Comparison of the effect of bacterial inoculation in musculocutaneous and fasciocutaneous flaps

The skin fascial flap is now recognized as a reliable flap for use in reconstructive surgery. The fasciocutaneous flap has been advocated for coverage of chronic infected wounds after debridement as an alternative to the musculocutaneous flap. Previous experimental and clinical studies have demonstrated the superior resistance of the musculocutaneous flap as compared to the random-pattern flap to bacterial inoculation. A canine model is presented for comparison of the effect of bacterial inoculation in fasciocutaneous and musculocutaneous flaps of similar dimensions. The area of skin necrosis secondary to bacterial inoculation was similar in these two flap types despite greater blood flow and skin oxygen in the fasciocutaneous flap. In a study of closed wound spaces formed by the deep surface of these two flap types, a greater degree of inhibition and elimination of bacterial growth and more collagen deposition are observed in the musculocutaneous wound space than in the fasciocutaneous flap.     

Expression of basic fibroblast growth factor and transforming growth factor-Beta 1 in patients with fasciocutaneous and muscle flaps

Angiogenesis involves multiple sequential mechanisms stimulating the growth of host endothelium. It occurs in surgical flaps at the interface with the reconstructed wound bed. In this study, concentrations of basic fibroblast growth factor (bFGF) and transforming growth factor-beta 1 (TGF-beta ) were analyzed in sera and wound fluids of 30 patients who underwent surgical treatment with muscle (n = 15) and fasciocutaneous flaps (n = 15). At 12 hours after operation, bFGF levels in wound fluids of patients with muscle flaps were significantly (p < 0.05) higher than in patients with fasciocutaneous flaps. At 24 and 36 hours after surgical treatment, there was no significant difference between them. Each group showed a significant decrease in bFGF levels after 24 and 36 hours. In sera, bFGF was not detectable. The two different groups presented no remarkable difference in TGF-beta concentrations in wound fluids. A correlation between angiogenic factors in sera and wound fluids could not be observed. The results show that angiogenesis is initially more activated in the wound bed of muscle flaps. This might be of great consequence to the healing process and might explain the curative effect of muscle flaps on bradytrophic tissue.     

Peripheral neovascularization of muscle and musculocutaneous flaps in the pig.

Late loss of free muscle flaps following surgical or accidental trauma to the dominant vascular pedicle has been reported. In this study, time-dependent ligation of the dominant vascular pedicle was undertaken in denervated latissimus dorsi musculocutaneous or muscle-only island flaps in the pig. Muscle flaps were covered with a skin graft, and silicon rubber sheets were inserted between the flaps and their bases to simulate a poorly vascularized bed. Hemodynamic and viability studies were then performed using intravenous fluorescein (skin viability), tetrazolium blue (muscle viability), and radiolabeled 15-micron microspheres (capillary blood flow). Blood flow did not change in acutely raised musculocutaneous flaps (n = 10) but was significantly elevated in acutely raised muscle-only flaps (n = 10), suggesting that the skin paddle may steal blood flow from the underlying muscle in musculocutaneous flaps. Peripheral neovascularization at 1 day to 8 weeks was assessed (n = 30). Viability increased during the first week of revascularization and was not different in musculocutaneous and muscle-only flaps. Revascularization of muscle-only flaps was enhanced compared with musculocutaneous flaps in the 2- to 8-week period.     

Treatment of ischial pressure ulcers with a posteromedial thigh fasciocutaneous flap.

This study describes the use of the posteromedial thigh fasciocutaneous flap for the treatment of ischial pressure sores. The authors prefer this flap because it is the fasciocutaneous flap nearest to the ischial region, it is easy to raise, and it causes no donor-site morbidity. In this study, 11 ischial pressure sores in 10 paraplegic patients were closed using the posteromedial thigh fasciocutaneous flaps. All flaps survived, although two caused distal necrosis; after these same two flaps were readvanced, they survived. After an average follow-up time of 77 months, seven of the 10 patients have had no recurrence of ulcers.This fasciocutaneous flap was previously described by Wang et al. However, this study revealed that the arrangement of the vascular pedicle was different from that described by Wang et al. To reveal the vascular supply of this flap, anatomic dissections were conducted. The source of circulation to this flap was the suprafascial vascular plexus, in addition to the musculocutaneous perforator. The dominant pedicle was the musculocutaneous perforator from either the adductor magnus muscle or the gracilis muscle. The key to safe elevation of this flap was the accurate outlining of the skin island directly over the vascular pedicle and the preservation of the proximal fascial continuity. Of the 11 flaps, two viability problems occurred. These partial flap losses resulted from the failure to properly include the perforator. It is the authors' conclusion that the width of the flap should be greater than 5 cm. In addition, it is safe to make a flap within a 1:3 base-to-length ratio in a fatty, diabetic patient. This posteromedial thigh fasciocutaneous flap was found to be a valuable alternative for reconstruction of primary or recurrent ischial pressure ulcers.     

