Orthotopic forelimb transplantation in a Yucatan minipig model: Anatomic and in vivo study.

INTRODUCTION: Above elbow transplants represent 19% of the upper extremity transplants. Previous large-animal models have been too distal or heterotopic, did not use immunosuppression and had short survival. We hypothesize that an orthotopic forelimb transplant model, under standard immunosuppression, is feasible and can be used to address questions on peri-transplant ischemia reperfusion injury, and post-transplantation vascular, immunologic, infectious, and functional outcomes. MATERIALS AND METHODS: Four forelimbs were used for anatomical studies. Four mock transplants were performed to establish technique/level of muscle/tendon repairs. Four donor and four recipient female Yucatan minipigs were utilized for in-vivo transplants (endpoint 90-days). Forelimbs were amputated at the midarm and preserved through ex vivo normothermic perfusion (EVNP) utilizing an RBC-based perfusate. Hourly perfusate fluid-dynamics, gases, electrolytes were recorded. Contractility during EVNLP was graded hourly using the Medical Research Council scale. EVNP termination criteria included systolic arterial pressure ≥115 mmHg, compartment pressure ≥30 mmHg (at EVNP endpoint), oxygen saturation reduction of 20%, and weight change ≥2%. Indocyanine green (ICG) angiography was performed after revascularization. Limb rejection was evaluated clinically (rash, edema, temperature), and histologically (BANFF classification) collecting per cause and protocol biopsies (POD 1, 7, 30, 60 and endpoint). Systemic infections were assessed by blood culture and tissue histology. CT scan was used to confirm bone bridging at endpoint. RESULTS: Animals 2, 4 reached endpoint with grade 0-I rejection. Limbs 1, 3 presented grade III rejection on days 6, 61. CsA troughs averaged 461 ± 189 ng/mL. EVNLP averaged 4.3 ± 0.52 h. Perfusate lactate, PO2 , and pH were 5.6 ± 0.9 mmol/L, 557 ± 72 mmHg and 7.5 ± 0.1, respectively. Muscle contractions were 4 [1] during EVNLP. Transplants 2, 3, 4 showed bone bridging on CT. CONCLUSION: We present preliminary evidence supporting the feasibility of an orthotopic, mid-humeral forelimb allotransplantation model under standard immunosuppression regimen. Further research should validate the immunological, infectious, and functional outcomes of this model.

Outcomes of Calvarial and Soft-Tissue Reconstruction with Latissimus Dorsi-Rib Osteomyocutaneous Free Flap.

BACKGROUND: The latissimus dorsi-rib osteomyocutaneous free flap (LDRF) has been used for autologous reconstruction of large composite calvarial and scalp defects. In this study, the authors aim to present clinical and patient-reported outcomes after LDRF reconstruction. METHODS: An anatomical study was conducted to evaluate the distribution of the connecting perforators between the thoracodorsal and intercostal systems. An institutional review board-approved retrospective review of 10 patients who underwent LDRF with one or two ribs for treatment of cranial defects was conducted. Patient-reported outcomes regarding quality of life, neurologic status, and functional status were evaluated using validated surveys. One-way analysis of variance and post hoc Tukey tests were used for anatomical outcomes. Preoperative and postoperative scores were compared using paired t tests. RESULTS: The tenth rib (4.65 ± 2.01) followed by the ninth rib (3.7 ± 1.63) had the highest number of perforators. A combination of the ninth and eleventh ribs exhibited maximal perforator number and pedicle length. All patients had stable LDRF reconstructions. Eight patients completed both preoperative and postoperative questionnaires; Median clinical follow-up was 48 months (range, 34 to 70 months). Scores trended toward improvement but did not reach statistical significance on the Karnofsky Performance Scale ( P = 0.22), the Functional Independence Measure (Motor, P = 0.52; Cognitive, P = 0.55), or the Headache Disability Index ( P = 0.38). The minimum clinically important difference was surpassed, demonstrating improvement of function for 71% of patients on the Barthel Index and 63% on the Selective Functional Movement Assessment test. CONCLUSION: The LDRF can improve cognitive and physical functional status in complex patients with prior failed reconstructions for composite scalp and skull defects. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Five Fraction Accelerated Partial Breast Irradiation Versus Intraoperative Radiation Therapy for Early-Stage Breast Cancer.

