Ryo KarakawaMD, PhD, FACS

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AI-generated image of a single dolphin moving toward the ocean surface, symbolizing research, collaboration, and surgical innovation

Academic / Global

Across borders.
Beyond today.

I work to extend the reach of reconstructive surgery through international education and collaboration.

In parallel, I develop less invasive techniques and devices aimed at reducing complications—and at making complex reconstruction safer, more reproducible, and more accessible.

Research Focus

Three lines of work

AI-edited side-view intraoperative photograph showing the thin profile of a PSP flap

01

Advance Reconstructive Techniques

Developing and extending less invasive reconstructive techniques to meet specific clinical needs—from thin perforator flaps and functional reconstruction to lymphatic preservation and repair.

SCIP flap / SAX flap / Lymphatic-preserving PAP flap / Scapular and parascapular flaps / Tendon transfer / Immediate lymphatic reconstruction / LVA after sarcoma resection

AI-edited ultrasound imaging system displaying a superficial ultra-high-frequency ultrasound image

02

Make Surgery Predictable

Combining precise preoperative planning, intraoperative imaging, and refined techniques to make complex surgery safer, more reproducible, and easier to teach.

Ultra-high-frequency ultrasound / ICG angiography / Suture-stent technique / Operative video education

AI-edited photograph of a robot-assisted ultrasound research prototype

03

Develop Medical Technologies

Developing practical devices and systems in response to unmet needs in patient care, surgical planning, and microsurgical education.

Lymphedema body suit / Microsurgical training systems / Robot-assisted ultrasound

Global Surgery

Invited surgery and teaching

2026

Bilateral DIEP flap breast reconstruction — Masaryk University, Brno, Czech Republic

2025

RPNI for sciatic nerve neuroma after MPNST resection — University of Michigan / Cancer Institute Hospital RPNI workshop, Tokyo

2025

LYMPHA (immediate LVA after axillary dissection) and UHF ultrasound planning demonstration — Aster Hospital, Bengaluru, India

2023

SCIP-PSP flap for post-burn hand contracture — Ramathibodi Hospital, Bangkok, Thailand

2023

SCIP flap for head and neck reconstruction — Rajiv Gandhi Cancer Institute, Delhi, India

2023

Fibula osteocutaneous flap for mandibular reconstruction — University of Peradeniya, Kandy, Sri Lanka

2020

LVA for upper limb lymphedema — Ganga Hospital, Coimbatore, India

Recent invited lectures

2026

Superficial abdominal axial pattern flap ／ Reconstructive strategy based on defect location ／ Scapular flap for sarcoma reconstruction — 17th EFSM Congress, Prague

2026

Re-defining the SCIP flap and introducing the "SAX flap": a 120-case series with UHF ultrasound ／ Bony reconstruction for sarcoma — 11th Turkish Society of Reconstructive Microsurgery, Dalaman

2025

L-shaped scapular and parascapular flap ／ Muscle preservation of the donor site (instructional course) — 13th WSRM, Barcelona

2025

PAP flap for breast reconstruction ／ LVA for upper limb lymphedema — BRASCON, Bengaluru

2024

Imaging application for flap surgery — 15th European Plastic Surgery Research Council, Brno

2024

SCIP-PSP flap for hand sarcoma ／ Impact of technological advancements on sarcoma reconstruction — KSRM, Korea

2023

Advances in sarcoma reconstruction ／ High-precision reconstructive surgery with advanced visualization — 12th WSRM, Singapore

Invited lecture, PRS Korea 2023
PRS Korea 2023

Publications

Peer-reviewed articles

43 peer-reviewed original articles as first or corresponding author, and 40 as co-author, in Plastic and Reconstructive Surgery, Microsurgery, JPRAS, Journal of Reconstructive Microsurgery, Journal of Surgical Oncology, and others.

