Intraoperative hemodynamic evaluation of the radial and ulnar arteries during free radial forearm flap procedure.

The purpose of this prospective study was to assess the blood flow of the radial and ulnar arteries before and after radial forearm flap raising. Twenty-two patients underwent radial forearm microvascular reconstruction for leg soft tissue defects. Blood flow of the radial, ulnar, and recipient arteries was measured intraoperatively by transit-time and ultrasonic flowmeter. In the in situ radial artery, the mean blood flow was 60.5 +/- 47.7 mL/min before, 6.7 +/- 4.1 mL/min after raising the flap, and 5.8 +/- 2.0 mL/min after end-to-end anastomosis to the recipient artery. In the ulnar artery, the mean blood flow was 60.5 +/- 43.3 mL/min before harvesting the radial forearm flap and significantly increased to 85.7 +/- 57.9 mL/min after radial artery sacrifice. A significant difference was also found between this value and the value of blood flow in the ulnar and radial arteries pooled together ( P < 0.05). The vascular resistance in the ulnar artery decreased significantly after the radial artery flap raising (from 2.7 +/- 3.1 to 1.9 +/- 2.2 peripheral resistance units, P = 0.010). The forearm has a conspicuous arterial vascularization not only through the radial and ulnar arteries but also through the interosseous system. The raising of the radial forearm flap increases blood flow and decreases vascular resistance in the ulnar artery.

P75 nerve growth factor receptor is expressed in regenerating human nerve grafts.

BACKGROUND: The purpose of this study was to elucidate the expression of p75 nerve growth factor receptor (p75NGFR) in human cross-facial nerve grafts and to compare the immunohistological findings with patient data and the functional outcome in facial reanimation. MATERIALS AND METHODS: The study comprised 37 sural nerve graft specimens. All of the patients had long-lasting complete facial paralysis and were operated on by the standard two-stage procedure involving cross-facial nerve grafts and microneurovascular muscle transfer. Nerve biopsies were taken 4 to 20 months (mean, 8 months) after the cross-facial nerve grafting. Immunohistochemistry for p75NGFR as well as for Schwann cells (S-100; Dako, Glostrup, Denmark) and for Neurofilament-200 (NF-200; Boehringer, Mannheim, Germany) was performed. RESULTS: In graft biopsies, the mean number of NF-200-positive axons amounted to 38% (range, 6-81%) of that in control samples. Further, regenerated axons were thinner than in control samples. Morphologically, the grafted nerves were characterized by fibrosis and invasion of inflammatory cells. A longer time between cross-facial nerve grafting and biopsy sampling correlated with a higher number of viable axons (NF-200) (P = 0.002). In all cases, expression of p75NGF receptor was clearly higher at the distal end of the grafted nerve. Expression of p75NGFR was lower in older than in younger patients (P = 0.003). A high expression of p75NGFR was often seen with better function of the transplanted muscle. CONCLUSION: Increased expression of p75NGFR in human nerve grafts was noted, especially in younger patients. We suggest that p75NGFR expression might be a contributing factor in a successful axonal regeneration and eventual recovery of muscle function.

Microscopic margins and results of surgery for dermatofibrosarcoma protuberans.

BACKGROUND: Dermatofibrosarcoma protuberans is a rare low-grade sarcoma of the skin with a tendency to recur locally after inadequate excision. Treatment has traditionally been wide excision with a 2- to 3-cm gross margin. Because of the variable results presented in mainly retrospective reports, it has been queried whether local control can be as good with conventional surgery as with micrographic surgery. METHODS: Forty patients with dermatofibrosarcoma protuberans treated by surgical excision were operated on at our center from 1987 to 2001. Data were recorded prospectively. Twenty-seven patients presented with a primary tumor and 13 with a locally recurrent tumor primarily operated on elsewhere. Gross and histologic margins were studied in detail. RESULTS: At a mean follow-up of 40 months, there were no recurrences. Thirty-four patients required single, five patients two, and one patient three operations before the margins were adequate (mean, 1.2 stages per patient). Twenty-three patients (58 percent) needed reconstructions. Tumor-free margins were obtained in 39 patients. The average thickness of surgical gross margins was 3.1 cm; histologically defined margins averaged 1.6 cm. CONCLUSIONS: Good local control can be achieved with wide surgery. Histologic tumor-free margins differ greatly from gross margins and are difficult to assess clinically and macroscopically. Careful postoperative histologic examination with margins measured in millimeters should be carried out to define the adequacy of excision in all directions. On average, a 1.6-cm histologic margin was adequate for complete local control. Most patients can be operated on in one stage. Reconstructions are often needed.

