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Biomedical subjects

U Kneser

Publications and source records attributed to U Kneser.

At least 19 recordsLinked to original sources
PubMed2006

[The importance of vacuum therapy in the treatment of sternal osteomyelitis from the plastic surgeons point of view].

BACKGROUND: Since its introduction in 1997 the vacuum assisted closure therapy has gained widespread and is for its indications international accepted. It is also well established in the treatment of sternal infections a dreaded complication after median sternotomy in cardiac surgery. The well known positive effects of the vacuum therapy act as a dignified cleaning procedure between debridement and plastic coverage or as a temporarily closure method if the first debridement was properly not sufficient. METHOD AND PATIENTS: Between January 2003 and December 2005 twenty eight patients with advanced sternal infection after median sternotomy were treated by radical debridement, vacuum assisted closure therapy and definitive plastic coverage by muscle flaps. In this article three patients are exemplarily introduced. RESULTS: In all patients a sufficient plastic coverage was achieved after radical debridement an vacuum assisted closure therapy. The patients received a pedicaled muscle flap. Stable wound condition with no signs of a recurrent sternal infection were observed in all patients. DISCUSSION: Vacuum assisted closure therapy acts as a link between radical Debridement and definitive plastic coverage in prolonged sternal infection after median sternotomy. Before the invention of V.A.C.(R) dressing changes were obliged every day in patients with deep sternal infection. The V.A.C.(R) therapy reduces the frequency of this painful dressing changes significantly and on this behalf makes life more comfortable for this mostly multi-morbid patients.

Aged↗
PubMed2006

[Vacuum assisted closure (V.A.C.) therapy is an essential tool for treatment of complex defect injuries of the upper extremity].

INTRODUCTION: Complex injuries of the upper extremity remain a therapeutic challenge. The prognosis of the damaged extremity is often limited by soft tissue defects. Vacuum Assisted Closure (V.A.C.) therapy facilitates temporary coverage of soft tissue defects prior to surgical reconstruction. METHODS: In a retrospective study all patients with complex defect injuries of the upper extremity that were treated by V.A.C. prior to reconstruction between August 2003 and September 2005 were analyzed. RESULTS: 7 patients (6 male, 1 female, 14-70 years) were included in the study. The patients suffered from subtotal upper arm (n = 1) and forearm (n = 1) amputation, complex multilevel amputation injury of the forearm (n = 1), slash wound of the forearm with skin defect and discontinuity of all volar structures (n = 1), complex open forearm fractures with skin and soft tissue defects (n = 2), and almost complete necrosis of the flexor compartment following distal radius and proximal ulnar fracture and compartment syndrome (n = 1). Stabile defect coverage was achieved in all patients following V.A.C. therapy by myocutaneous free flaps (n = 2), split thickness skin grafts (STSG) (n = 2), sequential secondary suture (n = 1), and STSG + secondary suture (n = 2). Wound conditions improved significantly under V.A.C. therapy. 5 patients reported pain relief following induction of V.A.C. therapy. Due to reduction of tissue oedema secondary suture was facilitated in 3 patients. DISCUSSION: V.A.C. therapy represents an essential tool for treatment of complex injuries of the upper extremity with extended soft tissue defects. Decreased frequency of dressing changes as well as reduced tissue oedema considerably improved patient's comfort. Posttraumatic compartment syndrome or skin necrosis, which are often associated with macro amputations of the upper extremity, are efficiently treated with V.A.C., and secondary sutures may be performed despite initial skin defects.

Adolescent↗
PubMed2006

[Application of V.A.C.-therapy during plastic surgical treatment of a bifocal Marjolin ulcer].

Marjolin ulcers are scar carcinomas most often found in old instable burn scars, the majority histopathologically characterized as squamous cell carcinomas. Surgical therapy includes radical excision and subsequent defect closure. We report about a 69 year old patient suffering from two scar carcinomas on the right cheek and right chest and abdomen due to an extensive infant burn injury. During a 2 stage procedure, both ulcers were initially excised and resulting soft tissue defects were closed temporarily by applying V.A.C. therapy. During a second procedure defect closure on the right cheek was achieved by using a free radial forearm flap following neck dissection. Additionally, the extensive defect including chest and abdominal wall as well as the flap donor site on the left forearm were covered with split thickness skin grafts and subsequently secured by applying V.A.C. therapy for 5 days. 13 days later, the patient was discharged from our clinic. All skin grafted areas as well as the free flap were stably healed. Our report demonstrates that the application of vacuum therapy is not only useful during temporary closure of large wound sites but also secures healing of large and critical areas grafted with split thickness skin grafts in tumour patients.

