AIM:Two clinically established PMMA bone cements (Refobacin Palacos R and Palacos R + G) and two newer cements not yet in widespread clinical use (Refobacin Bone Cement R and SmartSet GHV) were tested in vitro for practically relevant differences.METHODS:The tests included chemical analyses, handling properties and testing according to the ISO standard for PMMA bone cements.RESULTS:The results obtained indicate clearly that the copolymers used in Refobacin Bone Cement R and SmartSet GHV differ from those used in the Palacos cements. There were also significant differences in viscosity behaviour and waiting time (p < 0.01 for Palacos cements versus Refobacin Bone Cement R) as an expression of different handling properties. The hardening times under ISO 5833 conditions also differed significantly (p < 0.01 and p < 0.05 for Palacos cements compared with Refobacin Bone Cement R and p < 0.01 for Refobacin Bone Cement R compared with SmartSet GHV).CONCLUSION:In view of these differences in material properties, the clinical data from long-term use of the bone cements Refobacin Palacos R and Palacos R + G cannot be extrapolated to the newly developed PMMA cements Refobacin Bone Cement R and Smart GHV. Before broad clinical use of these cements, prospective clinical studies using RSA or DEXA and, as a second step, statistically powerful prospective comparative studies should be performed. Until these data are available, patients in whom Refobacin Bone Cement R and SmartSet GHV are used should be informed that the material employed deviates from the standard procedures for cemented joint replacement in the Scandinavian arthroplasty registers and that the long-term consequences cannot, in the final instance, be foreseen. This is essential in order to avoid later malpractice claims on the grounds of inadequate information.

Even though the discussion for desisting from wound drainage has arisen, this is not reflected in the reality of surgical treatment. In more than 90% of all procedures wound drainage is used. It remains to be proven whether suction drainage actually is superior to gravity drainage in everyday use. In a random study with 200 patients it was proven that suction drainage shows no significant advantage in liquid quantum, haematoma and the frequency of complications. We conclude that the economically favourable gravity drainage can replace the more expensive suction drainage in most cases.

Withagrowing percentage of elderlypeople in the population and, correspondingly, an increasing rate of fracturesof the proximal femur,the question how tostabilize m edial femoral-neck fracturesisgaining increasing importance. Especiallyin Hun-gary and Scandinaviancountries,femoral-head-preserving surgery isadvocated. However,the main problemsof thisproce-durearere-dislocation and necrosisof the femoral head. Encour-aged by twotheoretical m athematicalconsiderations, a biomechanical experiment wasperformed to investigatetwo d ifferent methodsof screwfixation of medial femoral-neck fractures.The results showed thatahead-preserving internal fixation withtwo cranialscrews and athree-point s upported screwat t he bottom of the neck had distinctbiomechanicaladvantagescompared to conventionalscrewfixation. Thishasencouraged us to more fre-quentlyperformthisminimallyinvasiveand head-preserving surgery in PauwelsI a nd II medial fracturesof the femoral head.

Physical methods became recently more important as an alternative to anticoagulation for prophylaxis of thromboembolism and were studied for their efficacy. The AV-impulse-system proved efficient in reducing thromboembolic complications in patients undergoing hip surgery by increasing the return of venous blood in the deep veins of the leg. In a preclinical trial we studied the influence of the AV-impulse-system and of active forefoot movement on venous blood return in 12 lower extremities of 6 healthy individuals immobilized in below the knee plaster casts. Our results show a significant increase in venous blood flow caused by the AV-impulse-system (p < 0.05) and by active forefoot movements (p < 0.05). Prevention of thromboembolic complications in trauma and orthopaedic patients immobilized in plaster cast seems possible by using the AV-impulse-system which significantly increases the venous blood flow independent from patient compliance.

Popliteal cysts may occur with diseases of the knee and may cause several complications. We report about a patient with a popliteal cyst, that contained calcified concrements after a femur fracture and a complex knee injury and that we found to be a rare cause of persisting knee pain and effusions. The etiology of the concrements will be discussed, that we think are more likely to be posttraumatic loose joint bodies than traumatically induced chondromatosis.

