Preoperative CT imaging as a tool to predict incisional hernia outcomes following abdominal wall reconstruction: A retrospective cohort analysis.

INTRODUCTION: Ventral wall hernia often causes significant morbidity and requires complex abdominal wall reconstruction (AWR). This study aims to determine whether subcutaneous abdominal fat thickness (AFT) measured with preoperative CT scans could predict postoperative outcomes in patients undergoing AWR. METHODS: A retrospective cohort study was conducted on all patients who underwent AWR at our institution between 2009 and 2021, with a minimum follow-up of 12 months. Using preoperative CT scans, AFT was measured at the xiphoid process, umbilicus, and pubic tubercle, as well as the hernia dimensions. Demographic, operative, and surgical outcome data were also collected and analyzed using statistical tests. RESULTS: The results showed that 9 of 101 patients (8.9%) experienced hernia recurrence. Smoking was associated with an increased risk of hernia recurrence (p < 0.001) with a predictive odds ratio (OR) of 18.27 (p = 0.041). Increased AFT at the xiphoid (p = 0.005), umbilicus (p < 0.001), and pubic tubercle (p < 0.001) were also associated with hernia recurrence and risk of infection. Only AFT at the pubic tubercle reached significance in the regression model predicting recurrence (OR=1.10; p = 0.030) and infection (OR=1.04; p = 0.021). A cut-off value of 67 mm was associated with a positive predictive value of 42.14% (sensitivity of 67% and specificity of 91%). Hernia defect area was not associated with risk of recurrence or infection. CONCLUSIONS: Smoking and increased AFT at the pubic tubercle are significant predictive factors for recurrence and infection in patients undergoing AWR, and preoperative optimization should focus on reducing these factors.

Achieving optimal clinical outcomes in autologous fat grafting: A systematic review of processing techniques.

BACKGROUND: Autologous fat grafting (AFG) is a versatile technique in reconstructive and cosmetic surgery. Graft processing is a key source of variability resulting in unreliable clinical outcomes, with no consensus on the optimal methodology. This systematic review identifies the evidence base supporting different processing paradigms. METHODS: A systematic literature search was conducted using the PubMed, Scopus and The Cochrane Foundation databases. Studies comparing AFG processing methods and reporting long-term patient outcomes were identified. RESULTS: Twenty-four studies (2413 patients) were identified. Processing techniques evaluated included centrifugation, decantation, washing, filtration, gauze rolling, as well as commercial devices and adipose-derived stem/stromal cell (ASC) enrichment methods. Objective volumetric and subjective patient-reported outcomes were discussed. There was a variable reporting of complications and volume retention rates. Complications were infrequent; palpable cysts (0-20%), surgical-site infections (0-8%) and fat necrosis (0-58.4%) were the most reported. No significant differences in long-term volume retention between techniques were found in AFG in the breast. In head and neck patients, greater volume retention was documented in ASC enrichment (64.8-95%) and commercial devices (41.2%) compared to centrifugation (31.8-76%). CONCLUSIONS: Graft processing through washing and filtration, including when incorporated into commercial devices, results in superior long-term outcomes compared to centrifugation and decantation methods. ASC enrichment methods and commercial devices seem to have superior long-term volume retention in facial fat grafting.

Comparison of the compressive mechanical properties of auricular and costal cartilage from patients with microtia.

Children born with a small or absent ears undergo surgical reconstruction to restore their auricle. Currently, rib (costal) cartilage is used to carve the auricle. However as alternative, tissue engineered and synthetic materials are being developed to restore the auricle shape to overcome donor site morbidity and limited availability of rib cartilage. However, to date there is limited knowledge regarding the mechanical properties of the auricular and costal cartilage to optimise the required compressive properties of the graft. The remnant auricular and costal cartilage from 20 patients undergoing stage-1 microtia surgery was harvested. On the day of surgery, the cartilage was evaluated in compression, with each sample loaded to 300 g at 1 mm/s. RESULTS: The costal cartilage was observed to have a significantly higher Young's Elastic Modulus than auricular cartilage (average costal cartilage 11.43 MPa vs average auricular cartilage 2 MPa, p < 0.0001). The auricular cartilage showed a significantly higher relaxation rate than costal cartilage (average costal cartilage 0.72 MPa10-4 vs average auricular cartilage 1.93 MPa10-4, p < 0.05). The final absolute relaxation was significantly lower for elastic cartilage than costal cartilage (average costal cartilage 3.35 MPa vs average auricular cartilage 0.2 MPa, p < 0.0001). Alloplastic cartilage replacements used as alternatives for reconstruction were also evaluated. Silicone, Gore-Tex and Medpor were observed to have significantly higher Young's Elastic Modulus than costal and auricular cartilage. Costal cartilage has a higher Young's Elastic Modulus in compression compared to auricular cartilage. Current synthetic materials used to replace synthetic cartilage do not mimic costal cartilage, which should be addressed in the future.

