Twelve uncemented, arteficial patellar components clinically and radiologically without signes of loosening after an implantation period of 9-48 Months were invastigated histologically and microradiographically. The components correspond to the system GSB-,,old'', GSB-,,new'', PCA and APS. Within the observed implantation periode the arteficial patellar components GSB-,,old'', GSB-,,new'' and PCA showed severe patho-morphological changes of the surrounding tissue and point to loosening. The dowel system according to APS shows after the longest period of time of 14 Months morphologically a fully bony encasement with wide spread direct contacts between the living bone and the metallic Titanium surface. The observation points urgently to the fact, that Polyethylene must not be in direct contact with the bony bed. On the basis of the patho-morphological reations a partial armament of the polyethylene surface with metallic structures must be rejected as a general principle.

Description of a male and six female patients with diastrophic dwarfism. In one case the observation was possible since birth. The typical clinical features and roentgenographic characteristics of this epi-, metaphyseal dysostosis with an autosomal recessiv mode of inheritance are summarized and compared with reported cases in the medical literature. It is important to establish the diagnosis early in order to apprise the parents of the prognosis and the likelihood of subsequent children being affected. This demonstrates our report of two affected siblings in one family and three affected siblings in another family. In one case we found an aplasia of both patellae, this finding was not described in the combination with this entity until now.

Explantierte, nach Obduktion gewonnene, fest sitzende Polyäthylenschraubpfannen mit einer Implantatliegezeit zwischen 16 und 54 Monaten wurden makroskopisch, radiologisch und histologisch untersucht. Im Beobachtungszeitraum zeigen sich im Bereich der Gewindegänge und am Pfannenboden knorpelige Metaplasien, die durch ihre Verknöcherungstendenz den Versuch einer sekundären Stabilisierung darstellen. Durch die geringe Standfestigkeit des Polyäthylens wird dadurch ein vermehrter Abrieb des Pfannenbodens bewirkt. Die kleinen, im Bereich der Gewindegänge gefundenen Defekte des Polyäthylens in Form des “Mäusefraßes” stellen möglicherweise den Ausdruck einer Biodegradation dar. Aufgrund der aufgezeigten geweblichen Reaktionen ist der Werkstoff Polyäthylen hinsichtlich seiner Standfestigkeit zu verbessern oder die Implantation einem stark eingeschränkten Indikationsbereich zuzuführen.

Die Osteochondrosis dissecans (OD) tali ist eine chronische Erkrankung des subchondralen Knochen und wird den aseptischen bzw. aseptischidiopathischen Knochennekrosen zugezählt. Die Mosaikplastik ist eine Möglichkeit zur Auffüllung von talaren osteochondralen Defekten. Dabei werden Knorpel- Knochenzylinder vom medialen ipsilateralen Femurcondylen entnommen und mittels Press-fit-Technik in die talare Defektzone transplantiert. Von 1999 bis 2003 wurden insgesamt 10 Patienten (5 Männer, 5 Frauen) von durchschnittlich 39,1 Jahre (16–66 Jahre) mit einer Osteochondrosis dissecans tali mit der Mosaikplastik-Technik operiert. Eine Osteotomie des Malleolus (9×medial, 1×lateral) war in allen Fällen notwendig. Die mittlere Nachuntersuchungszeit beträgt 24,1 Monate (5–61 Monate). Der durchschnittliche präoperative Kitaoka-Score von 56,4 Punkten (48–84) verbesserte sich postoperativ auf durchschnittlich 83,4 (64–100) Punkte. Es kam durch den Eingriff in allen Fällen zu einer Scoreverbesserung, die durchschnittlich 30 Punkte betrug. Postoperativ kam es bei allen Patienten zu einer Verbesserung der Dorsalextension um durchschnittlich 4°. Auf der visuellen analogen Schmerzskala kam es zu einer Verbesserung von prä-operativ durchschnittlich 7,1 auf post-operativ auf 0,8. 9 von 10 Patienten zeigen sehr gute und gute Ergebnisse und sind mit dem Operationsergebnis sehr zufrieden. Nativröntgen und MRT zeigen gute Integration der Transplantate. Die Zylinderentnahmestelle zeigt bei 40% der Patienten für ca. 16 Wochen eine geringe Schmerzhaftigkeit. Die Knöchelosteotomie bereitet bis auf lokale Schmerzen für ca. 5 Wochen keine weiteren Probleme. Zusammenfassend zeigen die frühen Ergebnisse, dass es sich bei der autologen Knorpel-Knochen-Transplantation bei talaren Defekten um ein viel versprechendes Verfahren handelt. Die letztendliche Potenz dieses Therapieregimes wird man aber erst nach vorliegen von Langzeitergebnissen beurteilen können.

