Anatomical study of terminal peroneal artery perforators and their clinical applications.

INTRODUCTION: Peroneal artery gives off plenty of perforators that pass through fascial septum to supply skin and tenosynovium of peroneal muscles. AIM: The aim of this study was to study the anatomical basis of perforators from terminal part of peroneal artery axiality and to make use of this knowledge in reconstructing defects of posterior heel with the advantage of reducing the morbidity of conventional flaps.
MATERIALS AND METHODS: Our study was conducted at Department of Plastic surgery, Madras Medical College and Rajiv Gandhi Government General Hospital, India. We have carried out eleven cadaver dissections (from six cadavers-four fresh cadavers and two preserved cadavers) and delineated all septocutaneous and septosynovial perforators of distal peroneal axis and studied their relation with short saphenous vein (SSV) and sural nerve. Using this anatomical knowledge we have fashioned perforator based flaps in 13 patients (three propeller, four V-Y advancement, six tenosynovial flaps) for reconstruction of defects over tendo achilles and pericalcaneal region.
RESULTS: In all cases, SSV and sural nerve were preserved and donor site was closed primarily. No total flap loss was noted.
CONCLUSION: Perforator based flaps from distal most part of peroneal artery provide a good and reliable method for reconstruction of pericalcaneal and tendo achilles region defects with preservation of SSV and sural nerve. It also avoids contour deformity of the grafted donor site of the classical lateral calcaneal artery axial flap.

INTRODUCTION

Soft tissue defects of the posterior heel present difficult reconstructive problems due to the bony prominence, limited availability of local tissue, requirement for thin, pliable tissue and the limitations imposed by donor site morbidity. Also, the recipient sites are stimulated continuously by footwear. The calcaneal region and the posterior and plantar heel especially are exposed to pressure, friction, and shearing forces.

Local random flaps are limited by the availability of mobile skin. Several types of reverse flow island flaps have been developed in the form of fasciocutaneous or septo-cutaneous flaps but they require sacrifice of an important leg artery and create obvious contour deformities at the donor site.[1]

Lateral calcaneal artery (LCA) flap originally described by Grabb and Argenta in 1981 is axial pattern Fasciocutaneous flap that includes the LCA, short saphenous vein (SSV) and the sural nerve. Peroneal vessels are last to be affected by age, Diabetes mellitus or smoking, making it a safe flap. Disadvantage of the flap are donor site grafting, over the periosteum giving a depression deformity. Patients also have sensory disturbance at the lateral part of the dorsum of foot.[2]

Island modification has been described to prevent the problems associated with classic lateral calcaneal artery skin flaps such as kink in the pedicle, dog-ear deformity, and the need for sacrificing the normal skin bridge for flap inset. It also has a greater arc of rotation. But it could not solve the problems associated with the donor-site area.[345] Another disadvantage is the possible compression over the pedicle by the skin bridge between the donor site and the recipient site.

The use of free flaps has improved the ability to cover soft tissue defects in this region. However, the flap bulk, the need for secondary procedures, and the risk of vascular failure are considerable obstacles.[1]

A new retrograde tenosynovial flap of peroneal tendons with split skin graft to resurface the exposed Achilles tendon has also been defined.[6] Being deep to the deep fascia, the flap tissue remains protected in trauma of moderate severity. Apart from resurfacing, the inner lining provides functional synovium which helps in gliding and simultaneously enhancing nutrition to the tendon to promote tendon healing. Since the flap is being supplied by a different source vessel, i.e., the musculofascial perforator, future harvesting of peroneal perforator-based flap remains feasible. The flap is thin and provides excellent aesthetic results. It has no functional donor site morbidity except a linear scar. It is also technically simple and easily accessible.

Perforator flaps, originally pioneered by Koshima in Japan in 1989, involve the dissection of terminal blood vessels into a tissue segment. The advantages over the traditional flap include reduced bleeding, preservation of the muscle and its function, versatility of the flap design to yield a better match to the defect and increased mobility of the flap.[7] It has proven to be effective as both a free flap and a pedicled flap.

Our study aims at the application of perforator based flaps concept with the background knowledge gained from cadaver dissections in planning reconstruction of soft tissue defects in the posterior heel from distal peroneal artery axiality to achieve the optimal reconstruction with preservation of sural nerve, short saphenous vein and primary closure of donor site, thereby greatly reducing donor site morbidity and contour deformity also.

MATERIALS AND METHODS

Cadaver studies

These were conducted in preserved cadavers (two cadavers-four specimen) in the Department of Anatomy, Madras Medical College and in fresh cadavers (four cadavers-seven specimen, as one cadaver had one mutilated lower limb) of unclaimed bodies in the Department of Forensic medicine, Government General hospital, Chennai after obtaining permission and consent from respective department Heads and Institutional Ethical committee approval.

Procedure for cadaver dissection

Incision made along the axiality of distal part of peroneal Artery. Both antegrade and retrograde dissection done. Axial vessel delineated. Number and location of all septocutaneous and septosynovial perforators noted. Relationship of these pereforators to short saphenous vein and sural nerve studied [Figures 1 and 2].

Figure 1

Cadaver dissection

Figure 2

Cadaver dissection tenosynovial sheath

Clinical case studies

These were conducted in the Department of Plastic Surgery, Rajiv Gandhi Government General Hospital and Madras Medical College over a period of 46 months from November 2008 to September 2012. Institutional Ethical committee approval was obtained.

Patient selection

Patients with post traumatic small and medium sized soft tissue defects and unstable scars over TendoAchilles and Pericalcaneal region were included in this study. Smokers were also included after a minimum of two weeks abstinence.

