In vivo analysis of tissue response to plasma-treated collagen-I-coated titanium alloys.

PURPOSE: The aim of this study was to evaluate the in vivo tissue response to low-pressure plasma-pretreated collagen-I-coated titanium implant in a middle-term mouse model. METHODS: Plasma-treated collagen-coated titanium implants were transplanted into the dorsal skinfold chambers of BALB/c mice. Untreated, regular titanium implant material served as control. The neovascularization (functional vessel density) of the implant border zone and of the surrounding muscle tissue was analysed by intravital fluorescence microscopy. Additional histological analysis was performed to observe the inflammatory reaction. RESULTS: Statistical analysis revealed that the vessel density in the border zone of the implants was significantly enhanced in the plasma-treated collagen-I-coated group compared to controls. The histological examination of the two groups confirmed that the inflammatory response to the collagen-coated titanium implants was reduced compared to controls. CONCLUSION: Plasma pretreatment and collagen I coating of titanium implant material leads to an enhanced tissue vascularization and a reduced inflammatory response.

Enhanced cell adhesion to silicone implant material through plasma surface modification.

Silicone implant material is widely used in the field of plastic surgery. Despite its benefits the lack of biocompatibility this material still represents a major problem. Due to the surface characteristics of silicone, protein adsorption and cell adhesion on this polymeric material is rather low. The aim of this study was to create a stable collagen I surface coating on silicone implants via glow-discharge plasma treatment in order to enhance cell affinity and biocompatibility of the material. Non-plasma treated, collagen coated and conventional silicone samples (non-plasma treated, non-coated) served as controls. After plasma treatment the change of surface free energy was evaluated by drop-shape analysis. The quality of the collagen coating was analysed by electron microscopy and Time-Of-Flight Secondary Ion Mass Spectrometry. For biocompatibility tests mouse fibroblasts 3T3 were cultivated on the different silicone surfaces and stained with calcein-AM and propidium iodine to evaluate cell viability and adherence. Analysis of the different surfaces revealed a significant increase in surface free energy after plasma pre-treatment. As a consequence, collagen coating could only be achieved on the plasma activated silicone samples. The in vitro tests showed that the collagen coating led to a significant increase in cell adhesion and cell viability.

[Uncemented arthroplasty of the hip]. / Zementfreie Endoprothetik des Hüftgelenks.

Prognosis of cemented total hip replacement seems to be excellent for elderly patients. In younger age the outcome is less favourable and early revision is more common. Thus, different concepts with better prognosis and preservation of bone stock for possible revisions were needed. After more than 30 years of application with excellent short-term and long-term results, uncemented total hip arthroplasty is nowadays generally regarded as the standard procedure for younger patients. New bone-preserving implants, such as surface replacement or short-stemmed femoral shaft prostheses, have been introduced especially for younger patients. Some of these new procedures are still under development, and the long-term results of new implant concepts have to be evaluated over the next decades. Regarding recently published scientific studies an overview about non-cemented total hip arthroplasty is given and current concepts and developments are presented.

[Desmoplastic neurotropic melanoma. Diagnosis and therapeutic procedures for a rare clinical entity]. / Spindelzelliges desmoplastisches Melanom. Ein seltenes Krankheitsbild--Diagnostik und therapeutisches Vorgehen.

Desmoplastic neurotropic melanoma is an exceedingly rare variant of the malignant melanomas. Since the initial description, only about 500 cases have been reported in the literature. These melanomas mostly occur on the head, neck, and face, and a wide local excision of the tumor is probably the most important prognostic factor. Therefore, in most cases the tumor resections result in large tissue defects. To gain a good cosmetic result, tissue movement using flaps or grafts will most likely be required to cover the defect. In this paper, a 79-year-old patient with a basal cell carcinoma and desmoplastic melanoma on the scalp is described, and the therapeutic procedure is discussed.