PURPOSE/OBJECTIVE(S): Accelerated partial breast irradiation (PBI) delivered in 5 fractions with intensity modulated radiation therapy (IMRT) has been shown to have comparable clinical outcomes to whole breast irradiation with reduced toxicity profiles. In contrast, intraoperative radiation therapy (IORT) offers patients the potential to complete adjuvant radiation therapy in a single treatment. While early data were promising, concerns exist regarding long-term rates of local recurrence after IORT. We present a comparison of 5 fraction PBI versus IORT. MATERIALS/METHODS: We performed a retrospective review of 473 patients with early-stage breast cancer treated at a single institution from 2011 to 2021 with 258 receiving PBI and 215 receiving IORT. PBI patients received 30 Gy in 5 fractions delivered with IMRT. IORT patients received 20 Gy in 1 fraction prescribed to the applicator surface at surgery using the low-energy TARGIT technique. RESULTS: Mean age was 71 years old (IQR:67-74) for IORT patients and 67 years old (IQR:62-72) for PBI patients. Median follow up was 5.7 years (IQR:4.2-7.0) for IORT patients and 2.4 years (IQR:1.8-3.3) for PBI patients (P < .001). Recurrence at any time (locoregional and distant) was seen in 7.9% (n = 17) of patients receiving IORT as compared to 0.8% (n = 2) of patients receiving PBI. IORT was associated with reduced rates of locoregional relapse free survival at 5 years (93.6% vs. 99.4%, P = .05) with no difference in overall survival(92.8% vs. 95.1%, P = .99). CONCLUSION: Low-energy TARGIT IORT was associated with higher rates of locoregional recurrence compared to PBI. These outcomes, consistent with other series and current guidelines, suggest a limited role for low-energy IORT as monotherapy.

Comparing the educational quality of free flap technique videos on public and paid platforms.

BACKGROUND: Surgical videos are reshaping the landscape for surgical education. As this form of education has rapidly grown and become a valuable resource for experienced surgeons, residents, and students, there is great variability in the presentation of what is offered. This study aimed to assess and compare the educational quality of free flap instructional videos on public and paid platforms. METHODS: Free flap videos from public (YouTube) and paid (American Society of Plastic Surgeons Education Network and Plastic and Reconstructive Surgery Journal) sources were screened independently by three reviewers. Sample size was calculated to reach 80% power. The educational quality of the videos was determined using a modified version of Laparoscopic Surgery Video Educational Guidelines (0-6 low, 7-12 medium, 13-18 high). Professionally-made videos were identified per lighting, positioning, and video/imaging quality. Interrater reliability between the three reviewers was calculated. The educational quality of the videos was compared between public and paid sources using Mood's median test. Pearson's correlation coefficient was utilized to assess the correlation between video length and educational quality. RESULTS: Seventy-six videos were included (40 public, 36 paid). The median video lengths for public and paid platforms were 9.43(IQR = 12.33) and 5.07(IQR = 6.4) min, respectively. There were 18 high, 16 medium, and 6 low-quality public videos, versus 13 high, 21 medium, and 2 low-quality paid videos. Four public and seven paid videos were identified as professionally made. Interrater reliability was high (α = .9). No differences in educational quality were identified between public and paid platforms. Video length was not correlated with quality (p = .15). A video library compiling public high-quality videos was created (https://www.youtube.com/playlist?list=PL-d5BBgQF75VWSkbvEq6mfYI--9579oPK). CONCLUSIONS: Public and paid platforms may provide similar surgical education on free tissue transfer. Therefore, whether to subscribe to a paid video platform for supplemental free flap education should be determined on an individual basis.