Abdominal Wall↗
PubMed2006

[Vacuum-assisted closure (V.A.C.) of disastrous wound conditions in Madelung disease].

INTRODUCTION: A 54 year old patient presented with a Madelung disease. Symmetrically fatty deposits were present on both upper arms, at the abdomen and both thighs. Dermatitis was seen in the axillary fold at the skin bearing surfaces. Shoulder movement was impaired. Liposuction of both upper arms has already been performed, but no significant improvement was obtained. METHODS AND RESULTS: We performed a dermolipectomy of both upper arms. Postoperatively the patient suffered from a severe wound dehiscence with fulminant wound infection and septic clinical condition. Because of the large wound surface ((1/3) of the upper arm circumference) anemia occurred and had to be treated with blood transfusions. Wound exsudation caused a general hypoproteinemia. Multiple surgical debridements were necessary in order to clean the wound from necrotic tissue and afterwards moist dressings were applied. Furthermore the patient received intravenous antibiotic treatment. After stabilisation of the general condition of the patient and the wound situation a polyvinyl sponge and a vacuum-sealing were applied and continuous suction was performed (125 mm Hg). This resulted in a significant improvement of the wound situation in regards to wound cleaning, induction of granulation tissue, diminished wound size, reduction of oedema and pain reduction. After four weeks of vacuum therapy defect coverage was possible and split thickness skin grafting was performed. The skin graft was attached to the wound using a vacuum-dressing. After removal of the vacuum dressing on the fifth day the skin graft has completely healed. DISCUSSION: Vacuum therapy is suitable for disastrous wound conditions in order to achieve a defect size reduction, pain reduction and create a clean wound with granulation tissue for further surgical defect coverage using skin grafts or flaps.

Arm↗
PubMed2006

[Modified gloving technique for vacuum therapy in the hand].

INTRODUCTION: During the last 10 years sub-atmospheric pressure dressings (Topical Negative Pressure Therapy = TNP) has become a well accepted standard therapeutic modality in the management of acute and chronic wounds. However, in the hand and the fingers TNP treatment is not as an established method as elsewhere in the body. This is mostly due to difficulties in the technique of sealing wounds near the interdigital folds, especially when the interdigital folds are affected themselves. MATERIALS AND METHODS: Over a period of 36 months we treated 9 extensive open wounds of the hand with the TNP dressing procedure. To optimize the effective sealing procedure several methods of closure were applied: sterile vinyl gloves, split V.A.C. gel-straps and the "Sandwich"-principle. RESULTS: In all cases we were able to achieve a tight vacuum sealing with the use of our vinyl or latex free surgical glove as an aid to cover the interdigital spaces. There was a rapid and complete remission of the symptoms in terms of edema, redness, tenderness and range of motion. The indication spectrum encompassed infection control, temporary coverage of exposed bone or tendons, intermittent irrigation with local antiseptics as well as wound preconditioning before skin grafting or flap coverage. For the definite closure or coverage a second operation was necessary in all cases. CONCLUSIONS: The TNP-dressing can be securely achieved even in wounds encompassing the interdigital folds or adjacent to the in digital spaces with a modified surgical gloving technique to aid the standard sealing foil. It is a suitable principle for the management of severe hand infections with a reduction of clinical symptoms, reduction of the frequency of dressing changes compared to open approaches and a significant amelioration in the quality of life both for patients and health care personnel.

Amputation, Surgical↗
PubMed2006

[Use of vacuum therapy in a huge arterialized venous flap to reconstruct a complete avulsion of a thumb].

Arterialized venous flaps are normally raised from the anterior and distal third of the forearm by integration of a venous pathway. Basically, they are composed of skin, subcutaneous tissue, and subdermal venous plexus. Following transposition to the recipient site one vein is linked to a nourishing artery while the other veins are connected to one or more regional veins. The atypical blood perfusion and the delayed opening of intervenous shunts may result in edema, epidermolysis, or even some degree of skin necrosis that disappear during subsequent treatment. We report the salvage of an atypically raised oversized arterialized venous flap for total soft tissue reconstruction in a complete avulsion of a thumb. By applying V.A.C. therapy atypical perfusion and early intervenous shunt formation was treated successfully, resulting in stable healing and survival of the flap.

