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ABSTRACT: Data of 64 consecutive patients with malignant tumors of the knee treated with tumor endoprostheses between 1976 and 1996 were reviewed. The study was retrospective before 1990 and prospective since then. Four patients were lost to followup and are not included in the study. The average age of the remaining 60 patients was 33.2 years (range, 9-72 years). Fifty patients had surgery for primary sarcoma and 10 patients had surgery for metastases of carcinoma. In the patients in the sarcoma group, the probability of 5 years survival was 72% and 10 years survival was 69%. The overall clinical score of 47 patients with a followup more than 9 months was 81% using the evaluation system of the International Society of Limb Salvage. Fifty-eight reoperations were done in 29 patients because of complications. Twenty reoperations were attributable to soft tissue complications, 34 reoperations were because of mechanical problems related to the prostheses, and four were because of local tumor recurrence. The probability of survival of the leg of the patient after 10 years was 95%. Despite a high rate of complications after limb salvage with endoprostheses, the final clinical outcome usually was good.
Clinical Orthopaedics and Related Research 01/2003; · 2.53 Impact Factor
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ABSTRACT: Calculation of new orthopedic implants prior to manufacturing of prototypes can be economic in the case of complex production processes. The use of composite materials for highly loaded hip stems is one application of the Finite-Element Method. Due to the anisotropic behaviour of composite structures, special routines had to be programmed for element alignment and failure analysis. Stability of carbon fibre-reinforced epoxy hip stems could be confirmed by experimental results. The risk of neck fracture was found to be one of the critical features in the design process.
Medical Engineering & Physics 08/1997; 19(5):431-9. · 1.62 Impact Factor
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ABSTRACT: Verschleiß der artikulierenden Komponenten (vor allem PE-UHMW) ist in der Hüftgelenkendoprothetik der wichtigste limitierende
Faktor für eine Langzeitstabilität. Um den Abrieb zu minimieren, werden seit 1969 keramische Komponenten (Al
2O3 nach ISO 6474) und seit 1975 die Kombination Al2O3/PE-UHMW verwendet. Die Paarung Aluminiumoxidkeramik und kohlenstoffaserverstärktes Epoxidharz (Caproman®) wird seit 1988
klinisch eingesetzt. Bei dieser Kombination zeigten In-vitro-Experimente und In-vivo-Untersuchungen im Gegensatz zu PE-UHMW
geringe Abriebraten und eine günstige biologische Reaktion auf Abriebprodukte. Die Reibflächen von explantierten keramischen
Hüftköpfen (Al2O3– Biolox®) und zementfrei implantierten Caproman®-Pfannen wurden anhand von rasterelektronenmikroskopischen Untersuchungen,
Sphärizitätsmessungen und computergestützten Rauheitsmessungen (incl. der erweiterten Rauheitsparameter Rvk oder Rpk nach ISO 4287 [18]) untersucht. Die mittelfristigen Ergebnisse im Rahmen einer klinischen Studie zeigen, daß mit der Paarung
Al2O3/Caproman® auch im Körpermilieu die in den Voruntersuchungen ermittelten günstigen Reibeigenschaften erreicht werden und eine
Verbesserung gegenüber den herkömmlichen Werkstoffpaarungen erzielt werden kann. Die dabei ermittelten geringen Verschleißraten
liegen im Bereich der Tribopaarung Al2O3/Al2O3, ohne deren materialspezifische Probleme bei Keramik-Keramik-Kombinationen aufzuweisen.
Wear of the articulating components (especially PE-UHMW) of total hip endoprostheses is the most important technical factor
limiting the functional lifetime. To minimize wear debris, ceramic heads, according to ISO 6474 (Al2O3), have been used, from 1969 paired with Al2O3 and since 1975 paired with PE-UHMW. Al2O3 balls articulating with cups made from CFRP have been in clinical use since 1988. Laboratory experiments and in-vivo testing
showed minimized wear debris and mild biological response to wear products using CFRP (carbon fiber reinforced plastic) instead
of PE-UHMW as the cup material. The articulating surfaces of retrieved ceramic heads (Al2O3– Biolox®) and cementless CFRP cups (carbon fiber reinforced plastic, Caproman®) were compared using sphericity measurement
techniques, scanning electron microscopy (SEM) and roughness measurements (including advanced roughness parameters Rvk or Rpk according to ISO 4287). Altogether, the first results of the clinical study showed that the combination Al2O3-ball/CFRP-cup came up to the expected lower wear rates compared with the conventional combinations. The wear rates are comparable
with the combination Al2O3/Al2O3 without the material-related problems of ceramic components in all ceramic combinations.
