The Effect of Narrow-Band Ultraviolet B Irradiation on the Vascularized Composite Allotransplantation Rat Model.

INTRODUCTION: Vascularized composite allotransplantation (VCA) allows functional and esthetic reconstruction for patients with complex anatomical defects. However, acute and chronic graft rejections are significant obstacles to VCA. Ultraviolet light is an oncogenic environmental hazard. However, ultraviolet B (UVB) has an immunomodulation effect. Therefore, this study aims to elucidate the impact of UVB irradiation on the VCA rat model. METHODS: The rat vascularized bone marrow allotransplantation model was used. A vascularized bone marrow from a Brown Norway rat (RT1Ac) was transplanted into a Lewis rat (RT1Ab). The allograft and surrounding abdominal skin were exposed to narrow-band ultraviolet B (NB-UVB) (311 nm) radiation with an energy of 1350 mJ/cm2 3 times a week until the end of the study period. There were 5 study groups: syngeneic transplantation (group 1), allogeneic transplantation (group 2), allogenic transplantation-NB-UVB (group 3), allogenic transplantation-antilymphocyte serum (ALS)-tacrolimus (group 4), and allogenic transplantation-antilymphocyte serum-tacrolimus-NB-UVB (group 5). RESULTS: Group 5 had decreased graft survival compared with group 4. In the donor cell chimerism analysis, donor cell chimerism decreased significantly after UVB irradiation and was unresponsive to the administered immunosuppressants. After UVB irradiation, the CD8 T-cell ratio was increased, and the regulatory T-cell ratio was decreased. CONCLUSIONS: The preliminary data showed that NB-UVB irradiation of the VCA rat model may decrease graft survival. However, further studies are needed to elucidate the possible mechanisms of this phenomenon.

Popliteal Artery Injury After Fracture and/or Dislocation of the Knee: Risk Stratification for Revascularization Outcome.

BACKGROUND: Managing complex knee trauma involving both vascular and osseous injuries is challenging, yet the available guidelines for efficient popliteal artery injury management after high-velocity blunt knee trauma remain conflicting and inconsistent. In this study, the authors aim to identify the risk factors associated with delayed limb amputation and ischemic muscular sequela postrevascularization. Furthermore, we propose a treatment algorithm to improve the limb salvage rate. METHODS: Patients who presented with traumatic popliteal artery injury resulting in vessel occlusion or rupture, followed by fracture and/or dislocation of the knee from January 2008 to December 2013, were included for retrospective review. RESULTS: Overall delayed amputation rate was 24% (7/29) and 16% (4/25) after successful revascularization. Mangled Extremity Severity Score is higher in the delayed amputation group than the limb-salvaged group (P = 0.02). Higher-impact force (P = 0.03), ischemic limb on presentation (P = 0.03), prolonged ischemia time (P = 0.04), unstable hemodynamics (P = 0.01), longer operation time (P = 0.04), and prolonged intensive care unit stay (P = 0.03) are risk factors of delayed amputation. Longer ischemia time (P = 0.04) and length of popliteal artery injury (P = 0.02) are associated with ischemic muscular sequela. CONCLUSIONS: Mangled Extremity Severity Score is a reliable predictor of limb salvage. An algorithmic approach may improve the outcome of popliteal artery injury after high-velocity blunt knee trauma.

Effects of Systemic and Local Caffeine on Vessel Diameter, Anastomosis Patency, and Intimal Hyperplasia in the Rat.

BACKGROUND: The use of caffeine is not recommended prior to elective microsurgery due to its demonstrated negative effects on vessel anastomosis by the presumed sympathomimetic induction of vasoconstriction. In this study, we aimed to elucidate the systemic and local effects of caffeine on vessel diameter, anastomosis patency, and degree of intimal hyperplasia during the healing process. METHODS: Twenty-five rats were randomly assigned to five groups: (1) negative control, (2) preoperative systemic caffeine, (3) postoperative systemic caffeine, (4) perioperative systemic caffeine, and (5) a local caffeine group. Both the right and left femoral arteries were used. Ten anastomoses were performed per group. The arterial diameter was measured by micrometer, anastomosis patency was assessed surgically and histologically, and the histological examination was conducted 3 weeks postoperatively to determine intimal hyperplasia. RESULTS: The overall patency rate was 96%. Mild vasoconstriction was observed in the systemic caffeine groups (statistically insignificant); however, there were no negative effects on anastomosis patency. Local caffeine irrigation resulted in significant vasodilatation in the local caffeine group (p = 0.001); a similar effect was not observed in the other groups. There was a significant decrease in the intima/media ratio in the local caffeine group (p < 0.01), when compared with the control and systemic caffeine groups. No other intima/media ratio differences were observed among other comparison groups. CONCLUSION: The systemic administration of caffeine, although statistically insignificant, has an observable effect on vasoconstriction. However, it does not appear to have negative effects on anastomosis patency regardless of its application period (pre-, post-, or perioperatively). The local application of caffeine resulted in considerable vasodilatation as opposed to the vasoconstriction effect in the systemic caffeine groups. Decreased intimal hyperplasia at the anastomosis edge, and antifibrotic properties in the surgical field were also observed in this group. Histologically, the local caffeine group demonstrated an additional beneficial effect on anastomosis remodeling.

