| Abstract|| |
Background: Skin coverage for defects in the lower 2/3 of leg, ankle region and posterior heel has always been a difficult challenge for reconstructive surgeon.
Methods: We describe our experience with the distally based superficial sural artery flap coverage in 48 patients with moderate sized defects in these difficult areas.
Results: One out of 48 flaps (in 48 patients) was lost totally and 3 suffered marginal necrosis which did not require any secondary procedure. These complications could have been avoided by proper selection of cases and refining technical skills.
Conclusion: This simple procedure could be an important and versatile tool for any reconstructive surgeon in providing skin coverage in the distal leg and proximal foot. Preservation of major arteries of the lower limb, minimal donor defect, relatively uninjured donor area in compound fracture or poly trauma involving distal leg are some of the advantages of the flap.
Keywords: Skin coverage, Sural artery flap, Distal 2/3rd leg and proximal foot.
|How to cite this article:|
Kamath B J, Shetty M S, Ajith Kumar M, Bhardwaj P. Distally based superficial sural artery flap for soft tissue coverage in the distal 2/3 of leg and foot. Indian J Orthop 2005;39:169-73
|How to cite this URL:|
Kamath B J, Shetty M S, Ajith Kumar M, Bhardwaj P. Distally based superficial sural artery flap for soft tissue coverage in the distal 2/3 of leg and foot. Indian J Orthop [serial online] 2005 [cited 2013 May 22];39:169-73. Available from: http://www.ijoonline.com/text.asp?2005/39/3/169/36726
| Introduction|| |
Several random local flaps  , distally based muscle flap[ 2],, staged and undelayed fascial , and fascio cutaneous flaps ,,,, , reverse flow arterial flaps , and free flaps  have been described for the coverage of defects in the distal leg and foot. They are either indicated in, small defects, involve multi staged procedures, un-reliable, and require sacrifice of major vessels or technically highly demanding. Ever since Masquelet described and popularized the concept of neurocutaneous flaps in clinical use, several simpler distally based adipo- fascial pedicled fascio cutaneous flaps from the posterior calf based either on the neuro cutaneous perforators accompanying the sural, lateral superficial sural nerve or venocutaneous perforators accompanying short saphenous vein have been described and practiced clinically with great success.
We have used the distally based superficial sural artery flap described by Hasegawa etal  and Rajacic etal  and later classified by Nakajima  as his A'flap, in 48 patients with moderate sized defects in the distal 2/3 leg and proximal foot, with good results. The anatomical basis, brief surgical technique, the advantages and the disadvantages of this simple procedure has been discussed.
| Material and methods|| |
Between 1998 August and 2002 September, 48 patients with moderate sized skin and soft tissue defects (any raw area whose any one dimension is more than 5cm is considered moderate defect, any raw area whose any one dimension is more than 15cm is considered large defect and is excluded from the study) in the lower 2/3 of leg, posterior heel and dorsum of the hind foot were treated with distally based superficial sural artery flap. Forty patients were males and 8 females. The average age of these patients was 32 years (ranging between 9 to 66 years). In 43 cases the indication for flap surgery was traumatic defect. One case had a defect produced after excision of a recurrent giant cell tumor arising from the lower end of tibia. There were 2 diabetic ulcers, one post burn scar contracture and varicose ulcer. The average dimension of the defect was 7.5cm x 5cm ranging from 5cm x 2.5cm to 12.5cm x 5cm. The recipient sites of the defect were over the medial aspect of the ankle joint (10 cases), tendoachilles (6 cases), posterior heel (8 cases), distal 1/3 of tibia (8 cases), middle 1/3 of tibia (12 cases) and dorsum of the foot (4 cases). All the 20 cases where the defects were present on the distal 2/3 of tibia had concomitant fracture tibia with or without fracture fibula. These associated fractures were treated either with external fixator (8 distal 1/3 tibia and 6 middle 1/3 tibia) and interlocking nailing (6 in middle 1/3 of the tibia). Four patients had diabetes mellitus. One of the elderly diabetics (case no. 14) had total loss of flap presumably due to micro angiopathic changes in the vessels.
