Fundamentals of expanded tissue

Baker, Shan R.

doi:10.1002/hed.2880130410

Cited by 37 publications

(19 citation statements)

References 23 publications

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“…Furthermore, it has been well documented in histologic examination of tissue-expanded skin specimens that expanded dermis is thinner with greater elastosis and zonal fragmentation of elastic fibers. 24,25 Lastly, it has been speculated that the contractile forces arising from the capsule around the breast implant cause further loss of nipple projection in this unique group of patients. 12 Since the original description of the skate nipple reconstruction, there has been little in the literature describing its modern-day modifications.…”

Section: Discussionmentioning

confidence: 98%

Surgical Outcomes and Nipple Projection Using the Modified Skate Flap for Nipple-Areolar Reconstruction in a Series of 422 Implant Reconstructions

Zhong¹,

Antony²,

Cordeiro³

2009

Annals of Plastic Surgery

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Numerous techniques have been used in an attempt to achieve long-term nipple projection following nipple-areolar reconstruction (NAR). A common setback, however, is the diminution of projection over time; this phenomenon is particularly evident following implant based breast reconstruction. The purpose of this report was thus to evaluate surgical outcomes and long-term nipple projection with the use of "modified skate flap" technique in exclusively implant based postmastectomy reconstructions. A retrospective review was performed for the period between 1993 and 2007. All consecutive patients with 2-staged tissue expander/implant reconstructions followed by NAR using the modified skate flap technique performed by the senior author (P.C.) were identified in a prospectively maintained breast reconstruction database. Only patients with a minimum of 1-year follow-up were included in the study. Patients with a history of irradiation to the breast were excluded from nipple projection assessment. Clinical outcome measurements included long-term nipple projection as well as incidence of complications from the NAR procedure using the modified skate flap technique. Over the 15-year study period, 475 patients underwent 2-staged tissue expander/implant reconstruction followed by NAR using the modified skate flap technique. Of these, there was a total of 292 patients with the minimum requirement of 1-year follow-up post NAR (61% follow-up rate). The total number of reconstructed nipple areolar complexes evaluated in this series was 422 (130 bilateral and 162 unilateral NAR). Forty patients (28 unilateral and 12 bilateral NAR) who received radiation to their breasts were excluded from nipple projection assessment. At a median follow-up of 44 months (range: 12-84 months), mean nipple projection was 2.5 mm (range: 1-4 mm). Minor complications occurred in 7.2% of the patients (n = 292). Skin graft donor site dehiscence was the most common complication (3.1%) followed by partial skin graft nontake of the areola (2.1%). This report documents the largest series of NAR using a single technique in the setting of postmastectomy reconstructions. This technique can be safely performed over breast implants with acceptably low rates of complications and predictable results. Long-term nipple projection over implant reconstructions using this technique is modest and this must be forewarned to patients completing the final stage of their implant reconstruction.

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Section: Discussionmentioning

confidence: 98%

Surgical Outcomes and Nipple Projection Using the Modified Skate Flap for Nipple-Areolar Reconstruction in a Series of 422 Implant Reconstructions

Zhong¹,

Antony²,

Cordeiro³

2009

Annals of Plastic Surgery

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“…In what follows, we will compare the response of our model to skin growth experiments in the literature [9, 10, 12, 64, 66, 68]. Unfortunately, almost all existing data are based on in vivo tissue expansion studies.…”

Section: Discussionmentioning

confidence: 99%

“…Acutely, tissue expansion has been associated with slight epidermal thickening and significant dermal thinning [9], resulting in an overall thinning and a reduced tensile strength [10]. Mechanically, a study in rodents reported an acute increase in uniaxial stretch of approximately 36% [12].…”

Section: Discussionmentioning

confidence: 99%

“…Chronically, tissue expansion is associated with the gradual restoration of baseline histology, baseline mechanics, and baseline structure [10]. Histologically, a comparison of piglet tissue in expanded and non-expanded regions demonstrated a chronic restoration of the number of epidermal cell layers and a chronic restoration of the epidermal thickness [64].…”

Section: Discussionmentioning

confidence: 99%

“…In addition, the growth process itself could be modeled as anisotropic [21], e.g., attributed to a pronounced growth along specific microstructural directions. Similarly, through the deposition of large bundles of compacted immature collagen [10, 33], the underlying collagen network could reorient itself, e.g., to align with the maximum principal strains [29, 38]. Here, we model growth as a strain driven process.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

