Summary
The medial thigh, rich in lymphatic vessels, presents risks of seroma and lymphoedema after flap elevation. This study discusses a novel approach using indocyanine green (ICG) to preserve lymphatic vessels while harvesting a descending genicular artery perforator (DGAP) flap for knee reconstruction. Here, we present the case of a 44-year-old woman who developed a skin defect below the right knee after cellulitis and abscess debridement. Preoperative ICG lymphography identified the lymphatic pathways, allowing for a meticulous flap design to avoid vessel damage. The surgery resulted in successful flap integration and a full range of knee motion without complications. Follow-up ICG lymphography confirmed the preservation of the lymphatic vessels. This case underscores the importance of lymphatic preservation in medial thigh flap procedures to minimise postoperative complications, such as seroma, cellulitis, and transient lymphoedema. Further research is required to explore the applications of this technique in broader clinical settings.
Keywords: Knee reconstruction, Lymph vessel preservation, Descending genicular artery perforator flap
Introduction
The medial thigh contains abundant collective lymphatic vessels, and flap elevation from the medial thigh may result in seroma and lymphoedema in the donor area. Harvesting the descending genicular artery perforator (DGAP) flap from the medial thigh is one of the most valuable techniques to reconstruct skin defects around the knee. In this article, we report on a case where the medial thigh lymphatic vessels were preserved using indocyanine green (ICG) preoperatively for a skin defect on the anterior knee of the lower leg, and the patient had a good outcome without postoperative complications. As there have been no reports of lymph vessel preservation in DGAP, we share the usefulness of this technique.
Case
Methods: The patient is a 44-year-old woman with no previous medical history. Two months before she visited our department, she suffered from right lower limb cellulitis of unknown origin. Subsequently, she developed an abscess under the skin below the right knee, and debridement was performed in the emergency department of our hospital. After the infection was under control, she was referred to our department.
Physical examination
At the time of the patient's initial visit to our department, the wound was a 13 cm × 6 cm skin defect below the right knee. No prominent bone or nerve exposure was observed, and good granulation of the wound bed was achieved (Figure 1). However, considering the risk of contracture owing to the presence of an ulcer near the joint, the wound was covered with a cutaneous flap.
Figure 1.
Initial picture from our departmentThe wound measures 13 cm × 6 cm and is located below the right knee. The wound bed shows good granulation.
Surgical procedure
ICG was injected between the right lower limb's first and fourth interdigital web spaces before flap design to identify the lymphatic vessel pathway. All lymphatic vessels exhibited a linear pattern and ascended to the inguinal region within 5 min. A 17 cm × 5 cm flap was designed on the medial thigh to avoid damaging the identified collective lymphatic vessels, with the DGAP pre-operatively identified by ultrasound (Figure 2, Supplemental Figure 1). The flap was created along the long axis following previous studies, ensuring it did not extend past the thigh midpoint.
Figure 2.
Preoperative design of the surgeryRed line shows lymphatic vessels confirmed by indocyanine green (ICG) lymphangiography.
The flap was elevated according to the design and dissected beneath the fascia up to the perforator arteries. ICG lymphography was performed after flap elevation to preserve lymphatic vessels (Supplemental Movie 1). ICG was subsequently administered via the vein, and ICG angiography was performed (Supplemental Movie 2). The flap was promptly confirmed to be fully contrasted with ICG and well vascularised, and it was rotated anticlockwise before being sutured to the skin defect (Supplemental Figure 2).
Results
The DGAP flap entirely survived, and the postoperative results showed a good appearance (Figure 3a). The range of motion of the knee joint was 0–130° with no constraints. No postoperative complications, such as lymphoedema, cellulitis, or seroma of the donor area, occurred. ICG lymphography performed postoperatively showed that the lymphatic vessels identified preoperatively were undamaged, showed the same linear pattern, and ascended to the inguinal region within 5 min (Figure 3b, Supplemental Figure 3).
Figure 3.
Postoperative pictures. (a) The postoperative course was aesthetically good, and there were no complications on the patient's limb. (a) Superimposing indocyanine green (ICG) lymphangiography on the patient's limb shows no dermal backflow.
