Scientific Abstract Presentations: Research & Technology Session 2 Thursday, October 9 Thu, Oct 9 5:00-6:00 p.m. CDT

PURPOSE: Traditional wound evaluation methods, such as visual inspection and histology, are often limited by their invasiveness and high cost. This study explores the use of Digital Image Speckle Correlation (DISC) as a non-invasive technique for quantifying wound healing progress through spatially resolved imaging of mechanical properties. By detecting subtle mechanical changes in tissue, DISC allows for frequent, real-time assessments without requiring invasive biopsies. This capability has the potential to improve patient-specific wound management and advance telemedicine applications (1). METHODS: The DISC approach applies controlled mechanical deformation using a modified tensiometer for direct imaging. Digital image correlation algorithms track natural surface features (e.g., pores, hair follicles) to measure displacement and strain, distinguishing intact, healing, and regenerated tissue. A deep partial-thickness burn model was created on Yorkshire pigs using a standardized vertical progression burn method. Wounds were treated with collagen-fibrin scaffolds, followed by autologous skin cell suspension (ASCS) from the RECELL Autologous Cell Harvesting Device. DISC imaging was conducted at multiple time points before biopsy collection (Days 14 and 28), providing real-time force propagation analysis. Heatmaps and displacement profiles were used to assess scaffold integration and mechanical changes in the wound bed, with control measurements taken from healthy skin. Histological cross-sections were obtained using a 3 mm biopsy punch at specific wound locations-10 mm from the corners at early time points and from the center at the final time point. Although the locations of histology samples and DISC force measurements were not identical, DISC imaging enabled a dynamic, quantitative assessment of healing before tissue extraction. RESULTS: DISC and histological analysis revealed distinct differences in force propagation and tissue remodeling: Control Skin: • Heatmaps showed uniform force propagation, indicating optimal mechanical stability. • Histology displayed a well-organized epidermis, dense collagen, and stable vasculature, characteristic of mature tissue. Wound (Day 14): • Heatmaps showed disrupted force propagation, suggesting incomplete scaffold integration. • Histology revealed partial epithelialization, disorganized collagen, and limited vascularization. Wound (Day 28): • Heatmaps indicated improved force uniformity, approaching control levels. • Histology showed complete epithelialization, organized collagen, and increased vascularization, marking the final maturation phase. CONCLUSION: DISC presents a promising, non-invasive, and quantitative approach to wound assessment by detecting subtle mechanical changes in tissue. It enables timely interventions, reduces dependence on invasive biopsies, and enhances patient-specific wound management. Preliminary findings suggest that long-term DISC tracking could offer valuable insights into contracture-related biomechanical changes and hypertrophic scarring. Further studies beyond Day 28 are needed to optimize scaffold-based therapies for burn injuries.

1. Fritz JR, Phillips BT, Conkling N, et al. Comparison of native porcine skin and a dermal substitute using tensiometry and digital image speckle correlation. Annals of plastic surgery. 2012;69(4):462-467.