[Outcome quality in trauma surgery]. / Ergebnisqualität in der Unfallchirurgie.

Trauma surgery and orthopedic trauma surgery have been accompanied not only by internal quality assessment, but also by external quality assessment procedures right from the beginning. The reasons for these mechanisms were based on legal regulations of treatment of work-related accidents. In 1958, the Arbeitsgemeinschaft für Osteosynthese (Working Group on Osteosynthesis, AO group) was founded. The results of the AO's scientific activities built the basis of osteosyntheses. In 1988, legal regulations changed again in Germany. Since this reform of some important facets of public health care, each hospital or institution is committed to perform external and internal quality assessment. In addition, the introduction of a payment system based on diagnosis-related groups makes it necessary to install basic quality management systems within the next few years. This paper presents some well-established procedures, especially the diagnosis-related study in the whole district of Westphalia-Lippe. The aim of the study was a quality assessment of the treatment of intracapsular fractures of the collum of the femur. Problems in data analysis and interpretation are shown. Because of some grave problems, certain changes in the study design seem to be warranted. Despite these facts, however, we are convinced that we not only need this kind of quality assessment, but that we should try to expand these studies based on the experiences we gained.

[Radio-ulnar and radio-scaphoid-lunate arthrodesis in chronic polyarthritis. Clinical and radiologic follow-up of 32 cases]. / Radiolunäre und radioskapholunäre Arthrodese bei chronischer Polyarthritis. Klinische und radiologische Nachuntersuchung an 32 Fällen.

INTRODUCTION: In 75% of all cases of rheumatoid arthritis the wrist is affected and in 12% is the region of initial manifestation of this chronic inflammatory joint disease. To prevent destruction of the wrist through carpal dislocation, radiolunate and radioscapholunate arthrodeses have increased in importance. METHODS: During a 6.5-year period, 28 radiolunate and 4 radioscapholunate arthrodeses were performed in 30 patients. The indication for operation was progressive carpal translation and increasing subluxation of the wrist in which existent radiological damage had not reached more than grade III according to the classification of Larsen and co-workers. RESULTS: The results obtained during the follow-up study (median: 17.3 months) showed in most treated patients after partial arthrodesis of the wrist no or fewer complaints concerning swelling and pain and an acceptable remaining range of motion of the wrist in everyday life. In patients with preoperatively existing ulnar deviation less than 15 degrees progressive carpal collapse and dislocation could be mostly prevented. CONCLUSION: All told radiolunate and radioscapholunate arthrodeses successfully stabilized the wrist in patients suffering from rheumatoid arthritis.

[Long-term results after resection arthroplasty according to Girdlestone for treatment of persisting infections of the hip joint]. / Langzeitresultate der Resektionsarthroplastik nach Girdlestone beim therapierefraktären Hüftgelenkinfekt.

INTRODUCTION: Persisting infections of the hip joint are regarded as one of the most feared complications following total hip arthroplasty or failed osteosynthetic treatment of fractures of the proximal femoral part. In these cases resection arthroplasty according to Girdlestone often is the ultimate treatment. METHODS: Twenty-seven patients (11 men and 16 women) who had undergone resection arthroplasty according to Girdlestone could be included in this study. In all cases Girdlestone operations had been performed because of persisting infections of the hip joint. The mean follow-up was 7.1 years. RESULTS: In 22 out of 27 cases (81.5%) eradication of the infection was finally achieved. At the time of re-evaluation 6 patients had no pain, 12 sometimes suffered from moderate pain, 7 from pain during physical activities and 2 patients experienced pain even at rest. At the time of follow-up, 11 patients used a cane, 14 patients needed two canes or crutches and in 2 cases a wheelchair was necessary. The mean shortening of the leg was 5.2 cm (range 3-15 cm). Clinical evaluation using the score according to Merle d'Aubigné and Postel to assess the functional results showed a mean of 6.7 points (range 2-10 points). Of our patients, 59.3 % were satisfied with the functional results obtained. CONCLUSION: In the long run the Girdlestone procedure still seems to be a reasonable salvage operation for persisting deep infections following hip surgery.