Long-term adaptation of human microneurovascular muscle flaps to the paralyzed face: an immunohistochemical study.

The purpose of this study was to characterize microneurovascular (MNV) muscle transplants immunohistochemically up to 10 years after transfer. Histological data was related to long-term functional outcome. The study comprised 17 patients with a mean age of 41 years suffering from complete unilateral long-lasting facial paralysis. A two-stage procedure was performed between 1986 and 2001. The gracilis, latissimus dorsi, and serratus muscles were used in four, eight, and five patients, respectively. Eighteen biopsy samples were taken from MNV muscle grafts during secondary refinement procedures. In one patient, the tissue samples were collected at two different time points. Immunohistochemistry testing revealed muscle fiber type distribution (anti-myosin fast), proliferating satellite cells (Ki-67), and reinnervation (S-100). Muscle atrophy was assessed histomorphometrically. In a recent study, patient characteristics and the function of the flap were evaluated. Histological data were compared with clinical data and long-term functional outcomes of the patients. In biopsy samples taken 1-10 (mean 31 months) years after MNV muscle transfer, the mean muscle fiber diameter was 38 (range 14-70) microm, indicating a 40% decrease compared with control values. Muscle atrophy was not type-specific and the mean percentage of type II fibers was not altered. Individual variation was, however, considerable. Proliferative activity of satellite cells was seen in 60% of the samples but it tended to decline with an increase in follow-up time. All samples showed intramuscular reinnervation. In statistical analysis severe atrophy correlated with prolonged intraoperative ischemia (P=0.04). The good long-term functional outcome correlated with dominance of fast fibers in muscle grafts (P=0.03). Atrophy tended to be more pronounced in the serratus than in the other muscles (ns). In summary, despite dense muscle reinnervation, morphology of the muscle is not fully restored after muscle transfer. Ischemia time affects muscle morphology. Adaptation of the graft to fast-twitch muscle activity favors better mimic function. The proliferative activity of satellite cells declines with prolonged follow-up time.

Changes in articulatory proficiency following microvascular reconstruction in oral or oropharyngeal cancer.

Articulatory proficiency of /r/ and /s/ sounds, voice quality and resonance, speech intelligibility, and intraoral sensation were examined prospectively before operation, and at four time points during a 1-year follow-up after microvascular transfer. Forty-one patients with a large oral or oropharyngeal carcinoma undergoing tumor resection and free-flap reconstruction usually combined with radiotherapy participated in the study. Articulation, voice, and resonance were investigated both live and from recorded speech samples by two trained linguistic examiners. The patients completed a self-rating of their speech intelligibility and were assessed for anterior intraoral surface sensation by means of 2-point moving discrimination. Misarticulations of /r/ and /s/ increased significantly after the therapy. Voice quality and resonance remained essentially normal. Speech intelligibility deteriorated significantly. Intraoral sensation decreased postoperatively but was not related to speech outcome. Sensate flaps did not prove to be superior in relation to speech tasks. A multidisciplinary approach is advocated in assessment of speech outcome after cancer surgery. Speech therapy is strongly recommended, even in the absence of a gross articulatory handicap.

Quality of life after free-flap reconstruction in patients with oral and pharyngeal cancer.

BACKGROUND: Our aim was to investigate quality of life and outcome after microvascular free-flap reconstruction after oncologic surgery. METHODS: Forty-four patients with a large carcinoma in the oral cavity, oral pharynx, or hypopharynx underwent free-flap surgery with or without radiotherapy. Patients completed the University of Washington Quality-of-Life Questionnaire preoperatively and four times during the 12 postoperative months. Survival rates and complications were analyzed. RESULTS: Postoperative composite quality-of-life scores were significantly lower than before treatment with no significant overall improvement during the follow-up. The scores for disfigurement, chewing, speech, and shoulder function remained significantly below the preoperative level throughout the follow-up. Sociodemographic factors predicted quality of life. Heavy drinking and unemployment caused a 2.4-fold and a 4.4-fold increase in risk of death, respectively. The rates for overall survival, tumor recurrence, flap success, and surgical complications were consistent with previous literature. CONCLUSION: Sociodemographic variables affect quality of life and patient survival in patients with oral cancer treated with microvascular free-flap reconstruction.

