Complication Rates With Human Acellular Dermal Matrices: Retrospective Review of 211 Consecutive Breast Reconstructions.

BACKGROUND: Human acellular dermal matrix (HADM) is commonly used to provide coverage and support for breast reconstruction. The primary purpose of this study was to evaluate the complication rates associated with breast reconstruction procedures when performed in conjunction with multiple types of HADM in a consecutive series. METHODS: After receiving institutional review board approval, medical records from a single surgeon were retrospectively reviewed for 126 consecutive patients (170 breasts and 211 procedures) who received a breast reconstruction or revision with implantation of HADM between 2012 and 2014. Patient demographics, surgical technique, and the complication profile of 4 major types of HADM were evaluated by procedure. Complication data were primarily evaluated for infection, seroma formation, necrosis, and other complications requiring additional surgery. RESULTS: The total complication rate was 19.4%. The complication rates were not statistically different between all 4 types of HADM: Alloderm (n = 143); Alloderm RTU (n = 19); FlexHD (n = 18); hMatrix (n = 32) (P > 0.05). Smokers and large-breasted women (≥500 g) had a significantly higher complication rate than the rest of the population (P < 0.01 and P < 0.03, respectively). The complication rates associated with all other patient cohorts analyzed (age, body mass index, comorbid conditions, cancer diagnosis, prepectoral technique) showed no influence on complication rates (P > 0.05). CONCLUSIONS: In characteristically similar cohorts, there was no statistically significant difference in complication rates based on type of HADM; however, certain risk factors and anatomy should be considered before HADM-assisted breast reconstruction.

Comparison of the osteogenic potential of OsteoSelect demineralized bone matrix putty to NovaBone calcium-phosphosilicate synthetic putty in a cranial defect model.

The purpose of this study was to compare the osteogenic potential of a synthetic and a demineralized bone matrix (DBM) putty using a cranial defect model in New Zealand white rabbits. Paired, bilateral critical-size defects (10 mm) were prepared in the frontal bones of 12 rabbits and filled with either OsteoSelect DBM Putty or NovaBone calcium-phosphosilicate putty. At days 43 and 91, 6 rabbits were killed and examined via semiquantitative histology and quantitative histomorphometry. Defects filled with the DBM putty were histologically associated with less inflammation and fibrous tissue in the defect and more new bone than the synthetic counterpart at both time points. Histomorphometric analysis revealed that the defects filled with DBM putty were associated with significantly more bone formation at day 43 (70.7% vs 40.7%, P = 0.043) and at day 91 (70.4% vs 39.9%, P = 0.0044). The amount of residual implant was similar for both test groups at each time point.

Sex matters in the establishment of murine tendon composition and material properties during growth.

The existence of sex-based differences in tendon and ligament injury rates has led investigators to test the hypothesis that sex plays a significant role in modulating tendon and ligament composition and material properties. To date, no studies have attempted to characterize how such differences develop during the course of normal tissue maturation and growth. Thus, the primary aim of the present study was to use a murine model to test the hypothesis that sex-based differences in the normal age-related development of tendon composition and material properties exist by assessing these parameters in the Achilles and tail tendons from 4-, 6-, 9-, 12-, and 15-week-old male and female C57Bl/6J mice. Despite significantly lower levels of total collagen content in females subsequent to sexual maturity (p<0.0001), as well as a significant effect of sex on glycosaminoglycan content (p<0.0001), Achilles tendon elastic modulus was not compromised in females. Female Achilles tendons did exhibit a significantly higher failure strain (p=0.0201) and strain energy density (p=0.0004) than did males, as well as a trend toward higher ultimate strength (p=0.0556). In contrast to the high load-bearing environment of the Achilles tendon site, sex did not have a statistically significant effect on any compositional or material property in the low load-bearing tendon fascicles of the tail. These data support recent studies by others, which suggest that male and female tendons have a differential adaptational response to their local mechanical loading environment.

Sexual dimorphism in the effect of GDF-6 deficiency on murine tendon.