[Osteogenetic activity of BMP-3-coated titanium specimens of different surface texture at the orthotopic implant bed of giant rabbits]. / Osteogene Aktivität BMP-3-besichichteter Titanprüfkörper unterschiedlicher Oberflächenbeschaffenheit im orthotopen Lagen des Riesenkaninchens.

INTRODUCTION: The successful combination of osteoinductive factors with current materials used in both endoprosthetics and implantology improves bony ingrowth and long-term stability of the chosen implants. The aim of the present experimental animal study was to clarify in what way faster bony integration can be achieved through additional BMP-3-coating of titanium test implants of different surface textures (hydroxy-apatite-coated or corundum-blasted). METHODS: Thirty of 60 cylindrical titanium test implants with a hydroxy-apatite or corundum-blasted surface were coated with 230 microg porcine, high-purified BMP-3-precipitate per implant to check their osteoinductive potential in a bioassay. In each case a BMP-3-coated and an uncoated control-device were implanted with a gap formation of 1 mm into the femoral part of the patellofemoral joint of the right and left leg of 30 adult giant rabbits. Serial saw slices of all explanted specimens were prepared, and the osseous integration of the implant and time-dependent bone neoformation were analyzed microscopically and histomorphometrically 14, 35, and 56 days after implantation. RESULTS: Coating of TiAl4V6-test devices with BMP-3 led in both groups after gap implantation to an improved osseointegration, that was histomorphological and histomorphometrical verifiable. Statistical evaluation using the t-test for matched samples showed 5 weeks after surgery a significant higher volume of new formed bone of the BMP-3-coated corundum-blasted or hydroxy-apatite-coated TiAl4V6 test devices compared to the non-coated controls of the same type (P < 0.01). Light microscopy demonstrated osseointegration without connective tissue membrane around the surface of the implants after 2, 5, and 8 weeks. Better osseointegration was achieved in the hydroxy-apatite-coated implants than in the corundum-blasted implants. CONCLUSIONS: Our results indicate that composite metal implants, as used in endoprosthetics and implantology, are suitable carriers for BMP-3 and improved fixation of the implants can be achieved.

[Histologic and histomorphometric follow-up observations of osseointegration of corundum-blasted BMP-3 coated titanium test implants (Ti6Al4V) at orthotopic site in the giant rabbit]. / Histologische und histomorphometrische Verlaufsbeobachtungen zur knöchernen Integration von korund-gestrahlten BMP-3-beschichteten Titanprüfkörpern (Ti-6Al-4V) im orthotopen Lager des Riesenkaninchens.

AIM: To establish whether the additional coating of titanium implants with Bone Morphogenetic Protein-3 (BMP-3) might enhance osseous integration. METHOD: Each of 15 cylindrical titanium test implants (Ti-6AI-4V) was coated using 230 micrograms porcine BMP-3. A further 15 implants with identical (corundium-blasted) surface served as negative controls. An uncoated and a BMP-3-coated test object were implanted into the femurs of 15 adult giant rabbits. New formation of bone around the implants was examined microscopically and histomorphometrically on postoperative days 14, 35 and 56. RESULTS: Coated implants revealed superior osseointegration with statistical evaluation using the t-test for matched samples showing a significantly higher volume of new bone 5 weeks after surgery. Microscopic examination revealed osseointegration with no connective tissue membrane around the surface of the implants. CONCLUSIONS: Our results indicate that composite metal implants are suitable carriers for BMP-3 and that improved fixation of the implants can be achieved.

Superior efficacy in suppression of heterotopic bone formation using fractionated irradiation of 5 x 2 Gy compared to a single dose of 7 Gy. An experimental study in rats.

