| BackgroundAutologous fat has recently been considered a valid option for facial soft-tissue augmentation in both reconstructive and aesthetic surgery. Even though fat grafting has become a well-established and frequently applied procedure, it has been limited by variable and unpredictable rates of fat absorption (10%-80%). Among the steps of lipotransfer, different fat-processing techniques may impact the survival of fat grafting. Currently, several common techniques (sedimentation, centrifugation, and filtration) have been used in clinical to process lipoaspirated fat. However, it is hard to reach a consensus on which fat-processing technique will reveal better volume retention unless there is objective and comparative evidence. Recently, the term "percentage volume maintenance" has emerged as a promising indicator in evaluating the effect of fat grafting with three-dimensional (3D) technology. But the majority of literatures just have emphasized the importance of a certain fat-processing technique. Therefore, the innovation of this thesis was to compare the effect of different fat-processing techniques with 3D technology and laboratory tests and then to explore the optimal fat-processing technique.ObjectiveThe purpose of this study was to compare different fat-pocessing techniques with 3D technology:1. To establish a scientific 3D measurement system suitable for facial analysis based on the facial volumetric change; 2. In laboratory, a comparative study was conducted among three groups of purified fat (sedimentation, centrifugation, and cotton pad filtering group) to explore the optimal fat-processing technique, which can obtain higher fat content; 3. A comparative study was conducted among three groups of fat-processing technique (sedimentation, centrifugation, and cotton pad filtering) to explore the optimal fat-processing technique, which can obtain higher volume retention.Methods1.10 cases of facial asymmetry were included in this study. The 3D pre-scan of 10 facial images was completed using Artec Spider 3D Scanner. The simulated post-scan was constructed in facial depressed regions using 3D software. The true value of volumetric change was calculated as T value. Volumetric change of every case was measured and repeated 10 times by Geomagic Qualify 12.0 software and 3-matic 7.0 software. The mean volumetric change of Geomagic Qualify 12.0 software was calculated as Q value. The mean volumetric change of 3-matic 7.0 software was calculated as M value. The difference from T value for Q value and M value was analysed with the paired t-test, intraclass correlation coefficient (ICC) and Bland-Altman analysis.2. Lipoaspirated fat was purified with different fat-processing techniques (sedimentation, centrifugation, and cotton pad filtering). In laboratory, isometric purified fat tissue from three groups were centrifuged at 5000g for 5 minutes to quantify the content of oil, fat, and aqueous fraction of them. H&E staining was applied to evaluate the effect of different fat-processing techniques on the integrity of adipocyte.3. From March 2015 to March 2016,30 cases of facial asymmetry undergoing facial lipostructure with different fat-processing techniques were included (10 cases in sedimentation group,10 cases in centrifugation group, and 10 cases in cotton pad filtering group). After informed consent, all patients underwent 3D scanning preoperatively and postoperatively in three time-points (1 month:post-1m,3month: post-3m,6month:post-6m).Three groups of percentage volume maintenance were calculated with 3D technology and were analysed with variance analysis.Results1. The mean difference from the T value was 0.0181±0.0117ml for the Q value of Geomagic Qualify software. The mean difference from the T value was 0.3810±0.1478ml for the M value of 3-matic software. The paired t-test results showed that the difference (0.0181ml) from the true value for Geomagic Qualify software was significantly smaller than the difference (0.3810ml) from the true value for 3-matic software, P<0.0001. After calculating 10 times of every case with two softwares, the ICC was 0.9999 for Geomagic Qualify software and 0.9973 for 3-matic software. Bland-Altman analysis showed a 95% confidence interval (CI) of-0.006ml to 0.042 ml for Geomagic Qualify software and 0.008ml to 0.69 ml for 3-matic software.2. In laboratory test, the fat content, aqueous content, and oil content of the cotton pad filtering group was respectively 86.0%,9.6%, and 4.4%. The fat content, aqueous content, and oil content of the centrifugation group was respectively 74.4%,14.8%, and 10.8%. The fat content, aqueous content, and oil content of the sedimentation group was respectively 62.0%,28.4%, and 9.6%. In the H&E histologic findings, no significant difference was observed in the integrity of adipocyte of three groups of fat-processing techniques (P>0.05).3. The mean percentage volume maintenance of three fat-processing groups at post-lm, post-3m, and post-6m was 48.82%±3.79%,45.26%±3.45%, and 42.77%±3.08% respectively for 10 cases of cotton pad filtering group; 41.27%±2.97%,38.35%±4.29%, and 35.80%±3.62% for 10 cases of centrifugation group; 36.95%±3.87%, 34.03%±4.31%, and 31.04%±3.38% for 10 cases of sedimentation group. The variance analysis result showed that the difference among three groups during the follow-up period was statistically significant (P<0.05). The maximum kinetic loss of volume of three groups was observed at post-1m. Fat absorption was obvious at post-1m. After post-1m, the decreasing trend of the percentage volume maintenance of three groups slowed down.Conclusion1. Through simulating the volumetric change of facial soft tissue, a scientific 3D measurement system suitable for facial analysis was proposed. Firstly, the pre- and post-scan can be automatically registered by Geomagic Qualify software. Then, this software will produce 3D colorimetric topography for the volumetric discrepancy. With 3D colorimetric analysis, the 3-matic software can be applied to calculate the volumetric change with Boolean Subtraction. The proposed 3D system will provide excellent accuracy, reliability, and precision in measuring volumetric change of facial fat grafting.2. In laboratory test, the composition ranking of purified fat tissue in three groups of different fat-processing techniques showed that:①oil content:centrifugation group> sedimentation group> cotton pad filtering group;②aqueous content:sedimentation group> centrifugation group> cotton pad filtering group;③fat content:cotton pad filtering group> centrifugation group> sedimentation group.In comparision with the sedimentation group and the centrifugation group, more fat content, less oil content and aqueous content was observed in the cotton pad filtering group.3. At post-1m, post-3m, and post-6m, the cotton pad filtering group demonstrated a statistically significant higher percentage volume maintenance in comparison with the centrifugation group and the sedimentation group (P<0.05). The comparative study among different fat-processing techniques with 3D technology is the innovation of the thesis. At post-1m, the fat absorption of three groups was all obvious. After post-1m, the decreasing trend of the percentage volume maintenance slowed down. These findings of 3D volume retention coincide with laboratory results.The purification of cotton pad filtering technique was observed to have more volume retention of facial fat grafting, which is worthwhile for clinical application. |
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