Application of free serratus anterior fascial flap for reconstruction of ear deformity due to hemifacial microsomia: A report of two cases

Update on Total Auricular Construction

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Understand principles of preoperative planning for microtia repair. 2. Understand key techniques for flap design, skin envelope dissection, framework creation, and donor-site reconstruction. 3. Describe important components of postoperative management.

SUMMARY

Total auricular construction remains a challenge for reconstructive surgeons. This article describes current surgical strategies and advancements for microtia construction. The authors' focus is to describe the several keys for success that are useful for young surgeons who wish to train themselves to create satisfactory results.

Reconstructive Techniques in Pediatric Congenital Microtia: A Systematic Review and Meta-analysis

Autografts and allografts are commonly used in microtia reconstruction. We aimed to systematically review and compare these reconstructive materials in pediatric congenital microtia reconstruction. A systematic review of the literature was performed. MEDLINE, Embase, PubMed, Web of Science, and CINAHL databases were searched for original studies on congenital microtia reconstruction in pediatric patients since database inception to 2021. Microtia grade was stratified as high or low. Meta-analysis of pooled proportions and continuous variables was performed using inverse variance weighting with a random effects model to compare between the autograft and allograft groups. Sixty-eight studies with a total of 5,546 patients used autografts (n = 5,382) or alloplastic implants (n = 164). Four other studies used prosthesis, cadaveric homografts, or tissue engineering. The allograft group was on average younger than the autograft group (8.4 vs. 11.1 years). There were no syndromic patients in the allograft group, compared to 43% in the autograft group. Patients treated with allografts had higher microtia grade than those treated with autograft (98 vs. 72%). Autografts were more commonly utilized by plastic surgeons and allografts by otolaryngologists (95 vs. 38%). No autografts and 41% of allografts were done concurrently with atresiaplasty or bone conduction implant. Satisfaction rates were similarly high (>90%) with similar complication rates (<10%). Microtia reconstruction using autografts and allografts had similar satisfaction and complication rates. Allografts were preferred for younger patients and concurrent hearing restoration. Further large-scale studies are required to evaluate the long-term efficacy of these reconstructive techniques.

Morphologic Variability of Bone and Soft Tissue in Microtia With Hemifacial Microsomia

Objective: Microtia patients with hemifacial microsomia (HFM) have a host of distinct anatomical disorder of skeletal and soft tissue asymmetries. The purpose of this study was to assess soft tissue discrepancies in microtia patients with HFM and their correlation with skeletal discrepancies. Methods: A total of 42 patients were enrolled and studied prospectively using a 3-dimensional superimposition and color mapping of the soft and hard tissues. Mirroring techniques created perfectly symmetric models for comparison. Differences between affected and normal sides were evaluated in 5 areas: retroauricular mastoid, malar, maxillary frontal, mandibular frontal, and gonion areas. Pearson correlations were used to assess the relationship between skeletal and soft tissue asymmetry. Results: Hard tissue asymmetry ranged from 0.79 mm (mandibular frontal) to 1.29 mm (malar), while soft tissue asymmetry ranged from 1.34 mm (maxillary frontal) to 5.26 mm (retroauricular mastoid). Correlations between skeletal and soft tissue asymmetry varied, with the strongest correlation observed at the retroauricular mastoid area and the weakest at the maxillary frontal area. Conclusion: There was a high correlation between bone and soft tissue hypoplasia at the retroauricular mastoid area, while the other evaluated areas showed poor correlation between skeletal and soft tissue asymmetries. Clinicians should assess each component separately for optimal treatment planning in microtia patients with HFM.

Surgical Microtia Reconstruction in Hemifacial Microsomia Patients: Current State and Future Directions

Background:

Hemifacial microsomia (HFM) is one of the most common congenital craniofacial disorders. Among many other features, microtia is present in the large majority of these patients. However, mainly due to the unilateral hypoplastic anatomy, microtia reconstruction among this patient population remains a reconstructive challenge for plastic surgeons. Given that no clear standards exist, an evidence-based synthesis of the literature was devised.

Methods:

A systematic search of Pubmed, Medline, and Embase was carried out, in accordance with the PRISMA guidelines. Studies discussing surgical microtia reconstruction for HFM patients were retained. Qualitative data regarding study design, challenges addressed, specific recommendations, and their respective strengths/limitations were extracted from each. Retrieved recommendations were consolidated and assigned a level of evidence grade.

Results:

Although only 11 studies were included in this review, these provided 22 main recommendations regarding the eight HFM-specific challenges identified, which were of either grade C (n = 5) or D (n = 17). Included studies addressed construct location (n = 7), the low hairline (n = 6), soft tissue construct coverage (n = 6), earlobe reconstruction (n = 6), construct projection (n = 5), anomalies of the relevant neurovascular systems (n = 2), retroauricular construct coverage (n = 2), and sizing of the construct (n = 2).

Conclusions:

Given the many persisting reconstructive challenges regarding surgical microtia reconstruction for HFM patients, the authors present a comprehensive and evidence-based consolidation of recommendations specific to these challenges. The authors hope this systematic review can appropriately guide plastic surgeons and will ultimately improve care for this patient population.