Most of the flaps in post traumatic cases (36 cases, excluding case no. 12) have been undertaken as delayed primary procedure and the average time gap between injury and flap procedure was 7.5 days (1 to 21 days).
Anatomical basis of flap: Popliteal artery in the popliteal region gives off a dominant arterial branch each to the medial and lateral heads of gastrocnemius. In addition to these muscular branches it also gives sural artery which divides into median, lateral and medial branches, the first one being constant and the last one being quite variable. Some times these medial and lateral branches may be derived from inferior genicular arteries or the muscular sural artery supplying the gastrocnemius. These medial and lateral branches are reciprocal to each other in size. There is also a reciprocal relation in size between the direct cutaneous sural vessels and muscular arteries supplying the two heads of the gastrocnemius. The median sural artery generally accompanies the sural nerve and short saphenous vein in the proximal calf. Branches of the median sural artery supply the skin and the subcutaneous area of the posterior part of the middle 1/3 of the calf. This suprafascial plexus of vascular network arborises both longitudinally and radially and anastomoses with the septocutaneous perforators of the peroneal artery in the distal 1/3 of the calf. It is this reliable suprafascial anastomoses of vascular network of 2 different sources that forms the basis of distally based adipofascial pedicled fasciocutaneous flap from the middle 1/3 of the calf. Peroneal septocutaneous perforators are quite constant in number and the most distal one is given off well within 5 cm proximal to the tip of the lateral malleolus. Hence the pivot of this distally based flap can be as distal as 5cm from the tip of the lateral malleolus. Careful dissection and mobilization of these perforators can permit further distalisation of the pivot of the flap to cover distal foot and sole.
Recent concept of venocutaneous perforators from the arterial branches accompanying the short saphenous vein can also supply these distally based flaps independent of the neurocutaneous perforators. Hence theoretically and practically these distally based flaps can include the skin and subcutaneous tissue of the proximal 1/3 of the calf (Type B1 and D1 lesser saphaenous VA flaps of Nakajima) provided the flap is raised with the short saphenous vein without damaging accompanying artery  .
Surgical procedure: With the patient in prone position (patient can also be put in lateral position with the involved side up) the recipient raw area is measured. The flap with a radius of 0.5cm more than that of recipient raw area is designed, marked on the posterior or postero lateral aspect of the calf on its middle 1/3, disposed either vertically or transversely as required by the pre-operative planning. The distal limit of the flap should not extend into the proximal third of the posterior calf. The pivot of the flap is about 5cm proximal to the tip of the lateral malleolous. The pedicle of the flap between the pivot and the proximal margin of the flap is exposed with a zig zag incision of the skin where the skin flaps are elevated with a single layer of subdermal fat. The actual fascio cutaneous flap is raised with the deep fascia anchored to the skin in order to prevent the shearing between the skin and deep fascia injuring the precarious supra fascial plexus of vessels. At the distal end of the flap the median sural artery, short saphenous vein and the sural nerve are ligated and cut. Pedicle of appropriate length (till the pivot point) with a minimum of 2-2.5cms width is raised along with the deep fascia. At this stage of the dissection the tourniquet may be removed and viability of the flap may be assessed carefully. Sufficient time of more than 5 minutes may be allowed for this purpose with the flap in unstretched position. Once the viability is confirmed the flap may be transferred to the recipient defect either by tunneling or by opening the skin bridge, taking care that there is no undue tension over the pedicle and the flap. The stay sutures between the skin and deep fascia are removed. The flap is sutured loosely to the margin of the defect without any tension with minimum sutures. Multiple drains are left behind under the flap. The donor defect generally needs split skin graft coverage. Plaster of Paris slab given without compression bandage with a provision to inspect the flap at regular intervals. The limb post operatively is elevated with care to prevent any compression over the pedicle or the grafted donor area. Marginal discoloration may be present particularly in elderly patients which usually settle as the edema subsides.
