| It is a challenge to reconstruct the distal lower leg defect with deep tissue exposure,which always leads to a prolonged disease and physical disability if not having a prompt resurfacing.In particular,the treatment would be more difficult with the aging population and the increase in the proportion of sub-healthy people.The perforatorbased propeller flaps are commonly used to repair such defects with the advantages of relatively simple techniques,less donor morbidity,and like-to-like tissue reconstruction.However,their complication rates are comparable to free flaps in clinical practice.Therefore,to improve the success rate of the surgery,it is crucial to accurately identify the dominant perforator vessels and determine the flap perfusion area preoperatively.Compared with traditional perforator navigation methods,the smartphone-based infrared thermography has demonstrated comprehensive advantages of convenience,economy,quickness,accuracy,and noninvasiveness for dominant cutaneous perforator detection in the trunk and thigh.Nevertheless,its application in the lower leg is still not satisfactory due to multiple interference factors.Therefore,how to improve the infrared thermography method and correctly interpret the thermal images and videos needs further research.This dissertation can be divided into three parts:The first partTitle: A digital anatomical study of the propeller flap’s perforator vessels in the lower legObjective: Through quantitative digital analysis and 3D reconstruction,the anatomical characteristics of the dominant perforator vessels supplying the posterolateral and medial skin territory are accurately and visually demonstrated,providing an anatomical basis for the interpretation of infrared thermography results and the design of the perforator-based propeller flap in the lower leg.Methods: Multiplanar reconstruction(MPR),maximum intensity projection(MIP),and volume rendering(VR)tools of the Radiant DICOM viewer software were used to study 12 DICOM data sets of the lower leg from six whole cadaver perfusion specimens.First,the distances from the skin entry points of the dominant cutaneous perforators(diameter ≥ 0.5 mm)in the posterolateral and medial skin territory to the tips of the lateral and medial malleolus were measured with MPR and MIP,respectively.Next,the distribution patterns of the perforator vessels were analyzed by the k-means clustering method.Then,the travel characteristics of the main source artery and the perforator vessels were observed in VR from multiple angles by applying the image segmentation method.Finally,the digital layer dissection viewed the distribution and anastomosis of these perforators within the skin.Results:(1)The posterolateral perforator vessels of the 11 lower legs were well visualized,with 58 perforators,averaging 5.3,including 46 septo-cutaneous and 12 myo-cutaneous perforators.Except for one perforator from the posterior tibial artery in each of the three distal lower legs,the remaining 55 perforators originated from the peroneal artery.The vascular entry points of the lower leg posterolateral perforators formed a total of 4 clustering centers at 13%,31%,53%,and 72% of the entire length of the fibula proximal to the tip of the lateral malleolus,with 14,20,14,and 10 perforators in each center,respectively.(2)The medial perforator vessels of the nine lower legs were well visualized,with 44 perforators averaging 4.9,including 32 septocutaneous and 12 myo-cutaneous perforators.In addition,three clustering centers of the vascular entry points of the medial perforators were formed at 19%,43%,and 64% of the full tibial length proximal to the tip of the medial malleolus,with 16,15,and 13 perforators in each center,respectively.(3)Trunk vessels were well visualized in 12 lower legs,of which four(33%)showed anatomic variation.(4)5 posterolateral and 3 medial skin territories clearly showed the course,distribution,and anastomosis of the perforator vessels within the skin level.Conclusions: The digital dissection truly,visually,and comprehensively shows the anatomical morphology and distribution patterns of the posterolateral and medial perforators in the lower leg,providing a reliable anatomical basis for accurate interpretation of the thermography images and precise design of perforator-based propeller flap in the lower leg.The second partTitle: Establishment of tourniquet reperfusion augmented thermal imaging methodObjective: To investigate the potential factors affecting the infrared thermographic results for perforator mapping in the lower leg and propose an improved thermographic method through a volunteer study.Methods: Sixteen volunteers,six males and ten females,with a mean age of 39 years(24-72 years),the median age of 32.5 years,and a BMI of 22.9 ± 2.7 were recruited.Volunteers were examined with a smartphone-based FLIR ONE Pro thermal camera using static thermography,alcohol-enhanced thermography,and tourniquet reperfusion augmented thermal imaging method(TRATIM).The cutaneous perforators in the lower leg’s medial and posterolateral skin territories were detected.The clinical value of the thermograms for each volunteer in the three thermographic methods was assessed according to the display of hot spots(excellent,fair,poor).The influence of gender,age,BMI,and location on the static thermographic results were analyzed.The observing phases of hot spots in the real-time video of TRATIM were proposed with their durations for each period.Finally,the percentage