Under certain well-defined indications alloplastic material may be used in cruciate ligament surgery. The stability and survival of such a synthetic ligament is to a great extent dependent on the anchorage with which it is fastened to the bone. Most fixation methods have proved to be too weak or have revealed other essential drawbacks, resulting in clinical and experimental failure. A new ligament fixation device (LFD) was developed and tested biomechanically and in animal experiments. In the biomechanic investigation the new LFD was compared to single staples, double staples in the belt-buckle technique, and ligament guidance through additional bone tunnels (Z-technique). The tests were carried out on human cadaver knees, plastic bones, and dog stifle joints. The evaluated parameters were linear and maximum load, stiffness, and elongation. In addition, hysteresis tests were performed to assay the long-term resistance of the fixation. The tests showed a significant superiority of the LFD in all measured variables compared to the other anchorages. The pull-out strength, at 1866±43 N (cadaver knee), was about four times that for the single staple, and about twice as high as that for the double staple and Ztechnique. The animal experiments were performed on German shepherd cross-breed dogs. In six animals the anterior cruciate ligaments were excised bilaterally and replaced by a 6-mm Trevira ligament, on one side anchored with staples in the Z-technique, on the other with the LFD. Postoperatively the dogs were allowed to move freely: no additional protection was employed. After 6 months the animals were sacrificed and the knees examined macroscopically. radiologically, microscopically, and by biomechanical testing. After half a year of implantation, the pull-out strength of the alloplastic ligament was 662±62 N for the LFD and 531±67 N for the staples. Three ligaments in the staple group and one in the LFD group had ruptured completely, and two ligaments partially, one in each group. The average anterior drawer in the LFD group was 2.8 mm, in the staple group 4.0 mm. In all cases the alloplastic ligament was separated from the bone by a fibrous interface. None of the fixation devices showed signs of loosening. There was no foreign body reaction around the anchorages. Major cartilage degeneration was observed in two stifle joints of each group, mainly associated with instability.

The knee radiographys of 77 patients were examined by two physicians not involved in the operation a mean of 41.2 months after implantation of a synthetic ligament (Trevira hochfest). They evaluated the increase of degenerative osteoarthritis on a five-grade scale (0–4) by Jonasch and Mohing as modified by Holz, and using the IKDC score. Fifty patients with acute rupture had the synthetic ligament implanted for protection of anterior cruciate repair. Twenty-seven patients had a salvage procedure with the alloplastic ligament functioning as a prosthesis. Both examiners found a statistically significant increase of degenerative arthritis. Patients with acute anterior cruciate tears had a lower degree of osteoarthritis on the day of surgery compared to the patients with chronic insufficiency, but the postoperative increase was identical in both groups. Statistical analysis revealed correlations between osteoarthric changes and several factors such as concomitant meniscus or posterior cruciate injury and demonstrated no correlation to the grade of postoperative stability or injuries to the medial or lateral collateral ligaments or capsule.

