C. Burri

The stabilizing effect of various implants on the torn acromioclavicular joint

SummaryA biomechanical in vitro test was performed to determine the stabilizing effect of various implants for the surgical treatment of the torn acromioclavicular joint. In a specially designed testing device, plastic and cadaver specimens of the shoulder girdle were stressed in various ways. Different dislocations between the acromion and the clavicle and between the clavicle and the coracoid were determined, as well as the stiffness of the implants. A convenient stabilizing effect combined with less rigid fixation to secure the newly treated AC joint was provided by K-wire fixation with cerclage. Interfering shear and bending stresses could be avoided with this method, while the other implants showed various disadvantages. From a biomechanical point of view, a carbon-fiber ligament replacement provides sufficient stability in cases of chronic acromioclavicular separation.ZusammenfassungDie stabilisierende Wirkung verschiedener bei der Behandlung der Schultereckgelenkssprengung Verwendung findender Implantate wurde in einem biomechanischen Test in vitro untersucht. In einer speziellen Testvorrichtung wurden Kunststoffmodelle and Leichenpräparate auf verschiedene Weise beansprucht. Neben der Höhe der acromioclavicularen Gelenksstufe wurden die coracoclaviculare Abstandszunahme wie such die Implantatssteifigkeit bestimmt. Ein guter Stabilisationseffekt, verbunden mit einer zufriedenstellenden, weniger rigiden Fixation des AC-Gelenkes zum Schutz des frisch rekonstruierten Kapselbandapparates, wurde für die Spickdrahttransfixation mit kombinierter Cerclage ermittelt. Die auftretenden Scher- and Biegekräfte können mit dieser Methode neutralisiert werden, wdhrend die anderen Verfahren zum Teil gravierende Nachteile aufweisen. In Fallen chronischer AC-Gelenk-Instabilität kann mit einem Kohlenstoffaserband biomechanisch geniigende Stabilitäterzielt werden.

Intraoperative transesophageal two-dimensional echocardiography in total hip-replacement

SummaryA number of studies in medical literature suggest that during implantation of hip prostheses pulmonary embolism of medullary contents and of air may occur. Proof of this suggestion was based on histological examination of lung tissue in animal experiments as well as on post mortem examinations of human tissue. In vivo evidence of this suspected embolism has been lacking so far, since an appropriate technique has not been available. Using transesophageal two-dimensional echocardiography, continuous imaging of the right atrium and the right ventricle can be performed in order to prove this suspected embolization in vivo. Thus, in a prospective randomized study of 26 patients undergoing hip surgery, the right atrium and right ventricle were continuously imaged. Simultaneously, the end-expiratory CO2 partial pressure was recorded. The medical literature suggests that a venting hole in the shaft of the femur prevents the rise in pressure in the medullary space and thus also averts embolism. Therefore, prior to the implantation of the shaft prosthesis, and in order to vent the medullary space, in 13 patients a 4.5-mm lateral borehole was drilled into the femoral shaft, located two finger breadths distal to the point were the end of the prosthesis would be positioned. In 12 of 13 patients in the control group without boreholes, transesophageal two-dimensional echocardiography revealed that air bubbles formed during the implantation of the shaft. In the group with boreholes, however, presence of air could be demonstrated in only four patients (P < 0.01). Emboli were detectable in eight patients in the control of group, but in only two patients in the group with boreholes (P < 0.05). In the control group the median end-expiratory CO2 partial pressure dropped from 35 to 33 mmHG (P < 0.01) because of embolism, but in the group with venting holes this value was 35 mm Hg before as well as after implantation. Transesophageal two-dimensional echocardiography proves that embolization of air and medullary space contents occurs during the implantation of hip prostheses. A venting hole in the shaft of the femur may help to reduce the incidence of intraoperative embolization of air and medullary space contents occuring during shaft implantation, but it cannot eliminate this completely.

