[Incidence and causes of malalignment following tibial intramedullary nailing]. / Häufigkeit und Ursachen von Fehlstellungen nach Unterschenkelmarknagelungen.

After intramedullary nailing of the tibia a malpositioning is frequently seen. Incidence and cause are discussed controversially. We evaluated 386 postoperative radiographs after intramedullary nailing of the tibia. Type and location of the fracture, site of nail-insertion and postoperative axis-deviation were evaluated. Correlation-tests performed for these parameters proved significant correlation only between malpositioning in recurvation and height of nail-insertion at the tibial tuberosity. Especially proximal fractures of the tibia tended to this misplacement. Other assumed correlations could not be statistically confirmed in this retrospective analysis.

[Significance of shape differences between medial and lateral knee joint menisci for functional change of position]. / Zur Bedeutung von Formunterschieden zwischen medialem und lateralem Kniegelenkmeniskus für funktionelle Lageveränderungen.

The attachments of the anterior and posterior horn of the menisci to the tibial plateau are of a most important functional value. At the medial meniscus the circumference is more widely configurated, because of the greater distance between anterior and posterior horns. The areas of sagittal cuts through the menisci slightly differ regarding medial and lateral side. A higher area momentum of inertia of the medial meniscus, related to a vertical axis within the examinated sagittal plane, is found. It derives from a geometrical distribution of partial areas more distant from the axis. The medial meniscus therefore has a higher stiffness against sagittal bending stress. Experiments and theoretical stress simulation prove these results. According to them, the medial meniscus is less mobile in comparison to the lateral. These findings are discussed as a basic geometrical cause for the higher incidence of injuries of the medial meniscus.

[Tension band wiring osteosynthesis--studies on tension and fixation of the osteosynthesis wire]. / Die Drahtzuggurtungsosteosynthese--Untersuchungen zu Spannung und Fixierung des Osteosynthesedrahtes.

In tension band wiring different tensioners and wire-connections are in use. Both of these were examined on tensile force during and after connection with help of a material-testing machine. Additionally the different connections were examined under traction-load. The results show that none of the tensioners for monofilament wire are capable of establishing a permanent tension at the end of the fixation-procedure. Consequently we must ask if the theoretical principle of B. G. Weber concerning tension band wiring is efficient in practice. Only the use of twisted wires in combination with fixation clamps could produce a permanent tension. The limit of elasticity is 2 to 3% for monofilament wires as well as for twisted wires. Further stretching causes plastic, i.e. irreversible deformation in monofilament wire and its connections. In twisted wires further tension stress causes ruptures especially at the border of the fixation clamp. In conclusion extreme active exercise of fractures treated with tension band wiring should not be emphasized.

[Experimental determination of sliding friction during insertion of femoral intramedullary nails]. / Experimentelle Bestimmung der Gleitreibungskräfte beim Einschlagen von Oberschenkelmarknägeln.

No data have published concerning the procedure of driving in intramedullary nails. An extensive experimental device consisting of a contact-free distance measurement, a dynamograph connected to strain gages and an accelerometer now enabled this investigation. Among other things we determined the range of sliding friction for each stroke at different levels of nail-progression. Depending of the depth of nail-progression forces between 200 N und 400 N were measured. When the nail is stuck these values rise to over 1000 N. The sliding-process lasted between 10 ms and 20 ms. Knowledge of these data is of major importance for improvement of surgical technique and possible development of mechanical nail-insertion aids.

[Detection and effects of bone marrow intravasations in operations in the area of the femoral marrow cavity]. / Nachweis und Effekte von Knochenmarkeinschwemmungen bei Operationen im Bereich der Femurmarkhöhle.

In recent years, during total hip replacement and intramedullary nailing large sonographic echoes some centimeters in length have been observed on transesophageal echocardiography of the right heart. The echoes have always appeared after rise in pressure in the femoral cavity. The substrate of the echoes was not known. We could not imagine that particles of bone marrow of the size observed were passing through the vessels of the femur, but on the other hand there was no other suitable explanation. For clarification of the substrate of the sonographic echoes an animal study was performed in sheep. After the application of a known pressure on the femoral cavity the distal vena cava was investigated sonographically through a laparotomy; proximally blood was taken from the vein. The study identified the large sonographic echoes as "mixed emboli" consisting of a core of bone marrow and surrounding apposition of thrombotic material. The observations explain the frequent observations of pulmonary impairment after elevation of the intrafemoral pressure. It seems possible that the intravasation of bone marrow is involved in the pathogenesis of thrombosis after orthopedic surgery.

[Managing pathologic femoral fractures in malignant bone tumors and skeletal metastases]. / Versorgung pathologischer Femurfrakturen bei malignen Knochentumoren und Skeletmetastasen.

In adults pathological fractures of the femur are mostly caused by skeletal metastases. In our own collective of femoral fractures 58 were caused by skeletal metastases and five by multiple myeloma. Average age was 59.8 years, women prevailed. In most of the metastatic fractures breast cancer was found to be the primary tumour. In all cases fracture stabilization as a palliative measure was the only possible therapy. Two patients could not be operated on because of other vital problems. In femoral neck fractures resection and endoprosthesis was the operative measure of choice. The pertrochanteric and subtrochanteric fractures were mostly treated by composites of cement and the 95 degrees condylar-plate. Also in shaft fractures cement-implant composites were performed with straight plates. Rarely, intramedullary nailing was done. Exercising stability could always be achieved, weight-bearing stability in most of the cases. The mean survival time was 7.2 months regarding 43 patients with well documented course. Six patients are controlled regularly, the operative treatment was done on an average 16 months before.

[Electromanometric studies of the sphincter zone using unperfused probes on children with a healthy anus]. / Elektromanometrische Untersuchungen der Sphinkterzone mit nicht perfundierten Sonden an analgesunden Kindern.

With regard to the measuring technique with unperfused water-filled tubes, many authors report different standards concerning the anorectal pressure zone. In order to define standards, 133 infants with healthy anorectal sphincter from 1 to 12 years of age were examined by this method. As a result, it must be stated that this method cannot reproduce standards. For this reason, very thin perfused tubes with very low rates of perfusion should be used to obtain at least the anorectal pressure profile. The reasons for the poor results achieved with this method, due to the measuring technique, are demonstrated.