Comparison of the Characteristics of Three Acellular Dermal Matrices Subjected to Distinct Processing Methods Using Five Types of Histochemical Staining.

BACKGROUND: Acellular dermal matrix (ADM) is treated using various devitalization and aseptic processing methods. The processing effects on ADM were evaluated by histochemical tests. METHODS: From January 2014 to December 2016, 18 patients [average age, 43.0 (range, 30-54) years] who underwent breast reconstruction with an ADM and tissue expander were prospectively enrolled. During the permanent implant replacement, a biopsy of the ADM was performed. We used three different human-derived products, namely, Alloderm®, Allomend®, and Megaderm®. Hematoxylin and eosin, CD68, CD3, CD31, and smooth muscle actin were used to evaluate the collagen structure, inflammation, angiogenesis, and myofibroblast infiltration. Each ADM was semi-quantitatively analyzed. RESULTS: Significant differences in collagen degradation, acute inflammation, and myofibroblast infiltration were observed among the ADMs. Collagen degeneration (p<0.001) and myofibroblast infiltration (smooth muscle actin-positive, p=0.018; CD31-negative, p=0.765) were the most severe in Megaderm®. Acute inflammation, represented by CD68, was most severe in Alloderm® (p=0.024). Both radiation and freeze-drying treatment physically damaged the collagen structure. Collagen degeneration was most severe in Megaderm®, followed by Allomend® and Alloderm®. Since Alloderm® is treated using chemicals, an assessment of the chemical irritation is warranted. CONCLUSIONS: The biopsy results were inconclusive. Therefore, to better interpret processing, more large-scale, serial, histochemical studies of each ADM are needed. LEVEL OF EVIDENCE IV: This journal requires that authors 38 assign a level of evidence to each article. For a full 39 description of these Evidence-Based Medicine ratings, 40 please refer to the Table of Contents or the online 41 Instructions to Authors www.springer.com/00266 .

A comparative study for tension-reducing effect of Type I and Type II keystone perforator island flap in the human back.

The keystone perforator island flap (KPIF) is popular in reconstructive surgery. However, despite its versatility, its biomechanical effectiveness is unclear. We present our experience of KPIF reconstruction in the human back and evaluate the tension-reducing effect of the KPIF. Between September 2019 and August 2020, 17 patients (51.82 ± 14.72 years) underwent KPIF reconstruction for back defects. In all cases, we measured wound tension at the defect and donor sites before and after KPIF reconstruction using a tensiometer. All defects occurred after complete excision of complicated epidermoid cysts and debridement of surrounding tissues. The defects were successfully covered with Type IIA KPIFs. All flaps survived, and there were no significant postoperative complications. The mean "tension change at the defect after Type I KPIF" and "tension change at the defect after Type II KPIF" were - 2.97 ± 0.22 N and - 5.59 ± 0.41 N, respectively, (P < 0.001). The mean "rate of tension change at the defect after Type I KPIF" and "rate of tension change at the defect after Type II KPIF" were - 36.54 ± 1.89% and - 67.98 ± 1.63%, respectively, (P < 0.001). Our findings confirm the stepwise tension-reducing effect of KPIF and clarify the biomechanics of this flap.

Keystone Flaps for Coverage of Defects in the Posterior Neck and Lower Occipital Scalp: A Retrospective Clinical Study.

ABSTRACT: The coverage of the posterior neck and lower occipital scalp defects should be approached carefully. Thick, stiff, and inelastic skin properties of these areas tend to make coverage of even small defects difficult. Herein, the authors present a retrospective review of our experience with posterior neck and lower occipital scalp reconstruction using the keystone flap (KF) and describe the expanding versatility of KF reconstruction. The medical records of 17 patients who underwent KF reconstruction to cover the posterior neck and lower occipital defect from April 2017 to May 2020 were reviewed. Clinical and operative data were collected. All defects were successfully covered with the KFs. The defect sizes ranged from 2.5 × 3.5 cm to 6 × 11 cm, and the flap sizes ranged from 3 × 5.5 cm to 9 × 18 cm. All flaps fully survived, although marginal maceration developed in one case; however, it healed with conservative management. The final results were favorable, and all patients were satisfied with their final outcomes. Consequently, the KF can be considered as a good reconstruction modality with few complications and provides an alternative to other reconstructive options for coverage of the posterior neck and lower occipital defects.

Use of Keystone Flaps in Consideration of the Facial Aesthetic Subunit Concept as an Alternative Reconstructive Option for Nasal Defect Coverage.

ABSTRACT: Nasal defect coverage has some challenging aspects for plastic surgeons because of the midfacial location of the nose and the relationship between convexities and concavities of nasal subunits. The authors described our experience with performing keystone flap (KF) nasal reconstruction in accordance with the facial aesthetic subunit concept and demonstrated the expanding versatility of KFs in nasal reconstruction. Between January 2017 and February 2020, 15 patients (average age, 72.07 ±â€Š13.00 years, range: 38-88 years) underwent KF reconstruction for nasal defects. We performed KF reconstruction in accordance with the facial aesthetic subunit concept. Data, including the defect causes and locations, defect sizes, flap sites and sizes, types of KFs, flap survival, complications, and follow-up period for each patient were reviewed retrospectively. Cosmetic outcomes were evaluated by independent plastic surgeons and patients through satisfactory postoperative surveys. Sixteen defects occurred in 15 patients. The defect sizes ranged from 0.8 × 1 cm to 2.5 × 3 cm. The flap sizes ranged from 1.5 × 3.5 cm to 4 × 6 cm. All defects were successfully covered with KFs from adjacent subunits. All flaps survived without any postoperative complications. At the mean follow-up period of 8.33 ±â€Š2.92 months, the objective cosmetic outcomes were rated favorably, and the average subjective patient satisfaction score was 7.93 ±â€Š1.28 on a scale of 1 to 10. We suggest that using KF reconstruction in consideration of the facial aesthetic subunit concept can be a promising alternative modality for covering nasal defects with outstanding aesthetic outcomes.