Weight gain is an early indicator of injury in ex vivo normothermic limb perfusion (EVNLP).

PURPOSE: There are no established criteria for discontinuing ex vivo normothermic limb perfusion (EVNLP) before irreversible damage occurs. This study evaluates weight gain as an indicator of injury during EVNLP. METHODS: Sixteen Yorkshire pig forelimbs were procured and preserved using EVNLP with a hemoglobin-based oxygen carrier (HBOC-201) or static cold storage. EVNLP continued until termination criteria were met: arterial pressure ≥ 115 mm Hg, compartment pressure > 30 mm Hg, or 20% reduction of oxygen saturation. Limb weight, contractility, hemodynamics, perfusate electrolytes, metabolites and gases were recorded. Muscles were biopsied 6-h, and muscle injury scores (MIS) calculated. Forearm compartment pressures and indocyanine green (ICG) angiography were recorded at endpoint. Outcomes were compared at 2%, 5%, 10%, and 20% limb weight gain. RESULTS: EVNLP lasted 20 ± 3 h. Weight gain was observed after 13 ± 5 h (2%), 15 ± 6 h (5%), 16 ± 6 h (10%), and 19 ± 4 h (20%). Weight correlated positively with MIS (ρ = 0.92, p < 0.0001), potassium (ρ = -1.00, p < 0.0001), pressure (ρ = 0.78, p < 0.0001), and negatively with contractility (ρ = -0.96, p = 0.011). At 5% weight gain, MIS (p < 0.0001), potassium (p = 0.03), and lactate (p < 0.0001) were significantly higher than baseline. Median muscle contractility was 5 [3-5] at 2% weight gain, 4 [1-5] at 5%, 3 [0-4] and 2 [0-2] at 10% and 20%, respectively. At 20% weight gain, contractility was significantly lower than baseline (p = 0.003). Percent weight gain correlated negatively with endpoint ICG hoof fluorescence (r = -0.712, p = 0.047). CONCLUSIONS: Weight gain correlated with microscopic muscle injury and was the earliest evidence of limb dysfunction. Weight gain may serve as a criterion for discontinuation of EVNLP.

Appropriate Imaging for Geriatric Trauma.

BACKGROUND: Trauma is the leading cause of preventable death in the United States. Early detection of life-threatening injuries leads to improved survival. Computed tomography (CT) scanning has become the modality of choice for early detection of injuries in the stable patient. Some studies have associated selective imaging (Selective-CT) with equivalent outcomes compared to whole body imaging (Pan-CT) with lower costs and radiation exposure. Within the geriatric population, however, the utility of Pan-CT remains controversial. Therefore, the aim of this study was to determine if a difference exists between Selective-CT and Pan-CT imaging in the geriatric trauma patient. METHODS: A retrospective analysis of Level 3 (G60) trauma activations presenting to our urban Level I trauma center between June 2016 and June 2019 was performed. Pan-CT was defined by ICD-10 codes indicating a head, cervical spine, chest, abdomen, and pelvis CT series. Patients with missing images and those who were transferred from other institutions were excluded. Logistic regression controlling for age, gender, injury type, severity, and Glasgow Coma Score was performed. RESULTS: A total of 1014 patients met inclusion criteria. Of these, 30.9% underwent Pan-CT (n = 314), 48.9% had Selective-CT (n = 497), and 20.2% received no CT imaging (n = 203). After logistic regression, no clinically significant variations in emergency department length of stay (LOS), hospital LOS, ICU LOS, ventilator days, discharge disposition, missed injury rate, or mortality rate were observed between imaging strategies. CONCLUSIONS: Pan-CT provides no clinically significant advantage over Selective-CT in the geriatric trauma patient.