Swallowing after free-flap reconstruction in patients with oral and pharyngeal cancer.

Swallowing and intraoral sensation outcome were investigated prospectively after microvascular free-flap reconstruction. Forty-one patients with a large oral or oropharyngeal carcinoma underwent free-flap surgery usually combined with radiotherapy. The patients completed modified barium swallow, self-rating of swallowing, and 2-point moving discrimination preoperatively and at four time points during the 12-month follow-up period, and a plain chest X-ray one year after operation. Swallowing was impaired with respect to an objective and subjective measure after therapy. Rates for nonsilent and silent aspiration increased during the follow-up. Intraoral sensation deteriorated. Swallowing outcome was not related to sensation. One year after surgery, 86% of the patients ate regular masticated or soft food. Microvascular transfers offer a reasonable option for oral reconstruction. This study does not support the need for sensate flaps. Swallowing problems should be routinely sought and patients rehabilitated during a sufficiently long follow-up with videofluorography regardless of the patient's perception of swallowing.

Speech aerodynamics and nasalance in oral cancer patients treated with microvascular transfers.

The purpose of the current study was to assess speech aerodynamics and nasal acoustic energy during a follow-up period of 12 months in patients having undergone microvascular free flap reconstruction after tumor ablation from the oral cavity or oropharynx, usually followed by radiotherapy. Velopharyngeal function was assessed in terms of velopharyngeal orifice size by a pressure-flow measurement technique as well as by determining the instrumental correlate of perceived nasality (i.e., nasalance) during speech production. Velopharyngeal closure and nasalance were estimated to be adequate before operation both in oral cavity and oropharyngeal cancer patients. After the operation, at the group level, the oral cavity patients showed adequate velopharyngeal closure and nasalance. In contrast, the postoperative velopharynx orifice size was significantly bigger in the oropharyngeal cancer patients as compared with the oral cavity patients 6 months after operation. However, based on average aerodynamic as well as the nasalance data, the impairment of velopharyngeal function was not regarded clinically significant at the group level in either group of patients. The present treatment protocol served to maintain the prerequisites for normal or close to normal speech physiology.

Ki-67, Bcl-2 and p53 expression in primary and metastatic melanoma.

The aim of this study was to clarify the roles of the tumour proliferation marker Ki-67, the anti-apoptotic protein Bcl-2 and the cell cycle regulator p53 in primary cutaneous and metastatic melanoma. One hundred and seventeen primary melanomas and 18 metastatic tissue samples were analysed for immunohistochemical expression of Ki-67, Bcl-2 and p53. The staining results were correlated with disease progression and clinical outcome. The patient population comprised patients diagnosed with melanoma between 1988 and 1991. The clinical follow-up period for disease recurrence was 4.6 years (median; range, 0.2-7.5 years) and the follow-up period for overall survival was 10.0 years (median; range, 8.6-15.6 years). Ki-67 expression was not a prognostic factor in primary melanoma. High Bcl-2 expression was associated with such adverse prognostic factors as male gender, old age of the patient and tumour ulceration. High Bcl-2 expression was also associated with an adverse prognosis in intermediate-thickness (1.01-4.0 mm) melanomas (n=52) for disease-free (P=0.09) and overall (P=0.08) survival. In multivariate analysis, tumour thickness was the strongest prognostic factor for disease-free survival (P<0.01). High p53 expression indicated a poorer prognosis (P=0.05). In metastatic melanoma, the expression levels of Bcl-2 and p53 were lower than those in their primary counterparts (P=0.08 for each). Ki-67 expression showed no remarkable changes. It can be concluded that high p53 expression in tumour cells is associated with a poorer prognosis in primary melanoma, and high Bcl-2 expression in tumour cells is an adverse prognostic marker in intermediate-thickness primary melanoma.

Cyclooxygenase-2 expression in human soft-tissue sarcomas is related to epithelial differentation.

BACKGROUND: Cyclooxygenase-2 (Cox-2) is expressed by several types of epithelial malignancies, i.e., carcinomas, and inhibition of Cox-2 may have a therapeutic role in chemoprevention and treatment of cancer. The role of Cox-2 in non-epithelial malignancies, however, is unclear. MATERIALS AND METHODS: We investigated, by immuno- histochemistry, the expression of Cox-2 in 103 human soft-tissue sarcomas. RESULTS: All 10 biphasic synovial sarcomas were positive for Cox-2, but positivity was observable only in the epithelial component of these tumours. Excluding sarcomas with epithelial differentation, uniform staining of the tumour was observed in only 2 samples. In addition, positivity for Cox-2 appeared in tumour cells in only 18 samples around necrotic areas. CONCLUSION: In human soft-tissue sarcomas, Cox-2 expression seems to be associated with epithelial differentation and, in some types of sarcomas, to be expressed in otherwise negative tumours at sites of necrosis.