Discussion
Various methods for treating large ulcers are available, including secondary wound healing, skin grafting, and flap placement.1 In the present case, although suitable granulation was achieved, which would have made skin grafting feasible, a pedicled flap was used, considering that the peri‑articular area has a risk of postoperative contracture. Although flap closure can be performed at various sites around the knee,2 the medial thigh was chosen as the donor site because of its distance from the ulcer site. The DGAP flap used in this study was supplied by the perforating arteries of the descending genicular artery running through the medial thigh. The DGAP flap is one of the most valuable flaps for treating defects in the knee because of its thin and flexible tissue.3 However, many lymphatic vessels run along the medial thigh, and complications due to damage to medial thigh lymphatic vessels during flap elevation have been reported. Permanent lymphoedema is thought to be rare, but postoperative seroma, cellulitis, and transient lymphoedema reportedly occur in 3–10 % of cases.4 The profunda artery perforator (PAP) flap, which similarly uses the medial thigh as the donor site, reportedly reduces these complications by using lymphatic vessels preserving the profunda femoris artery perforator (LpPAP) flap when elevating this flap.5,6 This indicates that when raising the flap from the medial thigh, lymph vessel-sparing reconstruction should be performed, if possible.
Karakawa et al. reported that lymphatic vessels travelling in the medial thigh have a certain degree of predetermined course and gradually move from the gracilis muscle towards the proximal region.6 However, to ensure lymphatic preservation, ICG should be performed to confirm the exact course of the lymphatic vessels. Then, both intraoperatively and postoperatively, the lymphatic vessels should be confirmed to have no damage. As a result, the surgery was completed without complications.
One limitation of this study is that it was a single case report. In addition, although lymphatic flow was assessed based on ICG, it is possible that the lymphatic vessels identified in this case may not be all lymphatic vessels present in the lower limb, as the lymphatic vessels that are contrasted differ depending on the ICG injection site7. There are also lymphatic vessels that are not contrasted on ICG8. However, as the lymphatic vessels that contrast more strongly are considered the main drainage pathways from the lower limbs, preserving these predominant lymphatic vessels could have contributed to reducing the risk of complications.
Therefore, careful attention should be paid to operating the lymphatic vessels when harvesting flaps from the medial thigh. Although there are no other reports on lymphatically preserved DGAP flaps, it is essential to plan surgery with lymphatic preservation in mind, even when performing this flap.
Conclusion
Lymphatic vessel-preserving DGAP flap reconstruction is a viable technique for anterior knee skin defect wounds. Injury to the lymphatic vessels in the medial thigh may result in transient oedema, seroma, and an increased risk of cellulitis. To the best of our knowledge, designing a flap to avoid injury at the same site is advisable.
Ethical approval
Not required.
Declaration of competing interest
None.
Acknowledgments
Acknowledgements
None.
Funding
None.
Footnotes
Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.jpra.2024.09.018.
Appendix. Supplementary materials
Indocyanine green (ICG) lymphography was performed after flap elevation to preserve lymphatic vessels.
Indocyanine green (ICG) was subsequently administered via the vein, and ICG angiography was performed.
Overlaying ICG lymphangiography on the patient's limb.
Intraoperative pictures
a: The descending genicular artery perforator (DGAP) artery confirmed by ultrasound examination is identified.
b: The edge of the flap is abandoned because of poor staining in indocyanine green (ICG) angiography.
c: The flap is then placed to cover the skin defect.
ICG lymphangiography from the medial side also shows no dermal backflow.
References
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Associated Data
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Supplementary Materials
Indocyanine green (ICG) lymphography was performed after flap elevation to preserve lymphatic vessels.
Indocyanine green (ICG) was subsequently administered via the vein, and ICG angiography was performed.
Overlaying ICG lymphangiography on the patient's limb.
Intraoperative pictures
a: The descending genicular artery perforator (DGAP) artery confirmed by ultrasound examination is identified.
b: The edge of the flap is abandoned because of poor staining in indocyanine green (ICG) angiography.
c: The flap is then placed to cover the skin defect.
ICG lymphangiography from the medial side also shows no dermal backflow.