Total “internal” hemipelvectomy

SummarySeveral authors have described resections of tumorbearing parts of the pelvis including reconstructive plastic surgery. With extensive tumor growth present mutilating hemipelvectomies often have been the last resort. Even the most sophisticated prostheses hardly ever enabled the patients to walk again. We have therefore performed total “internal” hemipelvectomies in three cases. The necessary substitute consisted of half a pelvis made of polyacetal resin produced from a given model. The models measures and shape was established by computer tomograms thus resulting in an individually shaped pelvis half. The operative procedure aims at the maintenance of osseous muscular insertions and origins and their reconstruction. Utmost care has to be taken in avoiding damage to nerves and vessels. Fixation of the implant is performed by screws aiming through the sacroiliac joint into ala and corpus of the sacrum and cortico-cancellous grafts incorporated in the implant. The symphyses are united by means of plate fixation. The hip joint is substituted by a total prosthesis.With the procedure described we have managed three cases of extensive malignant tumors of the pelvis. One patient suffered a nerve lesion and skin necrosis with infection. The two remaining patients are capable of weight-bearing and standing on the inflicted leg alone.ZusammenfassungKontinuitätsresektionen und Ersatzplastiken am Becken sind von mehreren Autoren beschrieben werden. Bei ausgedehntem Tumorbefall und Rezidiven mußte bisher auf den verstümmelnden Eingriff der Hemipelvektomie zurückgegriffen werden. Diese Patienten werden auch nach qualifizierter und sorgfältiger prothetischer Versorgung kaum je gehf ähig. Wir haben deshalb bei drei Patienten die totale innere Hemipelvektomie durchgeführt. Der dazu notwendige prothetische Ersatz besteht aus einer Beckenhälfte aus Polyacetalharz, die nach einer vorgegebenen Form hergestellt werden kann. Die exakten Beckenmaße Bowie die Form des Beckens können durch Computertomographie nachgebildet werden, so daß uns von der Industrie eine individuell angepaßte Beckenhälfte zur Verfügung gestellt werden kann. Der operative Eingriff trachtet danach, die Muskelansätze und -ursprünge ossär zu erhalten und der Reinsertion zuzuführen. Größte Schonung hat den wichtigen Nerven-und Gefäßgebilden des Beines gewdhrt zu werden. Die Verankerung am Iliosacralgelenk erfolgt durch Schrauben vom Kunststoffbecken her in Ala und Corpus des Sacrums in bestimmter Richtung und in den Kunststoffblock eingefügte cortico-spongiöse Späne. Die Symphysen werden durch Plattenosteosynthese verbunden, das Hüftgelenk in der üblichen Weise durch eine Totalendoprothese ersetzt.Unter Anwendung dieser Voraussetzungen konnten wir drei Patienten mit ausgedehnten malignen Tumoren des Beckens durch eine totale innere Hemi pelvektomie versorgen. Dabei ist eine Nervenläsion und eine Hautnekrose mit Infekt in einem Fall aufgetreten, die beiden anderen Patienten belasten voll und vermögen den Einbeinstand durchzuführen.

Experimental studies on the influence of fibrin adhesive, factor XIII, and calcitonin on the incorporation and remodeling of autologous bone grafts

SummaryIn an experimental study on sheep the effects of fibrin adhesive system (FAS), plasma factor XIII (FXIII), and calcitonin on autologous cancellous bone grafts were studied. Drill holes in the tibia were filled with transplant bone, either untreated or locally treated with fibrin adhesive, with or without plasma factor XIII. We used 24 sheep, divided into three groups. Plasma factor XIII and calcitonin were administered parenterally; the third group received no treatment. For evaluation we carried out quantitative bone and fluorescence morphometry and microangiography. We found that local fibrin adhesive significantly decreased the remodeling and growth of the transplanted cancellous bone. Plasma factor XIII, given parenterally, increased the amount of bone in the transplant site; calcitonin showed no visible effect.

