Chang, Edward I. M.D.; Chang, Eric I. M.D.; Soto-Miranda, Miguel A. M.D.; Zhang, Hong Ph.D.; Nosrati, Naveed M.D.; Robb, Geoffrey L. M.D.; Chang, David W. M.D.
Since it was first described in 1979, the free transverse rectus abdominis musculocutaneous (TRAM) flap has become one of the most popular and reliable methods of microsurgical breast reconstruction. Over the years, the free TRAM flap has evolved to the muscle-sparing TRAM flap and the deep inferior epigastric perforator (DIEP) flap theoretically to minimize donor-site morbidity by harvesting less muscle and less anterior rectus fascia. One presumed advantage of the free DIEP flap over the free muscle-sparing TRAM flap is decreased morbidity at the abdominal donor site because no muscle is harvested with a DIEP flap.
The number of contralateral prophylactic mastectomies, and thus the number of bilateral breast reconstructions, has increased in recent years.1–9 Given the increasing frequency of contralateral prophylactic mastectomies, there is a pressing need for plastic surgeons to be able to provide accurate information about the potential risk of donor-site morbidity to patients pursing bilateral breast reconstruction using autologous tissue.
Several studies have explored the donor morbidity after harvest of abdominally based free flaps.10–16 However, whether free DIEP flaps are superior to free muscle-sparing TRAM flaps in terms of reducing the donor-site morbidity remains controversial. Some studies demonstrate a benefit, whereas others fail to demonstrate a difference. Furthermore, there is a relative lack of data that directly compare bilateral donor-site morbidity relative to unilateral donor-site morbidity.14–16 In addition, current studies on the donor morbidity after harvest of abdominally based free flaps have focused on the amount of muscle harvested comparing DIEP to full-muscle TRAM flaps and muscle-sparing TRAM flaps. However, to our knowledge, no study has directly examined the extent of rectus fascia sacrificed and how the fascia was repaired as it impacts the development of an abdominal bulge or hernia.
We hypothesized that patients undergoing bilateral autologous breast reconstruction using abdominally based free flaps are at higher risk for developing a donor-site complication compared with patients undergoing unilateral reconstruction. Further, we hypothesized that the amount of fascia harvested and how the fascia is closed have a direct impact on abdominal integrity regardless of the type of abdominal flap harvested.
This study aimed to (1) examine the differences with abdominal integrity after different types of abdominally based free flap harvest, (2) compare the differences with abdominal integrity after unilateral or bilateral reconstruction, and (3) examine donor-site morbidity as it relates to the amount of the fascia sacrificed and how the fascia was repaired.
A retrospective review of all patients undergoing autologous breast reconstruction using abdominally based free tissue transfer between January of 2000 and December of 2010 was performed. The type of abdominal free flap (TRAM, muscle-sparing TRAM, DIEP, and superficial inferior epigastric artery) was identified, and patients undergoing reconstruction with nonabdominal free flaps were excluded. The method for closure of the donor site was also recorded (primary closure versus placement of mesh). Flaps were also categorized into those that used a single row of perforators or flaps in which both the medial and lateral rows were incorporated. Patients’ medical records were reviewed, and documentation of a bulge or hernia based on physical examination and confirmed during operative exploration was noted. A hernia was defined as dehiscence of the fascia closure with either a palpable fascial defect on physical examination or identification of a hernia sac on operative exploration. Abdominal bulge was defined as any significant asymmetric abdominal bulging without a palpable fascia defect. Patient demographics, such as age, body mass index, smoking history, medical comorbidities, and surgical history, were also examined.
Flap harvest and closure of the fascia were routinely performed in identical fashion based on dictated operative notes. In general, a fascia-sparing technique was used to open the rectus sheath fascia, incorporating only a minimal cuff of fascia around the perforators and then connecting these islands. Typically, only a minimal amount of fascia was sacrificed, and primary closure of the fascia was performed if there was no tension and the quality of the fascia was adequate. However, flaps harvested with both the medial and lateral rows of perforators usually required more fascial sacrifice than did a single row regardless of flap type. A standard free TRAM flap resulted in the largest fascial defect compared with a muscle-sparing TRAM or a DIEP flap.
Using the fascia-sparing technique, primary fascial closure was routinely performed with interrupted nonabsorbable sutures followed by plication with a running suture. In cases in which the quality of the fascia was poor or there was excessive tension, an inlay placement of mesh was used. No surgeon routinely placed mesh during closure of the donor site. The choice of a bioprosthetic or a synthetic mesh was surgeon dependent but grouped together for statistical analysis.
Univariate analysis was performed using a chi-square test or Fisher’s exact test to analyze the association of each patient characteristic to developing an abdominal hernia/bulge or need for reoperation. Characteristics with a p value less than 0.25 were entered into the final multiple logistic regression model. We examined the association of flap type, donor-site closure, and perforator distribution with each outcome in univariate analysis. All analyses were performed using SAS 9.2 software (SAS Institute, Inc., Cary, N.C.), and p values less than 0.05 were considered statistically significant.
