Institutional Experience and Orthoplastic Collaboration Associated with Improved Flap-based Limb Salvage Outcomes

Abstract

Background

Flap-based limb salvage surgery balances the morbidity and complexity of soft tissue transfer against the potential benefit of preserving a functional limb when faced with a traumatized extremity with composite tissue injury. These composite tissue injuries are well suited for multidisciplinary management between orthopaedic and plastic surgeons. Thus, it makes intuitive sense that a collaborative, orthoplastic approach to flap-based limb salvage surgery can result in improved outcomes with decreased risk of flap failure and other complications, raising the question of whether this orthoplastic team approach should be the new standard of care in limb salvage surgery.

Questions/purposes

(1) Is there an association between increased annual institutional volume and perioperative complications to include free and local flap failure (substantial flap viability loss necessitating return to the operating room for debridement of a major portion or all of the flap or amputation)? (2) Is an integrated orthoplastic collaborative approach to managing combat-related traumatic injuries of the extremities individually associated with a decreased risk of flap failure and overall flap-related complications? (3) What other factors, such as location of injury, injury severity score, and initial inpatient length of stay, were associated with flap necrosis and flap-related complications?

Methods

We performed a retrospective review of the electronic medical records of all patients who underwent flap-based limb salvage for combat-related extremity trauma in the United States Military Health System’s National Capital Region between January 1, 2003 and December 31, 2012. In total, 307 patients underwent 330 flap procedures. Of the 330 flaps, 59% (195) were local or pedicled flaps and 41% (135) were free flaps. Patients were primarily male (99% [303]), with a median (interquartile range) age of 24 years old (IQR 21 to 29), and 87% (267 of 307) of injuries were sustained from a blast mechanism. We collected data on patient demographics, annual case volume involving flap coverage of extremities, mechanism of injury, flap characteristics, perioperative complications, flap failure, flap revision, isolated orthopaedic management versus an integrated orthoplastic approach, and other salvage procedures. For the purposes of this study, orthoplastic management refers to operative management of flap coverage with microvascular surgeons present for soft tissue transfer after initial debridement and fixation by orthopaedic surgery. The orthoplastic management was implemented on a case-by-case basis based on individual injury characteristics and the surgeon’s discretion with no formal starting point. When implemented, the orthoplastic team consisted of an orthopaedic surgeon and microvascular-trained hand surgeons and/or plastic surgeons. In all, 77% (254 of 330) of flaps were performed using this model. We considered perioperative flap complications as any complication (such as infection, hematoma, dehiscence, congestion, or necrosis) resulting in return to the operating room for re-evaluation, correction, or partial debridement of the flap. We defined flap failure as a return to the operating room for debridement of a major portion of the flap or amputation secondary to complete or near-complete loss of flap viability. Of the flap procedures, 12% (40 of 330) were classified as a failure and 14% (46 of 330) experienced complications necessitating return to the operating room. Over the study period, free flaps were not more likely to fail than pedicled flaps (11% versus 13%; p = 0.52) or have complications necessitating additional procedures (14% versus 16%; p = 0.65).

Results

Our multiple linear regression model demonstrated that an increased number of free flaps performed in our institution annually in any given year was associated with a lower likelihood of failure per case (r = -0.17; p = 0.03) and lower likelihood of reoperation for each flap (r = -0.34; p < 0.001), after adjusting for injury severity and team type (orthoplastic or orthopaedic only). We observed a similar relationship for pedicled flaps, with increased annual case volume associated with a decreased risk of flap failure and reoperation per case after adjusting for injury severity and team type (r = -0.21; p = 0.003 and r = -0.22; p < 0.001, respectively). Employment of a collaborative orthoplastic team approach was associated with decreased flap failures (odds ratio 0.4 [95% confidence interval 0.2 to 0.9]; p = 0.02). Factors associated with flap failure included a lower extremity flap (OR 2.7 [95% CI 1.3 to 6.2]; p = 0.01) and use of muscle flaps (OR 2.3 [95% CI 1.1 to 5.3]; p = 0.02).