Die reaktion des körpers auf implantierte kohlenstoffmikropartikel

SummaryFor the durability of artificial joints the reaction of the surrounding tissue to friction particles is of great importance, since microparticles of less than 20 μm in size can produce tissue reactions different from those seen with solid material.Carbon materials are of great interest for joint replacement because of their great strength and elasticity module which corresponds to that of bone.We have implanted small particles of LTI-carbon and of carbon reinforced with carbon fibres of less than 20 μm in size into knee joints and periarticular tissue, intraperitoneal and intravenous in 82 rats. After observation up to 1, 2 and 3 days, 2 and 6 weeks, 3 and 6 months the results indicate:1.Histologically, there is no difference in the reaction of tissue to CFC and LTI.2.Intraarticular implanted carbon dust is removed within 1 week without any macroscopic or microscopic visible alteration of the cartilage.3.The substance is carried off by lymphatic routes as well as hematogeously and collects in parenchymal organs.4.Small carbon particles may be deposited within cells; however, the deposition of bigger particles usually is extracellular.5.Foreign body giant cells are identified adjacent to both periarticular and subperitoneal carbon deposits.6.No foreign body reaction was found in the synovium and the parenchymal organs.ZusammenfassungFür die Haltbarkeit von künstlichen Gelenken ist die Reaktion des umgebenden Gewebes auf Abriebpartikel von größter Bedeutung, da derartige Abriebpartikel mit einem Durchmesser von weniger als 20 μm eine starke Fremdkörperreaktion erzeugen können.Aufgrund ihrer hohen Festigkeit and ihres elastischen Verhaltens rind Kohlenstoffmaterialien von besonderem Interesse für den kiinstlichen Gelenkersatz. Daher wurden Mikropartikel von low temperature isotropic carbon and kohlenstoffaserverstärktem Kohlenstoff intra- und periartikular, intraperitoneal sowie intravenös eingebracht. Nach einer Beobachtungszeit von 1, 2 und 3 Tagen, 2 and 6 Wochen sowie 3 und 6 Monaten ergab die histologische Untersuchung folgende Resultate:1.Einen Unterschied in der Reaktion auf kohlenstoffaserverstärkten Kohlenstoff und LTI-Carbon besteht nicht.2.Intraarticulär implantierte Kohlenstoffabriebpartikel sind nach 1 Woche aus dem Gelenkraum verschwunden, ohne makroskopisch oder mikroskopisch sichtbare Veränderungen des Knorpels zu bewirken.3.Die Kohlenstoffpartikel wurden über die Lymphwege abtransportiert, gelangen in den Kreislauf und lassen sich in den parenchymatösen Organen nachweisen.4.Kleine Kohlenstoffpartikel liegen intrazellulär, größere Partikelansammlungen extracellulär.5.Riesenzellen lassen sich periartikulär sowie in den subperitonealen Kohlenstoffdepots nachweisen.6.Keine Fremdkörperriesenzellen wurden in der Synovia sowie in den parenchymatösen Organen gefunden.

Continuous passive motion after knee-joint arthrolysis under catheter peridural anesthesia

SummaryThe results of arthrolysis of a stiff knee are often poor because postoperative pain prevents the early active mobilization that is so essential. Adequate analgesia may be ensured by the use of continuous anesthesia via a peridural catheter; in combination with continuous passive motion, such analgesia is able to maintain, and often improve, the range of movement obtained at surgery. Twenty-two patients treated in this way showed improvement in the range of movement between 39° and 120°. Patients with post-traumatic knee stiffness achieved an average improvement in the range of movement of 93%, while those with stiffness following infection improved by only 55% on the average. The preoperative loss of movement does not appear to determine the end result; the etiology of the stiffness is more important.