Postoperative irradiation of the operative field is an established method to prevent heterotopic ossification in total hip arthroplasty. In this study two theoretical dose-equivalent regimens of radiation therapy were compared. Allogenic bone matrix was implanted in both thighs of 50 adult male Wistar rats to induce heterotopic ossification. Immediately after operation the implants of 40 animals were irradiated using a single-dose of 7 Gy or 5 fractions of 2 Gy each. Ten rats served as a controlgroup and did not undergo irradiation. Radiation therapy with 5 x 2 Gy led to a highly significantly better suppression of heterotopic ossification than irradiation with 1 x 7 Gy (p < 0.001; paired-t-test). Single-dose irradiation reduced the mean calcium contents to 138.87 +/- 22.84 micrograms Ca2+/mg implanted bone matrix; fractionated irradiation obtained a reduction to 63.35 +/- 21.16 micrograms Ca2+/mg implanted bone matrix. In thigh implants not exposed to irradiation the mean calcium content was 191.50 +/- 11.46 micrograms Ca2+/mg implanted bone matrix. Radiographically better suppression of bone formation could be documented after irradiation with 5 x 2 Gy compared to 1 x 7 Gy and non-irradiated implants. The histological aspect of the explanted specimens showed quantitatively more new bone formation in the non-irradiated controls than in both irradiation groups. In view of experimentally demonstrated better effects, as well as the reduced side effects, fractionated irradiation appears preferable.

Fusion of the septic knee with external hybrid fixator.

Arthrodesis is a well-recognized salvage procedure in patients with septic destruction of knee joints. It offers the opportunity for restoring weight bearing capability and significant pain relief as well as eradication of infection, but at the expense of joint motion. However, arthrodesis in order to joint sepsis may be difficult to achieve because of poor bone stock, persistent infection and soft tissue compromise. From 2000 to June 2004, in 70 consecutive patients arthrodesis of the knee was indicated. Nineteen patients were considered to have external hybrid fixator (EHF) and were therefore included to the prospective study protocol. Forty-three stabilisations of destructed knee joints were done by a modular titanium rod. In these cases bony fusion was very unlikely to be achieved because of devastating defects due to infected total knee arthroplasties. Eight patients were treated by compression nailing. In these situations EHF was not indicated. In three patients minor complication occurred. In two out of 17 patients fusion failed because of primary underestimated bony defects (11.8%). The use of EHF for arthrodeses after septic destruction of knee joints can be recommended according to our results. However, EHF will not be successful or applicable in each case. Therefore, physicians and institutions that offer this special method should have not only experiences with EHF but also with arthrodeses and alternative procedures.

[An open wedge tibial head osteotomy using continuous callus distraction. An alternative method for the treatment of of varus arthrosis]. / Die aufklappende Tibiakopfosteotomie mittels kontinuierlicher Kallusdistraktion. Ein alternatives Verfahren in der Behandlung der Varusgonarthrose.

High tibial osteotomy is an accepted method for treatment of medial osteoarthritis. An alternative technique is an open-wedge osteotomy and consecutive callotasis (CO) using an external fixator. The purpose of this study was to evaluate the clinical and radiological results and the efficiency of this technique for precise correction. This prospective study included 41 patients (44 knees) evaluated by the HSS score, radiological stage of osteoarthritis, bone healing, and complications after a follow-up period of 49 (36-61) months. The HSS score increased from median 67 preoperatively to 82 points at the time of follow-up (p<0.001). Of 44 knees, excellent/good results were found in 70.5% and fair/poor in 29.5%. The median preoperative femorotibial anatomical angle was 3.6 degrees varus and 9.4 degrees valgus at the latest follow-up examination. The total time in external fixation was median 80 (61-125) days. We observed one early collapse of the new bone wedge, one complete corticotomy, and pin tract infections in ten cases. Furthermore, two hematomas required revision surgery. Hemicallotasis with external fixators allows constant manipulation of alignment during the healing process to optimize alignment. The disadvantage of the external fixation is the risk of pin track infection. Therefore, CO may constitute an important contribution to our algorithm in the treatment of varus gonarthrosis.