Adipose derived stem cells and platelet rich plasma improve the tissue integration and angiogenesis of biodegradable scaffolds for soft tissue regeneration.

Current surgical reconstruction for soft tissue replacement involves lipotransfer to restore soft tissue replacements but is limited by survival and longevity of the fat tissue. Alternative approaches to overcome these limitations include using biodegradable scaffolds with stem cells with growth factors to generate soft tissue. Adipose derived stem cells (ADSCs) offer great potential to differentiate into adipose, and can be delivered using biodegradable scaffolds. However, the optimal scaffold to maximise this approach is unknown. This study investigates the biocompatibility of nanocomposite scaffolds (POSS-PCL) to deliver ADSCs with and without the addition of growth factors using platelet rich plasma (PRP) in vivo. Rat ADSCs were isolated and then seeded on biodegradable scaffolds (POSS-PCL). In addition, donor rats were used to isolate PRP to modify the scaffolds. The implants were then subcutaneously implanted for 3-months to assess the effect of PRP and ADSC on POSS-PCL scaffolds biocompatibility. Histology after explanation was examined to assess tissue integration (H&E) and collagen production (Massons Trichome). Immunohistochemistry was used to assess angiogenesis (CD3, α-SMA), immune response (CD45, CD68) and adipose formation (PPAR-γ). At 3-months PRP-ADSC-POSS-PCL scaffolds demonstrated significantly increased tissue integration and angiogenesis compared to PRP, ADSC and unmodified scaffolds (p < 0.05). In addition, PRP-ADSC-POSS-PCL scaffolds showed similar levels of CD45 and CD68 staining compared to unmodified scaffolds. Furthermore, there was increased PPAR-γ staining demonstrated at 3-months with PRP-ADSC-POSS-PCL scaffolds (p < 0.05). POSS-PCL nanocomposite scaffolds provide an effective delivery system for ADSCs. PRP and ADSC work synergistically to enhance the biocompatibility of POSS-PCL scaffolds and provide a platform technology for soft tissue regeneration.

Breast Reconstruction with a Tissue Engineering and Regenerative Medicine Approach (Systematic Review).

Current techniques for breast reconstruction include an autologous-tissue flap or an implant-based procedure, although both can impose further morbidity. This systematic review aims to explore the existing literature on breast reconstruction using a tissue engineering approach; conducted with the databases Medline and Embase. A total of 28 articles were included, mainly comprising of level-5 evidence with in vitro and animal studies focusing on utilizing scaffolds to support the migration and growth of new tissue; scaffolds can be either biological or synthetic. Biological scaffolds were composed of collagen or a decellularized tissue matrix scaffold. Synthetic scaffolds were primarily composed of polymers with customisable designs, adjusting the internal morphology and pore size. Implanting cells, including adipose-derived stem cells, with combined use of basic fibroblast growth factor has been studied in an attempt to enhance tissue regeneration. Lately, a level-4 evidence human case series was reported; successfully regenerating 210 mL of tissue using an arterio-venous pedicled fat flap within a tissue engineering chamber implanted on the chest wall. Further research is required to evaluate whether the use of cells and other growth factors could adjust the composition of regenerated tissue and improve vascularity; the latter a major limiting factor for creating larger volumes of tissue.

Sidestream Dark Field (SDF) imaging of oral microcirculation in the assessment of systemic sclerosis.