Background: According to the 2015 Lancet Commission on Global Surgery, approximately 5 billion people lack access to safe and affordable surgical care. This burden is particularly severe in resource-poor settings, where trauma and burn injuries contribute significantly to surgical morbidity and mortality. However, low- and middle-income countries (LMICs) often prioritize other healthcare needs due to financial constraints, limited workforce, and competing public health concerns. In response, various global surgery models have emerged to address the gap in care. These include mission-based surgery, high-volume surgical trips, Centers of Excellence (CoEs), partner hospital models, and reciprocal institutional collaborations. Each model presents distinct benefits and challenges in sustainability, scalability, and training impact. Methods: We conducted a review of publicly available data on global surgical initiatives in plastic surgery, including Operation Smile, Smile Train, and academic institutional partnerships. Surgical volume, local training initiatives, capacity-building efforts, and program longevity were assessed to evaluate each model's effectiveness. Results: Mission-based surgery (e.g., Operation Smile) has provided over 220,000 cleft surgeries since 1982, delivering immediate care but with minimal follow-up and limited emphasis on local workforce development. High-volume surgical programs follow a similar model, with notable examples like Operation Smile's efforts in Asunción, Paraguay, where 125 cleft surgeries were performed by five surgeons in one week. While such efforts improve access during an intensive brief period, they lack continuity and training focus. Centers of Excellence (CoEs), such as Operation Smile's program in Guwahati, India, have performed 5,000 cleft cases in five years through partnerships between government and global surgeons. These centers enhance local capacity but are resource-intensive and require sustained funding and collaboration. The partner hospital model, exemplified by Smile Train, emphasizes local training and long-term sustainability. Between 1999 and 2014, Smile Train facilitated one million cleft surgeries across 87 countries, working with over 1,100 partner hospitals. Additionally, training initiatives for physicians and nurses led to a 30% increase in follow-up and secondary procedures. However, this model lacks significant engagement from trainees in resource-rich settings, limiting global bidirectional learning. Reciprocal institutional collaborations, such as the Vanderbilt-Kijabe and ReSurge International partnerships, have shown significant success in capacity building. In 2022, 14 trainees from the College of Surgeons of East, Central, and Southern Africa (COSECSA) took the Plastic Surgery Board Exams, the highest number to date, demonstrating the growing impact of these programs on long-term workforce development. However, these partnerships require detailed coordination and adherence to regulatory requirements for international rotations. Conclusion: We provide a comprehensive review of available models for plastic surgery care in low-resource settings to address the burden of surgical disease. While mission-based and high-volume trips provide immediate surgical care, they lack long-term sustainability. CoEs and partner hospital models enhance local capacity but require significant investment. Reciprocal collaborations foster bidirectional learning and workforce development but demand intensive coordination. We propose the benefit of a hybrid approach that integrates the strengths of these models offering a sustainable solution for expanding access to surgical care in underserved regions.

Purpose Patient-reported outcomes (PROs) play a crucial role in evaluating the quality of care for patients with cleft lip and/or palate (CL/P). CLEFT-Q, a validated PRO instrument, provides valuable insights into patients' perceptions of their appearance, function, and psychosocial well-being. However, translating CLEFT-Q data into actionable clinical insights remains challenging due to its high-dimensional structure. This study employs latent profile analysis (LPA), a statistical clustering method commonly used in psychology and personality research, to categorize CLEFT-Q responses into meaningful patient phenotypes. LPA has been increasingly applied in healthcare research, including geriatric quality-of-life and healthcare worker resilience studies, to identify subpopulations within heterogeneous datasets that would otherwise be missed using conventional analysis. By leveraging LPA, this study aims to facilitate a deeper understanding of patient experiences.

Methods Following institutional review board approval, all CLEFT-Q responses collected at a tertiary pediatric craniofacial center from September 2021 to March 2024 were analyzed. Patients aged 8 to 29 years with complete CLEFT-Q responses were included. LPA was conducted in R on 11 CLEFT-Q domains to identify distinct response profiles. Clinical characteristics and profile stability over time were assessed.

Results Responses grouped into six general profiles: two Universally Affected (UA1-Moderate, UA2-Severe), two primarily focused on Facial Appearance (FA1-Moderate, FA2-Severe), one primarily with Social, School, and Speech issues (SSS), and one Minimally Distressed (MD). Most patients fell into moderate or benign profiles, FA1 (148, 21.7%), UA1 (176, 25.8%), and MD (174, 25.6%), with smaller proportions in severe, FA2 (35, 5.1%) and UA2 (77, 11.3%), or specific, SSS (71, 10.4%), profiles. Patients in the more severe profiles were older (FA2: 14.9 years, UA2: 14.2 years) compared to the cohort average of 13.0 years (ANOVA p<0.001) and more likely to have complete cleft lip (UA2: 83.1%, cohort average: 79.1%, ANOVA p<0.001). Patients in the MD profile were younger (12.0 years vs. cohort average of 13.0 years) and more likely to have cleft palate only (MD: 43.7%, cohort average: 28.9%, ANOVA p<0.001). Among patients with multiple CLEFT-Q responses, 46.1% remained in the same profile over time without surgical intervention, suggesting moderate profile stability. The FA2 (60.0%), UA1 (55.8%), and MD (51.4%) profiles were the most stable, while FA1 (33.3%) and SSS (29.4%) demonstrated greater variability. Patients undergoing surgery exhibited a lower profile stability (38.2%), with procedures such as rhinoplasty leading to more favorable profile shifts. For instance, rhinoplasty patients commonly transitioned from universally affected profiles to those primarily affected by facial appearance concerns, reflecting improved psychosocial function.

