Xiojun Liu ,Rui Zho ,Xinyun Jin ,Lei Liu ,Guoling Shen,＊

aDepartment of Burn and Plastic Surgery,The First Affiliated Hospital of Soochow University,Suzhou 215006,Jiangsu,China

b Department of Burn and Plastic Surgery,North District of Suzhou Municipal Hospital,Suzhou 215008,Jiangsu,China

Keywords:Angiosome Perforator flap Upper limb Reconstruction

ABSTRACT Background: Repair of extensive deep wounds in the forelimb remains challenging for surgeons.The objective of this study was to evaluate the surgical technique and clinical significance of multiple-territory paraumbilical perforator (PUP) flaps in patients with massive soft tissue defects in the upper limbs.Methods: Between January 2017 and September 2021,16 patients (6 women and 10 men) aged 24–54 years(average,41.4 years)who were hospitalized at the First Affiliated Hospital of Soochow University and the North District of the Suzhou Municipal Hospital were investigated.Their injuries included damage to the fingers,dorsal skin of the hands,wrist,or forearm.Their tendons or bones were exposed after debridement.In some patients,multiple-territory PUP flaps that encompassed adjacent angiosomes were transplanted to cover the soft tissue defects.Results: All flaps survived and healed well.After a follow-up of 2–54 months,all patients recovered satisfactorily in terms of characteristic and functional review.Conclusions: The application of PUP flaps,especially those encompassing multiple angiosomes (multiple-territory PUP flaps),can be an optimal reconstruction method for repairing massive soft tissue defects in the forelimb.

1.Introduction

The clinical application of a paraumbilical perforator flap(PUP)was first reported by Taylor et al.1in 1983.To date,many studies have introduced its use in wounds of the upper limbs.2–4In addition,Taylor et al.5,6introduced theconceptof an angiosome.Froman anatomicalpoint of view,large PUP flaps may span their consolidated anatomical territory and contain several angiosomes.Therefore,these flaps are also known as multiple-territory perforator flaps or span-territory perforator flaps.7,8Although this type of flap is used broadly,its blood supply pattern remains obscure.Herein,we presented and elaborated on a multiple-territory PUP for the treatment of extensive acute wounds of the upper limbs.

2.Patients and methods

2.1.Study participants

Between January 2017 and September 2021,16 patients with skin and soft tissue defects in the forelimbs due to deep burn,electric injury,or compression injury and subsequently underwent reconstruction using PUP flaps were investigated (Table 1).Among the 16 cases,several severe wounds were repaired using a multiple-territory PUP flap.The operations were performed successfully,and the flaps survived without major complications,such as vein congestion,necrosis,or hemorrhage.The patients were followed up for 2–54 months.Except for bulkiness and color differences,the patients were satisfied with the outcomes of the reconstruction.

Table 1 Patient data.

2.2.Operative techniques

2.2.1.Stage 1

Deep burn,electric injury,burn injury,and compression injury were debrided until the following conditions were met:(1) there were no longer necrotic tissues and (2) asepsis was achieved after one or more operations including vacuum sealing drainage.All injuries involved damage in the fingers,dorsal hand,wrist,or forearm,with the tendons or bones exposed after debridement.Abdominal random flap and axial flap with superficial artery of the abdomen or PUP were adopted to coverthese soft tissue defects.If the size of the defect was larger than 5.0 cm × 4.0 cm,the PUP flap was used to achieve better viability and less morbidity.

We used an ultrasonic Doppler probe to detect the location of the main ipsilateral perforator around the umbilicus.The axis of the flap was obliquely located from the selected perforator to the inferior tip of the homolateral scapula.The square area of the perforator flap was designed to be slightly larger than the wound to cover the lesion accordingly.

With the patients in the supine position,we created an incision in the lateral boundary of the flap to the deep scarpa fascia.The flaps were then medially above the deep fascia.When we reached the anterior sheath of the rectus abdominis muscle,the flaps were dissected carefully until the structure near the marker or until the perforator was seen clearly.Generally,the flap pedicle should encompass two perforators,except for middle or small defects.The flap was elevated until the mid-axillary line or until near the posterior axillary line.Considering the ideal position of the arm,the flap was transferred directly to the wound,with its lateral part sutured in the distal defect.The pedicle was tucked using a loose gauze,and the flap was fastened gently,while the upper limb was fixed to the body using a bandage.In the following 3 weeks,we checked the perfusion of the flap and observed whether there was congestion,ischemia,or necrosis.If there were any of the aforementioned complications,proper correction was subsequently instituted.

2.2.2.Stage 2

Before the pedicle was severed,we conducted clamping exercises,which were necessary to determine whether the vascular area grew from the wound bed.Therein,we observed sufficient blood perfusion.After the division,the redundant part of the pedicle was sutured back in the abdomen to decrease the wound.The donor site was closed primarily when the width of the flap was less than 6–8 cm.Otherwise,a skin graft was necessary.