INTRODUCTION: Systemic sclerosis (SSc) is a systemic disease characterised by abnormalities in small blood vessels, skin and organ fibrosis. It is assessed using generalised skin thickening scores, autoantibodies and nailfold capillaroscopy. Sidestream Dark Field imaging (SDF) is a non-invasive imaging tool that assesses microcirculation. This study aims to investigate the potential of using SDF as a diagnostic tool in SSc. METHOD: Oral microcirculation of 20 patients with SSc was compared to 20 age and gender matched controls using SDF imaging. Sublingual, buccal and incisor regions of the mouth were examined. All volunteers were female averaging 48.0 (24-64) years old. Vasculature was assessed by calculating the De Backer score and Functional Capillary Density (FCD) on an imaging software. RESULTS: At all regions of the mouth, SSc patients had a significantly lower De Backer score compared to controls (SSc 3.484 ±â€¯0.1361/mm vs Control 5.184 ±â€¯0.1896/mm, unpaired t-test p < 0.0001). The SSc patients showed significantly lower FCDs compared to controls at all areas as well (SSc 19.65 ±â€¯0.9445% vs Control 29.45 ±â€¯1.681%, unpaired t-test, p < 0.0001). The incisor regions had significantly higher De Backer and FCD scores than buccal and sublingual regions in both control and SSc patients (one way anova, p < 0.05). De Backer/FCD scores showed significant correlation against Rodnan Skin Scores in patients with SSc (Pearson correlation, p < 0.05). CONCLUSIONS: SSc patients showed decreased oral vasculature compared to controls. SDF imaging has shown the ability to be a useful diagnostic tool in the assessment of SSc.

Argon plasma surface modification promotes the therapeutic angiogenesis and tissue formation of tissue-engineered scaffolds in vivo by adipose-derived stem cells.

BACKGROUND: Synthetic implants are being used to restore injured or damaged tissues following cancer resection and congenital diseases. However, the survival of large tissue implant replacements depends on their ability to support angiogenesis that if limited, causes extrusion and infection of the implant. This study assessed the beneficial effect of platelet-rich plasma (PRP) and adipose-derived stem cells (ADSCs) on synthetic biomaterials in combination with argon plasma surface modification to enhance vascularisation of tissue-engineered constructs. METHODS: Non-biodegradable polyurethane scaffolds were manufactured and modified with plasma surface modification using argon gas (PM). Donor rats were then used to extract ADSCs and PRP to modify the scaffolds further. Scaffolds with and without PM were modified with and without ADSCs and PRP and subcutaneously implanted in the dorsum of rats for 3 months. After 12 weeks, the scaffolds were excised and the degree of tissue integration using H&E staining and Masson's trichrome staining, angiogenesis by CD31 and immune response by CD45 and CD68 immunohistochemistry staining was examined. RESULTS: H&E and Masson's trichrome staining showed PM+PRP+ADSC and PM+ADSC scaffolds had the greatest tissue integration, but there was no significant difference between the two scaffolds (p < 0.05). The greatest vessel formation after 3 months was shown with PM+PRP+ADSC and PM+ADSC scaffolds using CD31 staining compared to all other scaffolds (p < 0.05). The CD45 and CD68 staining was similar between all scaffolds after 3 months showing the ADSCs or PRP had no effect on the immune response of the scaffolds. CONCLUSIONS: Argon plasma surface modification enhanced the effect of adipose-derived stem cells effect on angiogenesis and tissue integration of polyurethane scaffolds. The combination of ADSCs and argon plasma modification may improve the survival of large tissue implants for regenerative applications.

Systematic review of methodologies used to assess mastectomy flap viability.