Conclusions This study demonstrates the utility of LPA in distilling high-dimensional CLEFT-Q data into clinically relevant patient phenotypes. LPA enables the identification of nuanced patient subpopulations that may be overlooked in conventional analyses, offering a data-driven approach to cleft care. The identified profiles correlate with key clinical factors such as age, cleft severity, and surgical history, providing a framework for more personalized patient care. As PROs gain prominence in cleft care, integrating profiling methodologies like LPA may enhance the translation of patient-reported data into meaningful clinical decision-making.

Background Bilateral sagittal split osteotomy (BSSO) can significantly improve a patient's quality of life by aligning the jaw, improving the airway, and correcting dentofacial asymmetry. However, there is a high risk of neurosensory disturbance and injury due to the complexity of the anatomical space and limited visualization. Robot-assisted surgery offers a promising solution for BSSO by providing stable, tremor-free control of the surgical tool during the procedure. We aimed to develop and validate a cooperatively controlled robot system to enhance the precision and efficacy of the BSSO.

Methods We designed a cooperatively controlled robot system using the Galen robotic platform. This system had two modes to execute a patient-specific surgical plan: haptic guidance to help the surgeon align the surgical saw to the planned osteotomy plane and an active constraint to restrict deviations from the osteotomy plane. To evaluate the system, a medical student, resident, and attending each performed both a freehand osteotomy and a robot-assisted osteotomy on 3D printed mandible models from six different patients. Postoperative CT scans were taken, segmented, and compared to preoperative CT scans. We computed the cut volume from the difference between pre- and postoperative segmentation. The distance from each cut voxel to the planned plane was used to the determine accuracy and precision of the osteotomy. All participants took a NASA Task Load Index (TLX) survey to assess the mental workload of the freehand and robotic operations.

Results When cutting freehand, the medical student's osteotomies had the highest deviation from the planned plane (2.16 +/- 0.98 mm) compared to the resident (1.74 +/- 0.95 mm) and the attending (1.64 +/- 0.85 mm). In comparison, the robot-assisted cuts resulted in significantly lower deviations from the planned plane, indicating the accuracy of the cut, and lower standard deviations, indicating the precision of the cut (medical student: 0.71 +/- 0.53 mm, p=0.0015; resident: 0.53 +/- 0.35 mm, p=0.0010; attending: 0.63 +/- 0.24 mm, p=0.0024). The NASA TLX survey showed that the robot-assisted system made the mental, temporal, and physical demands of BSSO easier for the attending and the resident, whereas the medical student found both freehand and robot-assisted procedures to be difficult.

Conclusions Our results show that the cooperatively controlled robot system can significantly enhance the precision of the surgical cutting in BSSO. The medical student, resident, and attending were able to improve performance with robotic assistance, effectively narrowing the skill gap.

Purpose Lipedema is a debilitating disease involving chronic accumulation of subcutaneous fat that is resistant to compression garments and lifestyle change. Lipedema affects approximately 19% of women. Past research has examined outcomes and patient satisfaction post liposuction for lipedema treatment at various individual institutions, but there remains limited literature on lipedema treatment algorithms and staging recommendations. We present a treatment algorithm based a single institution experience, including patient treatment of various obesity classes.