[Application of low intensity, pulsed ultrasound on distraction osteogenesis of the humerus. Case report]. / Anwendung von niederenergetischem gepulstem Ultraschall bei der Kallusdistraktion am Humerus. Fallbeispiel.

Low intensity pulsed ultrasound accelerates fracture healing both clinically and experimentally. Based on recently published animal studies, an improvement in regenerative bone maturation after distraction osteogenesis due to low intensity, pulsed ultrasound is also expected. We report on an 18 year-old female patient suffering from an acquired shortening of the right upper arm of 10 cm after humeral osteitis as a baby. The patient was admitted to hospital for corticotomy and distraction osteogenesis at the afflicted humerus. Due to the published experimental results in animals which indicate an improvement in bone regeneration during callotasis with the additional application of low intensity, pulsed ultrasound, we decided to try this procedure. The calculated distraction consolidation index was 21 days/cm, which is below the mean of 30 days/cm reported in the literature for humeral lengthening by distraction osteogenesis. The calculated healing index according to Paley was 0.7 months/cm in our patient. Compared to reference data, in which a range of from 0.87 months/cm to 1.5 months/cm is reported, our patient showed an accelerated maturation of distraction callus. The duration of treatment of the patient was clearly shortened by the additional application of low intensity, pulsed ultrasound. If distraction osteogenesis is correctly indicated, the early use of low intensity, pulsed ultrasound should be considered, since an acceleration of callus formation with consecutive shortening of treatment time could be attained while wearing an external fixator, leading to a decrease in cumulative complications, such as pin tract infections. Further studies from our research group regarding this topic will follow.

[Improved osseointegration of titanium implants of different surface characteristics by the use of bone morphogenetic protein (BMP-3): an animal study performed at the metaphyseal bone bed in dogs]. / Verbesserte Osseointegration von Titanprüfkörpern unterschiedlicher Oberflächenbeschaffenheit durch Beschichtung mit Bone Morphogenetic Protein (BMP-3)--eine tierexperimentelle Studie im metaphysären Knochenlager des Hundes.

AIM: Aim of this study was to determine whether coating of titanium implants of various surfaces with BMP-3 would improve the osseous integration of the implants into the orthotopic bony implant bed. METHOD: In this experimental study 190 micro g per implant of highly purified bone morphogenetic protein 3 (BMP-3) precipitate isolated from porcine bone were available for the coating of each of 24 cylindrical test implants (12 with hydroxyapatite and 12 with plasmapore surface). The remaining 24 test implants with the same surface makeup served as negative controls. Implantation sites were randomly assigned for the 4 versions of implants available and all implants were embedded into the medial or lateral femoral condyle of both legs of 12 German shepherds. The drilling holes were performed in such a matter that after embedding the cylindrical devices a gap of 1 mm surrounding the implants remained. A biomechanical testing and histological evaluation was performed on the explants 42 days after surgery. RESULTS: In biomechanical testing forces necessary to extract the implants from the explanted bones in BMP-3 coated devices were up to 70% higher compared to the ones in the non-coated reference groups. Quantitative histomorphometric examination showed in BMP-3-coated implants an increasing formation of new bone close to their own surface (gap-healing) which was higher than in the corresponding non-coated controls (hydroxyapatite + BMP-3 32.1%, hydroxyapatite controls 20.3%, plasmapore + BMP-3 30.2%, plasmapore controls 13.1%). The extent of direct bone implant contact as percentiles of the corresponding implants perimeter (ongrowth) was also significantly higher in the BMP-3-coated implants compared to the non-coated controls (hydroxyapatite + BMP-3 37.7%, hydroxyapatite controls 22.4%, plasmapore + BMP-3 15.3%, plasmapore controls 6.4%). CONCLUSION: In this study it was proven the first time that implants of various surface textures as used in endoprosthetics are able to be coated by the osteoinductive growth factor BMP-3. In that way metallic implants can achieve osteogenic properties which have positive effects in osseointegration.