BACKGROUND: Accurate prediction of mastectomy skin flap viability is vital as necrosis causes significant morbidity, potentially compromising results and delaying oncological management. Traditionally assessed by clinical judgement, a more objective evaluation can be provided using intraoperative imaging modalities. This systematic review aimed to compare all intraoperative techniques for assessment of mastectomy flap viability. METHODS: A systematic literature review was performed using MEDLINE and Embase databases. Primary outcomes reported included specificity, sensitivity and predictive values of each test, and mean rates of mastectomy flap necrosis and reoperation. Secondary outcomes included cost analysis. RESULTS: Some 18 studies were included. Designs were prospective cohort study (8), retrospective case series (4), prospective case series (3), retrospective case-control study (1), prospective pilot trial (1) and cost analysis study (1). The studies compared indocyanine green angiography (ICGA) (16 studies) and fluorescein dye angiography (FA) (3 studies) with clinical judgement. Sensitivity and specificity were highest for ICGA (5 studies) ranging from 38 to 100 and 68 to 91 per cent respectively. Both methods overpredicted necrosis. Mean rates of flap necrosis and reoperation decreased with ICGA (7·9 and 5·5 per cent respectively) and FA (3 and 0 per cent) compared with clinical judgement (19·4 and 12·9 per cent). Two studies were designed to define numerical parameters corresponding to perfusion using intraoperative techniques. Two studies performed a cost analysis for ICGA; one claimed a cost benefit and the other advocated its use in high-risk patients only. CONCLUSION: ICGA and FA are potentially useful tools for mastectomy flap assessment. However, the predictive accuracy is subject to the specific settings and model of equipment used. Current recommendations support their use in high-risk patients.

Comparison of the mechanical properties of different skin sites for auricular and nasal reconstruction.

BACKGROUND: Autologous and synthetic nasal and auricular frameworks require skin coverage. The surgeon's decides on the appropriate skin coverage for reconstruction based on colour matching, subcutaneous tissue thickness, expertise and experience. One of the major complications of placing subcutaneous implants is the risk of extrusion (migration through the skin) and infection. However, knowledge of lessening the differential between the soft tissue and the framework can have important implications for extrusion. This study compared the mechanical properties of the skin commonly used as skin sites for the coverage in auricular and nasal reconstruction. METHODS: Using ten fresh human cadavers, the tensile Young's Modulus of the skin from the forehead, forearm, temporoparietal, post-auricular and submandibular neck was assessed. The relaxation rate and absolute relaxation level was also assessed after 90 min of relaxation. RESULTS: The submandibular skin showed the greatest Young's elastic modulus in tension of all regions (1.28 MPa ±0.06) and forearm showed the lowest (1.03 MPa ±0.06). The forehead demonstrated greater relaxation rates among the different skin regions (7.8 MPa-07 ± 0.1). The forearm showed the lowest rate of relaxation (4.74 MPa-07 ± 0.1). The forearm (0.04 MPa ±0.004) and submandibular neck skin (0.04 MPa ±0.005) showed similar absolute levels of relaxation, which were significantly greater than the other skin regions (p < 0.05). CONCLUSIONS: This study provides an understanding into the biomechanical properties of the skin of different sites allowing surgeons to consider this parameter when trying to identify the optimal skin coverage in nasal and auricular reconstruction.

Chemical group-dependent plasma polymerisation preferentially directs adipose stem cell differentiation towards osteogenic or chondrogenic lineages.

Human adipose derived stem cells (ADSCs) are being explored for the repair of craniofacial defects due to their multi-differentiation potential and ease of isolation and expansion. Crucial to using ADSCs for craniofacial repair is the availability of materials with appropriate biomechanical properties that can support their differentiation into bone and cartilage. We tested the hypothesis that different modifications of chemical groups on the surface of a nanocomposite polymer could increase human ADSC adhesion and selectively enhance their osteogenic and chondrogenic differentiation. We show that the COOH modification significantly promoted initial cell adhesion and proliferation over 14days compared to NH2 surfaces. Expression of focal adhesion kinase and vinculin was enhanced after plasma surface polymerisation at 24h. The COOH modification significantly enhanced chondrogenic differentiation as indicated by up-regulation of aggrecan and collagen II transcripts. In contrast, NH2 group functionalised scaffolds promoted osteogenic differentiation with significantly enhanced expression of collagen I, alkaline phosphatase and osteocalcin both at the gene and protein level. Finally, chorioallantoic membrane grafting demonstrated that both NH2 and COOH functionalised scaffolds seeded with ADSCs were biocompatible and supported vessel ingrowth apparently to a greater degree than unmodified scaffolds. In summary, our study shows the ability to direct ADSC chondrogenic and osteogenic differentiation by deposition of different chemical groups through plasma surface polymerisation. Hence this approach could be used to selectively enhance bone or cartilage formation before implantation in vivo to repair skeletal defects. STATEMENT OF SIGNIFICANCE: Human adipose derived stem cells (hADSCs) are an exciting stem cell source for regenerative medicine due to their plentiful supply and ease of isolation. However, the optimal environmental cues to direct stem cells towards certain lineages change have to has not been identified. We have shown that by modifying the surface of the scaffold with specific chemical groups using plasma surface polymerisation techniques we can control ADSCs differentiation. This study shows that ADSCs can be differentiated towards osteogenic and chondrogenic lineages on amine (NH2) and carboxyl (COOH) modified scaffolds respectively. Plasma polymerisation can be easily applied to other biomaterial surfaces to direct stem cell differentiation for the regeneration of bone and cartilage.

