The reconstruction of the middle 3rd of the leg poses a lesser challenge compared to the distal 3rd of the leg. Currently, the free flap is the treatment of choice for large soft tissue defects of the distal extremity. Though it solves the problem of donor site morbidity in the immediate vicinity of the flap, It is however a technically demanding procedure for surgeons with less microsurgical experience. In our environment where there is limitation in the facility and experience for free flaps, the reverse sural artery flap has proven to be one of the few safe options for soft tissue coverage
 in this part of the leg. The accompanying arteries of the lesser saphenous vein and sural nerve have been utilized with success for harvest of reverse flow sural flap
. The sural nerve remains the anatomic landmark for the inclusion of vessels in pedicle of the flap
. The sural artery reverse flow flap is nourished by the lowermost perforating branch of the peroneal artery. The sural nerve run vertically down the narrow groove between the two heads of gastrocnemius muscle and pierces the deep fascia halfway down the leg to run subfascially. Passing down this plane, it is joined by the peroneal communicating nerve
. In raising the sural artery flap, the sural and the peroneal communicating nerve are transected. Though the numbness in the distribution of sural nerve is not a major concern to many surgeons as it is self limiting
, there is the potential of patient developing painful neuroma if the stump is not buried in the deep muscular plane. Furthermore, a patient that is not well motivated may have recurrent injury to the numbed area while awaiting sensation to return which can be a recipe for chronic leg ulcer. In a diabetic, there is wisdom on preserving sensation to the foot so as not to contribute to their developing a neuropathic ulcer. In rural area where many walk unshodded to the farm, preserving protective sensation to the foot is no doubt important so as to rehabilitate patient back to his or her means of livelihood as soon as possible.
Though so much has been documented on the various modification of the reverse sural artery flap
[2–15], the literatures are quiet about the possibility of preserving the sural nerve while raising the flap. In the index patient, there was the problem of extensive tibia periosteal stripping exposing a length of about 23cm, with loss of skin and normal tissue architecture. The maximum flap size reported is 17x16 cm
. The soleus bulk can hardly cover the defect and there was still the fear of further stripping the periosteum while raising the soleus flap. After proper planning, knowing that the free flap technology is not available, the option left was to use the nerve preserving reverse sural artery flap and hemisoleus flap for the distal and upper part of the defect respectively.
This case demonstrates the possibility of raising the reverse sural artery flap up to the point of the sural nerve piercing the deep fascia without transecting the nerve. This case clearly demonstrates that the sural nerve should not routinely be transected in all cases where reverse sural artery flap is needed. As long as the planned pivot of the flap is about the point of the sural nerve piercing the deep fascia and the arc of rotation will not be more than 100°, there is no need to transect the nerve. In selected patients, this can be used to cover the upper part of the distal 3rd and the mid 3rd of the leg. It may also be possible to use the nerve preserving reverse sural artery flap as a cross leg fashion to cover the contralateral distal leg defect.
Raising this flap at this level is technically less demanding as the surgeon will be nowhere near the distal septocutaneous perforators which are 5 to 7 cm proximal to the tip of the lateral malleolus. Compared to the soleus muscle flap in the reconstruction of the middle 3rd of the leg, it is less invasive. The complementary function of the soleus muscle to the gastrocnemius is preserved. The procedure is easier for younger surgeon compared to the soleus muscle flap. The problem of painful neuroma at the point of transection of the sural nerve is eliminated. This procedure will not eliminate the aesthetic problem of secondary defect as seen in the classical reverse sural artery flap unless this can be closed directly. However, poor cosmesis would be of less concern in relation to function when dealing with trauma.
The nerve preserving reverse sural artery flap may be a good option for patients with diabetic and other sensoneural problem presenting with significant soft tissue loss involving the upper part of the distal 3rd and the middle 3rd on the ipsilateral leg. It can also be used for soft tissue defect involving the lower and middle 3rd on the contralateral leg. It is hoped that in the nearest future, the sural nerve can be selectively preserved while transposing or interposing the flap through the point of the distal septocutaneous perforator so as to achieve ankle and the heel cover. Further studies are needed to tell if patients who have had their sural nerve harvested for grafting can benefit from the reverse sural artery flap.