Aged, 80 and over↗
PubMed2006

[Prevascularisation strategies in tissue engineering].

INTRODUCTION: Experiments on animals have underlined the importance of vascularisation for biointegration and functionality of any given tissue engineering device. The aim of this investigation was to dissect the angiogenetic process in the frame of axial neovascularisation of a xenogenic solid matrix. The ultimate goal of this series of studies is the application of cells onto a prevascularised matrix, with the ambition to enhance cell survival after transplantation in vivo. MATERIALS AND METHODS: We performed a study in the rat with different vascular configurations in an isolation chamber. A disc-formed biogenic hard matrix (9 x 5 mm) was encased into an isolation chamber made of Teflon. In group 1, an arteriovenous fistula (AV loop) between the femoral vessels was microsurgically constructed and was placed around the matrix (n = 15). In group 2, the vascular carrier had the form of an arteriovenous ligated pedicle (n = 15). Evaluation intervals were two, four and eight weeks after implantation. The modes of evaluation included histology, scanning electron microscopy of corrosion casts as well as intravital micro-magnetic resonance imaging (MRI). RESULTS: The arteriovenous loop as vascular carrier revealed a higher capacity for angiogenesis over the bundle configuration. The neo-fibrovascular tissue displayed minimal inflammatory elements but dense vascularisation. Scanning electron microscopy demonstrated a vivid angiogenesis with rapid evolution of the vascular bead into mature, hierarchically organised network. Micro-MRI could be used for serial investigation in terms of flow measurements and detection of thrombosis. DISCUSSION: The presence of a vascular bed prior to cell transplantation might protect against hypoxia-induced cellular death, especially at central portions of the matrix, and therefore ensure physiological function of the device. The generation of vascularised bioartificial tissue substitutes might offer new modalities of surgical reconstruction for use in reparative medicine.

Animals↗
PubMed2005

Fibrin gel-immobilized primary osteoblasts in calcium phosphate bone cement: in vivo evaluation with regard to application as injectable biological bone substitute.

Osteogenic injectable bone substitutes may be useful for many applications. We developed a novel injectable bone substitute based on osteoblast-fibrin glue suspension and calcium phosphate bone cement (BC). Human osteoblasts were isolated from trabecular bone samples and cultured under standard conditions. Osteoblasts were suspended in fibrinogen solution (FS). BC was cured with thrombin solution. 8 x 4 mm injectable bone discs were prepared using silicon molds and a custom-made applicator device. Discs containing BC, BC/FS, or BC/FS/osteoblasts were implanted subcutaneously into athymic nude mice. After 3, 9 and 24 weeks, specimens were explanted and subjected to morphologic and biomechanical evaluation. In vitro fibrin gel-embedded osteoblasts displayed a differentiated phenotype as evidenced by alkaline phosphatase, collagen type 1 and von Kossa stains. A proportion of osteoblasts appeared morphologically intact over a 3-day in vitro period following application into the BC. BC/FS and BC/FS/osteoblast discs were sparsely infiltrated with vascularized connective tissue. There was no bone formation in implants from all groups. However, positive von Kossa staining only in BC/FS/osteoblast groups suggests engraftment of at least some of the transplanted cells. Biomechanical evaluation demonstrated initial stability of the composites. Young's modulus and maximal load did not differ significantly in the BC/FS and BC/FS/osteoblast groups. The practicability of osteoblast-containing injectable bone could be demonstrated. The dense microstructure and the suboptimal initial vascularization of the composites may explain the lack of bone formation. Modifications with regard to enhanced osteoblast survival are mandatory for a possible application as injectable osteogenic bone replacement system.

Adult↗
PubMed2004

[Breast-reduction surgery--a long-term survey of indications and outcomes].

Between 1986 and 2003, breast-reduction surgery was performed in a total of 814 women. The indication was established on the basis of physical complaints, chronic back pain, stiff neck or recurrent intertrigo in the foldbeneath the breasts. A proportion of the patients were interviewed postoperatively using a questionnaire, to determine the impact of the operation on their quality of life. 91% of those surveyed reported a postoperative improvement in the perception of their own body, and 80% were satisfied with the reduced size of their breasts. In conclusion, in the hands of an experienced breast surgeon, breast-reduction surgery for the proper indication results in a reliable and safe diminishment in breast size and tightening of slack tissue, leading to a significant enhancement in the patient's quality of life.