Comparison of the intracellular bacterial killing activity of leukocytes in musculocutaneous and random-pattern flaps

The in vivo physiologic response to gram-negative bacterial inoculation within wound cylinder spaces enclosed by the deep surface of paired musculocutaneous and random-pattern flaps was studied in the canine model. Leukocyte function was assessed by calculating the following values: leukocyte counts, bacterial counts, phagocytic indices, and intracellular bacterial killing ratios. The following results were observed in the wound cylinder spaces after bacterial inoculation with 5 X 10(7) of Pseudomonas aeruginosa bacteria: (1) the numbers of mobilized leukocytes within each wound cylinder space flap were not statistically different, (2) the bacterial counts were significantly lower in the musculocutaneous flap wound cylinder space at both 24 and 48 hours, (3) the phagocytic activity of the leukocytes within musculocutaneous flap wound cylinder space was 1.5 times greater than the leukocytes in the random-pattern flap wound cylinder space, and (4) the intracellular bacterial killing ratio of the musculocutaneous flap leukocyte was 83 percent versus 26 percent in the random-pattern flap leukocyte, a significant difference.     

Have we found an ideal soft-tissue flap? An experience with 672 anterolateral thigh flaps

The free anterolateral thigh flap is becoming one of the most preferred options for soft-tissue reconstruction. Between June of 1996 and August of 2000, 672 anterolateral thigh flaps were used in 660 patients at Chang Gung Memorial Hospital. Four hundred eighty-four anterolateral thigh flaps were used for head and neck region recontruction in 475 patients, 58 flaps were used for upper extremity reconstruction in 58 patients, 121 flaps were used for lower extremity reconstruction in 119 patients, and nine flaps were used for trunk reconstruction in nine patients. Of the 672 flaps used in total, a majority (439) were musculocutaneous perforator flaps. Sixty-five were septocutaneous vessel flaps. Of these 504 flaps, 350 were fasciocutaneous and 154 were cutaneous flaps. Of the remaining 168 flaps, 95 were musculocutaneous flaps, 63 were chimeric flaps, and the remaining ten were composite musculocutaneous perforator flaps with the tensor fasciae latae. Total flap failure occurred in 12 patients (1.79 percent of the flaps) and partial failure occurred in 17 patients (2.53 percent of the flaps). Of the 12 flaps that failed completely, five were reconstructed with second anterolateral thigh flaps, four with pedicled flaps, one with a free radial forearm flap, one with skin grafting, and one with primary closure. Of the 17 flaps that failed partially, three were reconstructed with anterolateral thigh flaps, one with a free radial forearm flap, five with pedicled flaps, and eight with primary suture, skin grafting, and conservative methods.In this large series, a consistent anatomy of the main pedicle of the anterolateral thigh flap was observed. In cutaneous and fasciocutaneous flaps, the skin vessels (musculocutaneous perforators or septocutaneous vessels) were found and followed until they reached the main pedicle, regardless of the anatomic position. There were only six cases in this series in which no skin vessels were identified during the harvesting of cutaneous or fasciocutaneous anterolateral thigh flaps. In 87.1 percent of the cutaneous or fasciocutaneous flaps, the skin vessels were found to be musculocutaneous perforators; in 12.9 percent, they were found as septocutaneous vessels. The anterolateral thigh flap is a reliable flap that supplies a large area of skin. This flap can be harvested irrespective of whether the skin vessels are septocutaneous or musculocutaneous. It is a versatile soft-tissue flap in which thickness and volume can be adjusted for the extent of the defect, and it can replace most soft-tissue free flaps in most clinical situations.     