Selected

  1. Outcome of secondary LVA for lymphedema and lymphorrhea following sarcoma resection. JPRAS. 2026. doi:10.1016/j.bjps.2026.07.037.
  2. Development and validation of a novel lymphedema monitoring system using a bodysuit and a smartphone: prospective comparative study. JMIR Mhealth Uhealth. 2026;14:e77935.
  3. Impact of technological advancements on short-term outcomes in flap reconstruction after soft tissue sarcoma resection: a retrospective comparative analysis. J Reconstr Microsurg. 2024.
  4. Ultra-high-frequency ultrasound mapping of the superficial circumflex iliac and superficial inferior epigastric vessels: an anatomical study. Diagnostics (Basel). 2025;15(10):1210.
  5. Association between body mass index and outcomes after autologous breast reconstruction: a nationwide inpatient database study in Japan. Breast Cancer Res Treat. 2024;204(1):69-78.
  6. Comparison of short-term outcomes between pedicled- and free-flap autologous breast reconstruction: a nationwide inpatient database study in Japan. Breast Cancer. 2022.
  7. L-shaped scapular and parascapular combined flap for reconstruction of a large surface defect after sarcoma resection using ICG angiography: a case series of 6 patients. Microsurgery. 2024;44(8):e31259.
  8. Supermicrosurgical suture-stent technique for a lymphaticovenular bypass. J Clin Med. 2021;10(12):2595.
  9. An anatomical study of the lymph-collecting vessels of the medial thigh and clinical applications of the lymphatic-vessel-preserving profunda femoris artery perforator (LpPAP) flap. JPRAS. 2020;73(9):1768-1774.
  10. Use of the superficial circumflex iliac artery perforator flap for reconstruction after sarcoma resection. J Surg Oncol. 2021;123(4):1067-1080.
  11. Super-microsurgical training using chick embryos within the "Egg-in-Cube" system. Plast Reconstr Surg. 2023.
  12. An anatomical study of posterior trunk recipient vessels, and comparisons of outcome following pedicled- and free-flap transfers for sarcoma of the posterior trunk. J Reconstr Microsurg. 2022.
  13. High-pressure injection of heparinized saline for reversing refractory intraoperative phenylephrine-induced venous vasospasm. Plast Reconstr Surg. 2019;143(2):448e-449e.
FULL LIST — first / corresponding author (43)
  1. Outcome of secondary LVA for lymphedema and lymphorrhea following sarcoma resection. JPRAS. 2026. doi:10.1016/j.bjps.2026.07.037.
  2. Development and validation of a novel lymphedema monitoring system using a bodysuit and a smartphone: prospective comparative study. JMIR Mhealth Uhealth. 2026;14:e77935.
  3. Intraoperative evidence of early neovascularization in a SCIP flap following postoperative trauma. Microsurgery. 2025;45(6):e70121.
  4. Assessment of aesthetic outcomes in autologous breast reconstruction using the profunda femoris artery perforator flap. Microsurgery. 2025;45(5):e70085.
  5. Ultra-high-frequency ultrasound mapping of the superficial circumflex iliac and superficial inferior epigastric vessels: an anatomical study. Diagnostics (Basel). 2025;15(10):1210.
  6. Impact of technological advancements on short-term outcomes in flap reconstruction after soft tissue sarcoma resection. J Reconstr Microsurg. 2024.
  7. L-shaped scapular and parascapular combined flap for reconstruction of a large surface defect after sarcoma resection using ICG angiography. Microsurgery. 2024;44(8):e31259.
  8. Breast reconstruction using a superficial inferior epigastric artery flap with pedicle elongation via an arteriovenous loop. Microsurgery. 2024;44(4):e31183.
  9. Association between body mass index and outcomes after autologous breast reconstruction: a nationwide inpatient database study in Japan. Breast Cancer Res Treat. 2024;204(1):69-78.
  10. Cannulation indocyanine green method for strategic management of postoperative arterial thrombosis after free jejunal flap transfer. Plast Reconstr Surg Glob Open. 2023;11(12):e5463.
  11. Postoperative hematoma-induced vasospasm after sarcoma reconstruction using a pedicled ALT flap. Plast Reconstr Surg Glob Open. 2023;11(9):e5271.
  12. Multiple flap transfer for multiple local recurrence of soft tissue sarcoma. Medicina (Kaunas). 2023;59(8):1489.
  13. Bilateral transposition flap for postoperative anal stenosis after reconstruction for Paget disease. Plast Reconstr Surg Glob Open. 2023;11(8):e5142.
  14. Comparison of outcomes following pedicled and free flap transfers for shoulder soft tissue sarcoma. JPRAS. 2023;83:373-379.
  15. Super-microsurgical training using chick embryos within the "Egg-in-Cube" system. Plast Reconstr Surg. 2023.
  16. Donor-site chyle leakage after breast reconstruction using a DIEP flap. Plast Reconstr Surg Glob Open. 2022;10(10):e4612.
  17. Comparison of short-term outcomes between pedicled- and free-flap autologous breast reconstruction: a nationwide inpatient database study in Japan. Breast Cancer. 2022.
  18. An anatomical study of posterior trunk recipient vessels, and comparisons of outcome following pedicled- and free-flap transfers for sarcoma of the posterior trunk. J Reconstr Microsurg. 2022.
  19. Immediate tendon transfer for functional reconstruction of a dorsal forearm defect after sarcoma resection. J Plast Surg Hand Surg. 2022.
  20. Coronoidectomy, condylectomy and free vascularized fibula osteomusculocutaneous flap transfer for severe trismus after maxillectomy. Microsurgery. 2022;42(2):187-191.
  21. Use of ultra-high-frequency ultrasound for aplasia cutis congenita of the scalp. Plast Reconstr Surg Glob Open. 2021;9(10):e3876.
