In response, we would first like to thank Dr. Knobloch et al. for their interest in our recent article entitled “Longitudinal Outcomes and Application of the Subunit Principle to 165 Foot and Ankle Free Tissue Transfers.”1 In the setting of lower extremity trauma, the question of whether to perform amputation versus limb salvage is a challenging one. Although injury scoring systems have a place in the initial assessment of these patients, we do not believe that the current systems offer a definitive answer. We base this conclusion on level 1 data from the Lower Extremity Assessment Project, which is a multicenter prospective study consisting of patients who have sustained lower extremity trauma.2–4 Specifically, Bosse and colleagues looked at five different scoring systems (including the Mangled Extremity Severity Scale) in the setting of the Lower Extremity Assessment Project data and found them to have a reasonably high specificity yet a low sensetivity.3 This translates into a system that is valid in predicting limb salvage but fails when attempting to predict amputation. Furthermore, in a follow-up study by Ly et al., the same five systems failed to predict functional outcome (as determined by the Sickness Impact Profile) following limb salvage.4 Thus, the clinical utility of these scoring systems is clearly limited in this setting. In our practice, scoring systems (such as the Mangled Extremity Severity Scale) serve only as an additional piece of information that may contribute to the overall decision to perform limb salvage or amputation.
Regarding our recent study, the Mangled Extremity Severity Scale score for 120 patients who sustained trauma would be difficult to accurately determine and would perhaps add to the confusion regarding the utility of these systems. This is because 61 patients had acute trauma and 59 patients had chronic wounds (>30 days from injury) resulting from trauma. Also of note, of the acute trauma patients, 28 were transferred from outside hospitals, making the initial Mangled Extremity Severity Scale assessments unreliable. Given these caveats and limitations of a retrospective chart review, for the acute trauma patients, we estimate a mean Mangled Extremity Severity Scale score of 4.4, with three patients having a Mangled Extremity Severity Scale score greater than 7. Of the 61 acute trauma patients reconstructed with free flaps, only one went on to require amputation (1.6 percent). This patient had a Mangled Extremity Severity Scale score of 7. Our status as a tertiary hospital also further obscures the importance of any conclusions regarding time from injury to reconstruction. Having stated that, we found that for patients with acute trauma, the mean time from injury to reconstruction was 11.5 days. This included a mean number of 1.9 operative débridements before definitive reconstruction. Currently, we continue to strive to reconstruct these patients as soon as possible, feeling that reestablishment of the soft-tissue envelope will ultimately promote improved bony healing and reduce overall contamination, which is a critical aspect of limb salvage. We do not feel that delayed treatment with the use of negative-pressure therapy or other methods is equivalent to definitive soft-tissue reconstruction.
In our hands, patients with foot and ankle free flaps will need secondary debulking procedures 22 percent of the time.1 We feel these secondary procedures are important and are driven by the demands of the close-fitting nature of footwear. In some cases, this is related to excess flap bulk, whereas in other cases, it is related to redundant skin. In general and perhaps related to our flap choices, we have not found liposuction to be as useful or precise as direct tissue excision for debulking purposes.
As Knobloch notes, we found an 11 percent incidence of late flap instability and wound breakdown.1 This occurred most frequently at the heel (subunit 5).1 In some cases, this occurred several years after the original surgery (mean time to flap instability, 30.9 months) and was often found to be located at the flap native skin interface. In general, we have tried to use insetting methods that stagger the interface of the flap and native skin (see Fig. 61). Moreover, when possible, we attempt to place the flap native skin interface in a non–weight-bearing location. Having the center of the flap on the weight-bearing surface does not appear to be as detrimental as having the interface at a high-demand region.
Ultimately, Dr. Knobloch and his group bring up many important concepts for the reconstructive surgeon taking care of patients with lower extremity injuries. Clearly, outcomes data with regard to free flap reconstruction for these patients are limited. With our retrospective study, we have attempted to illuminate important aspects of this care, including flap selection based on anatomical and aesthetic demands of the region, the need for frequent debulking procedures, and the incidence of late flap instability. Undoubtedly, there is a need for prospective, nonbiased, level 1 data to help us make better decisions for our patients. Although this may not be feasible in many areas of plastic surgery, certain areas such as free flap reconstruction for trauma seem appropriate for us to perform large outcome-based trials. Only after we complete these trials will we truly know the answer to many of these questions.
Scott T. Hollenbeck, M.D.
Department of Surgery
Division of Plastic, Reconstructive, Maxillofacial, and Oral Surgery
Duke University Medical Center
L. Scott Levin, M.D.
University of Pennsylvania Health System
1. Hollenbeck ST, Woo S, Komatsu I, Erdmann D, Zenn MR, Levin LS. Longitudinal outcomes and application of the subunit principle to 165 foot and ankle free tissue transfers. Plast Reconstr Surg.
2. Bosse MJ, MacKenzie EJ, Kellam JF, et al. An analysis of outcomes of reconstruction or amputation after leg-threatening injuries. N Engl J Med.
3. Bosse MJ, MacKenzie EJ, Kellam JF, et al. A prospective evaluation of the clinical utility of the lower-extremity injury-severity scores. J Bone Joint Surg (Am.)
4. Ly TV, Travison TG, Castillo RC, Bosse MJ, MacKenzie EJ; LEAP Study Group. Ability of lower-extremity injury severity scores to predict functional outcome after limb salvage. J Bone Joint Surg (Am.)
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