Bei 31 chronisch instabilen voroperierten Kniegelenken (sogenannten Salvage cases) wurde das vordere Kreuzband durch ein Polyethylenterephthalatband (Trevira® hochfest) in Zwei-Kanal-Technik ersetzt. Zusätzlich wurden Begleitschäden an den Kniebinnenstrukturen von 21 Gelenken operativ saniert. Die Patienten wurden jährlich nachuntersucht. Zur Abschlußuntersuchung nach 4,4 Jahren konnten 27 Patienten erfaßt und klinisch, röntgenologisch sowie mittels verschiedener Scores ausgewertet werden. Der präoperativ mit 59,8 (±16,7) niedrige Lysholm-Score zeigte durch den Eingriff einen signifikanten Anstieg ein Jahr postoperativ auf 75,4 (±18,9), fiel dann aber bis zur Abschlußuntersuchung auf 71,4 (±19,6) ab. Ähnliche Werte wurden in den übrigen Scores (OAK, IKDC, VAS) erreicht. Durch die Operation konnte das Aktivitätsniveau (nach Tegner) von 2,0 (±2,1) auf 3,1 (±1,9) gesteigert werden. Die Stabilität (Laxitätsdifferenz zur Gegenseite) betrug präoperativ 7,5 (±3,4) mm. Sie gab in den ersten beiden Jahren um 2,1 (±2,5) mm nach, hielt sich danach aber bis zur Abschlußuntersuchung konstant und betrug nach 4,4 Jahren 2,3 (±2,9) mm. Insgesamt erbrachte die Operation über den gesamten Untersuchungszeitraum eine signifikante Verbesserung aller untersuchten Parameter. Es wurden fünf Rupturen (davon eine durch Materialermüdung), ein Ausriß des Bandes aus der Klammer, eine suprakondyläre Fraktur durch die nahe beieinander eingebrachten Klammern, vier Arthrofibrosen und ein chronisches Reizknie als größere Komplikationen beobachtet. Die im Verlaufszeitraum festgestellte Befundverschlechterung wird vorwiegend auf eine Progredienz der bereits präoperativ vorhandenen langdauernden degenerativen Schäden zurückgeführt, die sich auch durch eine suffiziente Stabilisierung des Zentralpfeilers nur bedingt aufhalten lassen.

Thirty-one salvage cases of chronically unstable previously operated knees were stabilized by an anterior cruciate ligament prosthesis of polyethyleneterephthalate (Trevira hochfest) and additional repair of concomitant lesions. The patients were followed up at yearly intervals. For the final follow-up after 4.4 years 27 patients could be evaluated clinically, radiologically and by several scores. The pre-operative Lysholm score was 59.8 (+/- 16.7). It was raised significantly by the operation to 75.4 (+/- 18.9) after 1 year, but then gradually decreased to 71.4 (+/- 19.6) at the final examination. Similar values were reached for the other scores (OAK, IKDC, VAS). The degree of activity (as estimated by the Tegner activity scale) increased from 2.0 (+/- 2.1) to 3.1 (+/- 1.9). Pre-operative anterior translation revealed a side-to-side difference of 7.5 (+/- 3.4) mm. The stability, which was restored by the operation, gave way a little in the first 2 years up to a side-to-side difference of 2.1 (+/- 2.5) mm, but then remained constant and was measured 2.3 (+/- 2.9) mm after 4.4 years. On the whole, the patients gained a significant improvement from the operation in all investigated parameters. Major complications included 5 ruptures of the synthetic ligament (1 by material fatigue), 1 avulsion of a staple, 1 supracondylar fracture due to 3 closely located staples, 4 cases of arthrofibrosis and 1 case of chronic knee irritation. The gradual deterioration of the operated knees within the follow-up period is mainly caused by the pre-existing chronic degenerative changes, which progress in spite of a sufficient stabilization of the central pivot.

One of the weak points of augmentation or replacement of cruciate ligaments by synthetic material is the fixation of these artificial ligaments to the bone. The present investigation examines the mechanical properties of a newly developed anchoring technique (ligament fixation device = LFD) in regard to linear and maximum load, stiffness, creep, and long-term durability compared to single staples, double staples in belt buckle technique, and passing the ligament through an additional bone tunnel. The tests are carried out on cadaver knees and plastic bones under standardized conditions with the same artificial ligament in all experiments (Trevira hochfest). The LFD shows a linear load of 1866 N in cadaver knees and 1874 N in plastic bones. The stiffness is 68.3 N/mm respectively 51.9 N/mm, the elongation at 500 N load 12.7 mm respectively 10.9 mm. In the hysteresis tests with submaximum loads the ligament/LFD-unit lasts 8515 cycles in the plastic bone and 4431 cycles in the cadaver knee. These results are significantly superior to all other fixation techniques concerning linear load, stiffness and long-term durability. They permit aggressive functional treatment and immediate postoperative weight bearing of the operated knee.