A total of 1575 patients underwent autologous breast reconstruction using an abdominally based free flap during the study period. Of these patients, 1053 were grouped into the unilateral cohort, and the remaining 522 patients were considered to have bilateral abdominal flaps harvested.
Specifically, eight patients underwent bilateral breast reconstruction but used either a superior gluteal artery perforator flap (n = 5), a latissimus flap (n = 1), or an implant (n = 2) to reconstruct one of the breasts and were therefore grouped in the unilateral donor-site cohort. In contrast, 51 patients (3.2 percent) underwent a bipedicle flap in which the entire abdominal flap was used for reconstruction of a unilateral breast defect and were therefore included in the bilateral group. An additional 44 patients (2.8 percent) underwent bilateral breast reconstruction or a bipedicle flap reconstruction in which one flap was a superficial inferior epigastric artery flap and were therefore included in the unilateral cohort. A total of 68 patients received only superficial inferior epigastric artery flaps for either unilateral or bilateral reconstruction and were excluded from analysis, leaving a total of 1507 patients in the study.
Overall, a total of 1507 patients (1044 unilateral flaps and 463 bilateral flaps) were included for analysis. Patients undergoing bilateral breast reconstruction were significantly younger (47.9 years versus 50.1 years, p < 0.0001) and more likely to be obese (37.6 percent versus 26.9 percent, p < 0.0001). Similarly, the percentages of patients who had chemotherapy and radiation therapy among the bilateral patients were significantly higher than those for the unilateral patients (57.5 percent versus 46.0 percent; p < 0.0001 and 41.9 percent versus 33.3 percent; p = 0.001, respectively). The remaining patient demographics are listed in (Table 1).
Primary fascial closure was achieved in the overwhelming majority of patients in both unilateral and bilateral free flaps. Of 1044 unilateral flaps, 180 donor sites (17.3 percent) were closed with synthetic mesh (n = 153) or bioprosthetic mesh (n = 27) (Table 1). One patient had both synthetic and bioprosthetic mesh placed in the donor site and was included in the synthetic mesh cohort for analysis. Unilateral TRAM flaps had the highest incidence of mesh use compared with muscle-sparing TRAM and DIEP flaps (27.2 percent versus 19.9 percent and versus 6.2 percent; p < 0.001) (Table 2). For patients with muscle-sparing TRAM and DIEP flaps, harvesting of both rows of perforators had a higher incidence of mesh use for fascia closure compared with harvesting a single row of perforators (19.8 percent versus 9.8 percent; p < 0.0001) (Table 2).
Of 463 bilateral patients, 134 patients (28.7 percent) required synthetic mesh (n = 115) or bioprosthetic mesh (n = 19), which was significantly higher than among patients undergoing unilateral reconstruction (24.8 percent versus 14.7 percent; p < 0.0001) (Table 1). Similarly, bilateral TRAM flaps had the highest incidence of mesh use, followed by bilateral muscle-sparing TRAM flaps and then bilateral DIEP flaps (59.2 percent versus 32.3 percent and versus 7.6 percent; p < 0.0001) (Table 3). Mesh was used significantly more often when both flaps used both medial and lateral row perforators compared with when one flap used both rows and one flap used a single row. When both flaps were based on a single row, mesh was used least frequently (34.3 percent versus 20.8 percent versus 17.2 percent; p < 0.0001) (Table 3).
Overall Donor-Site Morbidity
With a mean follow-up of 53.8 months, 89 patients (5.9 percent) developed a postoperative bulge (n = 68) or hernia (n = 21), and 71 (n = 79.8 percent) required a subsequent operation to repair the complication. Patients undergoing a bilateral or unilateral TRAM were significantly more likely to require operative repair of a donor-site bulge or hernia than were patients undergoing reconstruction using other flaps types (p = 0.04). Patients undergoing bilateral reconstruction were 1.35 times more likely to develop an abdominal bulge/hernia than were patients undergoing unilateral reconstruction, but the difference was not significant (p = 0.22). Other patient characteristics were not found to be significant predictors of abdominal hernia or bulge formation (Table 4).
Follow-Up and Fascial Closure
Patients were more likely to develop a bulge/hernia with longer follow-up (Table 4). Average follow-up for patients who developed an abdominal complication was 64.1 months compared with 53.1 months in patients who did not develop a bulge/hernia (p = 0.003). Multiple regression analysis confirmed length of follow-up (p = 0.0006) and method of fascial closure (p = 0.003) to be significant predictors for developing a donor-site complication. Overall, placement of mesh (synthetic or bioprosthetic) reduced the odds of occurrence of bulge/hernia by 70 percent compared with patients undergoing primary fascia closure (Table 5). Univariate regression analysis demonstrated a 1 percent increase in the odds of hernia/bulge occurrence for every month of follow-up in patients who underwent primary fascial closure (p = 0.004); however, length of follow-up had no effect on odds of donor-site morbidity occurrence when mesh was placed (p = 0.35) (Table 6).