Osteogenic Differentiation of Human Adipose-Derived Stem Cells Seeded on a Biomimetic Spongiosa-like Scaffold: Bone Morphogenetic Protein-2 Delivery by Overexpressing Fascia

Human adipose-derived stem cells (hADSCs) have the capacity for osteogenic differentiation and, in combination with suitable biomaterials and growth factors, the regeneration of bone defects. In order to differentiate hADSCs into the osteogenic lineage, bone morphogenetic proteins (BMPs) have been proven to be highly effective, especially when expressed locally by route of gene transfer, providing a constant stimulus over an extended period of time. However, the creation of genetically modified hADSCs is laborious and time-consuming, which hinders clinical translation of the approach. Instead, expedited single-surgery gene therapy strategies must be developed. Therefore, in an in vitro experiment, we evaluated a novel growth factor delivery system, comprising adenoviral BMP-2 transduced fascia tissue in terms of BMP-2 release kinetics and osteogenic effects, on hADSCs seeded on an innovative biomimetic spongiosa-like scaffold. As compared to direct BMP-2 transduction of hADSCs or addition of recombinant BMP-2, overexpressing fascia provided a more uniform, constant level of BMP-2 over 30 days. Despite considerably higher BMP-2 peak levels in the comparison groups, delivery by overexpressing fascia led to a strong osteogenic response of hADSCs. The use of BMP-2 transduced fascia in combination with hADSCs may evolve into an expedited single-surgery gene transfer approach to bone repair.

Hemifacial Microsomia Review: Recent Advancements in Understanding the Disease

Hemifacial microsomia (HFM) is the second most common congenital disability of the face, with a prevalence of 1 in 3000 to 5600 live births. Although etiology is still not fully understood, including both genetics and environmental factors, the latest reports indicate the prominence of premature loss of the neural crest cells. What is more, a deficit of muscles of mastication, except the masseter, correlates in the pathomechanism of mandibular underdevelopment. Due to the significant phenotypic diversification, the typical picture of HFM cannot be determined. It may present as an esthetic concern-minor asymmetry with deformed auricle, and on the contrary, as microtia/anotia with conductive type hearing loss, hypoplastic mandible, and microphthalmia, impairing patient's daily activities. Referring to psychosocial problems, it has been proved that in population with HFM, there is a modestly elevated risk for behavior problems, social competence, and less acceptance. Over the years, more comprehensive methods of assessing the extent and severity of the HFM as the OMENS (+) classification have emerged. The authors like to summarize and present for plastic surgery resident and plastic surgeons the critical features of HFM, including the epidemiology, clinical presentation, pathogenesis, and innovative management reported in the current literature.

Using an expanded scalp flap without fascial flap harvest or skin grafting for total auricular reconstruction in hemifacial microsomia with low hairline

BACKGROUND

Total auricular reconstruction for hemifacial microsomia patients with extremely low hairline is a tough challenge in plastic surgery. In this work, a brand new technique using a singer expanded scalp flap without skin graft and combined with intense pulse light treatments (IPLT) for ear reconstruction is described in this special population.

METHODS

From January 2015 to April 2019, 41 hemifacial macrosomia (HFM) patients with 70-100% low hairline were enrolled in our study. Operative treatment was performed in 3 stages: 1. Expander insertion and inflation; 2. Expander removal, costal cartilage framework fabrication and auricular reconstruction; 3. Tragus reconstruction and reconstructed auricle refinement. Several IPLTs were performed every 45 days until local area become hairless during the whole course. The first IPLT could be executed either before all the operations or during the expansion period. The flap was treated with M22 system using a filter of 695-1200 nm. Follow up ranged from 10 months to 4 years.

RESULTS

During follow-up, 90.2% patients were surveyed as satisfied with the outcome, especially in the aspects of minimal scars, natural matched color and clear contour of the reconstructed ear. No serious complications happened. Patients starting the IPLT during the expansion period required less treatment times of depilation (p < 0.05).

CONCLUSION

Auricular reconstruction using a single expanded scalp flap combined with intense pulse light depilation is a safe, effective and less invasive technique for hemifacial microsomia with extremely low hairline, and providing highly satisfying results. Initialing the IPLD during the expansion period is recommended.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Osteoinduction within BMP-2 transduced muscle tissue fragments with and without a fascia layer: implications for bone tissue engineering

Bone can be engineered in vivo by implantation of gene-activated muscle tissue fragments. This expedited approach may be further improved by use of muscle tissue with attached fascia. The aim of this in vitro study was to provide an in depth comparison of the osteogenic differentiation capacity of muscle alone and muscle with fascia after BMP-2 transduction. Skeletal muscle tissue from rats was cut into pieces with and without a fascia layer on the surface. Adenoviral BMP-2 or GFP vectors were used for transduction. Osteogenic differentiation within the tissue fragments was evaluated and compared by qRT-PCR, alizarin red S staining, histomorphometry and immunohistology. Transduction efficiency and level of transgene expression were higher for muscle with fascia than muscle alone. Transduction with BMP-2 led to a significant upregulation of bone marker genes, proteins, and calcium deposition in both groups. Interestingly, histological evaluation revealed that osteoinduction did not occur within the fascia layer itself. The upregulation of bone marker genes in muscle with fascia was significantly lower after 2 weeks but similar after 4 weeks of in vitro culture in comparison to muscle alone. The fascia layer led to higher transduction efficiency and enhanced BMP-2 expression. Despite fascia's lower capacity for osteogenic differentiation, muscle implants may benefit from the fascia layer by the improved ability to deliver BMP-2. The presented data may contribute to the development of a novel, cost-effective, single-surgery bone engineering technology and encourage the evaluation of the osteoregenerative potential of muscle with fascia in an animal model.