Conclusion

Although prior reports of combat-related extremity trauma have described greater salvage success with the use of pedicled flaps, these reports are biased by institutional inexperience with free tissue transfer, the lack of a coordinated multiservice effort, and severity of injury bias (the most severe injuries often result in free tissue transfer). Our institutional experience, alongside a growing body of literature regarding complex extremity trauma in the civilian setting, suggest a benefit to free tissue coverage to treat complex extremity trauma with adequate practice volume and collaboration. We demonstrated that flap failure and flap-related complications are inversely associated with institutional experience regardless of flap type. Additionally, a collaborative orthoplastic approach was associated with decreased flap failures. However, these results must be interpreted with consideration for potential confounding between the increased case volume coinciding with more frequent collaboration between orthopaedic and plastic surgeons. Given these findings, consideration of an orthoplastic approach at high-volume institutions to address soft tissue coverage in complex extremity trauma may lead to decreased flap failure rates.

Level of Evidence

Level III, therapeutic study.

Introduction

Flap-based limb salvage uses pedicled or free tissue transfer to achieve functional limb preservation in the face of a soft tissue defect that may predispose a patient to infection and/or nonunion [1, 2]. Ideally, the coverage strategy is dictated by the demands of the defect and the optimal coverage that will lead to the highest functional outcome. Given the extensive zone of injury typical of combat-related blast injuries, free flap transfer offers greater flexibility with regard to tissue type and coverage area and enables transfer of tissue from an uninjured area. However, these benefits are only realized if the free flap procedure is successful. Flap failure necessitating alternative coverage or abandonment of limb salvage (amputation) is a major predictor of poor patient-reported and functional outcomes, and previous studies on combat-related extremity injuries advocate the use of local flaps based on unacceptably high free flap failure rates, which might occur because of the frequently massive zones of injury and systemic hyperinflammatory state of the patient [2-4].

Combat-related blast injuries often result in substantial composite tissue injuries that are well suited for management by both orthopaedic and plastic surgeons. A collaborative orthoplastic approach to complex extremity trauma has been associated with improved patient outcomes, decreased infection, increased fracture union, and earlier flap coverage; however, this has never been considered in a military or blast-related injury setting [5-9]. Given its specialized skillset and multidisciplinary collaboration required, this orthoplastic model must be routinely used to maintain its effectiveness [10]. Over the course of the study period, we observed increased frequency of soft tissue transfer for the management of complex extremity trauma suitable for flap-based limb salvage. However, little was known regarding the rates of flap failure and other perioperative complications associated with increased institutional experience in managing these complex injuries and implementation of the orthoplastic treatment approach. In addition, we sought to identify any risk factors associated with flap-related complications through analysis of our institutional experience with flap-based limb salvage for combat extremity trauma.

We therefore asked: (1) Is there an association between increased annual institutional volume and perioperative complications to include free and local flap failure (substantial flap viability loss necessitating return to the operating room for debridement of a major portion or all of the flap or amputation)? (2) Is an integrated orthoplastic collaborative approach to managing combat-related traumatic injuries of the extremities individually associated with a decreased risk of flap failure and overall flap-related complications? (3) What other factors, such as location of injury, injury severity score, and initial inpatient length of stay, were associated with flap necrosis and flap-related complications?

Patients and Methods

Study Design and Setting

We performed a retrospective review of the electronic medical record of all patients who underwent flap-based limb salvage for combat-related extremity trauma at tertiary care facilities within the United States Military Health System’s National Capital Region (comprised of the Walter Reed Army Medical Center and the National Naval Medical Center, which combined to form the Walter Reed National Military Center in 2011) between January 1, 2003 and December 31, 2012. Over this period, we assessed flap-type characteristics, annual flap performance, the effects of employing an orthoplastic treatment model, and associated flap-related complications. Major extremity trauma during this period was managed by orthopaedic surgery primarily or in collaboration with microvascular services. Orthopaedic surgeons included generalists, fellowship-trained traumatologists, and other subspecialists apart from hand surgery, whereas microvascular services included hand and plastic surgeons. Orthoplastic teams were considered any combination of both orthopaedics and microvascular services for the management of a specific extremity wound necessitating soft tissue transfer for coverage.