Simultane autologe Spongiosaplastik und Muskellappentransposition zur Kontinuitätswiederherstellung an der unteren Extremität bei osteitischem Defekt

SummaryAbout 12% of compound fractures of the lower leg give rise to posttraumatic osteitis. Loss of bone by sequestration causes many problems particularly if soft tissue quality is poor. Cancellous and corticocancellous bone from the iliac crest is used for bony reconstruction. To obtain bony union, a well vascularised recipient for the graft is essential. Local muscle flaps and distant microvascular flaps and distant microvascular flaps improve vascularity by their separate connection to the vascular system. We treated 54 soft tissue defects by local muscle flaps in 41 and by microvascular flaps in 13 cases. In 21 cases a cancellous or a corticocancellous bone graft was used. Necrosis or partial necrosis of the flap occurred in 12 cases. Skin closure and healing was obtained by secondary procedures. Combined muscle flap and bone grafting was found to allow full weight bearing within reasonable period of time.ZusammenfassungBei offenen Frakturen des Unterschenkels tritt eine posttraumatische Osteitis im Durchschnitt in ca. 12% der Fälle auf. Dabei kann Sequestrierung großer Tibiaanteile zu erheblichen Knochenverlusten führen, die angesichts der prekären Weichteilsituation am Unterschenkel erhebliche Probleme bieten. Zum Wiederaufbau und Herstellung der Statik ist die autologe Transplantation cortico-spongiöser Späne und Spongiosa aus dem Beckenbereich die Methode der Wahl. Voraussetzung zur Einheilung des Transplantates ist die Schaffung eines optimalen Transplantatlagers mit der Möglichkeit allseitiger Gefäßinvasion ins Transplantat. Durch autochthone Muskellappenplastiken sowie mikrovasculäre Transplantation von myocutanen Lappen läßt sich das Transplantatlager konditionieren. Mit ihrem separaten Gefäßanschluß an den Blutkreislauf wird humoralen und zellulären Antikörpern der Zutritt zum Transplantat erlaubt. 54 Weichteildefekte am Unterschenkel wurden 41mal mit Muskel- und 13mal mit mikrovasculären Lappen gedeckt. 21mal wurde neben der autologen Spongiosaplastik ein corticospongiöser Span fest verankert. Zur Lappennekrose bzw. Teilnekrose kam es in 12 Fällen, die über Sekundärmaßnahmen zur Deckung und Heilung führten. Durch die Spongiosaplastik und kombinierte Weichteildeckung mit Muskulatur oder mikrovasculären Lappen wurde das therapeutische Ziel der Schaffung einer belastungsfähigen Extremität erreicht.About 12% of compound fractures of the lower leg give rise to posttraumatic osteitis. Loss of bone by sequestration causes many problems particularly if soft tissue quality is poor. Cancellous and corticocancellous bone from the iliac crest is used for bony reconstruction. To obtain bony union, a well vascularised recipient for the graft is essential. Local muscle flaps and distant microvascular flaps and distant microvascular flaps improve vascularity by their separate connection to the vascular system. We treated 54 soft tissue defects by local muscle flaps in 41 and by microvascular flaps in 13 cases. In 21 cases a cancellous or a corticocancellous bone graft was used. Necrosis or partial necrosis of the flap occurred in 12 cases. Skin closure and healing was obtained by secondary procedures. Combined muscle flap and bone grafting was found to allow full weight bearing within reasonable period of time.

The influence of various carbon fibre braiding techniques and methods of fixation on the extensibility of ligament prostheses

An alloplastic ligament prosthesis with carbon fibres should not only be biocompatible but should also restore the biomechanical function of a natural system, which includes restoring its elasticity. Tests with new types of braided carbon fibre strands showed their elastic extensibility to increase with increasing number of filament tows and increasing braid angle. The best results were obtained with 32 tows and a 43 degrees braid angle. This strand type was tested in vitro as a medial collateral ligament prosthesis with two methods of fixation in human knees and, in like manner, in vivo in sheep knees. Biomechanical tests in vitro using human cadaver knees and sheep knees after 12 weeks implantation showed an elasticity similar to that of normal natural ligaments.