Der Orthopäde 04/1997; 26(2):152-159. · 0.51 Impact Factor
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ABSTRACT: Wear of the articulating components (especially PE-UHMW) of total hip endoprostheses is the most important technical factor limiting the functional lifetime. To minimize wear debris, ceramic heads, according to ISO 6474 (Al2O3), have been used, from 1969 paired with Al2O3 and since 1975 paired with PE-UHMW. Al2O3 balls articulating with cups made from CFRP have been in clinical use since 1988. Laboratory experiments and in-vivo testing showed minimized wear debris and mild biological response to wear products using CFRP (carbon fiber reinforced plastic) instead of PE-UHMW as the cup material. The articulating surfaces of retrieved ceramic heads (Al2O3-Biolox) and cementless CFRP cups (carbon fiber reinforced plastic, Caproman) were compared using sphericity measurement techniques, scanning electron microscopy (SEM) and roughness measurements (including advanced roughness parameters Rvk or Rpk according to ISO 4287). Altogether, the first results of the clinical study showed that the combination Al2O3-ball/CFRP-cup came up to the expected lower wear rates compared with the conventional combinations. The wear rates are comparable with the combination Al2O3/Al2O3 without the material-related problems of ceramic components in all ceramic combinations.
Der Orthopäde 03/1997; 26(2):152-9. · 0.51 Impact Factor
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ABSTRACT: Ruptures of the cruciate ligaments continue to pose both diagnostic and therapeutic problems. On the basis of structural analysis of MR images obtained after the accident and the results of conservative treatment, it can be shown that function healing of the rupture can result, when, for example, the synovial membrane (capsule) is preserved (70%). It proved possible to show and objectify this using MRI and measurements.
Fortschritte der Medizin 03/1997; 115(5):32-5.
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ABSTRACT: Although, in Europe, snowboarding is a young sport, it has already established itself and, in common with Alpine skiing, is represented in the Olympics. Its biomechanical aspects (technique, shoeboard connection), lead not only to a typical pattern of movements, but also to a snowboard-specific pattern of injuries, which differs from that seen with Alpine skiing. In the case of snowboarding, the upper limbs are appreciably more often involved in injuries than are the lower extremities. The most common injuries are fractures of or close to the wrist. Since many children and adolescents are to be found among snowboarding fans, the percentage of epiphyseal injuries is high. Depending on the style employed-Alpine or freestyle-the risk of lower limb injuries differ in terms of ankles and knee injuries. Through the use of special protective equipment, such as gloves provided with extra protection for wrist and fingers, (possibly also helmets, knee and elbow protectors for beginners), together with improvements in technique in a snowboard school, and the optimisation of the materials used by the industry, the risk of injury can be reduced.
Fortschritte der Medizin 03/1997; 115(5):26-8, 30-1.
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Biomedizinische Technik 02/1997; 42 Suppl:359-60. · 0.86 Impact Factor
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Biomedizinische Technik 02/1997; 42 Suppl:15-6. · 0.86 Impact Factor
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Biomedizinische Technik 02/1997; 42 Suppl:283-4. · 0.86 Impact Factor
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Biomedizinische Technik 02/1997; 42 Suppl:13-4. · 0.86 Impact Factor
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Biomedizinische Technik 02/1997; 42 Suppl:279-80. · 0.86 Impact Factor
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Biomedizinische Technik 02/1997; 42 Suppl:1-2. · 0.86 Impact Factor
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ABSTRACT: In an in vitro study of the sheep's meniscus, the possibilities to reduce the thermal tissue necrosis caused by high-frequency electrosurgery of the meniscus were studied. Under standardized conditions, machine-made sections through the meniscus were cut using electrodes of various thicknesses and different settings of the electric generator. The thermal tissue necrosis near the cut through the meniscus was determined using light microscopy and image analysis on the specimen stained according to Masson-Goldner. With a constant voltage of 250 V tissue necrosis was significantly less for electrodes of a diameter of 0.5 mm than for 1.5-mm electrodes (187.3 microns as compared with 368.0 microns). For electrosections carried out using a commercially available electrode with a low voltage of 250 V as well as with a power-controlled generator, tissue necrosis was also significantly less than with a constant high voltage of 395 V (181.4 microns and 210.2 microns as compared with 325.0 microns). Thus, an effective reduction of thermal tissue necrosis in arthroscopic partial meniscectomy is possible when thin electrodes and power-controlled generators are used.