Participants

All patients treated with flap-based limb salvage for combat-related extremity trauma at the aforementioned institutions during the study period were identified by querying the surgical scheduling system for procedures consistent with flap-based limb salvage. The corresponding electronic medical records for these patients were then cross-referenced to confirm that these procedures were performed for combat-related extremity trauma. We excluded all patients with follow-up duration less than 6 months after flap coverage. In addition, we excluded three patients who died during the initial hospitalization and an additional two patients who were lost to follow-up with no documented follow-up after initial hospital discharge. For this study, we only considered initial flap coverage for analysis; if a revision flap procedure was performed after the initial flap, these were considered as additional procedures relative to the index surgery and not as new flaps for the purposes of analysis.

Descriptive Data

Three members of the research team (BWH, SMW, CJH), who were not involved in the surgical care of these patients, evaluated images and medical records. Record review was performed in duplicate to reduce errors. We collected patient demographic data including sex, age, and inpatient data including injury pattern, dates of hospitalization, composition of the surgical team performing flap coverage, flap complications, type of flap coverage performed (free or pedicled), flap composition (fasciocutaneous or muscle), and flap failure. For this study, the terms pedicled and local flaps were used interchangeably, as the terms generally refer to a donor site location that is local to the soft tissue defect. The only exception was the use of a pedicled groin or abdominal flap for use in upper extremity reconstruction, which employs a pedicled blood supply but transfers tissue from a remote donor site. These represented 10% (19 of 195) of pedicled flaps in this cohort and remained in the pedicled flap cohort for analysis. Generalized severity of injuries was measured using injury severity scores as these are consistently documented and correlate well with many outcomes, including heterotopic ossification, intensive care unit stay, and mortality [11]. Complications included all flap complications (such as infection, hematoma, dehiscence, congestion, and necrosis) resulting in unplanned return to the operating room for evaluation, correction, or debridement. We defined flap failure as a return to the operating room for debridement of a major portion or all of the flap. Flaps were considered a failure even if subsequent additional coverage succeeded or the extremity necessitated, or the patient requested, an amputation. The decision to return the patient to the operating room was based on the treating surgeon’s assessment of clinical factors including the patient’s vital signs, flap appearance, drainage, and perfusion signal. We additionally collected data on the length of hospitalization and whether the patient underwent extremity amputation.

We identified 307 patients (303 men, four women) who met the inclusion criteria, 75 of whom were managed by an orthopaedic team alone and 232 of whom were managed by an orthoplastic team (Table 1). Of these patients, 16 underwent flap procedures on more than one extremity, which accounted for 323 limbs that underwent salvage operations with flap coverage, including 187 lower extremities and 136 upper extremities. Six extremities underwent more than one flap procedure for different soft tissue deficits, for a total of 330 primary flap procedures performed for limb salvage therapy. An additional 20 flap procedures were performed as revisions for failed flaps. Among the primary flaps used, 195 were pedicled and 135 were free flaps. During the study period, practice patterns transitioned from primarily pedicled (89% pedicled in 2003) to primarily free flaps (75% free flaps in 2012). Injuries were primarily blast-related (87%) with a median (interquartile range) injury severity 17 (IQR 9 to 25). Flap coverage was performed at a median of 18 days (IQR 13 to 26 days) after injury. The median patient age was 24 years (IQR 21 to 29). Twelve percent (40 of 330) of all flaps failed. All patients had available medical records with orthopaedic and/or plastic surgery follow-up for a minimum of 6 months after their flap procedure, with a median duration 6.5 years (IQR 3.1 to 9.1).

Table 1.

Characteristics of orthoplastic versus orthopaedic-only approach to extremity reconstruction

Characteristic	Orthoplastic (n = 232)	Orthopaedic (n = 75)	p value
Gender, men	99 (229)	99 (74)	0.98
ISS	20 (18-21)	15 (13-17)	0.003
Age in years	26 (25-26)	26 (25-28)	0.54
Blast injury	83 (193)	81 (61)	0.71
Upper vs lower extremity injury	46 (106)	43 (32)	0.96
Flap type	51 (119)	21 (16)	< 0.001
Flap type, fasciocutaneous	44 (103)	44 (33)	0.95
Associated neurovascular injury	62 (144)	55 (41)	0.67
Multiple extremities injured	85 (197)	75 (56)	0.49

Data presented as % (n) or median (IQR); ISS = injury severity score; IQR = interquartile range.