Ezrin in primary cutaneous melanoma.

Ezrin is a member of the ezrin-radixin-moesin family of proteins that link the actin-containing cytoskeleton to the plasma membrane. Ezrin is also connected to signaling molecules involved in the regulation of cell survival, proliferation and migration. Here, we examined the expression of ezrin in 95 primary cutaneous melanomas and correlated ezrin expression with conventional prognostic factors and biomarkers. From 12 patients metastatic tissue samples were also examined. In addition to ezrin staining, Mib-1 proliferation antigen, p53 and Bcl-2 were evaluated. Ezrin immunoreactivity was seen in most tumors; only 19 (20%) melanomas were negative. A total of 48 (51%) tumors had weak immunoreactivity and 28 (29%) strong immunoreactivity. The intensity of ezrin immunoreactivity was associated with tumor thickness (Breslow, P=0.0008) and with tumor invasion level (Clark, P=0.004), thicker tumors having stronger immunoreactivity. Also, there was a correlation between higher Mib-1 index in tumors and strong ezrin expression. All metastatic samples (n=12) showed positive ezrin immunoreactivity. In univariate analysis of survival, patients (n=76) with positive ezrin immunoreactivity had worse clinical disease behavior than those (n=19) without ezrin immunoreactivity, but the difference was not significant (P=0.19). In multivariate analysis of survival, the ezrin immunoreactivity was not a significant marker. The results indicate that ezrin is expressed in most primary melanomas of the skin and in all metastatic tumors. Ezrin expression correlates with tumor thickness and level of invasion suggesting an association between ezrin expression and tumor progression.

Births and perinatal health of infants among women who have had silicone breast implantation in Finland, 1967-2000.

BACKGROUND: Potential problems with breast implants have been widely discussed, but few data exist on the childbearing and offspring of women with implants. The purpose of this study was to investigate the occurrence and conditions of pregnancies of women who have had cosmetic breast implantation (exposed women), and the health of their newborns. METHODS: Women who had breast implants for cosmetic reasons in the period 1967-1999 (n = 2236) were identified from hospital surgical records. The births of the exposed women were identified through record linkage to the Population Register. The perinatal health of the infants was studied by the data in the Medical Birth Register in 1987-1999. For each birth to an exposed woman, 20 control mothers who gave birth in the same year were chosen randomly from the Medical Birth Register. Differences in mothers' background characteristics were adjusted by logistic regression. RESULTS: The women had received their first cosmetic breast implants at young ages (mean 31 years). By year 2000, 26% of the exposed women had one or more children. Half of these women had not had a liveborn child before getting implants. Of the 1661 exposed women who had not (yet) had children, 32% were less than 35 years of age at the end of follow-up. The women had children at a mean of 4.7 years after the implants. Some of the perinatal health indicators suggested poorer health and others better health for infants of exposed women, but only transfers to other hospitals and lower birthweight among infants of exposed multipara were statistically significant. CONCLUSIONS: The study shows that pregnancy and infant health are relevant considerations with regard to breast implants; further studies on implants are needed.

The effect of intravenous dopamine and dobutamine on blood circulation during a microvascular TRAM flap operation.

A study was conducted to assess the effect of intraoperatively administered inotropic agents on blood flow in the recipient and donor vessels, during breast reconstruction with a muscle sparing free TRAM flap. Twenty-one consecutive patients were randomized into 3 groups receiving either dopamine, dobutamine, or placebo. When the flap and all vessels had been fully dissected but not yet divided, the study drug was administered intravenously for 15 minutes. Hemodynamic parameters and transit-time flow of the thoracodorsal and inferior epigastric arteries were monitored. Both dobutamine and dopamine infusions resulted in significant raises in cardiac output and mean arterial pressure. However, while dobutamine resulted in a higher cardiac output (P = 0.001) and a decrease in systemic vascular resistance (P = 0.028), the increase in mean arterial pressure was greater with dopamine (P = 0.002). Only the dobutamine group showed increased blood flow, in both the thoracodorsal (P = 0.043) and the inferior epigastric (P = 0.043) arteries. If vasoactive agents are needed during microvascular anesthesia, dobutamine seems to be more advantageous than dopamine.