[Fatal soft tissue infections after arthroscopy of the knee joint. A diagnostic or therapeutic problem?]. / Letale Weichteilinfektionen nach Arthroskopie des Kniegelenks. Ein diagnostisches oder ein therapeutisches Problem?

After detection of a bacterial infection of the joint, an absolute indication for intervention is given. Systemic antibiotic drug therapy is indicated and drainage of the joint has to be performed immediately. The following therapeutic algorithm regimen is a proven remedy in treating pyoarthrosis of the knee joint: During the initial period, the infection can be controlled by arthroscopic irrigation and systemic antibiotic therapy. Depending on the progredient findings or if the symptoms persist, curing the joint by open synovectomy is the next step of treatment. If open joint revision including synovectomy is not performed or is performed too late, there will be a threat of irreversible damage of the afflicted joint up to septic spread endangering the patient's life. We report on two patients suffering from generalized sepsis resulting in death after delayed therapy for knee joint infection. Regarding the presented cases, it can be concluded that indication to early surgical joint debridement including open synovectomy of the knee is still rarely seen after development of pyoarthritis.

[Complications in the use of the halo fixator]. / Komplikationen beim Halo-Fixateur.

50 patients out of a total of 88 who underwent treatment using a halo-fixateur between 1987 and 1997 were available for a follow-up interview reviewing local complications and quality of life. Marginal discomfort was observed in 54% of patients, moderate complaints/transitory pain in 30%, prolonged and severe discomfort and pain in 16%. 62% of patients took no analgetics, 22% infrequently, and 16% continuously throughout treatment. In pin-tract infection local treatment was successful in 6 patients, in 3 patients the screws needed to be relocated. Complaints of dysphagia due to extended forced lordosis of the cervical spine could be corrected by adjusting the position of the halo ring in 3 out of 8 patients. 3 patients developed pressure sores which could be managed without surgical intervention. Proper fixation and placement of the pin-tracts are crucial in the application of the halo fixateur if complications are to be avoided. Superficial infections must be treated locally. If the infection persists immediate pin relocation and systemic antibiotic therapy have to be initiated.

[Intramedullary abscess of the spinal cord--a rare pathology. Case report, therapeutic regimen and review of the literature]. / Der intramedulläre Abszess des Rückenmarks--ein seltenes Krankheitsbild. Falldarstellungen, Behandlungskonzept und Literaturübersicht.

Although the presence of an intramedullary abscess of the spinal cord is extremely rare, it is most important to be aware of its existence in the differential diagnosis of neurological diseases. Existing neurological deficits with progressive symptoms of paraplegia should always be regarded as suspect and a differential diagnosis of an intramedullary abscess of the spinal cord should then be included in the therapeutical regimen. A correct diagnosis using MR-tomography followed by an early surgical treatment strategy are essential for the affected patients, simply because an early diagnosis and an immediate operative intervention represent decisive prognostic factors independent from the cause of infection. Surgical intervention must include a decompressive laminectomy, a myelotomy, and also a secure intraoperative abscess drainage. In this analysis two patients will be reported on, both of whom were already showing symptoms of paraplegia at the time they were admitted to hospital. In both cases MR-tomographically an intramedullary nodulary lesion of the spinal cord could be detected. However, due to a complete lack of any acute symptoms of inflammatory reaction in one patient, an intramedullary abscess was not actually diagnosed before surgical treatment was performed. These two cases, together with existing scientific literature, aim to present an overview of the pathogenesis, the clinical symptomatology, the treatment strategy, and the expected therapeutical outcome of an intramedullary abscess formation. It will be shown that by treating this disease as early as possible using adequate therapeutic interventions a functional improvement of the resulting neurological symptoms can be expected.