Operative Protocols

The decision to perform limb salvage was made by the surgeons in coordination with the patient, other care teams, and family, whenever possible. There was no specific protocol to determine which candidates were considered for limb salvage. Given that the high-energy blast mechanism of injury remained fairly constant throughout the study period, the characteristics and size of the soft tissue defects being managed also remained relatively stable. Flaps were chosen based on a combination of functional goals, coverage area, capability, and available tissue to perform flap reconstruction. Flap procedures were performed by an orthopaedic surgery team or an orthoplastic team. The care team was classified as orthopaedic or orthoplastic based on the mention of a microvascular-trained surgeon (orthopaedic hand surgeon or plastic surgeon) on the operative report for each flap procedure performed. Over the course of the study period, the indications for type of flap coverage shifted from a capability-based approach to a defect-oriented approach. Pedicled flaps were used in the early part of the study regardless of volume or character of tissue loss. With increased capability over time and with use of an orthoplastic team, the indications for pedicle flap coverage narrowed as free tissue coverage offers a greater range of donor sites and tissues available for reconstruction. Ultimately, pedicle flaps became primarily indicated for small volume defects with a limited zone of injury.

Primary and Secondary Study Outcomes

Our primary study goal was to determine whether there was any association between increased institutional volume and free and local flap perioperative complications and failure. To achieve this, we evaluated the medical record for flaps performed over the study period and any complications or failures that occurred. For the purposes of this study, we considered institutional flap volume to be the per annum free or pedicled flap cases. We then determined the correlation between annual volume and likelihood of these outcomes. We performed a multivariate regression to determine whether increased practice volume was individually associated with these outcomes, while controlling for the confounding potential of injury severity and a collaborative approach.

Our secondary study goals were to evaluate the flap-related outcomes for limb salvage cases performed with an orthoplastic approach, and to determine risk factors associated with an increased risk of flap failure and other flap-related complications. To achieve this, we reviewed the medical record for flap type, surgical team, injury characteristics, and length of admission and again considered the outcomes of flap failures and complications. We performed multivariate logistic regression analysis to determine which factors were associated with these outcomes while controlling for the effects of potential confounders including injury severity and practice volume.

Ethical Approval

Ethical approval for this study was obtained from Walter Reed National Military Medical Center, Bethesda, MD, USA (352329).

Statistical Analysis

The data analysis was performed using RStudio 1.2.1335 software (RStudio Inc). We used a Pearson chi-square and logistic regression to evaluate the relationship between the primary outcomes of flap failure, amputation, and the patient and surgical factors, including the injured extremity, flap type, and surgical team. Male and female patients were grouped, and no subgroup analysis was performed due to the sparsity of female patients available. We performed the Spearman correlation to evaluate any association between surgical volume and flap-related complications, and single or multiple regression models were used to assess patient factors such as area of injury, injury severity score, type of flap, and their association with flap failure and flap-related complications.

Results

Institutional Experience and Flap Complications/failures

As institutional experience increased, flap complications resulting in reoperation became less frequent. The frequency of flap failure for free flaps decreased over time (r = -0.293 [95% confidence interval -0.43 to -0.14]; p < 0.001) as the number of free flap procedures increased (r = 0.57 [95% CI 0.45 to 0.67]; p < 0.001) (Fig. 1). Our multiple linear regression model demonstrated that an increased number of free flap procedures performed annually in our institution was associated with lower likelihood of failure (r = -0.17; p = 0.03) (Fig. 2) and a lower likelihood of complications resulting in return to the operating room (r = -0.34; p < 0.001) after adjusting for the injury severity score and team type. A similar trend was also observed for pedicled flaps, with annual procedure volume associated with decreased risks of both flap failure and complications after adjusting for injury severity and team type (r = -0.21; p = 0.003 and r = -0.22; p < 0.001, respectively).

Fig. 1.

This graph shows the correlation of flap failure frequency with institutional volume. The horizontal axis describes annual number of flaps performed (free of pedicled procedure), and the vertical axis demonstrates the relative frequency of flap failure in years that number of flaps were performed. Trendlines for each flap type demonstrate an inverse relationship between annual volume and failure.

Fig. 2.