With these precautions and techniques most of the moderately sized defect between 5cm and 12.5cm can be covered in the distal 2/3 leg, ankle, posterior heel and dorsum of hind foot. Coverage of dorsum of fore foot and middle 1/ 3rd sole will need greater dissection of pedicle to distalise the pivot point, as described by some authors is dangerous and has not been tried in this series. Recently we have started using only fascial flaps with split skin graft to cover the tendoachilles area to decrease the bulk of the flap with good functional and cosmetic results.
| Results|| |
Of the 48 cases, 44 had uneventful post operative course. One elderly diabetic had a total loss of flap (case no.14) on the 4th post-operative day. Three patients (case no.8, 16 & 23) had marginal necrosis of the flap which settled with time and did not require any secondary procedure. These minor complications are attributed to technical problems like not selecting a slightly larger flap compared to recipient raw area, excessive tension on the pedicle, too many tight sutures during the final inset of the flap, non functioning drains and faulty post operative positioning of the limb compressing the pedicle. Selecting this distally based flaps in the elderly diabetics will be risky and probably be avoided. Our initial success and euphoria made us over confident in selecting this flap, in case no 14. Subsequently we have avoided this procedure in elderly particularly in diabetic. No donor raw area could be primarily sutured, hence all were grafted. There was no graft loss in any of the cases. No patient had pain or paraesthesia over the sural distribution. Though 12 patients complained of sural hypoesthesia, none of them had any functional deficit due to sural hypoesthesia. The mean follow up period of 48 patients was 2 years and 9 months (Ranging from 1 year to 6 years).
| Discussion|| |
Several procedures have been described for coverage of soft tissue defects of the distal 2/3 of the leg and foot,,,,,,,,,,,, with their own disadvantages. The advent of neurocutaneous flaps by Masquelet  has led to a new way of approaching the problem once considered a waterloo for reconstructive surgeons who are not familiar with the microvascular free flaps.
Septocutaneous perforators of the peroneal artery in the distal 1/3 of the calf are constant, reliable and well documented. Distally based fascial or fasciocutaneous flaps when raised with the deep fascia along with the sural nerve, short saphenous vein and the superficial anastomotic arcade connecting the peroneal septocutaneous perforators and the median sural artery, provides reasonably big, simple, safe and reliable flap to cover moderate sized defects in any part of the distal 2/3 of the leg, ankle and proximal foot. Ease of elevation, pedicle width and length, arc of rotation of the flap are some of the other advantages of the flap. Neurocutaneous and venocutaneous perforators provide reliable blood supply for the flap, with negligible functional deficit (pre operative Doppler study is not necessary).
Distalization of the pivot of the flap by careful dissection and mobilization of the perforator, and proximalizing the flap by including the saphenous vein and the venocutaneous perforators will enable the surgeon to extrapolate the indications of this flap to cover more distal raw areas in the forefoot and sole. Donor area of the flap is generally not involved in the zone of injury even in polytrauma. The donor raw area is also adequately vascularised for easy uptake of graft. Complexity of concomitant surgical intervention such as interlocking tibial nails, external fixator including Ilizarov apparatus does not pose any technical problems in flap elevation and flap inset.
Some of the disadvantages of the flap are:
- The need for prone position during surgery (can be avoided by positioning the patient in lateral decubitus).
- Sural hypoesthesia (can be avoided by sparing the sural nerve as in D' flaps of Nakajima).
- Unsightly post scar on the calf (can be avoided by using fascial flaps).
- This flap can deprive the orthopaedic surgeon of a useful posterolateral Harman's approach for bone grafting in tibial delayed or nonunion, as a part of secondary reconstructive procedures.
In conclusion, we recommend this extremely handy armamentarium which is available at the disposal of the reconstructive surgeons to deal with difficult problem of providing skin and soft tissue coverage for moderate sized defects in the distal leg and foot. This new procedure seems to overcome many problems faced by the surgeon during the contemporary alternative options.
| References|| |
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B Jagannath Kamath
Jyothi Mansion,1st floor, Opp. Prabhath Talkies, K.S.Rao Road, Mangalore-575001, Karnataka
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7]