Methods We utilized a treatment algorithm whereby patients were first assigned one of four stages of disease progression as described by Herbst(figure 1). In order to rule out other concurrent pathology, if indicated, we recommend lymphoscintigraphy, venous ultrasound, or CT/MRI. Patients with Stage I/II lipedema with single areas involved (bilateral upper extremities or bilateral lower extremities involving hips but not buttocks) undergo single stage LVL where both extremities are treated within the same operative session. Patients with Stage III/IV and multiple affected anatomical regions (such as lower extremities involving hips and buttocks, all extremities, and any involvement of the abdomen) undergo staged treatment. that the most afftected area is treated first. Typically, the hips and legs are more affected so we begin with the hips, anterior, medial, and lateral thigh, followed by liposuction bilaterally below the knee, the buttock and posterior thighs, the abdomen, and the arms. A maximum of 10 L of fat is removed per operative session or can be achieved within 3 hours of operating time. We limit operating time to 3 hours or less to minimize risks of thromboembolic events. Timing between each procedure is 3-4 months. A retrospective chart review was performed for all patients diagnosed with lipedema at a single institution from 2016 to 2024. Number of liposuction procedures and the volume collected per procedure was collected. All liposuction procedures were performed by one surgeon (DN).

Results A total of 76 patients with a total of 126 liposuction procedures were included in this study. Maximum collected lipoaspirate volume was 10L. BMI average was 36.68 ± 7.93 kg/m2 (range 19.7-56.5 kg/m2. Average outpatient follow up time was 101.4 ± 113.42 days. BMI was not a significant predictor of the likelihood of complications in this analysis (OR = 0.17, 95% CI: 0.006–4.59, p = 0.226). Patients who had liposuction reported having none or less limitations in usual work, household, or school activities (61.5%), vigorous activities (53.8%), moderate activities (69.2%), bathing(69.2%) than before surgery. Upper extremity (61.5%), lower extremity (61.5%), and hip (53.8%) pain was reported to be less severe than before surgery.

Conclusions We propose a treatment algorithm that allows for safe large volume liposuction and staged treatment, even in the setting of high patient BMI, and high lipoaspirate volume collected. Our approach successfully improved patient mobility, completion of daily activities, and pain.

Introduction. Learning objectives, written statements that outline expectations of learners after an educational activity, are critical for focusing the teaching experience for both educators and learners.[1] While mandated learning objective criteria exist at every stage of medical training, including Continuing Medical Education (CME), the implementation and quality of educational learning objectives in plastic surgery remains unclear.[2], [3], [4] This study evaluated the quality of learning objectives in all 2023 and 2024 educational sessions at Plastic Surgery The Meeting (PSTM) assessed by SMART goal setting criteria and Bloom's Taxonomy levels.[1], [5]

Methods. This study was a cross-sectional study of all educational sessions in the 2023 and 2024 meetings of PSTM. Educational sessions with missing or incomplete learning objectives were excluded. Learning objectives were stratified according to the program track of the educational session. Adherence to SMART goal setting criteria and Bloom's Taxonomy concordance between learning objectives and the primary verb used to communicate each learning objective were compared.

Results. In total, 193 educational sessions were included in the study, corresponding to 513 learning objectives. Comparison of SMART criteria showed that learning objectives were overwhelmingly Attainable (92.50%), Relevant (99.21%), and Time-Bound (99.80%), but not Specific (60.16%) or Measurable (24.06%). Learning objectives predominantly included learning goals in Bloom's Taxonomy Levels 1 – Remember (38.3%) and 2 – Understand (38.1%). However, learning objectives primarily used verbs in Bloom's Taxonomy Level 2 (58.3%). A comparison of discordant verbs showed that presenters most often assigned verbs from the "Understand" category to learning objectives in the "Remember" category. Learning objectives tended to be deficient in the "Specific" and "Measurable" criteria across all program tracks; however, the fewest deficiencies were observed in Craniomaxillofacial and Head and Neck educational sessions. The mean Bloom's Taxonomy level of learning objectives significantly differed by track (p < 0.001). Mean Bloom's Taxonomy levels were highest in the Reconstructive (2.41/6) and Aesthetic (2.32/6) program tracks and lowest in the Breast track (1.54/6).

