Response to: Eliminating the Sacral Component of the Lower Body Lift

We appreciate the profound and insightful comments by Swanson regarding our study introducing a de-epithelialized dermal flap to reduce sacral wound healing complications after lower body lift procedures.^1,2 Concerning our study design, the author supposes that we have omitted further patients who received our flap before November 2018. Our previous published article describes a 12-year evolution (up to the end of 2018) of our lower body lift technique.³ We reported that our dermal flap was a recent refinement of our technique introduced at the end of the study period. Its potential influence on sacral wound healing problems was discussed without any statistical statement and we did not credit the flap as being responsible for the low rate of complications. For this reason, we conducted the current study to focus on the impact of the newly introduced flap. The first ever sacral flap we performed by the presented technique is included in the current study.

Regarding statistics, we are grateful for the comment and agree that Fisher's exact test would be appropriate due to the small number of cases per cell. Nevertheless, although Fisher's exact test, contrary to the chi-squared test, exhibited nonsignificant differences (1-sided, P = 0.046; 2-sided, P = 0.091) the effect sizes for the parameters (sacral wound dehiscence, φ_c = 0.329; medium effect/occurrence of complication, φ_c = 0.267) indicate the differences are not random. Therefore, due to the effect sizes we believe that the difference would reach the level of significance for large samples. To confirm this statement, we performed additional analysis on an enlarged cohort. Since we published our article, we have performed 7 further lower body lifts with the sacral flap, and compared the outcomes to those of an enlarged cohort of 7 additional lower body lifts without the sacral flap performed prior to our introduction of the new technique. Two additional sacral wound dehiscences occurred, both in the “no-flap group.” Fisher's exact test for the enlarged cohort (original cohort + 14 additional patients) showed significant differences in the occurrence of sacral wound dehiscences between the “flap” and “no-flap” group (one-sided, P = 0.012; two-sided, P = 0.024) with similar effect sizes (sacral wound dehiscence, φ_c = 0.348, medium effect). In addition, the Clopper-Pearson intervals only slightly overlap between the groups (flap, 3.7% [0.0%-18.97%] vs no flap, 29.63% [13.75%-50.18%]). These additional data reinforce our initial statement in the original article.

We do not think that the significant difference in the duration of hospital stay is due mainly to rounding errors. To ensure the readability of the article several statistical parameters were not stated. We think the combination of the P-values and effect sizes supports our thesis. The duration was determined by the number of days each patient stayed in the hospital. Because the discharge from hospital was determined by predefined clinical parameters and the patient visits were within similar time slots, an hour-based determination of the hospital stay would not be more efficient. Furthermore, we think that the moderate to large effect sizes found for hospital stay (Hedge's g* = 0.59) contradicts the rounding-error thesis. A similar but less pronounced situation occurred for the number of visits. Despite an identical median value, 1 group exhibited a higher number of people with a larger number of visits, resulting in nonsignificant differences with a moderate effect (Hedge's g* = 0.45)

As the author points out, wound healing problems, particularly around the sacrum, are well-known after lower body lift procedures. Therefore, we designed our flap to reinforce this specific area. With reference to our results, the utilization of this flap showed statistically significant lower rates of sacral wound healing problems. Hence, draping the undermined skin flap over the flap does not lead to further wound healing problems or impaired perfusion of the undermined skin flap. Further, we have only observed absence of elongation of the gluteal cleft but reaching statistical signficance. Our technique enables the surgeon to redistribute the caudal skin excess in a lateral direction, thus avoiding skin collapse and cleft elongation. The mentioned maneuver is very limited in procedures avoiding direct skin excision over the sacrum. This potential positive side effect should be investigated in further studies, which is also recommended by Aly.⁴

Although our study clearly focuses on patient safety, our photographs serve to underline that the sacral flap procedure does not diminish aesthetic outcomes. Relating to our former study, only 21 out of 155 patients received gluteal autoaugmentation (the patient in Figure 5 did not receive gluteal autoaugmentation). However, we agree with the author that transposition flaps do not sufficiently augment lateral gluteal deficiency and their long-term efficacy should be examined in further studies.

With regard to the mentioned near-circumferential lower body lift technique, we agree with the author that 2 common complications (sacral wound healing problems and gluteal cleft elongation) might be eliminated. However, we believe that in patients exhibiting significant skin surplus after massive weight loss, a direct skin excision might often be indicated. Nevertheless, we congratulate the author on his results and will consider this alternative lower body lift technique in future.

In conclusion, we would like to thank the author for his insightful comments. The ultimate goal in all fields of plastic surgery is patient safety, which implies decreasing complications and risks. Therefore, we are grateful to be able to participate in ongoing research and objective scientific discussion in this current hot topic in body contouring surgery.

Disclosures

The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article.

Funding

The authors received no financial support for the research, authorship, and publication of this article.

REFERENCES

Author notes