Two new cutaneous free flaps: the medial and lateral thigh flaps

Two new cutaneous free-flap donor areas are described on the medial and lateral sides of the thigh. The medial thigh flap is supplied by an unnamed artery from the superficial femoral artery and is drained by the accompanying venae comitantes. Its nerve supply is from the medial femoral cutaneous nerve. The lateral thigh flap has its vascular pedicle from the third perforating artery of the profunda femoral artery and its accompanying vein. The lateral femoral cutaneous nerve provides sensation over the area. These flaps provide a large surface area of both skin and subcutaneous tissue without the usual bulk of subcutaneous fat and muscle. Their desirable features include long vascular pedicles with large vessel diameters and potential of being neurovascular flaps with specific sensory nerve supply and predictable anatomy. The principal disadvantage is that the donor site may leave a slight contour defect with primary closure or require grafting when a large flap is taken. We predict that these flaps will become important donor sites for reconstructive problems requiring resurfacing of cutaneous defects in various anatomic areas.     

Free-style free flaps

Free-tissue transfer has become the accepted standard for reconstruction of complex defects. With the growth of this field, anatomic studies and clinical work have added many flaps to the armamentarium of the microvascular surgeon. Further advancements and experience with techniques of perforator flap surgery have allowed for the harvest of flaps in a free-style manner, where a flap is harvested based only on the preoperative knowledge of Doppler signals present in a specific region. Between June of 2002 and September of 2003, 13 free-style free flaps were harvested from the region of the thigh. All patients presented with an oral or pharyngeal cancer and underwent resection and immediate reconstruction of these flaps. All flaps were cutaneous and were harvested in a suprafascial plane. The average size of the flaps was 108 cm2 (range, 36 to 187 cm2), and the average length of the vascular pedicle was 10 cm (range, 9 to 12 cm). All flaps were successful in achieving wound coverage and functional outcomes without any vascular compromise necessitating re-exploration. Free-style free flaps have become a clinical reality. The concepts and techniques used to harvest a free-style free flap will aid in dealing with anatomic variations that are encountered during conventional flap harvest. Future trends in flap selection will focus mainly on choosing tissue with appropriate texture, thickness, and pliability to match requirements at the recipient site while minimizing donor-site morbidity.     

Angiography of the iliofemoral arteriovenous system supplying free groin flaps and free hypogastric flaps.

The circulatory anatomy of the iliofemoral region was elucidated by doing detailed angiography in 50 cases, and we classified the vessels into 4 types. In most cases, the s.c.i.a. predominated over the s.i.e.a. Therefore, it is probably better to plan free flaps supplied by this artery. This vessel usually arises approximately two or three fingerbreadths inferior to the intersection of the femoral artery and the inguinal ligament, and the skin flap should be designed in the area inferior and parallel to the inguinal ligament.     

Pharmacologic action of isoxsuprine in cutaneous and myocutaneous flaps

The therapeutic effects of isoxsuprine on skin capillary blood flow and viability were studied in arterial buttock flaps, latissimus dorsi myocutaneous flaps, and random skin flaps in pigs. It was observed that parenteral isoxsuprine increased capillary blood flow to the skin of arterial buttock flaps and the skin and muscle of latissimus dorsi myocutaneous flaps in a dose-response manner, with a maximum vascular effect observed at 1.0 mg/kg. However, this maximum effective dose of isoxsuprine did not have any significant effect on skin viability in the cutaneous and myocutaneous flaps compared with the control. Examination of the distribution of capillary blood flow within the flaps at varying distances from the pedicle revealed that isoxsuprine did not increase capillary blood flow or perfusion distance in the distal portion of the skin of arterial buttock flaps, latissimus dorsi myocutaneous flaps, and random skin flaps. The increased capillary blood flow as a result of isoxsuprine treatment was limited only to the arterial portion of the arterial buttock flaps and latissimus dorsi flaps. Therefore, it is concluded that isoxsuprine alone is not effective in augmentation of skin viability in cutaneous and myocutaneous flaps. The pharmacologic action of isoxsuprine on the vasculature in the skin and muscle of flaps was also discussed.     