Facial reanimation by transplantation of a microneurovascular muscle: long-term follow-up.

The two-stage operation for reanimation of long-standing facial paralysis by cross-facial nerve grafting and later free microneurovascular muscle transfer has been the treatment of choice for nearly 25 years. However, the functional outcome may be unpredictable. We therefore need to know more about the factors that influence the final result. We have recorded the long-term results of microneurovascular surgery in facial paralysis, and evaluated which factors influenced the functional outcome. Twenty-seven of 40 patients aged 7 to 65 years (mean 40) operated on at Helsinki University Hospital between 1986 and 2000 were available for interview and video recording. The gracilis, latissimus dorsi, and serratus anterior muscles were used for microneurovascular transfer in 11, 10, and 6 cases, respectively. The outcome of microneurovascular muscle transfer was graded on House's scale 1 to 6. The mean follow-up period was 8.5 years (range 2 to 15). Sixteen patients (59%) displayed only mild or moderate dysfunction (grades 2 to 3) after reconstruction. In 8 patients (30%) dysfunction was graded as moderately severe, and in 3 (11%) as severe. There was a correlation between final functional outcome and the follow-up time after microneurovascular facial reanimation. The longer the follow-up time after muscle transplantation the poorer the functional result (p = 0.003). Twenty-one patients (78%) considered that their quality of life was better or much better after facial reanimation. Patients' satisfaction correlated with a good functional result.

Vascular endothelial growth factor-C gene therapy restores lymphatic flow across incision wounds.

Edema and insufficient blood perfusion are common problems in reconstructive surgery. The blood vasculature is reconstructed in microvascular flaps, whereas lymphatic vessel function is lost after surgical incision. Here, we demonstrate that vascular endothelial growth factor C (VEGF-C) gene transfer can be used to reconstruct a lymphatic vessel network severed by incision of skin flaps. We used adenoviral VEGF-C gene transfer at the edges of epigastric skin flaps in mice. Our results show that VEGF-C gene expression results in the formation of anastomoses between the lymphatic vessels of the skin flap and the surrounding lymphatic vasculature. Some spontaneous lymphangiogenesis also took place in the control mice, but the lymphatic vessels generated remained nonfunctional even 2 months postoperatively. In contrast, the VEGF-C treated mice demonstrated persistent lymphatic vessel function during the 2 month follow-up despite the transient nature of the adenoviral VEGF-C gene expression. The restoration of lymphatic function by VEGF-C in skin flaps provides new tools to promote vascular perfusion and to reduce tissue edema in skin and muscle flaps. These results have important implications for the prevention and treatment of surgically induced secondary lymphedema.

Matrilysin-1 (MMP-7) and MMP-19 are expressed by Paget's cells in extramammary Paget's disease.

BACKGROUND: Extramammary Paget's disease (EMPD) is a rare malignant neoplasm of apocrine gland bearing skin characterized by intraepidermal proliferation of adenocarcinoma cells. Tumor growth depends on the ability of tumor cells to migrate by proteolysis and on angiogenesis. The matrix metalloproteinase (MMP) enzymes have been implicated in both of these processes in other types of skin cancer. METHODS: The expression of MMP-1, MMP-2, MMP-3, MMP-7, MMP-9, MMP-13, and MMP-19 was analyzed by immuno- histochemistry and/or in situ hybridization in 27 EMPD and five mammary PD (MMPD) specimens. The distribution of laminin-5 (LN-5) and tenascin-C, two extracellular matrix proteins associated with tumor invasion, was studied by immunohistochemistry. RESULTS: MMP-7 (matrilysin-1) and MMP-19 were the most frequently expressed MMPs in Paget's cells. Overexpression of MMP-2, MMP-9, or MMP-13, which is seen in many cancers, was not evident in EMPD. LN-5 and tenascin-C positivity did not correlate with the level of invasion. MMP-7, MMP-13, and MMP-19 were detected abundantly in MMPD, while MMP-9 was absent. CONCLUSIONS: MMP expression did not generally associate with the level of invasion of EMPD. In three samples positive for MMP-7 and four samples positive for MMP-19, an underlying carcinoma was detected, suggesting the importance of these two MMPs as predictors of secondary EMPD or the putative origin of Paget's cells from the dermal adenocarcinoma cells of apocrine duct origin.