Conclusions. Educational sessions in national plastic surgery meetings tend to communicate Achievable, Relevant, and Time-Bound learning objectives, but not Specific or Measurable outcomes. Current learning objectives also tend to prioritize learner goals in lower Bloom's Taxonomy levels, with the most discordance in learning objectives and verbiage used occurring between the "Remember" and "Understand" Bloom's Taxonomy categories. Future guidelines should emphasize these two validated frameworks (SMART criteria and Bloom's Taxonomy) for future plastic surgery trainee and CME activities.   REFERENCES [1] E. M. Webb, D. M. Naeger, T. B. Fulton, and C. M. Straus, "Learning objectives in radiology education: why you need them and how to write them," Acad. Radiol., vol. 20, no. 3, pp. 358–363, Mar. 2013, doi: 10.1016/j.acra.2012.10.003. [2] "Standards, Publications, & Notification Forms | LCME." Accessed: Jul. 28, 2024. [Online]. Available: https://lcme.org/publications/ [3] "Program Requirements and FAQs and Applications." Accessed: Jul. 28, 2024. [Online]. Available: https://www.acgme.org/specialties/plastic-surgery/program-requirements-and-faqs-and-applications/ [4] "Criteria," ACCME. Accessed: Jul. 28, 2024. [Online]. Available: https://accme.org/rules/criteria/ [5] D. Chatterjee and J. Corral, "How to Write Well-Defined Learning Objectives," J. Educ. Perioper. Med. JEPM, vol. 19, no. 4, p. E610, Oct. 2017.

Introduction: Attrition from academic research, defined as the cessation of publication, is a phenomenon that disrupts medicine and science, with considerable impact on the field of plastic surgery. Existing literature has demonstrated a gender disparity in research attrition rates, yet despite the rising research trends in plastic surgery, there has not yet been an investigation into how these considerations affect the specialty. This study aims to examine the trends in research attrition amongst currently practicing plastic surgeons across three decades.

Methods: A longitudinal cohort study was conducted using a cohort of plastic surgeons identified from the American Society of Plastic Surgeons (ASPS) directory who published at least two articles in different years since 2000 with the keyword "plastic surgery." Articles were identified via Scopus search. The year of initial board certification, span of publishing, gender, fellowship training, and affiliation with an academic center were collected for each surgeon. The main outcome of interest was attrition in academic research, quantified as a lack of academic publication in the last three years or more. The probability of attrition over time was measured with Kaplan-Meier curves, and predictors of attrition were evaluated with a Cox proportional hazards model (p<0.05).

Results: The final cohort included 1,389 currently practicing plastic surgeons, 1,129 (81.3%) of which were male. The most common geographic region was New England/Middle Atlantic (322, 23.2%). The majority of surgeons were affiliated with an academic center (745, 53.6%) and were fellowship-trained (812, 58.5%). The median (IQR) number of publications was 6 (3-12), and the median span of publication was 10 (5-17) years. The overall rate of attrition was 58.7% (815 surgeons). The 20-year probability of attrition was significantly higher for female surgeons than male surgeons (72.1% vs. 64.8%, p=0.020). In a multivariable Cox proportional hazards model, male gender (HR: 0.78, 95% CI: 0.66-0.93, p=0.0067) and academic affiliation (HR: 0.61, 95% CI: 0.52-0.71, p<0.001) predicted a significantly lower likelihood of attrition. When compared to no fellowship training, aesthetic fellowship did not predict a significantly different likelihood of attrition (OR: 1.11, 95% CI: 0.88-1.40, p=0.38), whereas craniofacial, hand, and microsurgery fellowships all predicted a lower likelihood of attrition (p<0.05). Geographic region was not a significant variable in this model (p>0.05).

Conclusion: Female plastic surgeons are significantly more likely to leave academics than their male colleagues. Additionally, aesthetic fellowship may constitute a marker for the pursuit of a non-academically affiliated career. Those who maintained affiliation with an academic hospital were more likely to continue publishing. These trends highlight the continued gender imbalances in the field of plastic surgery and the need for organizational shifts that support and foster growth for all physicians who desire to remain in academic practice.

Introduction: Plastic surgery trainees report delayed childbearing due to the perceived incompatibility of surgical training with early family planning. Surgeon infertility rates are higher than that of the lay population and surgical training occurs during peak reproductive years, which contribute to poorer fertility, perinatal, and maternal outcomes. The unique challenges in the postpartum period that residents face including lactation and pumping once returning to clinical roles have not been studied. This survey aims to better understand plastic surgery trainees' experiences with parenthood and advocate for the normalization of the many facets of family planning.