Three members of the growth/differentiation factor (GDF) subfamily of bone morphogenetic proteins (BMPs), GDFs-5, -6, and -7, have demonstrated the potential to augment tendon and ligament repair. To gain further insight into the in vivo role of these molecules, previous studies have characterized intact and healing tendons in mice with functional null mutations in GDF-5 and -7. The primary goal of the present study was to perform a detailed characterization of the intact tendon phenotype in 4- and 16-week-old male and female GDF6-/- mice and their +/+ littermates. The results demonstrate that GDF6 deficiency was associated with an altered tendon phenotype that persisted into adulthood. Among males, GDF6-/- tail tendon fascicles had significantly less collagen and glycosaminoglycan content, and these compositional differences were associated with compromised material properties. The effect of GDF6 deficiency on tendon was sexually dimorphic, however, for among female GDF6-/- mice, neither differences in tendon composition nor in material properties were detected. The tendon phenotype that was observed in males appeared to be stronger in the tail site than in the Achilles tendon site, where some compositional differences were present, but no material property differences were detected. These data support existing in vitro studies, which suggest a potential role for BMP-13 (the human homologue to GDF-6) in tendon matrix modeling and/or remodeling.

Identification of a tendon phenotype in GDF6 deficient mice.

Increasing evidence suggests that the growth/differentiation factors, GDFs 5, 6, and 7 in particular, may play a role in tendon and ligament biology. Mice with genetic mutations in Gdf5 have altered tendon composition and mechanical behavior, whereas animals with functional null mutations in Gdf7 have a more subtle tendon phenotype. The present study demonstrates for the first time that a null mutation in Gdf6 is associated with substantially lower levels of tail tendon collagen content (-33%) in 4-week-old male mice, which has direct functional consequences for the mechanical integrity of the tissue (45-50% reduction in material properties). These data support a role for GDF6 in tendon matrix modeling.

Effect of GDF-7 deficiency on tail tendon phenotype in mice.

The subfamily of growth/differentiation factors (GDFs) known as GDFs 5, 6, and 7 appears to be involved in tendon maintenance and repair, although the precise nature of this role has yet to be elucidated. The aim of the present study was to examine the role of GDF-7 in tendon maintenance by studying tail tendon fascicle gene expression, composition, and material property strain rate dependency in 16-week-old male and female GDF-7 deficient mice. GDF-7 deficiency did not affect the biochemical composition of tail tendon fascicles, nor did it significantly affect the tensile material properties obtained at either slow (5%/s) or fast (50%/s) strain rates. Further, no difference was found between genotypes in the strain rate sensitivity of any tensile material property. Consistent with the compositional analyses, QRT-PCR data did not reveal any differences of twofold or greater in the gene expression levels of collagens I, III, V, nor in the proteoglycans decorin, fibromodulin, lumican, biglycan, versican, or aggrecan. Gdf5 expression was upregulated twofold in GDF-7 deficient tail tendons, and Bmp7 expression was downregulated twofold. No notable differences in expression levels for Bmp1-6 or Gdf6 were detected. GDF-5 protein levels were 50% higher in GDF-7 deficient tail tendon compared to wild type tail tendon. The results of this study support the intriguing possibility that compensation by Gdf-5 may be at least in part responsible for the absence of a strong phenotype in GDF-7 deficient mice.

Effect of y2 receptor deletion on whole bone structural behavior in mice.

Recent evidence has shown that mice deficient in the NPY Y2 receptor have an increase in trabecular bone volume as well as cortical bone mass due to increased osteoblast activity. However, the mechanical phenotype of Y2 -/- bone has not yet been assessed. Thus, the aim of the present study was to examine the effect of Y2 deletion on murine cortical bone structural behavior, as well as to assess the material and geometric contributions to that behavior. The results of this study indicate that Y2 -/- mice on a 129 SV x Balb/c background strain are smaller in body mass and have smaller bones than wild-type controls. As expected based on smaller bone cross-sectional properties, cortical bone structural strength was lower in -/- animals. Surprisingly, the structural stiffness of -/- bones was comparable to that of +/+ bones despite their smaller cross-sectional geometry. Comparable structural stiffness appeared to be achieved by means of an elevated effective shear modulus, which was associated with a small, but statistically significant, higher ash content in Y2 -/- bones. These data represent the first comprehensive characterization of the effect of Y2 deletion on cortical bone structural and material behavior to date.