[Septic arthritis of the shoulder following intra-articular injection therapy. Lethal course due to delayed initiation of therapy]. / Septische Arthritiden des Schultergelenks nach intraarticulärer Injektionstherapie Letaler Verlauf nach zeitverzögertem Therapiebeginn.

Detection of a bacterial arthritis of the shoulder represents an absolute indication for intervention. Irrespective of the cause of the infection, the most decisive prognostic factors are early diagnosis and therapy. We report on two patients who suffered from generalized sepsis and resulting death after delayed treatment of iatrogenic joint infections of the shoulder caused by intra-articular injection therapy. Both patients suffering from septic shock syndrome had been transferred to our hospital for surgical and intensive care treatment. They died in spite of maximal intensive care and aggressive surgical treatment. On the basis of the cases presented, it can be concluded that an acute infection of the shoulder joint must be excluded early when painfully limited range of motion in combination with clinical and laboratory signs of inflammation become apparent. Successful therapy of joint infection also requires early surgical treatment, including resection of infected tissue. If surgical joint revision is not performed or is performed too late, there is the risk of irreversible damage to the afflicted joint, even septic spread endangering the patient's life.

Injury prophylaxis in paragliding.

OBJECTIVES: To show trends in paragliding injuries and derive recommendations for safety precautions for paraglider pilots on the basis of accident statistics, interviews, questionnaires, medical reports, and current stage of development of paragliding equipment. METHODS: All paragliding accidents in Germany have to be reported. Information on 409 accidents was collected and analysed for the period 1997-1999. RESULTS: There was a substantial decrease in reported accidents (166 in 1997; 127 in 1998; 116 in 1999). The number of accidents resulting in spinal injuries was 62 in 1997, 42 in 1998, and 38 in 1999. The most common cause of accident was deflation of the glider (32.5%), followed by oversteering (13.9%), collision with obstacles (12.0%), take off errors (10.3%), landing errors (13.7%), misjudgment of weather conditions (4.9%), unsatisfactory preflight checks (4.9%), mid-air collisions with other flyers (2.2%), accidents during winching (2.2%), and defective equipment (0.5%). Accidents predominantly occurred in mountain areas. Fewer than 100 flights had been logged for 40% of injured pilots. In a total of 39 accidents in which emergency parachutes were used, 10 pilots were seriously injured (26%) and an additional three were killed (8%). CONCLUSIONS: Injuries in paragliding caused by unpredictable situations can be minimised by (a) using safer gliders in the beginner or intermediate category, (b) improving protection systems, such as padded back protection, and (c) improving pilot skills through performance and safety training.

[Retrogastral located gastrointestinal stromal tumor (GIST) as a sonographically detected rare incidental finding]. / Retrogastral gelegener gastrointestinaler Stromatumor (GIST) als seltener sonographischer Zufallsbefund.

Gastrointestinal stromal tumors (GIST) represent compared to carcinomas a rare group of neoplasias of the gastro-intestinal tract of unclear dignity. We report the example of a patient suffering from a big retrogastral located gastrointestinal stromal tumor which had been detected as an incidental finding without previous complaints. Because origin and dignity of the process could not definitely be diagnosed, total resection (R0-resection) without systemic lymphadenectomy of the process measuring 11.5 cm x 11 cm x 7 cm was performed. Mitotic activity and tumor-size are regarded as predictive factors of potenzial malignancy of GISTs. In general tumors with low mitotic activity of up to 5 mitoses per 50 high power fields (HPFs) and a diameter smaller than 5 cm are regarded as benign. In the presented case, up to 4 mitoses per 50 HPFs could be detected and thus, in connection with tumor-size, an uncertain biological behaviour of the process has to be expected. Since no generally accepted consensus on the treatment of the GISTs exists, also patients originally suffering from tumors regarded as borderline-malignant should undergo a close-meshed follow-up in regular intervals.