  22. Use of wearable smart glasses for intraoperative ICG lymphography in lymphatic surgery. Microsurgery. 2021;41(7):697-698.
  23. Supermicrosurgical suture-stent technique for a lymphaticovenular bypass. J Clin Med. 2021;10(12):2595.
  24. Application of intraoperative ICG angiography for detecting flap congestion in free DIEP flaps for breast reconstruction. Microsurgery. 2021;41(6):522-526.
  25. Use of the superficial circumflex iliac artery perforator flap for reconstruction after sarcoma resection. J Surg Oncol. 2021;123(4):1067-1080.
  26. Use of the profunda femoris artery perforator flap for reconstruction after sarcoma resection. Plast Reconstr Surg Glob Open. 2020;8(12):e3289.
  27. An anatomical study of the lymph-collecting vessels of the medial thigh and clinical applications of the LpPAP flap. JPRAS. 2020;73(9):1768-1774.
  28. Computer-aided design and syringe-aided manufacturing for mandibular reconstruction using a vascularized fibula flap. Plast Reconstr Surg Glob Open. 2020;8(5):e2819.
  29. Triple-lobe combined latissimus dorsi and scapular flap for reconstruction of a large defect after sarcoma resection. Microsurgery. 2020.
  30. The reconstruction after a giant phyllodes tumor resection using a DIEP flap. Plast Reconstr Surg Glob Open. 2020;8(4):e2760.
  31. Use of wearable smart glasses for indocyanine green angiography in flap surgery. Microsurgery. 2020;40(2):276-277.
  32. The correlation of the perforators and the accessory saphenous vein in a profunda femoris artery perforator flap for additional venous anastomosis: a cadaveric study and clinical application. Microsurgery. 2020;40(2):200-206.
  33. Successful balanced gait after reconstruction of the weight-bearing mid-plantar region using a free contralateral medial plantar flap. Plast Reconstr Surg Glob Open. 2019;7(9):e2456.
  34. Functional and aesthetic reconstruction for microtia using SCIP superthin flap transfer and skin grafting. Plast Reconstr Surg Glob Open. 2019;7(7):e2312.
  35. Mechanical versus hand-sewn venous anastomoses in free flap reconstruction: a systematic review and meta-analysis. Plast Reconstr Surg. 2019;143(2):441e-442e.
  36. High-pressure injection of heparinized saline for reversing refractory intraoperative phenylephrine-induced venous vasospasm. Plast Reconstr Surg. 2019;143(2):448e-449e.
  37. Microsurgery training using Apple iPad Pro. Microsurgery. 2018;38(8):926-927.
  38. Use of laser speckle contrast imaging for successful fingertip replantation. Plast Reconstr Surg Glob Open. 2018;6(9):e1924.
  39. Ratio of blood glucose level change measurement for flap monitoring. Plast Reconstr Surg Glob Open. 2018;6(7):e1851.
  40. The excised super-thin skin as a flap sizer for finger and hand free mini-flap reconstruction. Plast Reconstr Surg Glob Open. 2018;6(4):e1767.
  41. Light-emitting diode transilluminator for identification of recipient veins in finger reconstruction. Plast Reconstr Surg Glob Open. 2018;6(1):e1577.
  42. A new method for microsurgery training using a smartphone and a laptop computer. Microsurgery. 2018;38(1):124-125.
  43. Free anterolateral thigh full-thickness skin flap with vascularized lateral femoral cutaneous nerve for reconstruction of the facial nerve and external auditory canal after resection of facial nerve schwannoma. SAGE Open Med Case Rep. 2017;5.
FULL LIST — co-author (40)
  1. The Role of the Medial Vastus Branch of the Descending Genicular Artery as a Recipient for Free Flap Transfer: Anatomical Study and Clinical Application. Journal of Reconstructive Microsurgery. 2026.
  2. Redefining salvage in free flap breast reconstruction: Long-term breast volume symmetry after re-exploration. Journal of Plastic, Reconstructive & Aesthetic Surgery. 2026.
  3. Umbilical Necrosis Following Bilateral Deep Inferior Epigastric Artery Perforator Flap Breast Reconstruction with Concomitant Risk-reducing Salpingo-oophorectomy in Hereditary Breast and Ovarian Cancer: A Case Report. Journal of Plastic and Reconstructive Surgery. 2026.
  4. The role of lymphatic system transfer (LYST) for treatment of lymphedema: A long-term outcome study of SCIP flap incorporating the lymph nodes and the afferent lymphatic vessels. Journal of Plastic, Reconstructive & Aesthetic Surgery. 2025.
  5. Lymphaticovenular Anastomosis as a Treatment for Neurogenic Bladder in Patients With Lower Extremity Lymphedema After Gynecologic Cancer Treatment. Journal of Surgical Oncology. 2024.
  6. Using Descending Genicular Artery as the Recipient Artery for Free Superficial Circumflex Iliac Artery Perforator Flap. Plastic and Reconstructive Surgery Global Open. 2024.
  7. Indocyanine Green Lymphography-guided Lymphatic Vessel Suture Ligation for Superficial Abdominal Flap Donor Site for Breast Reconstruction. Plastic and Reconstructive Surgery Global Open. 2024.
  8. The Piggyback Superficial Circumflex Iliac Perforator Flap for Complex Free Flap Reconstructions. Plastic and Reconstructive Surgery Global Open. 2024.
  9. Ultrastructural changes of vascular smooth muscle cells and resistance to vasospasm treatment in femoral arteries of an arteriosclerotic rat model. Medical Molecular Morphology. 2024.
  10. Tube-in-Tube Phalloplasty with Tailor-made Bilateral Superficial Circumflex Iliac Artery Perforator Flaps Using Preoperative High-resolution Ultrasound. Plastic and Reconstructive Surgery Global Open. 2023.