3.Results

3.1.Patient outcomes

All flaps were elevated and transplanted without major complications,such as partial necrosis.After 3 weeks of performing pedicle division,the flaps were transferred successfully.All wounds subsequently resurfaced thoroughly.The square size of the flaps varied from 5.0×4.0 cm2to 45×22 cm2,and all patients were followed up for 2–54 months (average,25.6 months).One woman underwent a thinning procedure twice after 3 and 6 months,respectively.

3.2.Typical cases

3.2.1.Case 6

A 39-year-old man had his left forearm burned and compressed by a hot machine.Due to the wrist’s semi-annular eschar,debridement was performed immediately after admission to relax the pressure of the carpal canal (Fig.1).After observation for 5 days,we probed the perforator vessels around the umbilicus of the left abdomen.The patient underwent soft tissue reconstruction using a span-territory umbilical perforator flap.We grafted the donor site using a split-thickness skin graft,which was obtained from his scalp.The perforator flap survived without any complications.At the 8-month follow-up period,the patient was satisfied without any desire for a better contour.

Fig.1.(A)Burn and compression injury of the left wrist and forearm.(B) The tendon was exposed.The ulnar vessels were damaged after debridement.(C) Marking(red) of potent perforators using an ultrasonic probe.(D) The flap design was obliquely located from the umbilicus to the tip of the sculpture.(E)After elevation of the flap.(F) Demonstration of the perforator.(G)Transplantation to the wound.(H)There was no partial necrosis after division of the flap.(I)The appearance of the wrist after reconstruction.The wrist was quite bulky.However,there was no indication for further dissection.

Fig.2.(A) Burn and compression injuries of the right forelimb from the fingers to the elbow.(B) Bone and tendon exposed and massive muscle resected after debridement.(C) Marking of the perforators using an ultrasonic probe and design of the multiple-territory flap,including the deep inferior epigastric artery,lateral posterior intercostal artery,and superior epigastric artery,in combination with a superficial inferior epigastric artery flap.(D) Elevation of the multiple-territory PUP flap.(E) Flap pedicle with the deep inferior epigastric artery and superficial inferior epigastric artery.(F) Split skin graft of the donor site.(G) No partial necrosis after the flap severance.(H) Appearance of the forearm after reconstruction,with the thumb preserved.

3.2.2.Case 7

A 53-year-old woman had her right forelimb burned and compressed by a hot rotating machine for approximately 20 min.During the emergency operation,we checked the wound.There was approximately 3%total body surface area in the forearm and dorsal hand.Escharotomy was then performed (Fig.2).Around 18 days after the injury with three debridement operations performed,a span-territory PUP flap allied with a superficial epigastric artery flap was transplanted to reconstruct the extensive lesion in the distal forelimb.The donor site defect was repaired using a split-skin graft from the unilateral thigh.After 46 days,the pedicle was separated from the abdomen.Fortunately,the length of the limb and function of the thumb were preserved,while the other four fingers were amputated due to the absence of perfusion.The large composite flap had a size of 45 cm×22 cm without partial necrosis.After the operation,the patient experienced transient intestinal obstruction due to compression resulting from tight suturing and edema.The patient recovered 2 days after the occurrence of gastrointestinal decompression.

4.Discussion

The esthetics and function of the forelimb,as an exposed cosmetic unit of the body with subtle activity,should be taken into account in the reconstruction of acute wounds.Many methods have been applied,including skin grafting and application of regional flaps,random abdominal flaps,and free flaps.Skin grafts are constricted during reconstruction of the forearm and dorsal hand due to contracture and scar formation.Meanwhile,regional flaps and random abdominal flaps could not afford massive tissue and surface demand when confronted with extensive lesions.Moreover,in the current era of microsurgery,pedicle flaps are still indispensable in selected clinical scenarios,such as electric wounds.9Thus,PUP flaps can be an ideal option for the reconstruction of extensive defects in the upper limb due to their long pedicle,reliable perfusion,and large dimensions (up to 42 cm in length,as reported by Taylor et al.1) when they embrace multiple territories.

Since the report by Taylor et al.,in 1983,PUP flaps have been widely applied.In 1989,Koshima and Soeda10reported their performance in using the deep inferior epigastric artery (DIEA) to reconstruct the oral bottom and groin in a patient whose pedicle vessel was separated from his rectus abdominis muscle.In 1998,Koshima et al.11presented a PUP flap without the DIEA and summarized its many advantages,including the prevention of herniation of abdominal contents.Its anatomy and clinical application have been broadly researched.Blondeel et al.12found two to eight perforators larger than 0.5 mm on each side of the midline in a paramedian rectangular area.These were 2 cm cranial and 6 cm caudal to the umbilicus and between 1 cm and 6 cm paramedian.Generally,if the pedicle contains more than two potent adjacent perforators,partial flap failure is not expected,even if the flap territory exceeds two angiosomes.Morris et al.6reported in 2010 that the average diameter and area supplied by a single perforator from the trunk region were approximately 0.7 mm and 40 cm2,respectively.During operation,we considered that the distal part of the flap exceeded the boundary of one angiosome,which we called the choke district.As demonstrated in case 6,in the oblique flap design,the perforator flap encompassed the DIEA,superior epigastric artery (SEA),and lateral posterior intercostal artery(LPIA).Thus,we called it a multiple-territory PUP flap(Fig.3).

