double free - flaps are technically challenging due to the complex nature of the defect , harvest of two flaps and use of two pairs of recipient 's vessels . in such limb defects more
further the risk of distal limb ischaemia is imminent when collateral circulation is not adequate .
double fasciocutanous flaps either perfused independently or as chimeric flaps fulfil the requirements provided suitable recipient vessels are available .
the risk of distal limb ischaemia is minimal when a single vascular axial limb vessel is used as the recipient .
harvest of such flaps from a common donor site avoids the morbidity of distant second donor site .
we report successful resurfacing of large bimalleolar defects in a 14-year - old boy using the anterolateral and anteromedial fasciocutanous perforator flaps harvested independently and anastomosed to the proximal and distal cut ends of the anterior tibial vessels .
a 14-year - old boy presented to us with a 2 weeks old infected bimalleolar defect with dimensions of 12 cm  7 cm medially and 8 cm  4 cm laterally [ figure 1 ] at the ankle .
the patient was treated with cast application elsewhere for swelling of the ankle following a fall and had no bony injury .
he developed severe pain in the ankle soon after and fever a week later , .
on removal of the cast , necrosis of the skin was noted over the both malleoli which was debrided at the referral hospital and then he was referred to our institute for further management .
malleoli and the adjacent lower ends of tibia and fibula were exposed with open ankle joint - draining frank pus .
the foot was sensate and well vascularised with good dorsalis pedis and posterior tibial pulsations .
considering the dimensions and proximity of the two defects , a chimeric fasciocutanous anteromedial thigh ( amt ) and anterolateral thigh ( alt ) flap [ figure 2 ] based on the lateral circumflex , femoral vessels was planned and their perforators marked with hand held doppler .
the flaps were raised based on these perforators and the pedicles traced proximally for their confluence .
it was found to be very close to the origin of the lateral circumflex femoral artery precluding chimeric flap design and due to gross vessel size mismatch and excess pedicle length .
the vessels were healthy and amenable for the use with good pulsatile flow from both the proximal and distal cut ends of the recipient artery .
both flap vessels were anstomosed to the proximal and distal cut ends of the anterior tibial artery , in an end to end fashion .
the corresponding flap veins were anastomosed to the available two vena comitans of the anterior tibial artery in an antegrade direction .
at 11 months follow - up , the patient is ambulatory with a stiff ankle in slight varus position with x - ray showing extensive post - septic arthritic sequale of the ankle joint [ figure 4 ] .
medial and lateral malleolar defect chimeric anterolateral thigh and anteromedial thigh flaps settled anterolateral thigh and anteromedial thigh flaps x - ray showing post arthritic sequele
distal lower limb defects requiring double flaps can be resurfaced by a combination of two separate distally based flaps laterally and medially , a single pedicled flap with de - epithelisation of intervening skin bridge and use of chimeric free flaps .
chimeric free flaps resurface more than one defect based on single pedicle by innovation in the flap design .
lin et al . have demonstrated the feasibility of harvesting more than one skin and muscle components on the lateral circumflex femoral system .
two separate skin paddles based on the anterolateral and anteromedial perforators of the descending branch of the lateral circumflex femoral artery can be harvested as a chimeric flap .
however , the pedicle of the amt flap can arise from the lateral circumflex femoral artery or the femoral artery . when the chimeric anterolateral and anteromedial flap is harvested in such circumstances
, the confluence would be in a much more proximal position which was the case in our patient .
routine imaging has not been advocated for the harvest of these flaps by however , when chimeric flap harvest is planned , imaging can be helpful in assessing the location of the confluence .
the harvest of both the flaps did not incur additional morbidity in our case though the potential exists .
lin et al . in their preference for choosing chimeric flaps over double free - flaps have observed the following difficulties in advocating double free - flaps for limb defects namely , ( 1 ) the need for more than one pair of recipient vessels or a flow - through flap ( 2 ) morbidity of the second flap harvest and ( 3 ) the additional time for second anastomosis .
the choice of the recipient vessel for a free flap in the limb will depend on the location and the vascular status of the limb .
collateral circulation maintains distal limb perfusion and hence its intactness and adequacy are vital when one of the major limb axial vessels is utilised .
this is possible because of presence of collaterals at multiple levels between the anterior tibial , posterior tibial and peroneal vessels . in 3 of the 50 cases of park et al .
reverse flow from anterior tibial was used as the recipient vessel , and they suggested angiography and pulsatile flow intra - op to be usable criteria for the vessel .
thus , if both the proximal and distal cut ends have good flow , they can be utilised for perfusion of two flaps assuming that collateral circulation is adequate . both superficial and deep
park et al . have found the vena comitans to be better suited than superficial veins as they are less vulnerable to injury and located in the same operative field .
even though patency rates are similar to that of an end to end anastomosis , it has technical difficulties ( angle of vessel take off , arteriotomy , difficulty in diseased vessels ) and flow problems ( turbulence , insufficient flow , thrombosis ) .
although it gives a safer and more satisfactory outcome in size discrepancy , it is not feasible when flap vessel is larger than the recipient vessel which was the situation in our case .
thus , in a properly selected patient double free - flaps can be done safely with minimal additional morbidity as demonstrated in this case .
 double free - flaps are necessary when tissue cover can not be sufficed with a single flap . the other factors to be considered when using two free flaps for resurfacing of distal limb defects are the availability of more than one recipient vessel , the risk of distal limb ischaemia and the donor site morbidity of double flap harvest . 
 if these factors are adequately addressed , double free - flaps can be safely executed for resurfacing distal limb defects with minimal morbidity . 
 we report the simultaneous harvest and transfer of the anterolateral and anteromedial thigh flaps inset and vascularised as double free - flaps to resurface a large bimalleolar defect in a 14-year - old boy with no additional morbidity as compared to that of a single free tissue transfer . 
INTRODUCTION
CASE REPORT
DISCUSSION
Financial support and sponsorship
Conflicts of interest