Adolescent↗
PubMed2004

[Possiblities for breast reconstruction following cancer surgery].

Cancer of the breast is the most common malignant disease of women, and currently affects approximately 10% of all women. In the large majority of cases, mammary carcinoma can be treated without having to sacrifice the breast. In some 30% of the cases, however, amputation continues to be needed, in particular when a relatively large tumor presents, or when its removal with an adequate safety margin in a relatively small breast would result in appreciable deformation. Reconstruction of the breast is often an important psychological factor, since, as a visible organ, the breast is a determining feature of a woman's physical appearance and her effect on the opposite sex. The availability of various procedures and modern techniques of breast reconstruction make it possible to comply with the individual wishes of the woman concerned.

Breast Implantation↗
PubMed2004

[Use of vacuum therapy during defect coverage of the upper extremity with microsurgically grafted arterialized venous flaps].

Arterialized venous soft tissue flaps are defined as tissue portions usually harvested from the anterior and distal third of the forearm over a venous pathway to be transplanted to another recipient area. Basically, they are composed of skin, subcutaneous tissue, and subdermal venous plexus. At the recipient site flaps are perfused by a nourishing artery while the other veins are connected to one or more regional veins. The retrograde blood perfusion often results in edema, temporary epidermolysis, or even some degree of skin necrosis that disappear during subsequent treatment. To circumvent these drawbacks grafting of arterialized flaps was combined with local application of vacuum to overcome the venous initial stasis, resulting in improved healing and survival of these flaps.

Adult↗
PubMed2004

[Salvage of exposed alloplastic materials in irradiated wounds - a case report].

BACKGROUND: Modern multimodal concepts of complex reconstructions and advanced wound management enlarge strategies for surgical oncological therapies. One of the mainstays of classical surgical therapy in case of exposed alloplastic materials in irradiated wounds was to remove the foreign body due to the risk of infection. This loss of integrity and function of the contaminated host bed was to allow wound healing and closure. METHOD: We report the management of a 56-year-old female patient who developed a lyomyosarcoma at her left shoulder girdle 8 years after radiation of the left thorax because of breast cancer. After radical tumor resection and exarticulation of her left arm in the shoulder joint a necrosis of the soft tissue envelope developed, leading to an exposed alloplastic mesh. Staged debridement and continuous application of negative pressure was performed three times. Ultimate plastic coverage was performed by means of a pectoralis myocutaneous island flap from the other breast. RESULTS: After staged debridement and repeated vacuum application excellent wound cleaning, neovascularisation, wound contraction and formation of granulation tissue within the previously irradiated tissue zone was observed. Until fourteen months postoperative wound coverage remained stable and no signs of infection were observed. DISCUSSION: By means of negative pressure therapy even in radiated wounds excellent wound cleaning and sufficient formation of granulation tissue can be achieved. In some cases negative pressure therapy together with staged debridement allows reintegration of exposed and therefore potentially contaminated alloplastic meshes into new formed granulation tissue in radiated wounds respectively radiation ulcers. Thus leading to the possibility of ultimate plastic coverage.

Breast Neoplasms↗
PubMed2004

[Indication and clinical results of buried skin grafting to treat problematic wounds].

In 1920 Braun described a technique of skin grafting particularly designed for areas where shearing forces, high pressure and extensive secretion cause repetitive loss of conventionally transplanted skin. During the last 10 years we successfully used this technique when impaired wound healing was encountered due to various reasons. Clinical examples of application and results are presented. By combining this technique with vacuum therapy, formation of granulation tissue can be accelerated, thereby resulting in successful transplantation of problematic and therapy resistant wounds.

Adult↗
PubMed2004

Y chromosome detection of three-dimensional tissue-engineered skeletal muscle constructs in a syngeneic rat animal model.