A fasciocutaneous flap for vaginal and perineal reconstruction

A skin and fascia flap from the medial thigh is proposed for vaginal and perineal reconstruction. Dissection, vascular injection, and radiographs of 20 fresh cadaver limbs uniformly demonstrated the presence of a communicating suprafascial vascular plexus in the medial thigh. Three to four nonaxial vessels were consistently found to enter the proximal plexus from within 5 cm of the perineum. Preservation of these vessels permitted reliable elevation of a 9 X 20 cm fasciocutaneous flap without using the gracilis muscle as a vascular carrier. Fifteen flaps in 13 patients were used for vaginal replacement and coverage of vulvectomy, groin, and ischial defects. Depending on the magnitude of the defect, simultaneous and independent elevation of the gracilis muscle provided additional vascularized coverage as needed. Our experience indicates that the medial thigh fasciocutaneous flap is a durable, less bulky, and potentially sensate alternative to the gracilis musculocutaneous flap for vaginal and perineal reconstruction.     

Effects of sodium pentobarbital anesthesia on blood flow in skin, myocutaneous, and fasciocutaneous flaps in swine.

Drug effect on flap blood flow is most commonly determined in anesthetized animals, yet the effect of the anesthetic is often poorly understood. Halothane and nitrous oxide cause profound changes in skin blood flow and thus provide an unsuitable anesthetic technique for use in measuring drug effects on skin and myocutaneous flaps in swine. The goal of this study was to determine the effects of sodium pentobarbital anesthesia on cardiovascular parameters and blood flow in skin, myocutaneous, and fasciocutaneous flaps in pigs. In seven pigs, 7 forelimb skin flaps, 7 forelimb fasciocutaneous flaps, 14 arterial buttock flaps, and 14 latissimus dorsi flaps were created. Blood flow was measured at 2-cm intervals along each flap while the animal was awake and anesthetized. A cardiac depressant effect of pentobarbital was observed, but no change in blood flow could be demonstrated in control skin or control muscle. However, pentobarbital did significantly increase blood flow in all viable portions of arterial and random skin flaps, fasciocutaneous flaps, and the cutaneous segments of the latissimus dorsi flap. These demonstrated effects of pentobarbital should be taken into consideration in designing and analyzing studies of flap blood flow in the acute postoperative phase.     

Fasciocutaneous flaps: an experimental model in the pig

No experimental studies have substantiated the claim that fasciocutaneous flaps are superior to skin flaps. Using fasciocutaneous flaps designed in the pig, both flap survival and blood flow were assessed. The forelimb and hindlimb fasciocutaneous flaps survived to 8.2 +/- 0.3 cm and 7.9 +/- 0.3 cm, respectively, compared with 7.3 +/- 0.3 cm and 6.7 +/- 0.3 cm for the comparable cutaneous flaps, a statistically significant finding (p less than 0.01). Random fasciocutaneous flaps survive 12 to 18 percent longer than skin flaps. Using the radioactive microsphere technique, blood flow was measured after flap elevation, and flap survival was estimated using fluorescein. Again, a significant difference in flap survival was found, but there was no significant difference in measured blood flow. This can be explained by the relatively large interval between blood flow measurements (2 cm) compared with the observed difference in survival length (1.0 +/- 0.3 cm).     

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.     

Experimental pretransfer expansion of free-flap donor sites: II. Physiology, histology, and clinical correlation

There is a statistically significant increase in blood flow into expanded cutaneous and myocutaneous flaps in a pig model over controls. The vascular trees within flaps enlarge following expansion, and pronounced neovascularization is seen in the papillary dermis and capsular layers. Experimentally, there is differential thinning of all tissue layers except the epidermis. A successful clinical application of this technique, by free-tissue transfer of an expanded fasciocutaneous scapular flap, is described. The technique is applicable when altered flap size or contour is desired.     