Evolution and Diversity of Medial Sural Artery Perforator Flap for Hand Reconstruction.

The free medial sural artery perforator (MSAP) flap is a recently popularized flap. It has evolved from a composite myocutaneous flap to a pedicled perforator flap for lower limb reconstruction. It is also a versatile free perforator flap for extremity and head and neck reconstruction. The diversity of the flap designs with options for harvest of non-vascularized grafts enhances the versatility for hand and upper limb reconstruction. The adjunctive use of endoscopy and indocyanine green fluorescence imaging studies can assist and demystify the flap anatomy. The authors present their experience using free MSAP flaps for complex mutilated hand and upper extremity reconstruction.

Comparing Innervated and Non-Innervated Glabrous Skin Flaps for Volar Digital Defects: Insights from Patient-Reported Outcomes.

BACKGROUND: Volar soft tissue defects in digits necessitate reconstructions that restore appearance sensation and minimize complications. This study compares innervated toe pulp (TP) and non-innervated medialis pedis (MP) flaps for reconstructing such defects, focusing on objective and subjective outcomes. METHODS: Between 1998 and 2017, 101 free glabrous skin flap reconstructions were performed at our institution for volar digital soft tissue injuries, comprising 75 TP and 26 MP flaps. Follow-up assessments included the Michigan Hand Outcomes Questionnaire, Disabilities of the Arm, Shoulder and Hand Questionnaire, Foot and Ankle Disability Index, and sensory testing (static and moving two-point discrimination, Semmes-Weinstein monofilament test). Data analysis utilized the Mann-Whitney U test and Pearson correlation coefficients. RESULTS: The study cohort included 29 participants (15 TP, 14 MP) with an average follow-up of 106 months. Functional and sensory outcomes revealed no significant differences between TP and MP flaps. Both flap types achieved satisfactory function and sensibility, with no statistically significant distinctions in patient-reported outcomes. Subjective complaints were similarly distributed across both groups, with a few reports of cold intolerance and discomfort at the donor site in the TP group. CONCLUSIONS: TP and MP flaps provide adequate coverage and sensory outcomes for volar digital defects without significant differences between innervated and non-innervated flap transfers. The flap choice should be tailored to individual patient needs and defect characteristics, emphasizing the importance of patient-centered decision-making in reconstructive surgery. Further research is required to explore the long-term outcomes of these reconstruction methods, especially for larger defects.

Reconstructing complex peripatellar defects using the descending genicular artery perforator flap.

BACKGROUND: Complex peripatellar defects are commonly reconstructed with free flaps or pedicled muscle flaps, whereas pedicled fasciocutaneous perforator flaps are commonly overlooked. The descending genicular artery perforator (DGAP) flap is a versatile flap that offers thin and pliable tissue that provides ideal 'like with like' peripatellar soft tissue defect reconstruction. This paper aims to demonstrate the safe use of a pedicled fasciocutaneous DGAP flap for extensive traumatic peripatellar defect reconstructions and to exhibit the surgical pearls via a case series. METHODS: A retrospective cohort study of consecutive complex peripatellar reconstructions with DGAP flaps was conducted from January 2011 to December 2018. Patient demographics, medical comorbidities, aetiology/size/and location of the defects were reviewed. Flap, donor site, and overall surgical outcomes were clinically assessed and documented. Descriptive statistics were conducted and analysed by IBM SPSS Statistics 23. RESULTS: Five consecutive cases with complex peripatellar defects (5 × 8 to 8 × 10 cm) were recruited. Two were males, and three were females, with a mean age of 38.4 years. Four were trauma, and one was an oncological case. Descending genicular artery (DGA) perforators and DGA terminal branches were consistent. One patient needed a split-thickness skin graft to reconstruct the secondary defects. All the flaps survived with an average follow-up of 24 months. CONCLUSION: The DGAP flap provides a reliable alternative to free flap for the large, complex peripatellar defect. With the inclusion of the proximal long saphenous vein and judicious selection of DGA perforators and its terminal branches, the DGAP flap can be harvested and used safely in the high-velocity impacted knee.