  11. The Pedicled Anterolateral Thigh Flap for Donor Site Closure after a Large Superficial Circumflex Iliac Artery Perforator Flap Harvest. Plastic and Reconstructive Surgery Global Open. 2023.
  12. The Use of the Deep Brachial Artery as the Recipient Artery for Free Perforator Flap Transfer: An Anatomic Study and Clinical Applications. Medicina. 2023.
  13. Use of intraoperative indocyanine green angiography for detection and prediction of congestion in pedicled island flaps. Microsurgery. 2023.
  14. Use of the Head-mounted 4K Camera for Recording the Procedure of a Flap Surgery. Plastic and Reconstructive Surgery Global Open. 2023.
  15. Comparing seroma formation rate after harvest of the deep inferior epigastric artery perforator flap and the superficial abdominal perforator flaps in autologous breast reconstruction: A propensity-matched analysis. Microsurgery. 2023.
  16. Deep Fat Saving Elevation of the Superficial Circumflex Iliac Artery Perforator Flap. Medicina. 2022.
  17. Lymph-Venous Anastomosis for Breast Cancer-Related Lymphoedema after Docetaxel-Based Chemotherapy. Journal of Clinical Medicine. 2022.
  18. Filling the Upper Pole with the Pectoralis Major Muscle Flap in Profunda Femoris Artery Perforator Flap Breast Reconstruction. Medicina. 2022.
  19. Simultaneous Lymphatic Superficial Circumflex Iliac Artery Perforator Flap Transfer from the Zone 4 Region in Autologous Breast Reconstruction Using the Deep Inferior Epigastric Artery Perforator Flap: A Proof-of-Concept Study. Journal of Clinical Medicine. 2022.
  20. Multi-pedicled long fasciocutaneous free flaps in complex lower extremity reconstruction. Journal of Plastic, Reconstructive & Aesthetic Surgery. 2021.
  21. Superficial Circumflex Iliac Artery Perforator Flap Elevation Using Preoperative High-Resolution Ultrasonography for Vessel Mapping and Flap Design. Journal of Reconstructive Microsurgery. 2021.
  22. Breast Shape Evaluation After Free Flap Breast Reconstruction After More Than 10 Years Follow-up Using 3-Dimensional Imaging Device. Annals of Plastic Surgery. 2021.
  23. Pedicled anterolateral thigh flap transfer for the reconstruction of a large gluteal defect assisted by preoperative computed tomographic angiography and intraoperative indocyanine green angiography: A case report. Microsurgery. 2021.
  24. Novel Classification of the Branching Patterns of the Superficial Branch and the Deep Branch of the Superficial Circumflex Iliac Artery and the Superficial Inferior Epigastric Artery on Computed Tomographic Angiography. Journal of Reconstructive Microsurgery. 2021.
  25. Use of a combined SIEA and SCIP based double pedicled abdominal flap for breast reconstruction. Microsurgery. 2021.
  26. Ideal esthetic and functional full-thickness lower eyelid “like with like” reconstruction using a combined Hughes flap and swing skin flap technique. Journal of Plastic, Reconstructive & Aesthetic Surgery. 2021.
  27. Use of Preoperative High-Resolution Ultrasound System to Facilitate Elevation of the Superficial Circumflex Iliac Artery Perforator Flap. Journal of Reconstructive Microsurgery. 2021.
  28. Donor site morbidity of postauricular free flaps and full thickness skin grafts. Journal of Plastic, Reconstructive & Aesthetic Surgery. 2021.
  29. Posterior auricular artery free flap reconstruction of the retroauricular sulcus in microtia repair. Journal of Plastic, Reconstructive & Aesthetic Surgery. 2020.
  30. Breast reconstruction support system that derives the shape difference between the healthy breast and the reconstructed breast. Journal of Japan Society of Computer Aided Surgery. 2020.
  31. The Feasibility of Harvesting an Innervated Profunda Artery Perforator Flap for Breast Reconstruction. Plastic and Reconstructive Surgery Global Open. 2020.
  32. An Idea of Hemi-abdominal Free Flap for Breast Reconstruction: A Case Report. Plastic and Reconstructive Surgery Global Open. 2020.
  33. Combining the superficial circumflex iliac artery perforator flap with the superficial inferior epigastric artery flap or the deep inferior epigastric artery perforator flap for coverage of large soft tissue defects in the extremities and the trunk. Microsurgery. 2020.
  34. Lymphatic System Transfer for Lymphedema Treatment: Transferring the Lymph Nodes with Their Lymphatic Vessels. Plastic and Reconstructive Surgery Global Open. 2020.
  35. Additional venous anastomosis in free profunda artery perforator flap transfer using the posterior accessory saphenous vein. Journal of Plastic, Reconstructive & Aesthetic Surgery. 2019.
  36. Use of the transverse branch of the superficial circumflex iliac artery as a landmark facilitating identification and dissection of the deep branch of the superficial circumflex iliac artery for free flap pedicle: Anatomical study and clinical applications. Microsurgery. 2019.
  37. Visualization of the “Intradermal Plexus” Using Ultrasonography in the Dermis Flap: A Step beyond Perforator Flaps. Plastic and Reconstructive Surgery Global Open. 2019.
  38. Use of the Distal Facial Artery (Angular Artery) for Supermicrosurgical Midface Reconstruction. Plastic and Reconstructive Surgery Global Open. 2019.
  39. Lateral Crisscross Position for Lymphaticovenular Anastomosis: Comfortable for Both the Patient and the Surgeon. Journal of Reconstructive Microsurgery. 2019.
  40. The external jugular vein anastomosis under the sternocleidomastoid muscle technique for head and neck reconstruction. Plastic and Reconstructive Surgery. 2018.

