain-linked longitudinal or network vascular plexusin the surface of deep fascia on the lower 2/3 of medial upper arm isabundant, safe and reliable. The vascular plexus is the main source ofblood supply of superior ulnar collateral artery perforator flap. Thereare two veins following those perforators, their diameter is0.30mm-1.84mm.Inferior ulnar collateral artery originates from brachial artery at3.58±0.84cm proximal to internal condyle of humerus. The originaldiameter is 1.23±0.35mm. The fasciocutaneous perforator whichoriginated from inferior ulnar collateral artery join in the chain-linkedlongitudinal or network vascular plexus, which was mentioned above.Ulnar recurrent artery originates from ulnar artery on forearm at5.06±0.80cm distal to internal condyle of humerus. The originaldiameter is 1.45±0.22mm. There are 2-3 musculo-cutaneousperforators which originate from unlnar recurrent artery in the regionof sulcus for ulnar nerver. Similarly, these perforators also join in theplexus. Posterior arm cutaneous artery originates from brachial arteryor deep brachial artery with 1.42±0.21mm in diameter. Theanastomosis between posterior arm cutaneous artery and the proximalperforator artery of superior ulnar collateral artery are abundant,which is helpful in enhancing the blood supply of the flap.Venous drainage: The flap's venous blood is collected bymicrovenous connection, then be drained by deep venous systemthrough the perforating verins and the communicating that connectingthe superficial system to the profundal one. So this kind of bloodcirculation is physiological. The perforating veins at the pedicle offlap is the most important factor in system of venous drainage.2. Based on the above anantomical study, we designed thesuperior ulnar collateral artery perforator flap with proximal or distalperforating artery of superior ulnar collateral artery to reconstruct thesoft-tissue defect at the axillary fossa and elbow. The rotational pointof the flap is located at 3cm (distally-based flap) or 16cm(proximally-based flap) proximal to the internal condyle of humerus,where the perforators penetrate perpendicularly. The vessel axis isfrom axillary fossa to internal condyle of humerus. A flap should beobtained just under the hypo-deep fascia with a suitable donor areaaccording to the defect area. It should be ascertained that the length offlap be limited between internal condyle of humerus and upper 1/3 ofmedial arm, the width between anterior median line and posteriormedian line of arm. Clinically, one flap, measured 12cm×8cm withpivotpoint at 3cm above internal condyle of humerus, survivedcompletely and smoothly. The donor area was sutured directly. Atpresent, the long term follow-up is expected.【Conclusions】1. The study provides the anatomic data on the the origin,numbers, diameter, position and vascular anastomosis of perforatorartery originated from superior ulnar collateral artery, making theanatomical data about the angioarchitecture at medial upper armintegrated.2. To design the superior ulnar collateral artery perforator flapand provide the anatomic evidence for it. This flap can be used toreconstruct the soft-tissue defect at the axillary fossa and elbow.3. Compared with the conventional medial upper arm flapcontaining superior ulnar collateral artery or ulnar recurrent artery, theflap pedicled with perforating artery of superior ulnar collateral arteryhas the advantage of simplying the operating procedures, shorteningthe operationg time and decreasing the damage area of donor area.This method has been applied on a patient clinically, and the effect isgood.