Long-term morphometric and immunohistochemical findings in human free microvascular muscle flaps.

Reinnervation, muscle regeneration, density of microvessels, and muscle-type specific atrophy were studied 3-4 years after surgery in surgically nonreinnervated free microvascular muscle flaps to 13 patients transplanted to the upper or lower extremities. Routine histology and immunohistochemistry for PGP 9.5 and S-100 (neuronal markers), Ki-67 (cell proliferation), myosin (muscle fiber types), and CD-31 (endothelium) were carried out, and results were analyzed morphometrically. Three to 4 years after surgery, severe atrophy of predominantly slow-type fibers was seen in 9 cases. In 4 cases, muscle-fiber diameter and fiber-type distribution were close to normal. Long intraoperative muscle ischemia and postoperative immobilization were associated with poor muscle bulk in flaps. The density of microvessels in flaps did not differ from control muscles. PGP 9.5 and S-100 immunopositive nerve fibers were detected in 7 patients. Reinnervation was associated with good muscle bulk. In 4 patients, activation of satellite cells was evident. The results suggest that in some cases, spontaneous reinnervation may occur in free muscle flaps, and that several years after microvascular free flap transfer, the muscle still attempts to regenerate.

Soft-tissue sarcomas of the upper extremity: surgical treatment and outcome.

The objective of this retrospective follow-up study was to evaluate the outcome of patients with soft-tissue sarcoma treated by the authors' protocol, which consists of a selective combination of conservative surgery and radiotherapy. Patients who relapsed were especially evaluated to improve treatment results. The authors examined 80 patients with local soft-tissue sarcoma in the upper extremity referred to their multidisciplinary group. Fifteen patients were referred for first or subsequent local recurrence, and 65 patients were treated for primary tumor. The goal of treatment was local control and preservation of a functional limb. Wide excision was attempted. If the margin was less than 2.5 cm, postoperative radiotherapy was administered. Eighty-five percent of the patients were treated by limb salvage. Thirty patients needed reconstructive procedures such as pedicled (20 patients) or free flaps (10 patients). No free flaps were lost. The 5-year disease-specific overall survival rate was 75 percent, the local recurrence-free survival rate was 79 percent, and the metastasis-free survival rate was 68 percent. In univariate analysis, prognostic factors for local recurrence were extracompartmental site; for development of metastases, large size and extracompartmental site; and for decreased disease-specific overall survival, large size and extracompartmental site. Intramuscular, cutaneous, and subcutaneous tumors had a 5-year local control rate of 100 percent, and extracompartmental tumors had a local control rate of 69 percent. Extracompartmental tumors clearly have the worst prognosis and should be the main target for improving treatment strategies. After exclusion of patients with inadequate treatment according to the authors' protocol, the local control rate at 5 years was 90 percent. Strict adherence to treatment protocol should be practiced.

Satellite cell proliferation, reinnervation, and revascularization in human free microvascular muscle flaps.

BACKGROUND: Satellite cell proliferation, reinnervation, and revascularization were studied in human nonreinnervated free microvascular muscle flaps to characterize mechanisms of muscle regeneration after flap surgery. MATERIALS AND METHODS: Patient biopsies (n = 19) were taken at operation and five timepoints up to 9 months after operation, and corresponding clinical data were obtained. Immunohistochemistry for Ki-67 was used to detect proliferating satellite cells, CD-31 to identify endothelial cells, and S-100 and PGP 9.5 proteins to detect reinnervation. RESULTS: Two weeks after operation, the expression of PGP 9.5 and S-100 had virtually disappeared in all larger nerve fibers and half of smaller nerve fibers. By 6 months, however, a strong expression of PGP 9.5 and S-100 had reappeared in larger nerve fibers in three of four flaps, suggesting that reinnervation had taken place. The number of mitotic satellite cells already peaked at 2 weeks, indicating onset of muscle regeneration. The number of intramuscular capillaries first increased but later decreased to lower than original level. Flaps with more muscle volume showed more reinnervation and satellite cell mitotic activity. In cases of a delay occurring in reconstructive surgery, a low level of reinnervation was seen. CONCLUSION: Three patients of four showed spontaneous muscle reinnervation in microvascular free flaps with satellite cell activation followed by restored morphology. Late reconstruction and obesity lead to poor reinnervation, placing emphasis on timing of surgery and patient selection.