A-B These graphs show the institutional annual volume of (A) free flap and (B) pedicled flap procedures and failure frequency relative to time. The horizontal axis here is the year in which the flap procedure was performed, and the vertical axis demonstrates both the annual volume of flap procedures performed (left axis) and the frequency with which failure occurred (right axis).

Association of an Orthoplastic Team and Flap Complications/failures

On multivariate logistic regression analysis controlling for institutional volume and injury severity, the use of a collaborative orthoplastic team protected against flap failure (odds ratio 0.44 [95% CI 0.21 to 0.93]; p = 0.02). Orthoplastics teams were more likely to perform a free flap procedure (OR 3.2 [95% CI 1.8 to 5.8]; p < 0.001) and a fasciocutaneous flap procedure (OR 1.7 [95% CI 0.99 to 2.9]; p = 0.049) than an orthopaedic service alone.

Other Factors Associated with Flap Complications/failures

Over the study period, free flaps were not more likely to fail than pedicled flaps (11% versus 13%; p = 0.52) or be associated with complications necessitating return to the operating room (14% versus 16%; p = 0.65). Although free flap use was associated with a higher injury severity score than pedicled flaps (20 versus 17; p = 0.008), there was no difference in use for limbs with neurovascular injury (OR 1.4 [95% CI 0.83 to 2.2]; p = 0.18). In the setting of neurovascular injury, there was an increased risk of failure for pedicled flaps (OR 2.2 [95% CI 0.86 to 6.2]; p = 0.09) but not free flaps (OR 0.6 [95% CI 0.17 to 2.2]; p = 0.40). Other factors associated with flap failure included the use of a lower extremity flap (OR 2.7 [95% CI 1.3 to 6.2]; p = 0.01) and use of muscle flaps in lieu of fasciocutaneous flaps (OR 2.3 [95% CI 1.1 to 5.3]; p = 0.02) (Table 2). Flap failure was associated with an increased likelihood of amputation during the initial hospitalization (OR 4.9 [95% CI 1.38 to 16.0]; p = 0.007). The mean hospital length of stay did not differ between patients who received free flaps and those with pedicled flaps (60 days versus 56 days; p = 0.20), although the duration of hospitalization was increased for those who experienced flap failure (88 days versus 58 days; p < 0.001).

Table 2.

Injury and flap characteristics and association with flap failure

Parameter	Odds ratio (95% CI)	p value
Muscle flapa	2.3 (1.1-5.3)	0.02
Free flapb	1.0 (0.6-2.2)	0.77
Lower extremityc	2.7 (1.3-6.2)	0.01
Fracture	2.5 (0.5-61)	0.30
Vascular injury	0.9 (0.4-20)	0.84
Nerve injury	0.96 (0.5-1.9)	0.91
Orthoplastic teamd	0.4 (0.2-0.9)	0.02

^aVersus fasciocutaneous flap.

^bVersus pedicled flap.

^cVersus upper extremity.

^dVersus orthopaedics alone.

Discussion

Increased collaboration between orthopaedic- and microvascular-trained surgeons in the management of soft tissue coverage after major extremity trauma has demonstrated promising results with shorter time to definitive soft tissue coverage, increased fracture union rates, and decreased infection rates [12-14]. However, more widespread adoption of these orthoplastic models has been slow, secondary to centers lacking the case volume to support similar programs as well as limited long-term data surrounding outcomes in collaborative flap-based limb salvage efforts. The findings of the present study corroborate results from previous reports. Our results further suggest that both increased institutional experience and implementation of an orthoplastic approach for flap-based limb salvage independently may be associated with protection against flap failure and other complications. In addition, we found lower extremity flaps, use of a muscle flap in lieu of a fasciocutaneous flap, and any flap-related complication to be associated with subsequent flap failure.

Limitations

There are several notable limitations to our study. This study had three main kinds of bias that are present to a large degree in most retrospective studies about treatments: selection bias, missing data bias, and assessment bias. These biases all may result in overestimation of the apparent benefit of the interventions, including the benefit of experience and the benefit of an integrated team model.