Full record on researchmap Google Scholar

The lists above present peer-reviewed articles by authorship role. Conference presentations, grants, and the broader professional record are maintained on researchmap; citation metrics are available on Google Scholar.

Surgical Education

Operative video, published openly

Short, edited operative videos focused on the key steps and decisions of each procedure. Surgical knowledge should be shared openly, so useful techniques can travel beyond a single operating room.

Live surgery broadcast, BRASCON 2025, Bengaluru

Live surgery broadcast — immediate lymphatic reconstruction, BRASCON 2025, Bengaluru

SCIP flap

Superficial circumflex iliac artery perforator flap — elevation with preoperative UHF ultrasound mapping.

Rib-sparing IMA dissection

Internal mammary vessel exposure for breast reconstruction without rib resection.

LVA

Lymphaticovenular anastomosis — vessel selection, ICG lymphography, suture-stent technique.

PAP flap

Profunda artery perforator flap for breast and sarcoma reconstruction.

SCIA-based iliac bone flap

Vascularised iliac bone transfer for bony reconstruction.

Fibula flap

Fibula osteocutaneous flap for mandibular and long-bone reconstruction.

SIEA flap

Superficial inferior epigastric artery flap for autologous breast reconstruction.

Research grants

2025

JSPS KAKENHI, Early-Career Scientists (PI)

2023

AMED, Problem-solving projects by start-ups (PI)

2019

JSPS KAKENHI, Early-Career Scientists (PI)

2017

JSPS KAKENHI, Research Activity Start-up (PI)

Book chapters

Fibula osteocutaneous flap — The Colour Atlas of Head and Neck Surgery (2021)
Surgical treatment for lymphedema (2017)

Speaking / Collaboration

Enquiries

Invitations for lectures, instructional courses, live surgery, cadaver workshops, and research collaboration are welcome. Please send a direct message to my academic Instagram account and include the date, venue, audience and topic in your first message.

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