Taylor and Palmer13introduced the concept of the angiosome,which was based on the source artery.Although it helped us realize the three-dimensional structure of the source artery,it did not entirely represent the subtle foundation of the blood supply of the perforator flap.The perforasome,which was reported by Saint-Cyr et al.,14could serve as the best definition after the source vessel left the deep fascia.In fact,as far as their boundaries were concerned,they achieved mastery through a comprehensive study of the subject.In fact,at the flap’s subcutaneous plexus,we could see the boundary as a district where the choke vessels resided or where indirect links occurred.One perforator could support only one adjacent territory if the flap was not initially delayed because the choke vessels could not dilate instantly due to its reduced caliber.15In case 7,we demonstrated that the flap spanned more than three angiosomes,including the DIEA,LPIA,and SEA systems.Therefore,we called this flap a multiple-territory PUP flap.As Cormack and Lamberty16announced,partial necrosis in the potential territory might have occurred.5However,this did not occur in case 7 in our study.In our opinion,this flap was reliable probably because the oblique design encompassed the most potent cutaneous perforators among those radiating like the spokes of a wheel.1Moreover,the long flap,which covered multiple vascular territories,might have included the neurovascular bundle,which had a direct link.17

Fig.3.Angiogram of the integument of the anterior trunk.The colored vascular territories of the various source vessels are hereby shown.DCIA,deep circumflex iliac artery;DIEA,deep inferior epigastric artery;LPIA,lateral posterior intercostal artery;LTA,lateral thoracic artery;SCIA,superficial circumflex iliac artery;SEA,superior epigastric artery;SEPA,superficial external pudendal artery;SIEA,superficial inferior epigastric artery.(From Geddes CR,Tang M,Yang D,et al.In:Blondeel PN,Morris SF,Hallock GG,et al.,eds.Perforator flaps,anatomy,technique and clinical applications.St Louis (MO):Quality Medical Publishing;2006.Fig.18–3,p.365,Chapter 18).

If the injury of the elbow and upper arm was annular,we adopted an allied flap design.Since there were different sources of the arterial system,the PUP flap was simultaneously used with inferior abdominal flaps,such as superficial inferior epigastric artery flap or the superficial circumflex iliac artery flap.9According to the anatomy of the abdominal superficial artery,it was safe to elevate the flaps,including different source perforators in the pedicle.In case 7 in our study,the pedicle was transformed with the rectus abdominis muscle encompassing the DIEA.In addition,the broad cutaneous pedicle encompassed the SIEA.It seemed that a semi-wall of the right abdomen with a part wall of the inferior chest was mobilized.

As discussed above,it could be difficult to irrigate the potential territory16for a single perforator,thus resulting in partial necrosis of the flap.Therefore,many scholars have performed many surgical strategies,such as delay,13,18enhanced artery perfusion,and super-drainage of the veins.19All of these strategies are efficacious.However,they increased the operation time and risk of micro-anastomosis.Therefore,in recent years,many experiments on tissue engineering were conducted.After the discovery of neovascularization through main pathways,such as vascular endothelial growth factors,vascular endothelial growth factor receptor 2,20Ang-1,and Tie2,21many cell factors,proteins referred to in the pathway,and regulatory drugs in upstream genes,which could provoke or enhance angiogenesis,were selected to improve the blood supply of the choke zone.8,22A great diversity of drug-loaded release systems,such as liposomes,PLGA microspheres,and soluble micro-needles,23were applied in experiments to promote angiogenesis.Encouraging results were obtained to enrich the methods of the prefabrication of perforator flaps.Therefore,larger flaps with multiple vascular territories were anticipated in the clinical setting.24In a sense,it seemed arbitrary to neglect the boundary of the angiosome or perforasome.We prefer to be familiar with the anatomical territory of the perforator flap rather than depend on the conventional method.In the future,once an analogical extensive wound is encountered,we should utilize these new methods of angiogenesis to remold the multiple-territory flap to avoid necrosis.

5.Conclusion

Although anatomical vascular imaging underestimates the actual clinical vascular perfusion area,we have attested to harvest multipleterritory PUP flaps that are less than the size of a hemi-abdomen without any complications.This was based on recent anatomic developments.It is viable for PUP flaps,especially multiple-territory PUP flaps,to be used in the reconstruction of massive soft tissue defects in the upper limb.

Ethics approval and consent to participate

This study received ethical approval from the Ethics Committee of the First Affiliated Hospital of Soochow University.All participants provided written informed consent prior to study enrollment.

Consent for publication

All patients included in this study provided written informed consent to publish the data contained within this study.

Competing interests

The authors declare no competing interests.

Authors’contributions

Liu X:Writing-Original draft,Writing-Review and Editing.Zhao R:Investigation,Writing-Original draft.Jin X:Investigation,Writing-Original draft.Liu L:Investigation,Writing-Original draft.Shen G:Conceptualization,Supervision.