Robotic Diagnosis and Management of Acute Cholecystocolonic Fistula.

Cholecystocolonic fistula (CCF) is a rare complication of biliary tract disease. Increased use of imaging has aided in diagnosing these fistulae preoperatively and has established laparoscopy as a safe alternative to laparotomy. Here, we present a 79-year-old male who presented to the emergency room with abdominal pain and was diagnosed with choledocholithiasis. CT scan revealed a CCF, and he underwent endoscopic retrograde cholangiopancreatography (ERCP). He was followed closely to allow maturation of the fistula, and then, da Vinci® Xi robotic cholecystectomy and ligation were performed. Although current comparisons to laparoscopy have yet to demonstrate a clinical advantage, robotic assistance enhances dexterity, visualization, and ergonomics. Our case is one of the first documented successful operative management of CCF using the da Vinci® Xi robot.

Ex Vivo Normothermic Perfusion of Human Upper Limbs.

BACKGROUND: Ischemia-reperfusion injury remains a primary concern in upper extremity transplantation. Ex vivo normothermic perfusion (EVNP) enables near-physiological organ preservation, avoiding the deleterious effects of hypoxia and cooling. We investigated the effectiveness of human limb EVNP compared with static cold storage (SCS). METHODS: Twenty human upper extremities were procured. Ten were perfused at 38 °C with an oxygenated red blood cell-based solution, and contralateral limbs served as SCS control (4 °C). EVNP was terminated with systolic arterial pressure ≥115 mm Hg, compartment fullness, or a 20% decline in oxygen saturation. Weight, contractility, compartment pressure, tissue oxygen saturation, and uptake rates were assessed. Perfusate fluid dynamics, gases, electrolytes, and metabolites were measured. Myocyte injury scores and liquid chromatography-mass spectrometry analysis were performed. RESULTS: EVNP duration was 41.6 ± 9.4 h. Vascular resistance averaged 173.0 ± 29.4 mm Hg × min/L. Weight change and compartment pressures were 0.4 ± 12.2% ( P = 0.21) and 21.7 ± 15.58 mm Hg ( P = 0.003), respectively. Arterial and venous carbon dioxide partial pressure, oxygen saturation, and pH were 509.5 ± 91.4 mm Hg, 15.7 ± 30.2 mm Hg, 87.4 ± 11.4%, and 7.3 ± 0.2, respectively. Oxygen uptake rates averaged 5.7 ± 2.8 mL/min/g. Lactate reached 20 mmol/L after 15 (interquartile range = 6) h. Limb contractility was preserved for 30.5 (interquartile range = 15.8) h ( P < 0.001) and negatively correlated with perfusate potassium (ρ = -0.7, P < 0.001). Endpoint myocyte injury scores were 28.9 ± 11.5% (EVNP) and 90.2 ± 11.8% (SCS) ( P < 0.001). A significant increase in taurine ( P = 0.002) and decrease in tryptophan ( P = 0.002) were detected. Infrared thermography and indocyanine green angiography confirmed the presence of peripheral perfusion. CONCLUSIONS: EVNP can overcome the limitations of cold preservation by extending preservation times, enabling limb quality assessment, and allowing limb reconditioning before transplantation.

Ex vivo normothermic preservation of amputated limbs with a hemoglobin-based oxygen carrier perfusate.

