[Osteomyelitis: treatment concepts from the plastic surgeon's point of view]. / Osteomyelitis : Behandlungskonzepte aus Sicht der plastischen Chirurgie.

Despite promising advances in antibiotic and surgical therapy osteomyelitis remians a severe disease with a high morbidity. Nowadays it occurs mainly after traumata. Typical clinical manifestations are signs of local infection, non-healing wounds, pathological fractures or loosening of orthopedic implants. Besides the clinical judgement the diagnosis is consolidated by imaging procedures, histopathological and microbiological examinations. Ideally, the treatment plan is based on an interdisciplinary approach. Besides the radical surgical debridement a test appropriate antibiotic therapy is essential. Defect reconstruction after surgical debridement and optimization of local microcirculation is essential to preserve limbs and to obtain a good functional result. Microsurgical free tissue transfer is often necessary to achieve healing. An optimal therapeutic management with stable long-term clinical results can be achieved by the interaction of different surgical and medical disciplines.

[Malignant bone tumors of the hand]. / Maligne Knochentumoren der Hand.

Malignant bone tumors are very rare entities in the bones of the hand. The histologic subtypes (chondrosarcoma, osteosarcoma, Ewing-sarcoma) preferentially manifest in varying regions of the skeleton. Chondrosarcomas are the most frequent malignant bone tumor type in the hand. Cardinal symptoms of malignant bone tumors in the hand and in general are a new swelling and pain in the affected bones. The primary diagnostic tools are radiologic techniques (x-ray, CT, MRI) for assessment of local tumor growth and the oncologic staging. A definitive treatment of malignant bone tumors should be carried out in specialized centers, as these tumors are rare. Surgical therapy is completed by chemo- or radiotherapy, if required because of histologic subtype and local or systemic spreading. Safe margins of tumor resection should be preferred to function-preserving treatment for tumors of the hand while the preservation of functional units should be pursued whenever possible.

[Pathogenesis, classification and diagnosis of necrotizing soft tissue infections]. / Pathogenese, Klassifikation und Diagnose der nekrotisierenden Weichteilinfektionen.

Necrotizing soft tissue infections are caused by a variety of pathogens and may affect different types of soft tissue. Even today mortality and lethality are very high. The primary symptoms of necrotizing soft tissue infections are local pain out of proportion, swelling, erythema and crepitation in cases of subcutaneous gas. A systemic inflammatory response syndrome (SIRS) is often associated. During the last decades early recognition and initiation of an adequate therapy were able to reduce lethality to an average of 20%. The physical examination remains the diagnostic gold standard and may be supported by typical findings of imaging technologies, e.g. subcutaneous gas on x-rays and laboratory tests. After diagnosis an adequate antibiotic and surgical therapy should be performed immediately.

[Animal study of the bone substitute material Ostim within osseous defects in Göttinger minipigs]. / Tierexperimentelle Untersuchung des Knochenersatzstoffs Ostim im knöchernen Lager des Göttinger Miniaturschweins.

AIM: The aim of this study was to examine Ostim, a nanocrystalline hydroxyapatite suspension, with regard to its bio- and osteocompatibility, rate of resorption and remodeling dynamics within osseous defects. METHODS: Ostim was implanted in a randomised fashion into the proximal metaphysis of either the right or the left tibia of 18 Göttinger minipigs. RESULTS: Based on microradiographs and histological examinations Ostim showed biocompatibility, bioactivity and osteoconductivity. This substitute material exhibited osseous integration. The degradation process stopped after six weeks. With regard to osseous regeneration within the defects, there were no significant differences between the time intervals of follow-up. Ostim could still be detected in significant amounts after one year with no complete resorption. CONCLUSION: A restitutio ad integrum could not be observed in spite of the histological evidence of the above-described reactions within the implantation site. A thorough osseous incorporation seemed to impede the degradation of the bone substitute material. The paramount goal is to improve the biological behaviour in favour of a higher rate of degradation.

[Bone substitutes]. / Knochenersatzwerkstoffe.

A large variety of different bone substitutes are available for the treatment of congenital or acquired bone defects as an alternative to bone transplantation. Complications associated with graft harvesting, limited donor resources, and the potential risk of transmission of infectious diseases have led to the development of multiple concepts of new bone substitutes to minimize the wellknown problems. This article intends to give an overview of the products currently available on the market. Inorganic materials such as ceramics from hydroxyapatite and/or tricalcium phosphate, calcium phosphate cements, calcium sulfates and bioglass,organic materials (polymers) and composites, xenografts,and glass ionomer cements are discussed.

[New PMMA bone cements for vacuum mixing systems]. / Neue PMMA-Knochenzemente zur Anwendung in Vakuummischsystemen.

In cemented total hip replacement, fractures and cracks in the cement mantle may facilitate mechanical loosening of the prosthesis. Especially large voids and flaws within the cement can cause fatigue fractures. Reduction of cement porosity is a logical step in the attempt to improve the quality and durability of bone cement. An effective reduction of pores during vacuum mixing requires prechilling of Palacos R at 4 degrees C. For easier handling, new bone cements have been developed with characteristics similar to Palacos R, but with no chilling necessary prior to mixing under vacuum. In our study two newly developed bone cements (Palamed G, VersaBond) and a bone cement used widely in clinics (Palacos R) were mixed in three different vacuum mixing systems (Optivac, MixOR, Palamix). Macro-, micro-, and total porosity and bending strength (ISO 5833) were determined. All three mixing systems proved effective in reducing porosity and showed constant mixing results. All cement specimens that we tested fulfilled the ISO requirements for bending strength. VersaBond yielded the lowest porosities, but showed lower viscosity compared to Palacos R and Palamed G. The new cements are equal in vitro to Palacos R with regard to bending strength, but further clinical studies are necessary before widespread use is advisable.