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Introduction Autologous nerve grafts are the gold standard in peripheral nerve surgery. However, they involve donor site morbidities such as loss of sensation and painful neuromas due to the sacrifice of healthy nerves. Artificial nerve conduits have been developed around the world that consist solely of a scaffold, without cells, regenerative factors, or blood circulation. In artificial nerve conduits, efficient nerve regeneration has not yet been achieved. Therefore, we focused on bio-3D printer technology, which can construct three-dimensional tissues only with cells, and developed a three-dimensional nerve conduit (Bio 3D nerve conduit) with fibroblasts. The purpose of this study is to confirm nerve regeneration in the rat and canine peripheral nerve gap models and to start an investigator-initiated clinical trial for the treatment of a traumatic peripheral nerve defect in the hand. Methods In the rat nerve defect model, a 5-mm nerve defect was created at the right mid-thigh level of the sciatic nerve in immunodeficient rats, and the nerve gap was bridged using 8-mm Bio 3D nerve conduits fabricated from human fibroblasts. In the canine nerve defect model, dermal fibroblasts were isolated and cultured from canine inguinal-region skin to fabricate a Bio 3D nerve conduit with a 5-mm diameter for 8 weeks. A 5-mm nerve defect was created at the ulnar nerve in the forelimb, and the nerve gap was bridged using 8-mm Bio 3D nerve conduits. Results In the rat model, the nerve gaps were bridged successfully in all rats and significantly better nerve regenerations than the control group were confirmed kinematically, electrophysiologically, histologically, and morphologically. In the canine model, the ulnar nerves were successfully bridged using Bio 3D nerve conduits in all canines. The pinprick test indicated functional nerve recovery and the compound muscle action potentials of the hypothenar muscles were detected. Histological evaluation showed numerous well-myelinated axons in the Bio 3D nerve conduit group. No adverse events were observed. Discussion & Conclusions We obtained good nerve regeneration results from the rat model and non-clinical proof of concept using the canine model. Based on these results, an investigator-initiated clinical trial was performed to examine the safety and efficacy of Bio 3D nerve conduit transplantation for peripheral nerve injury. Bio 3D nerve conduit is prepared from the groin skin for 8 weeks and then transplanted to a traumatic peripheral nerve defect in the hand.

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Digital replantation has long stood as a cornerstone of reconstructive microsurgery, teaching surgeons the principles of microvascular anastomosis, nerve repair, tendon reconstruction, and multidisciplinary care. In advanced countries such as Korea, Japan, and Taiwan, this operation shaped generations of microsurgeons and fueled innovations ranging from toe transfers to free flaps. Yet today, the legacy of digital replantation is under threat. Declining industrial accidents, shrinking populations, and the high-cost, competitive medical environment have drastically reduced case volume. For the younger generation, opportunities to perform replantations are increasingly rare, and the demanding lifestyle of emergency microsurgery discourages trainees from pursuing this path. If left unaddressed, we risk losing not only a procedure but also a vital training ground that embodies the very spirit of microsurgery. In this lecture, I will reflect on the surgical heritage of digital replantation in East Asia, outlining its historical role in shaping our discipline and analyzing the socio-economic forces driving its decline today. I will also explore strategies to preserve this essential skill for the next generation, including regionalization of services, simulation-based training, and renewed investment in mentorship. Finally, I will share a dramatic case of total degloving amputation managed with an unconventional reconstructive pathway. This unusual recovery is presented not as a triumph, but as a question to the audience: if such extreme cases become rarer and the expertise dwindles, who will be there to attempt them in the future?

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Across different clinical settings, a variety of methods have been developed for digit and limb repair and reconstruction, yet true regeneration remains every plastic surgeon’s ultimate dream. Despite continuous advances in microsurgical salvage, many digits and limbs are still beyond replantation. In this presentation, we will review the spectrum of structural and functional salvage strategies currently used in clinical practice, from managing small distal fingertip injuries to reconstructing complex multisegmental amputations. We also explore how developmental biology and tissue-engineering breakthroughs are reshaping our understanding of human digit and limb regeneration. Drawing insights from nature’s masters of regeneration, such as salamanders, lizards, and mice, we will discuss how their regenerative processes may guide the design of future limb-building technologies. Although today’s approaches are increasingly sophisticated, many scientific and clinical challenges remain before true human limb regeneration becomes a reality. Limited experience of neurotization of major limb replantation will also be presented. We hope this review helps bridge the critical gap between bench and bedside, inspiring new collaborations and innovations that will one day make limb regeneration not just a wish, but a clinical possibility.

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The history of brachial plexus injury (BPI) reconstruction has evolved over the three centuries (19th-21st) and has had a dramatic changes from pessimism to optimism. The author has spent near 40 years (since 1985) in the brachial plexus patient’s evaluation and surgical treatment, recognizing that there are still filled with biases and debates, not only in terminology but also in surgical treatment. Although “Once debates, always debates”, the author listed 8 items of “Terminology changes” and 8 items of “Surgical treatment changes” in the presentation, trying to make such confusion or debates into universal acceptance in clinical application. The ”Terminology Changes” includes (1) postganglionic spinal nerve, not postganglionic root; (2) using number to level of BPI, not with words; (3) Sunderland 3˚ degree of peripheral nerve injury is one of neurotmesis (endoneurium disruption), not axonotmesis; (4) Level I BPI has 6 degrees (Yeow’s classification) of root injury, in P1-P2 root injury the stump is still available, but in P4-5 root injury the stump is unavailable; (5) brachial plexus birth injury, not obstetric brachial plexus palsy; (6) nerve transfer, not neurotization; (7) types of nerve transfer (Chuang’s classification); and (8) functioning free muscle transplantation, not functional muscle transfer’. The ”Surgical Treatment Changes” includes (1) exploration of brachial plexus should be generous (wide exploration), but manipulation of nerve should be gentle; (2) interfascicular repair is not good for direct nerve repair, but may be good for indirect nerve grafts; (3) tension-less suture is different from tension-free suture; (4) neuroma management: resection or neurolysis; (5) for total root avulsion of BPI, multiple nerve transfers vs. functioning free muscle transplantation, which is first in priority; (6) for incomplete root avulsion, proximal nerve graft/nerve transfer vs. distal nerve transfer, which is first in priority; (7) in gracilis musculocutaneous flap the skin flap is based on septocutaneous perforator, not on musculocutaneous perforator; and (8) deltoid muscle functional recovery should have the precondition of deltoid muscle contraction visible. Hope the presentation can energize your interest in BPI recognition and treatment.

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