BACKGROUND: Ex vivo normothermic limb perfusion (EVNLP) preserves amputated limbs under near-physiologic conditions. Perfusates containing red blood cells (RBCs) have shown to improve outcomes during ex vivo normothermic organ perfusion, when compared with acellular perfusates. To avoid limitations associated with the use of blood-based products, we evaluated the feasibility of EVNLP using a polymerized hemoglobin-based oxygen carrier-201 (HBOC-201). METHODS: Twenty-four porcine forelimbs were procured from Yorkshire pigs. Six forelimbs underwent EVNLP with an HBOC-201-based perfusate, six with an RBC-based perfusate, and 12 served as static cold storage (SCS) controls. Ex vivo normothermic limb perfusion was terminated in the presence of systolic arterial pressure of 115 mm Hg or greater, fullness of compartments, or drop of tissue oxygen saturation by 20%. Limb contractility, weight change, compartment pressure, tissue oxygen saturation, oxygen uptake rates (OURs) were assessed. Perfusate fluid-dynamics, gases, electrolytes, metabolites, methemoglobin, creatine kinase, and myoglobin concentration were measured. Uniformity of skin perfusion was assessed with indocyanine green angiography and infrared thermography. RESULTS: Warm ischemia time before EVNLP was 35.50 ± 8.62 minutes (HBOC-201), 30.17 ± 8.03 minutes (RBC) and 37.82 ± 10.45 (SCS) (p = 0.09). Ex vivo normothermic limb perfusion duration was 22.5 ± 1.7 hours (HBOC-201) and 28.2 ± 7.3 hours (RBC) (p = 0.04). Vascular flow (325 ± 25 mL·min-1 vs. 444.7 ± 50.6 mL·min-1; p = 0.39), OUR (2.0 ± 1.45 mL O2·min-1·g-1 vs. 1.3 ± 0.92 mL O2·min-1·g-1 of tissue; p = 0.80), lactate (14.66 ± 4.26 mmol·L-1 vs. 13.11 ± 6.68 mmol·L-1; p = 0.32), perfusate pH (7.53 ± 0.25 HBOC-201; 7.50 ± 0.23 RBC; p = 0.82), flexor (28.3 ± 22.0 vs. 27.5 ± 10.6; p = 0.99), and extensor (31.5 ± 22.9 vs. 28.8 ± 14.5; p = 0.82) compartment pressures, and weight changes (23.1 ± 3.0% vs. 13.2 ± 22.7; p = 0.07) were not significantly different between HBOC-201 and RBC groups, respectively. In HBOC-201 perfused limbs, methemoglobin levels increased, reaching 47.8 ± 12.1% at endpoint. Methemoglobin saturation did not affect OUR (ρ = -0.15, r2 = 0.022; p = 0.45). A significantly greater number of necrotic myocytes was found in the SCS group at endpoint (SCS, 127 ± 17 cells; HBOC-201, 72 ± 30 cells; RBC-based, 56 ± 40 cells; vs. p = 0.003). CONCLUSION: HBOC-201- and RBC-based perfusates similarly support isolated limb physiology, metabolism, and function.

Trauma center funding: time for an update.

BACKGROUND: Uncompensated care (UC) is healthcare provided with no payment from the patient or an insurance provider. UC directly contributes to escalating healthcare costs in the USA and potentially impacts patient care. In Texas, there has been a steady increase in the number of trauma centers and UC volumes without an increase in trauma funding of UC. The method of calculating UC trauma funds in Texas is imprecise as it is driven by Medicaid volumes and not actual trauma care costs. METHODS: Five years of annual trauma UC disbursement reports from the Texas Department of State Health Services were used to determine changes in UC economic considerations for level I, II, and III trauma centers in the largest urban trauma service areas (TSAs). Data for UC costs, compensation, and TSA demographics were used to assess variations. Statistical significance was determined using a Kruskal-Wallis test with Dunn's pairwise comparison post-hoc analysis and logistic regression. RESULTS: TSA-E (Dallas-Fort Worth area) has 33% of the level I trauma centers in Texas (n=6) and yet serves only 27% of the total state population across 14 metropolitan and 5 non-metropolitan counties. Since 2015, TSA-E has shown higher UC costs (p<0.02) and lower reimbursement (p<0.01) than the second largest urban hub, TSA-Q (Houston area). TSA-E level I trauma centers trended towards decreased UC reimbursements. DISCUSSION: The unregulated expansion of trauma centers in Texas has led to an unprecedented increase in hospitals participating in trauma care. The unbalanced allocation of UC funding could lead to further economic instability, compromise resource allocation, and negatively impact patient care in an already fragile healthcare environment. LEVEL OF EVIDENCE: Level IV; Retrospective economic analysis and evaluation.