Surgical reconstruction of muscle tissue lost by trauma or tumor ablation is limited by the lack of availability of functional native tissue substitution. Moreover, so far most inherited or acquired muscle diseases are lacking sufficient treatment, because only few alternatives exist to provide functional restoration of lost muscle tissues. Engineering those tissues and transplantation into sites of dysfunction may be an alternative approach and may allow replacement of such damaged or failing skeletal muscle tissues. Techniques attempting reconstruction of some human tissues and organs (tissue engineering) have been introduced into clinical practice recently. One major problem that previous transplantation studies were facing is the ability of detection of transplanted cells after integration. Using the Y chromosome in situ hybridization technique in a syngeneic rat model allows transplantation of cell constructs orthotopically, without manipulation of the cells, with no rejection or immunosuppression being implied, but providing a nondilutable genetic marker to identify transplanted cells. The purpose of our study was to create functional skeletal muscle tissue in vivo using the transplantation of primary myoblasts precultivated within a three-dimensional (3D) fibrin matrix and to determine the fate of the transplanted cells using the Y chromosome detection technique. 3D myoblast cultures were established derived from male donor rats and after 7 days of cultivation we performed an orthotopic transplantation of 3D cell constructs into a created muscle defect within the gracilis muscle of syngeneic female rats. Anti-desmin immunostaining and Y chromosome in situ hybridization indicated the survival and integration of transplanted male myoblasts into the female recipient animal, thus demonstrating the feasibility of this approach in tissue engineering and the research of cell transplantation in general.

Animals↗
PubMed2001

Hepatocyte transplantation using biodegradable matrices in ascorbic acid-deficient rats: comparison with heterotopically transplanted liver grafts.

BACKGROUND: Hepatocyte transplantation using polymeric matrices is under investigation as an alternative therapy for metabolic liver diseases. Long-term engraftment of hepatocytes in polymers has been demonstrated. However, the metabolic activity of hepatocytes in such devices has never been assessed in direct comparison with liver grafts. METHODS: Hepatocyte and partial liver transplantation were evaluated in the scurvy-prone osteogenic disorder Shionogi rat model. Biodegradable poly glycolic acid matrices seeded with hepatocytes equivalent to 20% of the recipient's liver mass, or 20% liver grafts were heterotopically transplanted into ascorbic acid- (AsA) deficient recipients. Recipients of cell-free matrices or AsA-deficient liver grafts served as controls. Recipients were set on AsA-free diet after transplantation. Plasma AsA levels, AsA concentrations in liver and adrenal gland tissue, and body weight ratios were assessed and H&E histology was performed. RESULTS: Recipients from the control groups showed symptoms of scurvy at 1 month after cessation of AsA supply. Hepatocyte transplantation and auxiliary liver transplantation prevented symptoms of scurvy and increased plasma and tissue AsA levels and body weight ratios. AsA levels in recipients of 20% liver grafts were comparable to normal control animals. CONCLUSIONS: Hepatocytes transplanted in polymeric matrices are able to compensate for liver-based metabolic deficiencies. Hepatocyte transplantation improves plasma AsA levels in AsA-deficient recipients. However, auxiliary liver grafts are superior to hepatocyte grafts in improving metabolic parameters. Further research work is needed to increase the efficiency of liver cell transplantation with regard to a clinical application.

Animals↗
PubMed2000

Priming of hepatocytes for cell culture by partial hepatectomy prior to cell isolation.

The combination of ex vivo gene transfer and a sufficient transplant model for hepatocytes may permit treatment of single enzyme-based metabolic liver diseases. Induction of replicative potential (priming) in hepatocyte cultures may enhance the efficiency of gene transfer under stable in vitro conditions. It is known that hepatocyte replication is increased in vivo after partial hepatectomy. We investigated the effect of partial hepatectomy prior to cell isolation on hepatocytes in vitro. Male Lewis rats served as donors. Hepatocytes were isolated by collagenase digestion from either intact livers or from livers 48 h after 70% hepatectomy (PH). Cells were seeded on collagen-coated culture dishes with hormone-supplemented culture media. Hepatocyte morphology, number, albumin secretion rate, and mono-ethyl-glycin-xylidid (MEGX)-biotransformation capacity were assessed on days 1, 3, and 5 in culture. PH significantly increased hepatocyte number and albumin secretion of cultured hepatocytes over the whole observation period. In contrast, MEGX-biotransformation capacity was significantly decreased. Morphology of cultured hepatocytes was not affected by PH prior to hepatocyte isolation. These results suggest a prolonged and complex response of hepatocytes to PH in vitro. Hepatocyte priming by PH is a promising approach toward stable cultures of proliferating hepatocytes and may provide a model for in vitro studies of hepatic regeneration mechanisms. Further research on hepatocyte priming toward an application in ex vivo gene transfer and hepatic tissue engineering seems justified.

Animals↗