On the biomechanics and mechanobiology of growing skin

Zöllner

Tepole

Kuhl

2012

Journal of Theoretical Biology

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Skin displays an impressive functional plasticity, which allows it to adapt gradually to environmental changes. Tissue expansion takes advantage of this adaptation, and induces a controlled in situ skin growth for defect correction in plastic and reconstructive surgery. Stretches beyond the skin’s physiological limit invoke several mechanotransduction pathways, which increase mitotic activity and collagen synthesis, ultimately resulting in a net gain in skin surface area. However, the interplay between mechanics and biology during tissue expansion remains unquantified. Here we present a continuum model for skin growth that summarizes the underlying mechanotransduction pathways collectively in a single phenomenological variable, the strain-driven area growth. We illustrate the governing equations for growing biological membranes, and demonstrate their computational solution within a nonlinear finite element setting. In displacement-controlled equi-biaxial extension tests, the model accurately predicts the experimentally observed histological, mechanical, and structural features of growing skin, both qualitatively and quantitatively. Acute and chronic elastic uniaxial stretches are 25% and 10%, compared to 36% and 10% reported in the literature. Acute and chronic thickness changes are −28% and −12%, compared to −22% and −7% reported in the literature. Chronic fractional weight gain is 3.3, compared to 2.7 for wet weight and 3.3 for dry weight reported in the literature. In two clinical cases of skin expansion in pediatric forehead reconstruction, the model captures the clinically observed mechanical and structural responses, both acutely and chronically. Our results demonstrate that the field theories of continuum mechanics can reliably predict the mechanical manipulation of thin biological membranes by controlling their mechanotransduction pathways through mechanical overstretch. We anticipate that the proposed skin growth model can be generalized to arbitrary biological membranes, and that it can serve as a valuable tool to virtually manipulate living tissues, simply by means of changes in the mechanical environment.

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Effect of strain on human keratinocytes in vitro

et al. 1997

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Tissue expansion, a technique to enlarge the skin surface area with an expandable balloon, has been widely used in reconstructive surgery. Although the effect of tissue expansion on in vivo skin physiology and histology has been well documented, it remains unclear whether keratinocytes or other cell types are responsible for these changes. Therefore, we investigated the in vitro effect of cyclic (10 cycles/min, 150 mmHg) or constant (continuous, 150 mmHg) strain on human keratinocyte phenotype and relevant mechanosignaling pathways. Our results demonstrate that keratinocytes subjected to cyclic strain exhibit a significant (P < 0.05) increase in cell proliferation (49.2+/-15.8%), DNA synthesis (37.7+/-4.5%), elongation (20.3+/-2.7%), and protein synthesis (17.9+/-6.6% increase) as compared with stationary controls. In contrast, keratinocytes subjected to constant strain were unaffected aside from a modest transitory increase in the proliferative rate. Keratinocytes subjected to cyclic strain aligned perpendicular to the force vector (24.2+/-1.6 degrees) as compared with stationary controls (40.4+/-2.2 degrees; the smaller degree indicates better alignment). We also report strain-induced reduction in the levels of cyclic adenosine mono phosphate (cAMP), protein kinase A (PKA), and prostaglandin E2 (PGE2) as compared with stationary controls (cAMP, 30+/-7.5%; PKA, 45+/-17%; PGE2, 58+/-4.3%; percent decrease vs. that of control). We conclude that direct application of cyclic strain on human keratinocytes modulates cell phenotype and cAMP-mediated signaling pathways in an inverse manner. Moreover, keratinocytes may play an important role in previously observed alterations in skin properties associated with tissue expansion and other strain-induced responses.

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Fundamentals of expanded tissue

Cited by 37 publications

References 23 publications

Surgical Outcomes and Nipple Projection Using the Modified Skate Flap for Nipple-Areolar Reconstruction in a Series of 422 Implant Reconstructions

Surgical Outcomes and Nipple Projection Using the Modified Skate Flap for Nipple-Areolar Reconstruction in a Series of 422 Implant Reconstructions

On the biomechanics and mechanobiology of growing skin

Effect of strain on human keratinocytes in vitro

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