Reliability of Postoperative Free Flap Monitoring with a Novel Prediction Model Based on Supervised Machine Learning.

BACKGROUND: Postoperative free flap monitoring is a critical part of reconstructive microsurgery. Postoperative clinical assessments rely heavily on specialty-trained staff. Therefore, in regions with limited specialist availability, the feasibility of performing microsurgery is restricted. This study aimed to apply artificial intelligence in postoperative free flap monitoring and validate the ability of machine learning in predicting and differentiating types of postoperative free flap circulation. METHODS: Postoperative data from 176 patients who received free flap surgery were prospectively collected, including free flap photographs and clinical evaluation measures. Flap circulation outcome variables included normal, arterial insufficiency, and venous insufficiency. The Synthetic Minority Oversampling Technique plus Tomek Links (SMOTE-Tomek) was applied for data balance. Data were divided into 80%:20% for model training and validation. Shapley Additive Explanations were used for prediction interpretations of the model. RESULTS: Of 805 total included flaps, 555 (69%) were normal, 97 (12%) had arterial insufficiency, and 153 (19%) had venous insufficiency. The most effective prediction model was developed based on random forest, with an accuracy of 98.4%. Temperature and color differences between the flap and the surrounding skin were the most significant contributing factors to predict a vascular compromised flap. CONCLUSIONS: This study demonstrated the reliability of a machine-learning model in differentiating various types of postoperative flap circulation. This novel technique may reduce the burden of free flap monitoring and encourage the broader use of reconstructive microsurgery in regions with a limited number of staff specialists.

Cell therapy in vascularized composite allotransplantation.

Allograft rejection is one of the obstacles in achieving a successful vascularized composite allotransplantation (VCA). Treatments of graft rejection with lifelong immunosuppression (IS) subject the recipients to a lifelong risk of cancer development and opportunistic infections. Cell therapy has recently emerged as a promising strategy to modulate the immune system, minimize immunosuppressant drug dosages, and induce allograft tolerance. In this review, the recent works regarding the use of cell therapy to improve allograft outcomes are discussed. The current data supports the safety of cell therapy. The suitable type of cell therapy in allotransplantation is clinically dependent. Bone marrow cell therapy is more suitable for the induction phase, while other cell therapies are more feasible in either the induction or maintenance phase, or for salvage of allograft rejection. Immune cell therapy focuses on modulating the immune response, whereas stem cells may have an additional role in promoting structural regenerations, such as nerve regeneration. Source, frequency, dosage, and route of cell therapy delivery are also dependent on the specific need in the clinical setting.

The intragraft vascularized bone marrow induces secondary donor-specific mystacial pad allograft tolerance.

Introduction: Vascularized bone marrow (VBM) is essential in tolerance induction through chimerism. We hypothesized that the inclusion of VBM contributes to the induction of mystacial pad allotransplantation tolerance. Method: In this study, 19 VBM, nine mystacial pad, and six sequential VBM and mystacial pad allografts were transplanted from Brown Norway (BN) rats to Lewis (LEW) rats to test our hypothesis. The VBM recipients were divided into antilymphocyte serum (ALS) monotherapy group (two doses of ALS on day 3 pretransplantation and day 1 posttransplantation), immunosuppressant group [a week of 2 mg/kg/day tacrolimus (Tac) and 3 weeks of 3 mg/kg/day rapamycin (RPM)], and combined therapy group. The mystacial pad recipients were divided into VBM and non-VBM transplantation groups, and both groups were treated with an immunosuppression regimen that consists of ALS, Tac, and RPM. For the recipients of sequential VBM and mystacial pad allotransplantations, additional Tac was given 1 week after mystacial pad transplantation. Allograft survival, donor-specific tolerance, and chimerism level were evaluated. Results: With the administration of ALS and short-term Tac and RPM treatments, VBM recipients demonstrated long-term graft survival (>120 days) with persistent chimerism for 30 days. CD3+ T cells from tolerant rats showed donor-specific hyporesponsiveness and tolerance to donor skin grafts but not to third-party counterparts. Furthermore, mystacial pad graft recipients with VBM transplantation exhibited a higher allograft survival rate than those without VBM transplantation [median survival time (MST) >90 days vs. 70 days, p < 0.05]. Conclusion: This study demonstrated that VBM transplantation is an efficient strategy to induce and maintain donor-specific tolerance for an osseous-free allograft.