: One of the weak points of augmentation or replacement of cruciate ligaments by synthetic material is the fixation of these artificial ligaments to the bone. The present investigation examines the mechanical properties of a newly developed anchoring technique (ligament fixation device = LFD) in regard to linear and maximum load, stiffness, creep, and long-term durability compared to single staples, double staples in belt buckle technique, and passing the ligament through an additional bone tunnel. The tests are carried out on cadaver knees and plastic bones under standardized conditions with the same artificial ligament in all experiments (Trevira hochfest). The LFD shows a linear load of 1866 N in cadaver knees and 1874 N in plastic bones. The stiffness is 68.3 N/mm respectively 51.9 N/mm, the elongation at 500 N load 12.7 mm respectively 10.9 mm. In the hysteresis tests with submaximum loads the ligament/LFD-unit lasts 8515 cycles in the plastic bone and 4431 cycles in the cadaver knee. These results are significantly superior to all other fixation techniques concerning linear load, stiffness and long-term durability. They permit aggressive functional treatment and immediate postoperative weight bearing of the operated knee.

Alloplastische Bänder zum Ersatz oder zur Augmentation rupturierter Kreuzbänder bedürfen einer sicheren Verankerung im Knochen sowohl für die frühfunktionelle Weiterbehandlung, als auch für die Dauerhaltbarkeit. Eine neuartige Verankerungstechnik, die auf dem Klemmbackenprinzip mit einem breiten Kragen zur kortikalen Abstützung beruht, wurde mit bisher bekannten Fixationstechniken wie Einzelklammer und Doppelklammer in Gürtelschnallentechnik verglichen. Die Zugversuche wurden an Leichenknien, Schafstibiae und Kunststoffknochen vorgenommen. Die neuartige „Klemmhülse“ war den übrigen Verankerungen hinsichtlich Ausreißfestigkeit, Steifigkeit und Minimierung der Längenänderung bei 500 N signifikant überlegen. Sie stellt somit eine deutliche Verbesserung für die Kunstbandchirurgie am Kniegelenk dar.

Die Hauptindikationen zur Bohrdraht-Osteosynthese stellen instabile extra- und unverschobene intraartikulären Frakturen vom Typ Colles sowie instabile kindliche Frakturen dar. Von 2760 Radiusfrakturen (1975–1989) wurden 626 (20,7%) operativ, darunter 326 (11,8%) mit Bohrdrähten behandelt, davon 53,5% primär nach dem Unfall. Unter sterilen Operationsbedingungen wurden von radial und von dorso-ulnar 3–4 Bohrdrähte nach Präparation subcutan versenkt und im Gips nachbehandelt. Bei der Nachuntersuchung einer Serie von 226 Bohrdraht-Osteosyn-thesen nach dem Score von Lidström fanden sich 79% gute, 16% mäßige und 5% schlechte Ergebnisse. Die klinischen Resultate korrelieren mit der Winkelstellung des Radiocarpalgelenkes und der Verkürzung. Die zusätzliche Verletzung des ulnaren Komplexes führt zu schlechteren Repositions-Ergebnissen. Daher sollte der Proc. sty-loideus ulnae fixiert werden.

The severity of a fracture of the distal radius is not only determined by the type of the fracture but also by concomitant ligamentous and carpal injuries, which are often underestimated and imply a higher degree of instability than the bony lesion alone. Therefore classifications are valuable, which combine fracture type and associated lesions, thus permitting conclusion about the therapeutic method of choice. The article discusses indication, operative technique and special features of radial fractures in combination with carpal injuries, of radial styloid fractures as well as Barton's and Reverse-Barton's fractures, of bilateral radial fractures and of radial fractures as part of a chain fracture. It is important to perform an early fasciotomy and carpal tunnel release in cases of severe soft tissue damage and threatening compartment syndrome.

Die Korrekturosteotomie stellt als Wahleingriff beim Kind eine besonders verantwortliche chirurgische Aufgabe dar und hat einen hohen therapeutischen Stellenwert. Dies gilt insbesondere für die untere Extremität, da hier neben funktionellen und kosmetischen Beeinträchtigungen auch statische Störungen mit Auswirkung auf das Becken und die Wirbelsäule vermieden werden können (Tabelle 1).