Osteochondritis dissecans (OD) tali is a chronic affection of the subchondral bone and is added to the group of aseptic respective aseptic-idiopatic osteonecrosis. Mosaicplasty technique represents one of the most important options for the treatment of talar OD and osteochondral defects. Using this technique, cartilage-bone plugs harvested from the ipsilateral proximal femoral condyle are used for autologous transplantation into talar dome defects. Between 1999 and 2003 we treated 10 patients (5 women and 5 men) with an average age of 39.1 (range: 16–66), using the mosaicplasty technique, for the treatment of osteochondrosis dissecans of the talus.

On the basis of the newly-formed capsular tissue of 80 cemented (Weber-Huggler, Müller-Charnley) and uncemented (ceramic/ceramic/titanium) total hip endoprostheses which had to be reoperated on because of aseptic loosening, the efficiency of the Sudan-III-staining reported in literature to identify polymethylmethacrylate (PMMA) bone cement particles is investigated, because the quantity as well as quality of the various wear products is discussed as possible factors of prostheses loosening.

We first treated a patient with fibrin sealant in an orthopedic procedure 18 years ago. This was a case of fistulous osteomyelitis following total hip replacement. We packed the bone cavity with homologous spongiosa and fibrin sealant, a technique which has proved successful. In numerous animal experiments and laboratory studies it has been demonstrated that the use of homologous fibrin sealant clearly conduces to the incorporation of bone grafts. This advantage is of particular significance when filling major defects, when no autologous bone is available for grafting, and when combating infections. The fibrin sealant system improves vascularization and this in turn enhances osseous remodeling of bone grafts. The adhesive strength of fibrin sealant is sufficient for refixation of osteochondral fragments. For its hemostatic effect, fibrin sealant is applied to seal major cancellous bone defects or to stanch oozing hemorrhages in patients with bleeding disorders. In cases of ruptured Achilles tendon with extensive necrotic areas, fibrin sealant improves the formation of granulation tissue on the surface of the defect. In general, vascularization and healing are significantly reduced when heterologous fibrin sealants are used.

Twelve uncemented, artificial patellar components clinically and radiologically without signs of loosening after an implantation period of 9-48 Months were investigated histologically and microradiographically. The components correspond to the system GSB-"old", GSB-"new", PCA and APS. Within the observed implantation period the artificial patellar components GSB-"old", GSB-"new" and PCA showed severe patho-morphological changes of the surrounding tissue and point to loosening. The dowel system according to APS shows after the longest period of time of 14 Months morphologically a fully bony encasement with wide spread direct contacts between the living bone and the metallic Titanium surface. The observation points urgently to the fact, that Polyethylene must not be in direct contact with the bony bed. On the basis of the patho-morphological reactions a partial armament of the polyethylene surface with metallic structures must be rejected as a general principle.

Firmly attached screw-in polyethylene acetabula which had been implanted for between 16 and 54 months were explanted after autopsies and subjected to macroscopic, radiologic and histologic examination. Metaplasias were seen around the threads and on the floor of the acetabulum. Their tendency to ossify represents an attempt at secondary stabilization. Due to the low stability of the polyethylene this causes increased wear on the floor of the acetabulum. The small defects in the polyethylene found in the threads, resembling damage done by mice, may be a sign of biodegradation. In view of the tissue reactions pointed out, the material stability of the polyethylene needs to be improved or implantation must be restricted to a very limited range of indications.

SUMMARY Among the great number of possible drive train configurations, the application of visco coupling elements combines an improved distribution of tractive forces with a driver independent performance. To investigate the straight ahead accelerating and kinematic cornering of a vehicle with such visco elements a simulation with a four wheel vehicle model is employed. The drive train thereby comprises engine characteristics, central distribution gear and rear differential, each with a different visco coupling. For the matter of comparison a completely locked drive train is considered also. The longitudinal transient tire characteristics approximation is valid for arbitrary slip values on high and low friction surfaces. The results compare the performance of 8 different drive train configurations for the cases: straight ahead acceleration on μ-split surface, kinematic cornering on high friction surface and the unilateral crossing of a low friction patch extending 1.5 times the wheel base with a medium acceleration. A configuration of a central distribution gear with a parallel visco coupling and a soft visco coupling at the rear differential can be found to be a good compromise for all the driving duties.