Fractures of the pelvis and associated intrapelvic injuries

Summary Patients with pelvic fractures are usually multiply injured and are in a critical condition due to the additive effect of the different injuries. After thorough evaluation and determination of the priorities of the associated injuries, unstable fractures of the pelvis should be treated by operation. This method facilitates early functional rehabilitation of the patient.

Die Vernderungen der physikalischen Eigenschaften von Polyacetalharz (Hostaform, C), Polyester (Hostadur), Polythylen (Hostalen) und Teflon (Hostaflon) nach tierischer Implantation und mehrfachem Autoklavieren@@@The change of physical properties of plastics (polyoxymethylenecopolymer, polyethyleneterephthalate, polyethylene, polytetrafluorethylene) after animal implantation and autoclavation

The change of physical properties of plastics (polyoxymethylene-copolymer, polyethyleneterephthalate, polyethylene, polytetrafluorethylene) and the bio-compatibility of these materials were examined by implantation in the backmuscle of 6-month-old male rabbits for 4 and 12 weeks and after autoclavation. We have found out, that after implantation and autoclavation polyethylene-terephthalate demonstrates a strong diminution of the visco-elastic qualities. Polyethylene and polytetrafluorethylene were not changed by these treatments. After an implantation of 12 weeks and an autoclavation of four times the visco-elastic properties of polyoxymethylene-copolymer were only slightly diminished by 10 to 15%. The histological investigation of the surrounding tissue demonstrated a very good bio-compatibility of polyethylene. After an implantation of 4 weeks polyoxymethylene-copolymer, polyethyleneterephthalate and polytetrafluorethylene produced a comparable foreign body reaction, which, however, was evidently diminished after an implantation of 12 weeks.SummaryThe change of physical properties of plastics (polyoxymethylene-copolymer, polyethyleneterephthalate, polyethylene, polytetrafluorethylene) and the bio-compatibility of these materials were examined by implantation in the backmuscle of 6-month-old male rabbits for 4 and 12 weeks and after autoclavation.We have found out, that after implantation and autoclavation polyethyleneterephthalate demonstrates a strong diminution of the visco-elastic qualities. Polyethylene and polytetrafluorethylene were not changed by these treatments. After an implantation of 12 weeks and an autoclavation of four times the visco-elastic properties of polyoxymethylene-copolymer were only slightly diminished by 10 to 15%.The histological investigation of the surrounding tissue demonstrated a very good bio-compatibility of polyethylene. After an implantation of 4 weeks polyoxymethylene-copolymer, polyethyleneterephthalate and polytetrafluorethylene produced a comparable foreign body reaction, which, however, was evidently diminished after an implantation of 12 weeks.ZusammenfassungNach 4- und 12wöchiger Implantation in der Rückenmuskulatur von 6 Monate alten gleichgewichtigen männlichen Kaninchen sowie nach ein- bis viermaligem Autoklavieren erfolgte die Untersuchung von standardisierten Probekörpern aus Polyacetalharz (Polyoxymethylen-Copolymer), Polyester (Polyäthylenterephthalat), Polyäthylen und Teflon (Polytetrafluoräthylen) im Rahmen eines Zugversuches. Dabei zeigte es sich, daß Polyester durch Implantation und Autoklavieren eine starke Verminderung der viscoelastischen Eigenschaften erfährt. Während Polyäthylen und Teflon nach beiden Behandlungen im wesentlichen unveränderte Eigenschaften aufweisen, läßt sich bei Polyacetalharz nach 12wöchiger Implantation und viermaligem Autoklavieren nur eine leichte Verminderung der viscoelastischen Eigenschaften im Sinne einer Versprödung von 10 bis 15% nachweisen.Die histologisch-qualitative Beurteilung des umliegenden Gewebes ergibt eine überragende Gewebsverträglichkeit von Polyäthylen, während bei den drei übrigen Kunststoffen Polyacetalharz, Polyester und Teflon eine vergleichbare Fremdkörperreaktion nach 4 Wochen erkennbar ist, die nach 12 Wochen jedoch deutlich abgenommen hat.