The National Center for Child Health and Development (NCCHD) , Tokyo, Japan, aims to promote medical care and research related to diseases occurring throughout the life cycle, from fetal development through adolescence to adulthood. The NCCHD performs surgeries for congenital differences, brachial plexus birth palsy, and malformations. It has become one of the world’s leading institutions in this field, based on the volume of cases it manages. Building on this background and philosophy, we have established a system to accept students wanting to undertake overseas clinical studies in the field of pediatric hand surgery and microsurgery. Our goal is to adopt a global perspective, recognize diverse values, and introduce innovative approaches to medicine. Our international students engage in outpatient clinics, surgeries, and conferences; gain valuable insights from academic papers; and prepare for presentations at international forums. We are continuously striving to enhance our training system to ensure that these students have a meaningful experience during their time studying in Japan. In this presentation, I would like to discuss the status of clinical study abroad and international exchange programs within our department, highlighting their significance.

　We investigated arterial and venous reconstruction for finger avulsion amputations in Tamai zonesⅢandⅣ, excluding the thumb. The study focused on the number of arteries and veins reconstructed and the necessity of vein grafts. We successfully replanted 22 fingers in 19 patients, comprising 16 males and three females, with a mean age of 50.1 years (range: 1-73 years) . The cases included seven complete amputations and 15 incomplete amputations. For revascularization of complete amputations, we performed A1V1 (four fingers) , A2V1 (two fingers) , and A1V2 (one finger) . We used vein grafts to arteries in three of seven complete amputations. For revascularization of incomplete amputations, we performed A1V1 (12 fingers) , A2V1 (two fingers) , and A1V2 (one finger) . Vein grafts to arteries were required in 9 of 15 incomplete amputations, and vein grafts to veins in 8 of 15 fingers. Our findings suggest that for successful replantation, a single artery and a single vein are sufficient for reconstruction. Vein grafts should be performed to obtain a high success rate if there is even a slight intimal injury to the arteries.

　We treated four cases of severe hand and forearm trauma using a free medial femoral condyle flap, utilizing the cutaneous and osteoarticular branches of the descending genicular artery. Two cases were open hand fractures with infected pseudarthrosis or soft tissue and bone defects, and two cases were open forearm fractures with soft tissue and bone defects. Two patients were treated with osteocutaneous flaps, and two patients with osteoadipofascial flaps. The bone defects ranged in size from 2×0.5 cm to 3×2 cm, and the dimensions of the elevated skin valves varied from 2×1 cm to 9×6 cm. In all cases, bone union was achieved within 6 months postoperatively. However, one case exhibited necrosis of the peripheral margins of the cutaneous flap extending 2 cm wide. No complications were observed in the other cases.　
　The medial femoral condylar flap, utilizing the cutaneous and osteoarticular branch of the descending genicular artery, was beneficial in managing bone and soft tissue defects of the hand and forearm, primarily due to its ease of elevation.

　After undergoing breast cancer treatments, including radiotherapy, patients often experience breast lymphedema. Despite conservative treatments, failures can occur. Herein, we present a case of breast lymphedema successfully managed using a pedicled thoracodorsal artery perforator flap that included axial pattern lymphatic flow. Preoperatively, we performed ICG fluorescence lymphography to evaluate the lymph flow in the recipient region and to determine flap design. The subcutaneous scar of the lymph node dissection was released and the area of stagnant lymphatic flow from the breast to the axilla was bridged by a flap to reconstruct the lymphatic flow. The flap was positioned to facilitate antegrade induction of lymphatic flow to the subscapular region. Postoperatively, both breast edema and the contour of the axillary area were improved. To our knowledge, this is the first report detailing the surgical treatment of breast lymphedema using a flap that includes axial pattern lymphatic flow. Inducing lymphatic flow through a flap with axial lymphatic flow may be a useful approach for managing breast lymphedema.

　Postoperative empyema associated with a bronchopleural fistula often becomes chronic and intractable, requiring a two-step management approach consisting of initial infection control by open-window thoracostomy, followed by obliteration of the thoracic cavity using tissue transfer techniques. Several studies have reported the use of free myocutaneous flap transfer for treating empyema; however, there are limited reports on free perforator flap transfer to the upper thoracic cavity using the internal mammary vessels as the recipient. We present a case of a 76-year-old man with lung cancer who underwent a right upper lobectomy, but postoperatively developed pulmonary apex empyema and underwent thoracostomy. The vessels perfusing the adjacent muscles had already been transected during the first and subsequent operations. Therefore, we performed free anterolateral thigh flap transfer using the internal mammary vessels as the recipient, successfully treating the empyema. While local pedicled flaps, such as the pectoralis major myocutaneous or latissimus dorsi flaps, are typically the first options for upper thoracic reconstruction, in complex cases following multiple thoracotomies or thoracostomies, where the vessels perfusing the adjacent muscles have been transected or sacrificed and are no longer viable, free tissue transfer is a viable option. Free anterolateral thigh flap transfer is a useful option in such cases.