A purely chondral lesion was inflicted at the medial or lateral femoral condyle of the knee joints of 54 adult male rabbits in order to study hyaline cartilage regeneration. The experimental group was given a sequential intraarticular instillation of trypsin and autologous blood, the control groups were given trypsin or blood or nothing. Only the experimental group (trypsin and autologous blood) showed hyaline cartilage regeneration in 2/3 of the cases examined. Apparently neither the healthy cartilage nor the synovial membrane suffered damage from the trypsin injection.A possible mechanism of cartilage regrowth may be the inhibition of chalones by the fermentative effect of trypsin, which stimulates the aggregation of thrombocytes and fibrin from the injected blood on the chondral lesion, thus initiating the regeneration of hyaline cartilage.

A low priced, efficient frozen section cutting device is described to produce 5 microns sections of frozen undecalcified bone specimen blocks in routine pathology. The device was developed by combining two commercially-available instruments, namely a frozen section microtome with methyl alcohol cooling and a hard tissue microtome. Bore holes were drilled in the hard tissue knife to permit cooling, using the methyl alcohol system of the other microtome.

We examined the rates of necrosis of newly formed capsula tissue (the number of newly formed capsular tissues with necrosis) after the reoperation of 95 cemented and 11 uncemented total and cup endoprostheses, consisting of different arteficial joint materials. A comparison was made to the joint capsular tissue of 492 patients with arthrosis. The necrosis rate shows a lack of statistical significance within the two year-groups over a period of 12 years and between the different types of prostheses by using PMMA-bone cement. Therefore, it is assumed that a biological equivalence of the prostheses wear products is reached. It is also argued that necrosis can possibly develop from the sudden increased accumulation of PMMA-bone cement particles from the bone bed, caused by the loosening of the prosthesis. In comparison the newly formed capsular tissue of the uncemented prostheses, of which no necrosis was shown, evidence is given that the development of necrosis is chiefly due the quantity of PMMA wear products present. Because of the difficulty to exactly identify the PMMA-bone cement wear products, the toxicity of the PMMA-bone cement--who ist good known and in agreement in recent literature--or its wear products continues to be of hypothetical value in the production of necrosis. This is inspite of the successful detection by the gaschromatograph of the highly toxic paratoliudine in PMMA-bone cement. On the basis of the high statistical significance of the rate of necrosis in comparing the arthrosis joint capsules (14.83%) to the newly formed capsules (73 : 100%) it is shown that the capsulare fibrosis and scar formation to the obliteration of the lymphatic vessels is of secondary importance.

Bei der Implanta tion eines alloarthroplastis chen Gelenkersat zes (T EP) wird die ursprüngliche Gelenkka psel o ft vollstä ndig entfernt un d zeigt bei ihr er Regenerati on eine gewisse Ähnl ichkeit mit de r ur sprünglichen Synovia lis, wo bei der Kap selau fbau du rch den implantierten Werkstoff bzw. die Werksto ffpaarung beeinflußt werden soll (28). Durch die Beanspruchu ng des Gelenkes und verme hrt bei Instab ilität de r TE P kommt es zum Auftreten eines Abriebgemisches und als Reakt ion darauf zur Entwicklung eines Granu lationsgewebes, welc hes nac h Art, Menge und Größe de r Abriebteilchen einen untersch iedlichen Gehalt an Makrophagen und Fremdkörperr iesenzellen aufweist (28). Die entstehenden Abriebteilchen werden nach der derzeit gängigen Me inung über die perivas kulären Lymphspalten abgeführt, wobei sich ein Gleichgewicht zwischen Materialabrieb und Gewebereaktion einstellen kann (28) . Bei stärkerem Anfall von Abri ebteilchen soll es zur Überladung der Phagozyten und bei gleichzeitig vorhandener Fibrose und Schrumpfung des Kaps elregenerate s zur Unterbindung des Lymphab st romes und dami t zur Überlastung des restlichen Lymphdr ain agesystems kommen und weiter s zur Einbeziehung de r zellulären Speicherk ap azität des gesa mten kn öcherenen Prothesenlagers. wo bei diese Vorgänge letzlieh eine der Prothesen lockeru ngsur sachen dar stellen sollen (28). Die im Regenerat kapselgewebe auftretenden Nekrosen werden nac h längerer Implantationszeit als Resultat der Fibrose, Phagozytenüberladung und de r Lymph st rom abflußübe rlastu ng aufgefaßt, wo bei auch toxische Einflü sse der einzelnen Abri ebkompon enten veran tw ortlich gemacht we rden (2, 13, 22, 25 , 28 ). Um dies zu überprüfen und um genauere Hin weise zur Genese der Kap selnek rosen zu erhalten, wollten wir die Nekrosera ten bei der Arthrose im Vergleich zu verschiedeZ usamm enfas sung