This study is a retrospective, observational study, which is limited by reliance on completeness of the medical record and accuracy of reported outcomes, which could predispose the study to assessment bias and favor a better outcome. Incomplete or inconsistently reported factors such as exact size of soft tissue defects, contamination severity, and bone loss at the time of injury versus time of debridement were therefore not included or available for analysis. We attempted to control for this by relying primarily on objective, consistently recorded patient- and treatment-related factors and endpoints such as failure leading to operative debridement and complications resulting in return to the operating room. We also used record reviewers who were independent from the treatment team.

Another limitation of our study is the lack of a standardized approach to soft tissue coverage throughout the study period. Overall, the indications used for soft tissue transfer were somewhat consistent as outlined previously. However, there is inevitable variation in approach, which may have resulted in improved patient selection for flap types over time or evolving techniques which would have been impossible to account for in this design. Due to the study type, we were unable to control for these subtle variations in treatment. Further, more than 15 surgeons performed the flap procedures in this study, and different skill and experience levels may be expected between them. Each individual surgeon may have had different preferences for specific flap types, techniques, or counseled patients differently regarding limb salvage versus amputation. However, these limitations are consistent with the complexity of decision-making for surgeons managing threatened limbs after high-energy trauma, and the overall findings despite these variations suggest that the specific improvements in outcomes associated with volume and a team approach are not dependent on any other specific grouping of features present in our cohort. This limitation may further support the importance of institutional experience, which favors hospital system volume over individual surgeon volume for outcomes of procedures with longer hospital stays and more intense monitoring [15]. Greater volume of limb salvage surgery within the hospital system may be the underlying factor rather than surgeon experience, although we were unable to differentiate between these features with our dataset.

Third, we were unable to control for patient selection; patients were selected for this study based on their injuries and treatment received, which was typically based on a collaborative decision between the patient and surgeon. Patients may have varied in age, sex, and comorbidities, although baseline comorbidities were largely limited by military health standards for deployment to combat zones. As a result, our study consisted primarily of young, healthy males. This selection bias may limit the generalizability of our findings because we were unable to selectively include patients with varied age, sex, or medical conditions or perform analysis assessing the effects of sex or these other covariates on our outcomes. Generalizability is also limited by the nature of the injuries and delays in flap coverage. In our study population, all patients sustained combat-related injuries, which were mostly blast injuries. This mechanism of injury results in high rates of traumatic brain injury, concomitant visceral trauma, and heavy bacterial and nonorganic contamination of the wound bed [16]. All patients also underwent a series of medical transfers from the overseas battlefield before arriving at the stateside tertiary medical facility capable of performing definitive soft tissue flap coverage. The injury severity, heavy wound bed contamination, and the extensive medical evacuation process contributed to an average 18-day delay from the injury date before soft tissue coverage was achieved. This nearly two-and-a-half-week flap coverage delay tends to be higher than in a typical civilian setting, with its more readily available access to microvascular reconstructive capabilities. These injury types and delays may have been associated with an increased likelihood of flap complications and failure [17]. However, they may also suggest that in these higher-risk patients with major trauma and greater delays to coverage, relatively good outcomes can be achieved with appropriate coverage by an experienced team.

Finally, our statistical analysis demonstrated that although many features of treatment including team approach and practice volume are associated with improved outcomes, there was substantial variability in confidence intervals, which suggests a sparse-data bias. These biases are common in models that attempt to control for multiple confounding variables [18]. Although this points to fragile evidence, making it difficult to make conclusions based on the strength of specific treatment factors, the multivariate regression does lend support, albeit cautiously, for our results.

Institutional Experience and Flap Complications/failures

As institutional experience increased, flap complications resulting in reoperation and flap failures became less frequent. We emphasize, though, that it is difficult in the context of this study to separate institutional experience (surgical volume) from the influence an orthoplastic treatment model may have had on this finding.

Association of an Orthoplastic Team and Flap Complications/failures

After controlling for potential confounding variables including increasing institutional experience, we found that flap-based limb salvage surgery performed by collaboration of orthopaedic and plastic surgeons was associated with decreased odds of complications resulting in reoperation after flap surgery and flap failures. Yarrow et al. [24] reported that patients with open tibia fractures initially admitted to facilities with high-volume orthoplastic services were more likely to undergo rapid wound debridement and receive care consistent with ideal management guidelines. However, even patients transferred to high-volume orthoplastic facilities could be treated within recommended timeframes with a high proportion of success, supporting a preference for transfer to specialty centers for patients with these injury patterns. Overall, data support a greater likelihood of flap success with earlier transfer to an orthoplastic referral center [19]. Taken together, these findings underscore the value of a collaborative orthoplastic approach and definitive treatment at high-volume centers and justify the greater demands on institutional resources and increased care coordination necessary for a successful multidisciplinary effort.

