distally based sural artery flap for reconstruction of lower limb flap

distally based sural artery flap for reconstruction of lower limb flap

1. THE SURAL FLAP Dr. Dilpreet Kaur PDT Department of Plastic and Reconstructive Surgery

2. Introduction T he sural flap is contained in the area of t he posterior calf between the popliteal fossa and the midportion of the leg. It is centered over the mid raphe between the medial and lateral heads of gastrocnemius. Sural flap is one of the most commonly used local flap in the lower limb due to its diverse use for coverage of knee, popliteal fossa, upper third of leg, ankle, heel defect and also for foot reconstruction.

3. A rterial and Venous basis Arterial supply: Superficial sural artery from the medial sural artery(50%) Popliteal Artery(46%) Lateral sural artery Perforators from peroneal artery Perforators from posterior tibial artery Neurocutaneous perforators from vasa nervosum of sural nerve Venous drainage: V enae comitantes of the named vessels above

4. A rterial anatomy Dominant Pedicle Sural artery perforator Regional Source Popliteal artery. Length 3 cm. Diameter 1.4 mm. Location This pedicle descends from the popliteal fossa between the heads of the gastrocnemius muscle and deep fascial layer and courses inferiorly, superficial to the gastrocnemius muscle.

5. A rterial anatomy Minor Pedicle Perforators from the peroneal artery Regional Source Peroneal artery. Length 1 cm. Diameter 1 mm. Location Distal third of the leg

6. A rterial anatomy Minor Pedicle Neurocutaneous perforators from the vasa nervorum of the sural nerve Regional Source Sural artery. Length 1 cm. Diameter Greater than 1 mm. Location The rich anastomotic vasa nervorum of the sural nerve gives off neurocutaneous perforating vessels to the skin and the fascia overlying it.

7. F lap innervation S ensory: medial sural cutaneous nerve branch of tibial nerve within the popliteal fossa.

8. F lap components T he flap may be harvested as: F ascia only F asciocutaneous M yo-fasciocutaneous

9. F lap Harvest

10. D esign and marking T he skin island can be raised anywhere in the lower two third of the leg. T he pivot point of the pedicle must be atleast 5cm above the lateral malleolus to keep the anastomosis with the peroneal artery.

11. Patient Positioning P rone positioning is preferred but the flap can also be harvested in lateral decubitus position.

12. F lap Dimensions S kin island dimensions L ength: 12 cm W idth: 6 cm

13. F lap marking T he flap is outlined over the raphe between the two heads of the gastrocnemius muscle. T he pedicle can be dopplered out by tracing th e lesser saphaneous vein from the lateral ankle up to central raphe between the two heads of the gastrocnemius muscle.

14. Flap dissection F or the antegrade flap, a doppler probe is used to determine thw location of the course of the pedicle within the flap. F lap borders are then incised through skin and deep fascia. F lap elevation begins distally. T he lesser saphaneous vein and sural nerves are encountered and divided, and both structures are included with the flap. A s the flap is elevated proximally towards the popliteal fossa, dissection is performed in a subfascial plane between the deep fascia and the underlying medial lateral gastrocnemius muscles. C areful dissection proceeds as the popliteal fossa is approached and the entrance of the medial superficial sural arteryinto the deep fascia is visualised. E levation proceeds until an acceptable arc of rotation is achieved to cover the defect.

15. F lap variants R everse sural flap A dipofascial flap D elayed flap S upercharged flap

16. R everse sural flap T he most common usage of this flap is for distal third defects of the leg. H ere the reverse sural flap permits soft tissue reconstruction without the need for microsurgery. I t does not sacrifice any of the three major blood supllies to the lower limb. T he distally based reverse sural flap is based on fasciocutaneous blood supply of the distal posterior lateral leg. T he structures supplying the flap inclyde sural nerve superficially, the sural arteries, and the lesser saphenous vein. T hese structures are all divided proximally while the flap is being elevated.

17. A dipofascial flap W hen the skin is not required, but soft tissue fill is necessary the sural flap can be harvested, leaving the skin in place, undermining in the subcutaneous plane, carrying only the adipose tissue and fascia for the fill.

18. D elayed flap One of the weaknesses of the sural flap, especially the reverse variant, is venous congestion, which may lead to partial flap loss. One solution is to perform the flap in stages and create a delayed flap. When creating a delay of the sural flap, the proximalmost portion of the flap is maintained with the skin bridge. The remainder of the flap is dissected as previously described, including complete elevation of the flap below the fascia. This means that the skin island is being supplied by the vessels that normally supply the flap, but a bridge of the skin has been maintained to allow venous egress. The sural artery, sural nerve, and lesser saphenous vein should be divided at the initial elevation, if possible. This allows axialization of vessels within the flap over time, which allows it to become more reliant on the retrograde vessels. At 7 to 10 days, this area of connection can be divided in the office, and the flap can be rotated into position at 2 weeks.

19. D elayed flap

20. S upercharged flap Another solution to the venous egress problem is to include the lesser saphenous vein and some extension of it in the flap. Once the flap is rotated into position, a venous anastomosis can be performed between the lesser saphenous vein and any recipient vein in the area. Another simple solution using this lesser saphenous vein is to cannulate the vein and to drain this at the bedside at intervals. This usually requires only 48 hours of such draining before flap congestion is no longer an issue

21. D onor site closure and management A STSG is used often for closure of the donor site if skin is included in the flap. T he donor site may be closed primarily if the island taken is small or if the skin is not incised.

22. O ptimising results T he venous congestion may be minimized by harvesting atleast 3cm of tissue on either side of the pedicle and with the overlying skin intact. V enous congestion may be further reduced by delaying the flap for 7-10 days after ligating the proximal lesser saphaneous vein and sural artery. S upercharging of the reverse sural flap can be done by anastomosing the proximal end of the small saphenous vein to any vein in the recipient site. I nset of flap is critical to avoid kinking of the pedicle, offloading the flap by any means including an ilizarovs type frame.

23. F lap Usage P edicled T ypical indications A nkle P osterioir heel Atypical indications Popliteal fossa Knee defects

24. P ost operative care G eneral P ain management and management of medical comorbidities R ecipient site T he operated site should be plastered and rested at an elevated level. D onor site T he donor site can be closed primarily if gfascia only flap is harvested. S tandard postoperative occlusive dressing can be applied. I f a skin graft is used a NPWT can be used.

25. O utcome T emporary venous congestion or distal flap loss is often encountered. M ajor donnor deficit of flap is loss os sensations on the lateral aspect of the foot and a skin grafted depression on the posterior calf donor site. I n a well vascularised extremity the pedicle can be removed after 3-4 weeks to improve the contour of the leg.

26. T hank you !!