Donor-Site Morbidity in Unilateral Breast Reconstruction
Of 1044 unilateral breast reconstructions, 57 patients (5.5 percent) developed abdominal bulge (n = 44) or hernia (n = 13). Unilateral TRAM flaps had the highest incidence of a bulge/hernia compared with muscle-sparing TRAM or DIEP flaps (9.9 percent versus 3.7 percent versus 5.9 percent; p = 0.004), but no difference was found between a muscle-sparing TRAM and a DIEP flap (3.7 percent versus 5.9 percent; p = 0.36) (Table 7). Analysis of the method for fascial closure demonstrated primary closure after a TRAM flap had the highest donor-site complication (11.8 percent TRAM versus 4.1 percent muscle-sparing TRAM versus 5.3 percent DIEP; p = 0.003). However, when mesh was incorporated, the difference was no longer significant although the trend still prevailed (4.8 percent TRAM versus 2.1 percent muscle-sparing TRAM versus 0 percent DIEP; p = 0.54) (Table 7). Multiple logistic regression showed that for all patients undergoing unilateral reconstruction, placement of mesh significantly reduced the odds of occurrence of bulge/hernia by 72 percent compared with primary closure (OR, 0.38; 95 percent CI, 0.15 to 0.79; p = 0.05) (Table 8). Flaps based on a single row or both rows of perforators did not demonstrate any difference in donor-site morbidity (4.6 percent versus 3.3 percent, p = 0.36).
Donor-Site Morbidity in Bilateral Breast Reconstruction
Of 463 bilateral breast reconstructions, 32 patients (6.9 percent) developed abdominal bulge (n = 24) or hernia (n = 8). Overall, there was no difference in donor-site morbidity among bilateral TRAM (8.2 percent), bilateral muscle-sparing TRAM (8.3 percent), and bilateral DIEP flaps (3.3 percent, p = 0.65) (Table 7).
Although there was a trend toward worse donor-site outcomes with bilateral TRAM flaps regardless of closure technique, the difference was not statistically significant. Patients undergoing primary closure after a bilateral TRAM had a 15.0 percent risk of developing a bulge or hernia compared with 11.5 percent (muscle-sparing TRAM) or 3.5 percent (DIEP), which was not significant (p = 0.22) (Table 7). In patients who had mesh closure of the fascia, patients undergoing TRAM flaps also had the highest incidence of abdominal complications (3.4 percent) compared with muscle-sparing TRAM flaps (1.6 percent) or DIEP flaps (0 percent), but the difference was not significant (p = 0.60).
Multiple logistic regression analysis showed that for all patients undergoing bilateral reconstruction, placement of mesh (synthetic or bioprosthetic) reduced the odds of occurrence of bulge by 84 percent compared with primary fascia closure (p = 0.02) and bilateral DIEP flaps reduced the odds by 81 percent (p = 0.04) compared with TRAM flap (Table 8).
Subgroup analysis of flap types did not demonstrate any significant differences in the occurrence of an abdominal complication. Specifically, there was no difference in donor-site morbidity with bilateral muscle-sparing TRAM or DIEP flaps. However, upon examination of fascia harvested, when both rows of perforators were harvested for bilateral reconstruction, there was a significant increase in the likelihood of developing an abdominal bulge or hernia compared with bilateral single-row flaps (OR, 2.9; p = 0.03). However, if one flap was based on a single row and the second flap was based on both rows, the difference was no longer significant (OR, 1.8; p = 0.25).
Autologous free tissue transfer is common for breast reconstruction, and the abdomen remains the primary donor site for free flap breast reconstruction. With an increasing trend toward contralateral prophylactic mastectomy and bilateral breast reconstruction, there is a need for better understanding of the donor-site morbidity, such as bulge or hernia, associated with abdominally based free flap breast reconstruction.17
Although several studies have examined the topic of donor-site morbidity, none has specifically or comprehensively compared bilateral flap harvest to unilateral flap harvest or critically evaluated the effect of the amount of fascia sacrificed and the means by which the fascia is repaired.
TRAM Flap versus Muscle-Sparing TRAM Flap versus DIEP Flap
In this study, we demonstrated that patients undergoing unilateral reconstruction with a TRAM flap were significantly more likely to develop an abdominal bulge/hernia than with a muscle-sparing TRAM flap or a DIEP flap; however, there was no difference between a muscle-sparing TRAM and a DIEP flap. Considering the extent of the muscle and fascia sacrificed in a traditional TRAM, it is not surprising that it was associated with significant risk of abdominal bulge/hernia formation, especially when the fascia was closed primarily, compared with other flap types (p = 0.003). However, when the fascia defect was closed with the aid of mesh, there was no longer an increased risk of donor-site complications, suggesting that reinforcement of the fascial closure with mesh should be performed in unilateral TRAM flaps (p = 0.54).