Methods: An electronic Qualtrics-based survey was adapted from previously validated surveys in the medical literature. This survey was distributed to the 113 plastic surgery resident members of the American Council of Educators Plastic Surgeons (ACEPS). Data on demographics, parenthood knowledge, experiences, and perceptions were collected and analyzed.

Results: A total of 39 responses were received and of those who reported their sex, 85.2% were female and 14.8% were male, for a total response rate of 34.5%. One-quarter of respondents (25.6%) were unsure about whether a parental leave policy existed in either their residency program or through the American Board of Plastic Surgery. Fourteen trainees, representing over one-third of the respondents (35.9%), had children during residency training. Of those who answered, eleven had children by birth, one had a child via adoption, and one had a child with their partner as the birthing parent. All took parental leave, with eight people taking leave in the form of family and medical leave (FMLA), four as vacation, and four as elective or research time. The mean amount of leave was eight weeks, with a range of 3 to 12 weeks. More than half (53.4%) experienced guilt during parental leave, of which 57.1% experienced guilt from themselves and 42.9% experienced guilt associated with their co-residents. Eleven trainees (28.2%) were the birthing parent during training. Of these, nine (72.7%) intended to pump. On average, respondents pumped for a total of 8.1 months during residency. Two respondents reported that faculty made them feel uncomfortable pumping at work. Complications related to inadequate pumping, including diminished milk supply and mastitis, affected half of trainees. Over half of trainees (55.6%) ceased pumping earlier than they would have liked due to insufficient time and diminished milk supply. 75% of trainees reported that residency limited their ability to pump due to reasons such as insufficient time, increased stress, and inability to adequately nourish themselves to produce milk.

Conclusions: Plastic surgery trainees experience significant barriers during parenthood including inadequate parental leave, few resources for parental leave policies and lactation support, and insufficient time to allow for pumping. A more supportive culture, conscious colleagues and faculty, and informed policy change can improve parenthood for plastic surgeons.

Purpose: Over 40,000 traumatic open fractures leading to volumetric muscle loss (VML) injuries are estimated to occur annually in the US (1,2). Even ~20% muscle loss causes disproportionate lasting strength deficits of 30 - 90% (3). The current gold standard, physical therapy, only achieves partial functional recovery of 17 - 58% (4, 5). Our prior murine model of VML showed that passive external mechanical stimulation (MS) improves muscular torque recovery (MMT +26%) and reduces fibrosis (-21%). Here, we hypothesize that MS has similar outcomes in a large animal model.

Methods: Left Peroneus Tertius muscle (PTM) VML injury was surgically induced in female (38-42 kg) Yucatan pigs; animals received no treatment (n=10) or MS of the PTM (n=8). Outcomes included post-injury day 35 (PID35) recovery of pre-injury MMT and baseline activity level (step count), PID35 strength in newton-centimeters per gram PTM (ncm/g), weekly gait assessments (Tarlov Score), PID 35 recovery of pre-injury fatigue resistance, PID35 Masson staining, and PID35 MRI for PTM inflammation/edema (T2) and fat fraction.

Results: MS significantly improved recovery of MMT (32±25% vs 12±6%; p=0.00019) and activity (110±75% vs 67±62%; p=0.028), increased PID35 PTM strength (3.3±3.1 ncm/g vs 1.5±1.4 ncm/g; p=0.0049), improved gait at PID 14 (4.9±0.7 vs 4.4±1.0; p=0.042) and 28 (5.0±0 vs 4.6±1.0; p=0.045), and insignificantly improved recovery of fatigue resistance (55±100% vs 26±31%; p=0.11). Histology and MRI showed reduced fibrosis (16±12% vs 24±16%; p=0.048) and reduced PID35 T2 signal (-27%) and fat fraction (-44%).

Conclusions: In a translational large animal model, MS promotes strength recovery, reduces fibrosis, and reduces inflammation/fat fraction after VML injury. These results should be confirmed in a pilot clinical trial.

References: 1. Court-Brown CM, Bugler KE, Clement ND, Duckworth AD, McQueen MM. The epidemiology of open fractures in adults. A 15-year review. Injury. 2012 Jun;43(6):891-7. doi: 10.1016/j.injury.2011.12.007. Epub 2011 Dec 27. PMID: 22204774.