The role of serum imbibition for skin grafts

Numerous studies of grafted skin suggest that full-thickness skin grafts are nourished by exudate from the recipient bed called a serum imbibition. However, whether serum imbibition by itself is sufficient for nourishment of skin grafts has not been shown definitely and directly. To clarify the role of serum imbibition, we performed a comparative study between 20 skin grafts and 20 musculocutaneous flaps. The nourishment of the cell in the skin graft is by serum imbibition. That in musculocutaneous flaps is mainly derived from blood supply. We evaluated the nourishment by means of the unique characteristics of the cell cycle. Once cells are put into a synthetic phase, they cannot reverse or stop the progress of the cell cycle. To take advantage of this characteristic of the cell cycle, prewounding methods (40 flaps were lifted once and put back to the original sites prior to the evaluation) were intended for the cells in pre-elevated skin to turn into a proliferating phase. Cells were examined by antibody against proliferating cell nuclear antigen immunohistologically, to determine whether they had turned into the proliferating phase or not. After 3 days, all flaps were reelevated; half (20 flaps) had their muscle layer and the neurovascular bundle removed to make a full-thickness skin graft. The rest (20 flaps) were only lifted. They were sutured back to the original sites. Ten skin grafts and musculocutaneous flaps each were harvested at 3 hours (1st day) and at 11 days (11th day) after the second operation. Bromodeoxyuridine, which is a thymidine analog and is taken into the cells in the synthetic phase, was introduced intraperitoneally 2 hours before the harvest. All flaps and grafts were evaluated histologically and immunohistologically. Proliferating cell nuclear antigen analysis showed that the prewounding method induced the cells of skin grafts and musculocutaneous flaps to proliferate before the implantation. Regarding the bromodeoxyuridine uptake, no significant differences could be seen between skin grafts and musculocutaneous flaps irrespective of their different nourishment. No structural changes, such as degenerative or necrotic, could be seen at the hair follicle and other glands even at the 11th day. Almost all of the layers of skin grafts survived as long as they were checked by light microscopy (hematoxylin and eosin stain). No differences could be seen between musculocutaneous flaps and skin grafts or between the 1st and 11th days in this study. We concluded that serum imbibition is sufficient for nourishment of skin grafts, just as blood supply is sufficient for nourishment of musculocutaneous flaps.     

Differential effects of venous stasis and arterial insufficiency on tissue oxygenation in myocutaneous island flaps: an experimental study in pigs.

The supply, consumption, and tissue tension of oxygen were studied in experimental bilateral myocutaneous island flaps in five control pigs and in eight pigs during progressive 1-hour intervals of flap ischemia. Progressive ischemia was obtained by partial to complete clamping of the artery in one flap, producing arterial insufficiency, and simultaneous clamping of the vein in the other flap, producing venous stasis. Blood flow was reduced to 50, 25, and 0 percent of baseline. In the arterial insufficiency flaps, the oxygen tension in subcutaneous tissue, muscle, and venous outflow was significantly reduced once blood flow was reduced to 50 percent of baseline. Oxygen consumption during partial vessel occlusion was lower in the venous stasis flaps than in the arterial insufficiency flaps when blood flow was reduced to 25 percent of baseline, suggesting either that cellular metabolism is reduced in the venous stasis flaps or that the oxygen which is delivered is unavailable for the cells. Increased presence of tissue fluid in the venous stasis flap inhibits the diffusion of oxygen through the interstitial tissue, and this may explain the lower oxygen consumption. During 3 hours of reperfusion, increased blood flow was observed in the arterial insufficiency flaps, whereas blood flow in the venous stasis flaps was sluggish. The arterial insufficiency flaps recovered more rapidly than the venous stasis flaps during the first hour of reperfusion, judged by the rate of increase in oxygen tension and the higher venous oxygen tension. Oxygen tension increased more rapidly in muscle than in subcutaneous tissue.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reconstruction of the weight-bearing surface of the foot with nonneurosensory free flaps

Neurotized fasciocutaneous flaps and split-skin grafted muscle flaps are the most frequently used free flap alternatives for the reconstruction of weight-bearing surfaces of the foot. An objective comparison of the innate characteristics of these two flap types, with respect to long-term stability, has not been possible because sensory reinnervation in the fasciocutaneous flaps has been a confounding factor. This study compares nonsensate fasciocutaneous flaps (n = 9) with nonsensate split-skin grafted muscle flaps (n = 11), with mean follow-up periods of 34.3 and 31.3 months, respectively. Patients completed a form that included questions regarding degree of pain at the operative site, presence of ulcers, ability to wear normal shoes, employment status, and time spent standing on foot. Touch and deep sensation were evaluated with Semmes-Weinstein and vibration tests, respectively. Significantly less pain and less ulceration (p < 0.05) were observed in the fasciocutaneous group. Semmes-Weinstein monofilament tests revealed poorer results with split-skin grafted muscle flaps, compared with fasciocutaneous flaps. These results indicate that even if the sensory protection of fasciocutaneous flaps is not considered, these flaps have superior properties, compared with split-skin grafted muscle flaps.     