Other Factors Associated with Flap Complications/failures

Secondary study findings associated with lower failure proportions included upper extremity flaps and the use of fasciocutaneous flaps rather than muscle flaps. This preference for coverage with free fasciocutaneous flaps is based on the ability to provide a larger volume of tissue with minimal donor site morbidity and is especially advantageous in the setting of multiple extremity injury. This contrasts with the typical orthopaedic preference for pedicle flaps based on familiarity with the technique. Many of these factors have been demonstrated in previous studies, including higher failure proportions of lower extremity flap procedures than for upper extremity flap procedures [3, 20]. Lee et al. [12] reported that the increased risk of failure with lower extremity flaps was due in part because of their higher frequency of osteomyelitis and deep venous thrombosis. We found that free flap reconstruction was not associated with higher proportions of flap failure and was more reliable than pedicle flap coverage in the setting of neurovascular injury, a common component of combat-related extremity trauma. In addition, free tissue transfer was not associated with increased proportions of late amputation, as has been reported [3]. Of note, many patients in that comparative series were also captured in this study cohort. We surmise that this free flap reconstruction benefit derives from improved flap selection as much as technical expertise or experience, with increased use of free tissue transfer obviating the need to attempt local flap coverage in the setting of large defects or compromised regional tissue viability.

Despite our findings in the present study and the trend toward free flap–based extremity reconstruction [22], many orthopaedic studies focusing on combat-related extremity trauma advocate for avoiding free tissue transfer based on a concern for high flap failure rates and logistical barriers to the coordination of care across specialties [3, 23]. These studies reported greater reliability of local flap coverage options, as well as decreased demand on institutional resources and need to coordinate care across multiple services. However, this approach is contrary to the growing body of literature reporting improved limb salvage outcomes with the use of an orthoplastic approach and liberal use of free tissue transfer in treating complex extremity trauma in the civilian setting [8, 13, 14, 24]. The findings of the present study suggest that the higher failure proportions and flap-related complications that have driven the avoidance of free tissue transfer at some military treatment facilities can be eliminated by adequate procedure volume and the use of a collaborative orthoplastic model for delivering care.

Conclusion

This study supports the potential benefits of increased procedure volume and orthoplastic approach in flap-based limb salvage for combat-related extremity trauma. Whether these factors also contribute to overall improved patient outcomes is beyond the scope of this work, but importantly, the previously reported association between free flap coverage and delayed amputation was not demonstrated in this large series. Regardless, delayed amputation is a flawed proxy for poor functional outcome because multiple studies have demonstrated the equivalence or superiority of amputation to limb salvage in the setting of combat-related extremity trauma. A true assessment of the role of coverage types on functional and global outcomes requires disease-specific outcome measures and assessment tools that are still lacking in this field. In the absence of more granular outcomes, the onus is on the limb salvage team to use a soft tissue coverage strategy that best balances the needs of the defect with morbidity and the complexity of flap transfer. Our findings suggest this can be accomplished most reliably in the setting of adequate institutional procedure volume and a collaborative orthoplastic approach to limb salvage.

In this institutional setting, both pedicled and free flap failure and flap-associated complications decreased with increased procedure volumes and with the use of an orthoplastic approach. The findings of our study suggest that the higher failure proportions and flap-related complications that have driven the avoidance of free tissue transfer at some military treatment facilities might be ameliorated by adequate procedure volume and the use of a collaborative orthoplastic model for delivering care. Given the morbidity and costs of failed or aborted limb salvage after flap failure, every effort should be made to optimize soft tissue coverage by fostering a collaborative approach to care and seeking opportunities to ensure adequate procedure volume at centers responsible for treating combat-related traumatic injuries of the extremities. Future studies may consider whether equivalent practice benefit to flap volume may be obtained through other modalities including animal models, simulation, or elective and reconstructive procedures.