of thermograms with different clinical values in the three thermographic methods was counted,through which their effects on the perforator detection in the lower leg were compared.Results:(1)In the medial skin territory,the clinical value of static thermogram was significantly higher in women than in men(P=0.021),and although BMI was not a significant influencing factor(P=0.256),the clinical value of thermogram was still better in volunteers with BMI﹤24 than those with BMI≥24.Age had no significant effect on the clinical value of thermogram in volunteers(P=0.309).In the posterior lateral skin territory,gender(P=0.202),age(P=0.58),and BMI(P=0.462)were not significant influencing factors on the clinical value of thermograms in volunteers.In the distal 1/2 segment of the lower leg,the percentage of the number of hot spots in both medial and posterolateral thermograms was significantly lower than in the proximal 1/2 segment.(2)According to the characteristics of hot spot rewarming,the real-time video of TRATIM could be divided into 4 phases: the period of no perfusion(19.4±4.2 seconds),the period of hot spot emerging(25.9±6.1 seconds),the period of hot spot progressing(96.3±14.8 seconds)and the period of hot spot fusion,respectively.Among them,the duration of 20-140 seconds after relaxing the tourniquet was the best observation period for locating the dominant perforator vessels by TRATIM.(3)There was no significant difference in the clinical value of both static thermography and alcohol-enhanced thermography for the lower leg(medial skin territory P=0.739,posterolateral skin territory P=1.0),and the clinical value of both TRATIM groups was significantly better than that of the static thermography group(medial skin territory P=0.001,posterolateral skin territory P﹤0.001).Conclusions: Compared with the static and alcohol-enhanced thermography,the tourniquet reperfusion augmented thermal imaging method(TRATIM)proposed in this study can significantly improve the perforator detection in the lower leg.The critical duration for thermogram interpretation is the hot spots emerging and progressing periods lasting about two minutes in the TRATIM real-time video.Direct or indirect information on the location,strength and anastomosis type of the dominant perforators in the lower leg can be achieved by TRATIM.In normal-sized women,the static thermography still has an excellent clinical value for the perforator detection in the proximal two-thirds of the lower leg.The third partTitle: Clinical application of the lower leg perforator-based propeller flap designed with the aid of TRATIMObjective: To compare the effects of TRATIM,CDU,and CTA in locating the lower leg dominant perforator vessels and summarize the clinical value of this modified infrared thermography as an assisted flap design method.Methods: From March 2019 to October 2021,35 patients with soft tissue defects in the distal lower leg repaired with perforator-based propeller flaps were prospectively included,29 of whom were male and 6 female,with a median age of 59 years and a defect size of 5.0 cm×4.0 cm to 16.0 cm×9.5 cm.Preoperatively,perforators in the flap donor area were detected and marked with CTA and/or CDU,including 19 cases of CTA and 24 cases of CDU(8 cases who received both examinations).TRATIM was used for identifying perforators after the onset of anesthesia.The actual position of perforators during dissection was used as the gold standard,and the masks with less than 10 mm around them were considered accurate(positive).The three methods’ sensitivity and positive predictive values were calculated separately,and the Kappa coefficient analyzed their degree of concordance.Paired-samples t-tests were used to compare the total time spent on localization(detection,reading,and labeling)of the perforators for each patient by TRATIM and CTA,and TRATIM and CDU,respectively.Postoperative flap survival and the long-term outcomes of the flap were followed up.Results: In this group,35 perforator-based propeller flaps were performed,including 20 peroneal artery perforator propeller flaps,with complete survival in 19 cases and superficial necrosis of the distal flap in one case;15 posterior tibial artery perforator propeller flaps,with complete survival in 14 cases and superficial necrosis of the distal flap in one case.The secondary donor defect was closed directly in 25 cases and covered with skin graft in 10 cases.The sensitivity of TRATIM for the detection of perforator vessels was 87.8%(108/123),with a positive predictive value of 96.4%(108/112);the sensitivity of CTA and CDU was 86.8%(59/68)and 90.2%(74/82),with a positive predictive value of 98.3%(59/60)and 98.7%(74/75),respectively.The total time to localize the dominant perforators in the lower leg was significantly less for TRATIM than CTA(P﹤0.0001)and CDU(P﹤0.0001).The flap color and texture were similar to that of the recipient area,the donor scar was concealed,and the patients were satisfied with the surgery results.Conclusions: TRATIM is a simple,quick,economical,accurate,reliable,and noninvasive method to detect the perforator vessels in the lower leg.It has a good concordance with CTA and CDU.The perforator-based propeller flap designed with the aid of TRATIM has the advantages of relatively simple techniques,reliable survival,time-saving,and primary closure in the donor site,making it ideal for the reconstruction of the distal lower leg defect. |
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