The blood supply of thigh skin

The pattern of blood supply to the integument of the thigh is reported. A new technique is described for analyzing the length, direction, and number of arterioles in specimens of cadaver skin and deep fascia. The information obtained from these studies adds to existing knowledge of the anatomic vascular basis of direct cutaneous and musculocutaneous flaps in this region and provides a scientific basis for the elevation of fasciocutaneous flaps in such a way as to aid the achievement of maximum length-to-breadth ratios.     

The "reduced" latissimus dorsi musculocutaneous flap

This report introduces a new device among latissimus dorsi flaps: the "reduced" latissimus dorsi musculocutaneous flap. This flap consists of a proximal musculocutaneous unit and a distal, thin fasciocutaneous unit (the "reduced" portion). The former unit carries a reliable blood supply from the thoracodorsal artery and is able to cover deeper recipient defects, while the latter provides a well-contoured reconstruction of the defect. If needed, an extended portion and/or a thin cutaneous flap can be carried along with the flap according to the defect. In our clinic, we have so far used four pedicled and one free reduced latissimus dorsi musculocutaneous flap in the repair of a variety of defects. All flaps survived, and satisfactory contour of the recipient site was achieved in each case. These clinical experiences clarify that a reduced portion 10 cm in length can be safely carried, and it is suggested that survival of this flap does not depend on its width-to-length ratio.     

An anatomic study of the septocutaneous vessels of the leg

The vascular anatomy of the skin and fascia of the leg were studied in 20 cadaver legs that were injected and dissected under magnification to identify the origin, course, and distribution of vessels from the subfascial level to the skin. In addition to the longitudinally oriented fasciocutaneous arteries and the musculocutaneous perforators, the study demonstrated a third and important system of blood supply: the septocutaneous vessels. These vessels arise directly from the posterior tibial, anterior tibial, and peroneal arteries, run along the intermuscular septum, pierce the crural fascia, and ramify radially in the subcutaneous tissue superficial to the fascia. Longitudinally oriented anastomotic arcades are formed along the leg between branches of adjacent septocutaneous vessels. Each septocutaneous vessel has one or two venae comitantes. Selected methylene blue injections of the septocutaneous vessels revealed rich staining of the superficial surface of the fascia, the subcutaneous tissue, and distinct longitudinally oriented skin territories. There was no injection of dye in the deep surface of the fascia. It is felt that the septocutaneous vessels constitute an important source of skin circulation in the leg and form the basis for various fasciocutaneous flaps that have useful clinical applications.     

Reconstruction of heel and sole defects by free flaps

One latissimus dorsi musculocutaneous flap and five radial forearm flaps were used in reconstruction of weight-bearing parts of the heel and sole, the follow-up period being 7 to 38 months. Additional injuries such as forefoot amputations or amputations of the other leg were present in four patients. There was no flap loss. The latissimus dorsi flap proved to be too bulky and showed recurrent ulcerations, several reoperations were necessary, and definite healing has not occurred. The five forearm flaps gave good results, with a walking range from 2 hours to unimpeded walking. Complications included fissuring at the edges of one large flap and a local infection which was successfully treated. Cutaneous sensation returned in all but one flap, where it was reduced preoperatively due to a meningomyelocele. The results indicate that the fasciocutaneous radial forearm flap should be taken into consideration for reconstruction of weight-bearing areas of the heel and sole. Shortcomings of this flap include an unsightly donor defect and possible hair growth on the flap.     

The dorsal thoracic fascia: anatomic significance with clinical applications in reconstructive microsurgery

The anatomic distribution and potential arterial flow patterns of the circumflex scapular artery were investigated by Microfil injection. These studies demonstrated that the circumflex scapular artery lies within the dorsal thoracic fascia, which plays a significant role in the circulation of the overlying skin and subcutaneous tissue. We conclude that scapular/parascapular flaps are fasciocutaneous flaps, the dorsal thoracic fascia can be transferred as a free flap without its overlying skin and subcutaneous tissue, and intercommunication exists between the myocutaneous perforators of the latissimus dorsi myocutaneous flap and the vascular plexus of the dorsal thoracic fascia. We present microvascular cases in which the vascular properties of the dorsal thoracic fascia facilitated wound closure with free fascia flaps or expanded cutaneous or myocutaneous flaps.