2. Population clock. https://www.census.gov/popclock/.

3. Garg K, Ward CL, Hurtgen BJ, Wilken JM, Stinner DJ, Wenke JC, Owens JG, Corona BT. Volumetric muscle loss: persistent functional deficits beyond frank loss of tissue. J Orthop Res. 2015 Jan;33(1):40-6. doi: 10.1002/jor.22730. Epub 2014 Sep 18. PMID: 25231205.

4. Corona, B.T. et al. (2013) 'Autologous minced muscle grafts: A tissue engineering therapy for the volumetric loss of skeletal muscle', American Journal of Physiology-Cell Physiology, 305(7). doi:10.1152/ajpcell.00189.2013.

5. Aurora, A. et al. (2014) 'Physical rehabilitation improves muscle function following volumetric muscle loss injury', BMC Sports Science, Medicine and Rehabilitation, 6(1). doi:10.1186/2052-1847-6-41.

Background: Vascularized composite allografts (VCAs) offer a promising solution for complex reconstructive procedures. However, their clinical application is constrained by a narrow preservation window, with prolonged ischemia hindering graft viability and post-transplant longevity. The University of Wisconsin (UW) preservation solution, the gold standard perfusate, extends viability by reducing cellular edema and scavenging for free radicals. However, its efficacy declines beyond the conventional 4–6-hour storage window, a significant drawback for muscle tissue, which is highly susceptible to ischemia. Muscle viability in VCAs, partly defined by structural characteristics, is difficult to assess due to the lack of a dedicated histological scoring system. Considering these challenges, adipose-derived stem cell-conditioned media (ADSC-CM), enriched with numerous growth factors and cytokines may mitigate ischemic damage. We therefore propose supplementing UW with ADSC-CM, creating UW-CM, to improve graft preservation, with evaluation using a novel histopathological injury scoring system (HISS).

Methods: Rat osteomyocutaneous grafts, comprising a superficial inferior epigastric artery skin flap, vascularized muscle, and femur, were perfused with and stored in one of three conditions: 1) saline, 2) UW, or 3) UW-CM. We evaluated graft muscle viability using hematoxylin and eosin (H&E) staining and a histological scoring system that categorized muscle integrity based on endomysium and fiber appearance (1 = normal, 2 = mild/moderate degradation, 3 = severe degradation). We performed pairwise comparisons using the Mann-Whitney U test where sample size allowed. Furthermore, inter-rater reliability was evaluated using Cohen's Kappa. Two independent raters analyzed a total of 84 regions of interest (ROIs) across 21 flaps.

Results: At 6 hours, the saline group exhibited the highest mean score for endomysium and fiber injury (2.38 ± 0.48), indicating moderate to severe muscle degradation. In comparison, UW-treated grafts achieved a mean score of 1.50 ± 0.13, while UW-CM-treated grafts reached a mean score of 1.81 ± 0.17, suggesting that both UW and UW-CM reduce the degree of histological injury relative to saline. At 24 hours, UW-CM-treated samples recorded a lower mean injury score (1.88 ± 0.63) compared to both UW (2.39 ± 0.48) and saline (2.38 ± 0.95). By 48 hours, UW-CM maintained a numerically lower mean score (2.20 ± 0.39) relative to UW (2.53 ± 0.33). Although the Mann-Whitney U test did not reach statistical significance at 48 hours (p = 0.234), these findings suggest that UW-CM may still offer slight improvements in preserving muscle integrity. Additionally, inter-rater reliability analysis showed substantial agreement (Cohen's Kappa = 0.691).

Conclusion: These findings indicate that supplementing UW with ADSC-CM may improve graft preservation by enhancing muscle integrity during extended storage. While UW alone provides consistent protection at early time points (6 hours), the addition of ADSC-CM appears to confer additional benefits at 24 and 48 hours. However, the lack of statistically significant differences at 48 hours highlights the need for further studies with larger sample sizes and optimized ADSC-CM concentrations. Overall, ADSC-CM shows promise as a supplement to extend VCA viability and improve reconstructive outcomes. Additionally, the scoring system provides a simple, useful tool for evaluating graft viability.