　Reconstruction of dorsal foot soft tissue defects requires both aesthetic recovery and effective wound coverage. Herein, we report a case of a dorsal foot soft tissue defect reconstructed using a thin groin flap in combination with an extracorporeal flap.　
　A 16-year-old female was referred to our hospital with a trauma-induced left dorsal foot soft tissue defect. The injury resulted in the loss of the extensor tendon and skin and exposure of the fourth metatarsal bone. The patient underwent reconstruction surgery on the 23rd day post-injury. The anterior tibial artery and collateral vein were exposed away from the wound. A thin groin flap was elevated and prepared for transfer. The iliotibial tract, dissected from the flap donor site, was transferred to the extensor defect. The distal end of the flap was secured to the defect, and the proximal end was overlaid with healthy skin. The pedicle was anastomosed end-to-end to the anterior tibial artery and vein. Three weeks post-surgery, the pedicle was cut, the flap was shaped to fit the wound, and the anterior tibial artery and collateral vein were reanastomosed. One year following the final surgery, the patient was satisfied with the aesthetic and functional outcomes of the procedure. Through this approach, we achieved successful aesthetic recovery in the reconstruction of the dorsal foot.

　We report two cases that underwent reconstruction using a free anterolateral thigh flap combined with fascia lata and iliotibial ligament for the treatment of infected extensive Achilles tendon defects. Both cases had previously undergone multiple debridements for reconstructed Achilles tendon infections following the Lindholm procedure. As a result, they had Achilles tendon defects measuring 13 cm and 13.5 cm in length for Case 1 and Case 2, respectively. Subsequent reconstruction of the Achilles tendon and soft tissue defects was performed using a free anterolateral thigh flap incorporating the fascia lata and iliotibial ligament. Case 1 achieved normal gait (10^o of dorsiflexion and 35^o of plantar flexion) . The patient was able to stand on both tiptoes 18 months postoperatively. Case 2 achieved normal gait (15^o of dorsiflexion and 30^o of plantar flexion) . The patient could jog and stand on tiptoe on the affected side 12 months postoperatively. Free anterolateral thigh flap combined with the fascia lata and iliotibial ligament is a useful option for the reconstruction of infected extensive Achilles tendon defects.

　Treatment strategies for open fractures are being established; however, reconstruction of open fractures with extensive soft tissue defects remains challenging. Herein, we report a case of an open fracture of the lower leg with extensive soft tissue defects successfully reconstructed using a combined flap. A 65-year-old man sustained an open fracture of his right lower leg with a large soft tissue defect following a motorcycle accident. Following debridement, a skin defect extended from the proximal 1/4 of the lower leg to the heel, requiring a flap coverage of approximately 42 cm in length. After osteosynthesis, the extensive soft tissue defect was reconstructed using a combined latissimus dorsi and intercostal artery perforator free flap on the eighth day post-injury. Several intercostal artery perforators, identified using preoperative ultrasonography, were secured during flap harvest, and an appropriate perforator was supercharged. Nine months post-injury, the flap has survived, and the patient is ambulatory. The combined flap was effective for reconstruction of open fractures with extensive skin defects that could not be adequately covered by a single flap.

　I completed a one-year clinical fellowship as a clinical nerve fellow at the Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital (CGMH) , Linkou branch in Taiwan, from July 2022 to June 2023. During this fellowship, my primary focus was on comprehensive reconstructive microsurgery and the reconstruction of brachial plexus injuries. A unique feature of CGMH is its clinical fellowship program, which allows fellows to actively participate in surgeries. Engaging in clinical and experimental work in a foreign country with a different culture, environment, and language proved to be an invaluable and irreplaceable life experience. In the current landscape, opportunities for clinical fellowships are becoming scarce, with many individuals opting for research fellowships instead. However, if the opportunity arises, I strongly advocate for pursuing overseas clinical fellowships in facilities where hands-on clinical work is possible, as it offers a broader and more enriching experience.