Large defects where primary closure of donor site was deemed not possible during preoperative planning were excluded from the study. These defects were covered with regional flaps.

Informed written consent was obtained from all patients explaining the nature of the procedure and study details. Patients had no added financial implications in lieu of the study.

All patients were submitted to Hand held Doppler study of perforators of the distal most part of peroneal artery and the most suitable perforator was selected taking into account the adequacy of audio signal, mobility of flap design and proximity of the perforator to the defect. All patients were operated under regional anaesthesia with the patient in extreme lateral position with knees slightly flexed. Adequate postoperative immobilisation was ensured.

Operative procedure for skin flaps

Dimensions of the skin defect are recorded. Flap raised as per preoperative plan and design. A visual assessment of the perforators is then made and the best perforator as preoperatively planned was selected as the pedicle [Figure 3]. Rest of the pedicles were sacrificed. Careful dissection around the pedicle is done up to the point where the pedicle penetrates the deep fascia. Meticulous division of all the fascial strands that would potentially cause vascular embarrassment through kinking of the vessels are performed under magnification. Once the flap perfusion is satisfactory, the flap is secured into position with the first two skin sutures placed on either sides of the axis of the pedicle ensuring that the pedicle is not put under any traction tension either in a proximal or distal direction. A drain is placed carefully under the flap if necessary and secured well away from pedicle [Figure 4]. The rest of the flap inset and wound closure is completed. The donor defect is closed primarily. Over tight bandaging is avoided to prevent vascular embarrassment. A window is made in the dressing to observe the flap, especially the tip.

Figure 3

V-Y advancement

Figure 4

Bilobed propeller design

Operative procedure for tenosynovial sheath flap

Lazy‘S’ incision was made on the lateral aspect of the leg starting from the edge of the defect or from 3-4 cm above the lateral malleolus up to mid-calf if required. Fasciocutaneous flaps raised on either side. Peroneal muscle with synovial sheath exposed. Proximal collar incision made in the sheath over the Peroneus longus and extended vertically downwards, on either side. Distal dissection carried on till the level of previously Doppler identified perforators. The flap was transferred to the defect either by transposing or by tunneling beneath subdermal flaps raised till the edge of the defect [Figure 5]. Split thickness skin graft was applied to cover the flap in case of skin defect. The donor site was closed primarily.

Figure 5

Distally based peroneal tenosynovial sheath flap over ta repair

RESULTS

Cadaver dissections

Three to five constant SeptoCutaneuos perforators were identified, the proximal most was on an average of 3 cm from tip of lateral malleolus and the distal most was at the level of tip of lateral malleolus. All are Septofasciocutaneous perforators directed downwards and laterally, running in the thick fascial septum between Peroneus Longus antero laterally, Tendo Achilles and Flexor Hallucis Longus medially. All the perforators were medial to sural nerve and short saphenous vein [Figure 6] [Table 1].

Figure 6

Schematic diagram

Table 1

Cadaver dissection studies

Two or three constant septosynovial perforators were present, arising from the septocutaneous perforators in all but one cadaver in which it was arising directly from the axial vessel, two cm from tip of lateral malleolus.

No major flap loss was noted in any of the patients. Two patients with Tenosynovial sheath flap had partial loss of flap of which one was following sepsis and a third patient with Tenosynovial flap had superficial necrosis of the bridging skin. One patient with V-Y advancement had distal inset line dehiscence and another had distal marginal loss, which were subsequently managed with secondary suturing [Table 2].

Table 2

Clinical case studies

DISCUSSION

The cadaver dissections have shown the constant nature of the septocutaneous perforators and septosynovial perforators arising from the terminal part of peroneal artery [Figures 7 and 8]. With this anatomical knowledge, it was possible to fashion skin flaps and Peroneal tenosynovial sheath flaps to cover critical defects over Tendoachilles and pericalcaneal region. The reliability of these flaps was proved by the clinical case studies. In all these patients, it was possible to preserve Short Saphenous Vein and Sural nerve thereby avoiding the anaesthesia over the lateral border of foot, which is of particular importance in our part of the world where sitting in the floor with the lateral border of foot coming in contact with floor is very common in day to day activities including eating habits. Also these flaps have a distinct advantage of avoiding the depression deformity of grafted donor site as in case of the classical flaps because the donor skin is recruited from proximal aspect and is closed primarily, and hence donor site morbidity is much reduced [Figure 9]. Also these flaps have a good contour, conformity and natural appearance and avoid the dog ear problems of the classical flaps and thus wearing shoes is not a problem.

Figure 7

Cadaver dissection study with dye injection flip side of the setptum

Figure 8

Cadaver dissection study with dye injection

Figure 9

Late postop V-Y advancement

The only limitation of this flap is the size constraints. In our study we have covered an average defect size of 2.36 cm × 2.37 cm with skin flaps and larger defects (maximum of 4 cm × 4.5 cm with tenosynovial sheath flap and SSG). We have used donor site primary closure as the guiding factor while preoperatively planning the skin flap dimensions. Much larger defects were covered with regional flaps. How much of skin can be harvested safely on a single perforator (perforosome) is a question still to be answered which requires further studies.

CONCLUSION

With the background anatomical knowledge, Any composition flaps (fascial, adipofascial, synovial, skin) can be fabricated safely and reliably based on the perforators of distal most part of peroneal artery, preserving sural nerve and SSV with no contour deformity of donor site, to cover small and medium sized critical defects over TendoAchilles and Pericalcaneal region.