Annals of Case Reports Case Report Large Vascular Malformation Resection and Reconstruction around the Knee with Combined Free DIEP and SIEA Flaps: Case Report

Introduction: Large vascular malformations close to joints are rare and their treatment multimodal. Case Report: We present a case of a young male patient with a large vascular malformation (30x10cm) around the knee, with no option for medical or interventional therapy. Radical surgical excision and immediate reconstruction was successfully achieved with a combined Deep Inferior Epigastric Perforator (DIEP) and Superficial Inferior Epigastric Artery (SIEA) free flap anastomosed to tibialis anterior vessels and to the descending branch of the lateral circumflex femoral vessel. Full range of motion and acceptable cosmesis were achieved. Discussion: Extensive excision and free flap reconstruction can be a reasonable alternative for one stage treatment of vascular malformation. Abdominal based free flaps are versatile options for reconstruction of large defects around the knee. Conclusion: Microsurgical reconstruction after large vascular malformations excision should be considered more often.


Introduction
Large vascular malformations close to joints are rare and the treatment many times multimodal [1,2]. In most scenarios nonsurgical treatment is evaluated before any surgery is considered. Non-surgical treatment comprises sclerotherapy, laser therapy, embolization, or a combination of the above, depending on the flow characteristics and vessel type [3]. The indications for surgical intervention are: lack of or non-responsiveness to other treatment modalities, large symptomatic lesions and/or aesthetic concerns [4]. Large soft tissue reconstruction around the knee can be mitigated by sequelae like decreased range of motion, scar contracture, pain and poor cosmesis. Proper reconstruction with soft and pliable vascularized tissue is mandatory for good outcomes [5].

Case Report
We report a case of a 20 year-old male healthy patient with a body mass indexo f 25.4 kg7m 2 . He presented with a congenital vascular malformation of the right knee involving the lateral aspect of the distal thigh, the lateral and posterior aspects of the knee and lateral aspects of the proximal leg (30 x 10 cm) (Figures 1 and  2). This lesion was noted soon after birth. Based on the findings on MRI, the lesion was diagnosed as na hypertrophic capillary malformation due to the presence of mostly capillary structures. Laser therapy had been previously tried on the lesion, without success. An increase in the longitudinal, transverse and superficial dimensions was seen over the last two years. The patient did not present any signs of steal syndrome, and his major concern was the appearance of the lesion, its continuous growth and difficulties with clothes fitting. The lesion was judged not treatable with interventional radiology techniques such as sclerotherapy or embolization, based on the vessel type and flow characteristics. In the present case, pre-operative embolization was not found necessary due to the well circumscribed nature of the lesion on imaging.   Figures  3 and 4). Preoperative MR angio was performed both to assess recipient vessels and the potential deeper vessel malformation. The flap was anastomosed to the anterior tibial pedicle via the DIEP pedicle with end to end anastomosis and to the descending branch of the lateral circumflex femoral artery and its vena comitans respectively by the SIEA and SIEV. On the first postoperative day the flap went into ischemia due to kinking of DIEP pedicle and as a consequence there was a thrombosis of the SIE vein. The flap was salvaged by DIEP pedicle release and vein graft to the SIE artery and vein (donor: saphenous vein). The postoperative period was still doomed by venous congestion, solved by leech therapy for 3 days. Gait was started in the second postoperative week with the patient wearing a range limiting orthosis and the patient was discharged at day 12. A smaller necrosis (about 15%) was revised in theatre at 3 weeks and the closure was facilitated by a local flap.  The patient is now on 9 months postoperative period. There are no signs of recurrence. Total range of motion of the knee was achieved, with a good cosmetic outcome (Figures 5 and 6). The donor site has healed with no complications nor sequelae.

Discussion
Vascular malformation treatment is usually multimodal [2,4,6,7]. Surgical radical excision is recommended for risk of malignant transformation, symptomatic malformations-pain, steal syndrome, bleeding, function impairment, continuous growth, aesthetic improvement and non-response to other forms of therapy [1,4,[8][9][10][11][12]. Scherotherapy is usually indicated for low flow lesions, while embolization is reserved for high flow lesions. Radical excision has proven effective in avoiding recurrence and is a modality able of providing cure [4,7]. However, surgical treatment is not always possible due to the malformation's extent or involvement of deeper structures such as muscles, bones and nerves. A multidisciplinar approach should be favored when dealing with such diagnoses. The resection of the vascular malformation led to exposure of the muscular fascia in the entire extent of the defect. No bone, ligaments or nerves were exposed. Other reconstructive options could have been skin graft or dermal matrix substitutes plus skin graft, local flaps after expander treatment or other free flaps.
The knee is a joint with a large range of motion, and this is dependent, among other factors, on supple soft tissue coverage [13]. Achieving this supple coverage in a single surgical procedure was only possible with a free flap. The massive defect precluded safe local flap reconstruction. Recipient vessels around the knee may be a challenge when a free flap is performed [5,14,15]. Options are branches from the popliteal vessels, descending genicular vessels, posterior tibial vessels, femoral vessels, medial sural vessels, descending branch of the lateral femoral circumflex vessels and the anterior tibial vessels [16][17][18][19][20][21][22]. The anterolateral location of the defect precluded the use of popliteal branches, posterior tibial vessels, femoral vessels, medial sural vessels and the descending genicular vessels. In fact, the recipient vessels were a main reason for the laborious postoperative period. The intraoperative dissection of the superolateral genicular artery was not successful.
An end to end anastomosis to the anterior tibial vessels was performed after verification of proper foot vascularization by the remaining main arteries after tibialis anterior clamping. The distal end of the descending branch of the lateral circumflex femoral artery had a small diameter and was also a reason for the vascular insufficiency suffering of the flap. The use of feeding vessels of the vascular malformation as recipient vessels has been described for lower extremity, however we think that lower recurrence rates may be achieved if a normal vessel can be used [6]. Soft tissue free flap reconstruction around the knee can has been described with latissimus dorsi myocutaneous and parascapular flaps, anterolateral thigh flap, omental flap, gracillis flap [5,14,[16][17][18]22,23]. As in any reconstruction, the donor site is chosen according to the defect needs, but also by the patient's body habitus and preference, besides the best operative workflow.
Abdominal based flaps have seldom been used for knee reconstruction, because of subcutaneous fat bulk [24,25] versatile, allow the harvest of a very large and pliable skin paddle, have long and well located pedicles and reliable blood supply with low donor site morbidity and even contour improvement [26]. Even if the longitudinal dimension of the defect allowed a proper accomodation of the flap in this case, later debulking procedures can be offered to improve recipient site contour. Louer et al. found an 18% rate of reexploration on their series of 34 free flaps for knee reconstruction, and no correlation to recipient vessels choice or use of vein grafts [5]. In this case, we believe the vascular crisis was caused by pedicle kinking on the powerful muscle masses around the joint and advise on proper muscle release, as well as close postoperative surveillance.

Conclusion
Radical excision of vascular malformations can cure these lesions. Abdominal based free flaps are versatile and can provide enough soft tissue for reconstruction of large defects around the knee. Tibial anterior pedicle and descending branch of the lateral circumflex femoral artery are useful recipient vessels for reconstruction around the knee. Multidisciplinary treatment of vascular malformations shuld be favored. Microsurgical reconstruction after large vascular malformation excision is a valuable option.

Declarations of interest
None. This work did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Funding
None.

Conflict of Interest
All authors declare that they do not have conflicts of interest.

Ethical approval
This is an observational study. The Uppsala University Hospital Research Ethics Committee has confirmed that no ethical approval is required.

Informed consent
The participant has consented to the submission of the case report to the journal.