Biomechanical Characterisation of the Human Auricular Cartilages; Implications for Tissue Engineering.

Currently, autologous cartilage provides the gold standard for auricular reconstruction. However, synthetic biomaterials offer a number of advantages for ear reconstruction including decreased donor site morbidity and earlier surgery. Critical to implant success is the material's mechanical properties as this affects biocompatibility and extrusion. The aim of this study was to determine the biomechanical properties of human auricular cartilage. Auricular cartilage from fifteen cadavers was indented with displacement of 1 mm/s and load of 300 g to obtain a Young's modulus in compression. Histological analysis of the auricle was conducted according to glycoprotein, collagen, and elastin content. The compression modulus was calculated for each part of the auricle with the tragus at 1.67 ± 0.61 MPa, antitragus 1.79 ± 0.56 MPa, concha 2.08 ± 0.70 MPa, antihelix 1.71 ± 0.63 MPa, and helix 1.41 ± 0.67 MPa. The concha showed to have a significantly greater Young's Elastic Modulus than the helix in compression (p < 0.05). The histological analysis demonstrated that the auricle has a homogenous structure in terms of chondrocyte morphology, extracellular matrix and elastin content. This study provides new information on the compressive mechanical properties and histological analysis of the human auricular cartilage, allowing surgeons to have a better understanding of suitable replacements. This study has provided a reference, by which cartilage replacements should be developed for auricular reconstruction.

Lipotransfer for radiation-induced skin fibrosis.

BACKGROUND: Radiation-induced fibrosis (RIF) is a late complication of radiotherapy that results in progressive functional and cosmetic impairment. Autologous fat has emerged as an option for soft tissue reconstruction. There are also sporadic reports suggesting regression of fibrosis following regional lipotransfer. This systematic review aimed to identify cellular mechanisms driving RIF, and the potential role of lipotransfer in attenuating these processes. METHODS: PubMed, OVID and Google Scholar databases were searched to identify all original articles regarding lipotransfer for RIF. All articles describing irradiated fibroblast or myofibroblast behaviour were included. Data elucidating the mechanisms of RIF, role of lipotransfer in RIF and methods to quantify fibrosis were extracted. RESULTS: Ninety-eight studies met the inclusion criteria. A single, definitive model of RIF is yet to be established, but four cellular mechanisms were identified through in vitro studies. Twenty-one studies identified connective tissue growth factor and transforming growth factor ß1 cytokines as drivers of fibrotic cascades. Hypoxia was demonstrated to propagate fibrogenesis in three studies. Oxidative stress from the release of reactive oxygen species and free radicals was also linked to RIF in 11 studies. Purified autologous fat grafts contain cellular and non-cellular properties that potentially interact with these processes. Six methods for quantifying fibrotic changes were evaluated including durometry, ultrasound shear wave elastography, thermography, dark field imaging, and laser Doppler and laser speckle flowmetry. CONCLUSION: Understanding how lipotransfer causes regression of RIF remains unclear; there are a number of new hypotheses for future research.

Biomechanical characterisation of the human nasal cartilages; implications for tissue engineering.