Histomorphometry in Peripheral Nerve Regeneration: Comparison of Different Axon Counting Methods.

BACKGROUND: Histomorphometry quantitatively evaluates nerve regeneration. Total myelinated fiber count (TMFC) is most accurately obtained manually across full nerve cross-sections, but most researchers opt for automated, sampled analysis. Few of the numerous techniques available have been validated. The goal of this study was to compare common histomorphometric methods (full manual [FM], sampled manual [SM], and sampled automatic [SA]) to determine their reliability and consistency. MATERIAL AND METHODS: Twenty-four rats underwent sciatic nerve (SN) repair with 20mm isografts; SNs distal to the graft were analyzed. TMFC was manually determined in each full cross-section. Counts were also extrapolated from sampled fields, both manually and automatically with ImageJ software. Myelinated fiber diameter, axon diameter, and myelin sheath thickness were measured manually in full and sampled fields; G-ratio was calculated. Repeated-measures MANOVA, Spearman correlation, and Wilcoxon signed-rank tests were performed. A systematic review of histomorphometry in rat SN repair was performed to analyze the variability of techniques in the literature. RESULTS: FM TMFC was 13,506 ± 4,217. Both sampled methods yielded significantly different TMFCs (SM:14.4 ± 13.4%, P< 0.001; SA:21.8 ± 44.7%, P = 0.037). All three methods strongly correlated with each other, especially FM and SM (rs = 0.912, P< 0.001). FM fiber diameter, axon diameter, and myelin sheath thickness did not differ from SM (P = 0.493, 0.209, and 0.331, respectively). 65% of papers used sampling; 78% utilized automated or semi-automated analysis. Software, sampling, and histomorphometric parameters varied widely. CONCLUSION: SM and SA analysis are reliable with standardized, systematic sampling. Transparency is essential to allow comparison of data; meanwhile, researchers must be cognizant of the wide variety of methodologies in the literature.

Ex-Vivo Normothermic Limb Perfusion With a Hemoglobin-Based Oxygen Carrier Perfusate.

INTRODUCTION: Ex-vivo normothermic limb perfusion (EVNLP) has been proven to preserve limb viability better than standard cold storage. Perfusates containing packed red blood cells (pRBC) improve outcomes when compared to acellular perfusates. Limitations of pRBC-based perfusion include limited availability, need for cross match, mechanical hemolysis, and activation of pro-inflammatory proteins. Hemoglobin-based oxygen carrier (HBOC)-201 (Hemopure) is a solution of polymerized bovine hemoglobin, characterized by low immunogenicity, no risk of hemolytic reaction, and enhanced convective and diffusive oxygen delivery. This is a preliminary study on the feasibility of EVNLP using HBOC-201 as an oxygen carrier. MATERIALS AND METHODS: Three porcine forelimb perfusions were performed using an established EVNLP model and an HBOC-201-based perfusate. The perfusion circuit included a roller pump, oxygenator, heat exchanger, and reservoir. Electrolytes, limb temperature, weight, compartment pressure, nerve conduction, and perfusion indicated by indocyanine green angiography and infra-red thermography were monitored. Histological evaluation was performed with hematoxylin and eosin and electron microscopy. RESULTS: Three limbs were perfused for 21.3 ± 2.1 hours. Muscle contractility was preserved for 10.6 ± 2.4 hours. Better preservation of the mitochondrial ultrastructure was evident at 12 hours in contrast to crystallization and destruction features in the cold-storage controls. CONCLUSIONS: An HBOC-201-EVNLP produced outcomes similar to RBC-EVNLP with preservation of muscle contractility and mitochondrial structure.