Most of the full-muscle TRAM flaps were performed early on in the study period; however, the majority of our current flaps are harvested using a fascia-sparing technique. Consequently, the only difference between a muscle-sparing TRAM flap and a DIEP flap is the amount of muscle sacrificed with only a minimal amount of fascia. Although some proponents believe that the muscle is the critical component, we believe preservation of the fascia should also be considered. This is supported by the fact that there was no difference in the risk of developing abdominal bulge/hernia between a muscle-sparing TRAM flap and a DIEP flap in our cohort.
Unilateral versus Bilateral
Although patients undergoing bilateral reconstruction were at a higher risk (OR, 1.35) of developing an abdominal bulge/hernia, the difference was not significant. Similarly, there was no difference in abdominal donor-site morbidity among different flap types in patients pursuing bilateral breast reconstruction, except that a bilateral DIEP was superior to a bilateral TRAM. In addition, subgroup analysis demonstrated a benefit when both flaps were based on a single row rather than if both rows were harvested in a bilateral reconstruction. However, no other differences were noted.
One possible explanation might be limited sample size, but another confounding factor might be that patients undergoing bilateral breast reconstruction had a higher percentage of mesh used compared with unilateral breast reconstruction patients. Patients undergoing bilateral TRAM flaps had the highest incidence of mesh placement, compared with other flap types (p < 0.0001). Regarding perforator distribution, bilateral flaps using both rows also required significantly more mesh use than did bilateral flaps using only single rows or if only one flap used both rows (p < 0.0001). Thus, we would recommend using mesh in the setting when the fascia quality is poor or if more fascia is sacrificed, as occurs in a traditional TRAM flap or when both rows of perforators are harvested.
We feel that the role of fascia and its impact on the donor-site morbidity have often been overlooked and overshadowed by the amount of the muscle harvested. In this study, we also aimed to evaluate whether the fascia could be a critical factor in determining the development of an abdominal hernia and bulge. We hypothesized that sacrificing more fascia would result in worse outcomes, as noted after a unilateral TRAM flap compared with a unilateral muscle-sparing TRAM or DIEP flap. However, no difference was seen when both rows and more fascia were harvested. We suspect that this might reflect the increased use of mesh in these circumstances, and failure to place mesh would have resulted in higher bulge/hernia rates with the loss of more fascia.
Multiple logistic regression showed that placement of mesh significantly reduced the odds of bulge/hernia occurrence in patients undergoing unilateral (72 percent risk reduction) or bilateral reconstruction (84 percent risk reduction). On the basis of this finding, the method of fascial repair is also critical for abdominal wall integrity after free flap harvest. Although we do not routinely use mesh in most muscle-sparing TRAM or DIEP flaps where there is a minimal fascia defect even for bilateral cases, one should consider the use of mesh if the quality of the fascia is poor or the primary closure is under too much tension due to a large fascia defect.
Furthermore, given the advances in cancer treatment and anticipated improvements in long-term survival, patients should be educated about the fact that they might develop a bulge/hernia years after the original reconstruction that might require another operation to repair the abdominal defect. We found that patients had a 1 percent increase in risk for developing a bulge or hernia per month if the fascia was closed primarily. However, if mesh was used, the length of follow-up was no longer significant. This further supports the need for careful and optimal repair of the fascia and the use of mesh if necessary.
One major weakness is the retrospective nature of the study involving many surgeons with minor variations in surgical flap harvest technique and closure of the donor fascia. However, the surgical technique described was fairly consistent despite the number of surgeons involved. On the basis of operative notes, no surgeon routinely placed mesh, and the decision to use mesh was based on the quality of fascia and amount of fascia sacrificed. To our knowledge, this represents one of the largest and most comprehensive analyses regarding donor-site morbidity after abdominally based free flap harvest, with a specific focus on comparing unilateral and bilateral reconstructions, examining the importance of the fascia sacrificed and closure, and analyzing the amount of muscle preserved.18–21
There was no significant difference in the risk of developing an abdominal bulge/hernia between bilateral and unilateral breast reconstruction. The extent of fascia harvested and how it is repaired play an important role in the development of donor-site morbidity. Placement of mesh should be considered for traditional TRAM flaps, if both rows are harvested, or to reinforce poor quality fascia.
The authors thank the current and past members of the faculty of the Department of Plastic and Reconstructive Surgery at the University of Texas M. D. Anderson Cancer Center for contribution of patients to this study.
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