"PMI System":A Personalized Method For Predicting The Location Of Profunda Femoral Artery Perforators

Objective: In recent years,the profunda femoral artery perforator flap has been widely used in postoperative reconstruction of head and neck defects and achieved good results.Correct prediction of the position of the perforator before surgery is the basis of the flap design,and there is currently no personalized method for predicting the position of the perforation position of the profunda fomeral artery perforators.The aim of this study is to invent a new,personalized method for predicting the location of the profunda femoral artery perforators.Method: This study included a total of 45 patients with soft tissue defects after head and neck tumor resection surgery,who underwent profunda artery perforator free flap repair surgery simultaneously from September 2020 to May 2023 at our study institution.Among them,the first 40 patients(27 males and 13 females)were selected as the measurement group,and the remaining 5 patients(2 males and 3 females)were selected as the validation group.In the measurement group,we used a coordinate axis:the origin was the pubic tubercle,the X-axis was the line connecting the pubic tubercle and medial femoral condyle(PML),and the Y-axis was the vertical line passing through the pubic tubercle,to measure and record the position(x,y)where the deep profunda artery perforators entered the deep fascia during the operation.At the same time,we measured and recorded the anterior-posterior position and distance d of the perforator relative to the line connecting ischial tuberosity and medial femoral condyle(IML)(d>0,d<0,d=0 represent that the perforator is located in front of,behind,and on the IML,respectively).After the operation,xp(the ratio of the perforator’s x value to the length of the PML)was calculated.Four methods were constructed to predict the perforator location using these four indicators: x-y,xp-y,x-d,and xp-d.The most accurate method,named the "PMI method," was determined by comparing the accuracy of each method.The regression line of this method was used as the predicting line,and the predicting area of the perforator location was established based on this line.In the validation group,we recorded the distance between the perforator and the predicting line during the operation and whether it was within the predicted area.The perforator coverage rate of the predicting area was also calculated.Results: All 45 cases were successful,and all flaps survived.In the measurement group,there were a total of 40 flaps with 98 perforators from the profunda artery.One,two,three,four,and five perforators were found in 10%(4/40),45%(18/40),37.5%(15/40),5%(2/40),and 2.5%(1/40)of the donor site respectively.The x-y,xp-y,x-d,and xp-d models all showed linear regression(p<0.05),and the equations for the regression lines were: y=-0.1245x+10.35,y=-4.417xp+10.29,d=-0.1928x+2.096,and d=-7.289xp+2.094.Among them,the xp-d method had the highest accuracy,and the PMI method was determined as follows: the perforators from the deep femoral artery followed the distribution line of d=-7.289xp+2.094,and the perforators were mainly distributed in three regions: upper,middle,and lower.The concentrated distribution points of the perforators in the middle,upper,and lower regions were the intersection point of the predicting line and the IML,as well as the points 3 cm above and 5.5 cm below the predicting line.A square area was established as the predicting area based on the criteria that at least 80% of perforators were covered,with the central point being the concentrated distribution points of the perforators in the upper,middle,and lower regions,and with a side length of 4 cm for each of the three square areas.In the validation group,there were five cases with five free flaps and 18 profunda artery perforators from were identified.The occurrence rate of the perforators in the upper,middle,and lower regions was 100%,and the distance between the perforators and the predicting line was 1.0±0.6 cm(ranging from 0 to 2.1 cm).The total coverage rate of the predicted area was 83.3%(15/18),and the coverage rates of the predicting areas in the upper,middle,and lower regions were 100%(5/5),83.3%(5/6),and 71.4%(5/7),respectively.Conclusions:The "PMI method" proposed in this study is a personalized method for locating perforating branches of profunda artery.It specifies a personalized predicted line and predicted area for perforators,providing a basis for positioning profunda artery perforator flaps,which can meet the clinical needs.