Nasal reconstruction is currently performed using autologous grafts provides but is limited by donor site morbidity, tissue availability and potentially graft failure. Additionally, current alternative alloplastic materials are limited by their high extrusion and infection rates. Matching mechanical properties of synthetic materials to the native tissue they are replacing has shown to be important in the biocompatibility of implants. To date the mechanical properties of the human nasal cartilages has not been studied in depth to be able to create tissue-engineered replacements with similar mechanical properties to native tissue. The young's modulus was characterized in compression on fresh-frozen human cadaveric septal, alar, and lateral cartilage. Due to the functional differences experienced by the various aspects of the septal cartilage, 16 regions were evaluated with an average elastic modulus of 2.72 ± 0.63 MPa. Furthermore, the posterior septum was found to be significantly stiffer than the anterior septum (p < 0.01). The medial and lateral alar cartilages were tested at four points with an elastic modulus ranging from 2.09 ± 0.81 MPa, with no significant difference between the cartilages (p < 0.78). The lateral cartilage was tested once in all cadavers with an average elastic modulus of 0.98 ± 0.29 MPa. In conclusion, this study provides new information on the compressive mechanical properties of the human nasal cartilage, allowing surgeons to have a better understanding of the difference between the mechanical properties of the individual nasal cartilages. This study has provided a reference, by which tissue-engineered should be developed for effective cartilage replacements for nasal reconstruction.

Nanoscale Surface Modifications of Medical Implants for Cartilage Tissue Repair and Regeneration.

BACKGROUND: Natural cartilage regeneration is limited after trauma or degenerative processes. Due to the clinical challenge of reconstruction of articular cartilage, research into developing biomaterials to support cartilage regeneration have evolved. The structural architecture of composition of the cartilage extracellular matrix (ECM) is vital in guiding cell adhesion, migration and formation of cartilage. Current technologies have tried to mimic the cell's nanoscale microenvironment to improve implants to improve cartilage tissue repair. METHODS: This review evaluates nanoscale techniques used to modify the implant surface for cartilage regeneration. RESULTS: The surface of biomaterial is a vital parameter to guide cell adhesion and consequently allow for the formation of ECM and allow for tissue repair. By providing nanosized cues on the surface in the form of a nanotopography or nanosized molecules, allows for better control of cell behaviour and regeneration of cartilage. Chemical, physical and lithography techniques have all been explored for modifying the nanoscale surface of implants to promote chondrocyte adhesion and ECM formation. CONCLUSION: Future studies are needed to further establish the optimal nanoscale modification of implants for cartilage tissue regeneration.

An update on the Application of Nanotechnology in Bone Tissue Engineering.

BACKGROUND: Natural bone is a complex and hierarchical structure. Bone possesses an extracellular matrix that has a precise nano-sized environment to encourage osteoblasts to lay down bone by directing them through physical and chemical cues. For bone tissue regeneration, it is crucial for the scaffolds to mimic the native bone structure. Nanomaterials, with features on the nanoscale have shown the ability to provide the appropriate matrix environment to guide cell adhesion, migration and differentiation. METHODS: This review summarises the new developments in bone tissue engineering using nanobiomaterials. The design and selection of fabrication methods and biomaterial types for bone tissue engineering will be reviewed. The interactions of cells with different nanostructured scaffolds will be discussed including nanocomposites, nanofibres and nanoparticles. RESULTS: Several composite nanomaterials have been able to mimic the architecture of natural bone. Bioceramics biomaterials have shown to be very useful biomaterials for bone tissue engineering as they have osteoconductive and osteoinductive properties. Nanofibrous scaffolds have the ability to provide the appropriate matrix environment as they can mimic the extracellular matrix structure of bone. Nanoparticles have been used to deliver bioactive molecules and label and track stem cells. CONCLUSION: Future studies to improve the application of nanomaterials for bone tissue engineering are needed.

A Review of Current Regenerative Medicine Strategies that Utilize Nanotechnology to Treat Cartilage Damage.