The Medial Sural Artery Perforator Flap in Lower Extremity Reconstruction.

Medial sural artery perforator (MSAP) flap is a thin, pliable, and versatile flap. It is a fasciocutaneous flap with chimeric design capacity. The donor site permits the synchronous harvesting of nonvascularized tendons and nerves. Free MSAP flap is suitable for foot, ankle, and distal one-third of the leg reconstructions. Pedicled MSAP flap is an alternative flap for knee and proximal two-thirds of leg defects, covering classical lower limb reconstruction territories of soleus, medial, and lateral gastrocnemius muscle flap. Computed tomography angiography, indocyanine green, and endoscopic-assist dissection enhances MSAP flap surgical planning and reduces its technical adversities and complications.

Unraveling the Crucial Roles of FoxP3+ Regulatory T Cells in Vascularized Composite Allograft Tolerance Induction and Maintenance.

BACKGROUND: The role of regulatory T cells (Treg) in tolerance induction of vascularized composite allotransplantation (VCA) remains unclear. This study was designed to examine characteristics of Treg after VCA and their capacity to rescue allografts from rejection. METHODS: Osteomyocutaneous allografts were transplanted from Balb/c to C57BL/6 mice. All mice received costimulatory blockade and a short course of rapamycin. To elucidate the role of Treg for tolerance induction, Treg depletion was performed at postoperative day (POD) 0, 30, or 90. To assess capacity of Treg to rescue allografts from rejection, an injection of 2 × 106 Treg isolated from tolerant mice was applied. RESULTS: Eighty percent of VCA recipient mice using costimulatory blockade and rapamycin regimen developed tolerance. The tolerant recipients had a higher ratio of circulating Treg to effector T cells and elevated interleukin-10 at POD 30. A significantly higher rejection rate was observed when Treg were depleted at POD 30. But Treg depletion at POD 90 had no effect on tolerance. Treg from tolerant recipients showed stronger suppressive potential and the ability to rescue allografts from rejection. Furthermore, transplanted Treg-containing skin grafts from tolerant mice delayed rejection elicited by adoptively transferred effector T cells to Rag2-/- mice. CONCLUSIONS: Circulating Treg are crucial for inducing VCA tolerance in the early posttransplant phase, and allograft-residing Treg may maintain tolerance. Treg may, therefore, serve as a potential cellular therapeutic to improve VCA outcomes.

Necrotizing fasciitis of the entire head and neck: Literature review and case report.

Necrotizing fasciitis (NF) is uncommon but potentially lethal when it is associated with systemic disorders. We report a case of odontogenic NF in a patient with uncontrolled diabetes mellitus. The patient was referred on day 10 since the onset of odontogenic NF. Protective tracheostomy, local facial-cervical fasciotomy were conducted and broadspectrum antibiotics were given, subsequent serial surgical drainage and debridement were performed in theater. Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumonia were isolated. Five staged debridements were performed to the targeted anatomic regions thus reducing surgical time and blood loss. The patient survived the acute infection and received subsequent reconstruction. Cervical NF with descending mediastinitis and periorbital NF is associated with high mortality rates. This is the only known report of an adult who survived NF affecting entire scalp, periorbital, cervical, and thoracic region. Early diagnosis and staged surgical planning minimize morbidity and mortality from NF.

Synchronous reconstruction of esophageal defect and voice with J-flap after laryngopharyngectomy: Indications and outcomes.

BACKGROUND: The primary reconstruction goal for patients with laryngopharyngectomy is the restoration of esophagus, whereas voice reconstruction is less readily reconstructed. J-flap is a novel surgical technique designed to reconstruct voice and esophagus synchronously, permitting functional rehabilitation of aerodigestive tract after laryngopharyngectomy. OBJECTIVES: This study aims to present indications, surgical steps, and outcomes of an innovative technique for synchronous reconstruction of the esophagus and voice tube with a free thigh flap (J-flaps). METHOD: Single-center study from 2011 to 2017 recruiting patients with hypopharyngeal cancer needing laryngopharyngectomy and J-flaps reconstruction. Patient details were analyzed, and surgical outcomes were examined. RESULTS: 20 patients were recruited with an average age of 61. Tumor staging was IIB or above. The average follow-up period was 15 months. 65% of these patients resumed a full diet. The row phonation rate was 75%. The average maximum phonation time was 8.9 s, and the average number of counting in a breath was 14. CONCLUSIONS: Most patients achieved a conversational level of speech capacity with a humanoid voice. J-flap can be utilized safely, supporting the social re-integration of these patients with their new voice.