Knee Surgery Sports Traumatology Arthroscopy 02/1997; 5(3):184-8. · 2.21 Impact Factor
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ABSTRACT: Complications associated with spinal metastases encompass not only pain, but often neurological deficits and possibly even paralysis due to transverse lesions. The differential indication for dorsal, ventral and combined surgical procedures depends on the nature and extent of the tumor, and the life expectancy and general state of health of the patient. Surgery must be carried out in good time, before additional damage to the spinal cord occurs. In recent years, 20 patients have been treated by GHG-vertebral body replacement. In 19 of these patients, pain was considerably improved. All patients were able to walk following surgery. Preoperative neurological deficits disappeared, in 9 of 13 patients resulting in a major improvement in the patients' quality of life.
Fortschritte der Medizin 12/1995; 113(31):437-40.
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Rontgenpraxis 09/1995; 48(8):217-22.
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Fortschritte der Medizin 08/1995; 113(20-21):310.
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ABSTRACT: The risks associated with homologous blood transfusion necessitates the development of strategies for reducing the need for it. The most effective method is certainly preoperative donation of autologous blood, which leads to an increase in the absolute numbers of erythr789789 by the time surgery is performed. Depending on the type of preparation and storage, erythrocytes may be viable for between 49 days (liquid storage) and many years (deep frozen). By employing preoperative plasmapheresis, high-quality autologous fresh frozen plasma can be made available for use during surgery. Donation of autologous blood and plasmapheresis are preoperative measures that need to be organized. Another possibility is the use of a cell separator to recycle blood lost during surgery, and may be applied intra-operatively (aspiration from the surgical wound) or postoperative (drainage). Hemodilution has but little effect in reducing homologous blood requirements. Instead of the technically complex and time-consuming acute normovolemic hemodilution (ANH), the simpler hypervolemic alternative version (HHD) should be employed. Applying all the measures described above, an appreciable reduction in the need for homologous blood can be achieved. A prerequisite, however, is close cooperation between the surgeon an anaesthesiologist.
Fortschritte der Medizin 11/1994; 112(29):401-4.
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ABSTRACT: Advantages and disadvantages of various fixation procedures for use in fractures of the femoral neck--blade-plate with temporary fixation by means of Kirschner wire insertion or dynamic hip screws--and hemi- or total allo-arthroplasty are described. The large number of fixation procedures for pertrochanteric fractures reflects the difficulty in achieving mobility and loading stability. On account of the possible intra- and postoperative complications, the highly propagated gamma nailing has proved problematic. Overall, the individual situation of the patient must be taken into account when choosing the appropriate fixation procedure.
Fortschritte der Medizin 06/1994; 112(15):218-20.
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ABSTRACT: Cemented cups in the young patient continue to show an unacceptable rate of early aseptic loosening. A well designed cementless prosthesis, implanted with good technique, is a better alternative. With the uncertainty surrounding the femoral stem, a hybrid total hip with a cemented stem and porous ingrowth cup remains an acceptable interim solution. There is an ongoing problem with the wear debris produced by the available implant materials. There is hope that the newer materials will help in this regard. Custom made prostheses at this time, seem most suited for those hips with marked deformity making the use of standard systems difficult. The use of cement in the elderly population remains an acceptable technique with the advantages of immediate fixation and early weight bearing.
Acta chirurgiae orthopaedicae et traumatologiae Cechoslovaca 02/1994; 61(2):103-8. · 1.63 Impact Factor
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ABSTRACT: We show two case reports to discuss the problem of fatigue fractures of non-cemented porous coated total hip prosthesis. Fatigue fractures occur in the region of highest tensile stresses. Because of the surface irregularities of the porous coating, tensile stresses in the surface of the stems are increased depending on the configuration of the pore. A thick porous coating also decreases the cross section of the stem. In addition the manufacturing process, the application of a porous layer can weaken the stem. Finally, cementless prostheses are implanted especially in young active patients, who exert high forces on their hip. For cementless porous coated hip prostheses, we need a standardized manufacturing process and test of the fatigue strength. In addition, there should be a minimum diameter of the core of the stem in order to avoid fatigue fractures. Key words: porous coated total hip prosthesis, fatigue fracture of the stem.
Acta chirurgiae orthopaedicae et traumatologiae Cechoslovaca 01/1994; 61(3):188-91. · 1.63 Impact Factor