BACKGROUND: Cartilage is an important tissue found in a variety of anatomical locations. Damage to cartilage is particularly detrimental, owing to its intrinsically poor healing capacity. Current reconstructive options for cartilage repair are limited, and alternative approaches are required. Biomaterial science and Tissue engineering are multidisciplinary areas of research that integrate biological and engineering principles for the purpose of restoring premorbid tissue function. Biomaterial science traditionally focuses on the replacement of diseased or damaged tissue with implants. Conversely, tissue engineering utilizes porous biomimetic scaffolds, containing cells and bioactive molecules, to regenerate functional tissue. However, both paradigms feature several disadvantages. Faced with the increasing clinical burden of cartilage defects, attention has shifted towards the incorporation of Nanotechnology into these areas of regenerative medicine. METHODS: Searches were conducted on Pubmed using the terms "cartilage", "reconstruction", "nanotechnology", "nanomaterials", "tissue engineering" and "biomaterials". Abstracts were examined to identify articles of relevance, and further papers were obtained from the citations within. RESULTS: The content of 96 articles was ultimately reviewed. The literature yielded no studies that have progressed beyond in vitro and in vivo experimentation. Several limitations to the use of nanomaterials to reconstruct damaged cartilage were identified in both the tissue engineering and biomaterial fields. CONCLUSION: Nanomaterials have unique physicochemical properties that interact with biological systems in novel ways, potentially opening new avenues for the advancement of constructs used to repair cartilage. However, research into these technologies is in its infancy, and clinical translation remains elusive.

Necrotising soft tissue infection in a UK metropolitan population.

INTRODUCTION: Necrotising soft tissue infection (NSTI) is a rare but life threatening diagnosis. Geographic, economic and social variances influence presentation and prognosis. As the current literature does not reflect a UK metropolitan population, we conducted a retrospective chart review to establish pertinent features relevant to our practice. METHODS: Patients with histologically confirmed diagnoses of NSTI presenting to two London teaching hospitals between January 2007 and July 2013 were included in the study. Features of presentation, surgical and medical management, microbiological findings and outcome were evaluated. RESULTS: Twenty-four patients with histologically confirmed NSTI were included. Two age clusters were identified, with means of 46 years (standard deviation [SD]: 10 years) and 80 years (SD: 6 years). Pain, erythema and sepsis were common findings. Hypertension, hypercholesterolaemia and type II diabetes mellitus were common co-morbidities. A third of younger patients had human immunodeficiency virus or hepatitis C, with a quarter dependent on drugs and/or alcohol. The mean Laboratory Risk Indicator for Necrotising Fasciitis (LRINEC) score was 5.8 (SD: 3.3). The lower extremities, groin and perineum were common sites of infection. Fourteen patients required inotropic support and seventeen required transfusions. The median number of surgical procedures was 5 (range: 1-17). Group A Streptococcus was the most frequently identified pathogen. Five patients died. Being elderly, female sex and failure to use clindamycin as a first-line antibiotic were associated with significantly higher mortality. CONCLUSIONS: In contrast to other recent series, group A streptococcal monomicrobial NSTI remains the most common presentation in our population. Survival is anticipated in young patients, regardless of premorbid status. Elderly patients have a poor prognosis. The negative predictive value of the LRINEC score is questioned. Use of clindamycin as a first-line antibiotic is supported.

A prospective study of the use of botulinum toxin injections in the treatment of Raynaud's syndrome associated with scleroderma.

Raynaud's syndrome contributes to the pain, paraesthesia, ulceration, and gangrene of scleroderma. Botulinum toxin has been shown to improve digital perfusion in patients with Raynaud's. This is the first study to objectively assess hand function following this treatment in patients with scleroderma. Twenty patients were treated with 100 units of botulinum toxin injected into the hand. An assessment of hand function and symptoms was performed prior to injection and then 8-12 weeks later. The outcomes assessed were change in pain, appearance, cold intolerance, pinch and power grip, ranges of movement, and Disabilities of the Arm, Shoulder and Hand (DASH) score. In total, 80% of patients reported an overall improvement in their symptoms, reduction in pain, and improved DASH score and 65% reported improvement in cold intolerance. Overall, 90% showed an improvement in pinch grip and 65% an improvement in power grip. Objective parameters were statistically significantly improved; however, subjective outcomes only showed a trend. We have found botulinum toxin to be an effective treatment for Raynaud's syndrome secondary to scleroderma.