Tissue and plasma levels of endothelin in free flaps

The goal of the study was to assess whether endothelin-1 levels are increased in tissue and plasma in free flaps. To assess this hypothesis, blood samples were taken from the general circulation before and after reperfusion and from the flap after reperfusion in 20 patients undergoing breast reconstruction with free transverse rectus abdominis musculocutaneous or deep inferior epigastric perforator flaps. Tissue samples were also taken from the flap before and after the period of ischemia. Peripheral blood samples of 10 ml each were taken before the vessels were clamped and at 10 minutes and 1 hour after the flap was recharged. The flap vein was catheterized with a smooth catheter to avoid endothelial trauma, and ischemic blood from the flap was obtained immediately after the artery was unclamped and 10 minutes later. Two skin samples of 2 cm each were taken: one after dissection of the flap before division of the vessels and one after reanastomosis of the veins (one or two veins). Statistical analyses were performed with the (nonparametric) Wilcoxon signed rank test. Flap ischemia time, from vessel division to the completion of the arterial anastomosis, ranged from 35 to 120 minutes (mean, 48 minutes). The plasma endothelin-1 level extracted from the flap was 4.34 +/- 0.85 pg/ml, significantly higher than baseline, 3.87 +/- 0.81 pg/ml (p < 0.0001). There was a small increase, 4.5 +/- 1.03 pg/ml (p = NS), 10 minutes after reperfusion. The peripheral level after venous anastomosis was 3.78 +/- 0.79 pg/ml, not significantly different from the peripheral plasma level, before the flap was raised. The peripheral plasma level 1 hour after reperfusion was 3.83 +/- 0.8 pg/ml, with no difference from baseline. The tissue level of endothelin-1 before clamping was 3.8 +/- 0.8 pg/mg and in postischemic tissue, 5.2 +/- 0.6 pg/mg, a statistically significant increase. The authors concluded that endothelin-1 levels are elevated in free flaps. This could be an explanation for vasospasm and may lead to therapy directed against the no-reflow phenomenon.     

The no-reflow phenomenon in experimental free flaps.

The no-reflow phenomenon was studied following reconstitution of blood flow by microvascular anastomosis in an ischemic and denervated free epigastric flap in the rabbit. Microscopic, histological, angiographic, and hematological studies demonstrated the progressive nature of this obstruction to the peripheral blood flow after increasing periods of ischemia. This obstruction reached a point of irreversibility after 12 hours of ischemia, leading to ultimate death of these flaps. These results are consistent with the hypothesis that an ischemia-induced no-reflow phenomenon is caused by cellular swelling, intravascular aggregation, and the leakage of intravascular fluid into the interstitial space. Similarities between these experimental findings and human observations are made. The clinical importance of early diagnosis and treatment of ischemic tissues is emphasized.     

The use of free groin flaps in children

The free groin flap is a well-established method of skin coverage. Although its use in children has been reported, there have been no published series specifically in such cases. The authors report 33 consecutive cases of free groin flaps in children in their unit over a period of 9 years (1992 to 2001). Tissue transfer was performed to provide soft-tissue coverage during reconstruction of congenital defects and tumor resection and following trauma. Twenty-six cases (79 percent) involved the upper limb, six cases (18 percent) involved the lower limb, and one case involved the head. The complication rate compares favorably with similar series published for adults, with only two complete failures (6 percent), three (9 percent) minor donor-site complications (superficial wound infection, hypertrophic scarring, and dog-ears), and nine flaps requiring debulking. The reexploration rate was 24 percent, with seven of the eight flaps undergoing reexploration surviving. The groin flap is a reliable flap that can be used safely in children, with minimal morbidity.     

Experimental comparison of bone revascularization by musculocutaneous and cutaneous flaps

Revascularization, one of the major components of bone healing, was examined in an experimental model. The radioactive microsphere technique demonstrated that after 4 weeks beneath a musculocutaneous flap, isolated bone segments had significant blood flow, whereas bone beneath a cutaneous flap did not. The muscle flap bone had a blood flow approximately half that of normal control bone. The muscle of the musculocutaneous flap had a blood flow three times that of the skin of the cutaneous flap. The bipedicle cutaneous flap used was designed to have a healthy blood supply, and at 4 weeks it had a blood flow twice that of control skin. Despite this, there was essentially no demonstrable blood flow in the cutaneous flap bone segments at 4 weeks. Only 3 of 17 bone segments underneath cutaneous flaps showed medullary vascularization, whereas 10 of 11 muscle flap bones did. All bone segments underneath muscle flaps showed osteoblasts and osteoclasts at 4 weeks; neither were seen in the cutaneous bone segments. The process of revascularization occurred through an intact cortex and penetrated into the cancellous bone. Because the bone segments were surrounded by an impervious barrier except for one cortical surface, the cellular activity seen is attributed to revascularization by the overlying flap. In this model, a muscle flap was superior to a cutaneous flap in revascularizing isolated bone segments at 4 weeks. This was documented by blood flow measured by the radioactive microsphere technique and by bone histology.