A comparison of plates with and without locking screws in a calcaneal fracture model

BACKGROUND: We compared different plates in an experimental calcaneal fracture model under biocompatible loading. METHODS: Four plates were tested: a plate without locked screws (Synthes), and three different plates with locked screws (Newdeal, Darco, Synthes). Synthetic calcanei (Sawbone) were osteotomized to create a fracture model, and the plates were fixed onto them. Seven specimens for each plate model were subjected to cyclic loading (preload 20 N, 1,000 cycles with 800 N, 0.75 mm/s), and load to failure (0.75 mm/s). Motion, forces, plastic deformation of the plate, and consequent depression of the posterior joint facet were analyzed. RESULTS: During cyclic loading, all plates with locked screws showed statistically significant lower displacement in the primary loading direction than the plates without locked screws. Mean values (mm) of maximal displacements for each plate during cyclic loading were as follows: Synthes, 3.5; Darco, 4.5; Newdeal, 5.0; Synthes without locked screws, 7.5; (p < 0.001). No statistically significant differences between the plates were found in relation to loads to failure and corresponding displacement. CONCLUSION: This is the first biomechanical study to assess the stability of different plates currently in use in our practice for the fixation of calcaneal fractures. Our results showed that plates with locked screws provided greater stability during cyclic loading than the plate without locked screws.     

Diffuse endometritis in the setting of umbilical endometriosis: a case report

BACKGROUND: Umbilical endometriosis is rare and can be a challenging diagnosis in the absence of classic signs and symptoms. CASE: A case of severe, primary, spontaneous umbilical endometriosis with foci of plasma cell endometritis and diffuse stromal lymphovascular presence occurred. CONCLUSION: Despite a lengthy differential, endometriosis must be considered in the evaluation of an umbilical mass. The presence of plasma cell endometritis and stromal lymphovascular elements in the absence of pelvic endometriosis lends evidence to the theory of lymphovascular transport as an etiology of extrapelvic endometriosis.     

The role of cartilage canals in endochondral and perichondral bone formation: are there similarities between these two processes?

We investigated the development of cartilage canals to clarify their function in the process of bone formation. Cartilage canals are tubes containing vessels that are found in the hyaline cartilage prior to the formation of a secondary ossification centre (SOC). Their exact role is still controversial and it is unclear whether they contribute to endochondral bone formation when an SOC appears. We examined the cartilage canals of the chicken femur in different developmental stages (E20, D2, 5, 7, 8, 10 and 13). To obtain a detailed picture of the cellular and molecular events within and around the canals the femur was investigated by means of three-dimensional reconstruction, light microscopy, electron microscopy, histochemistry and immunohistochemistry [vascular endothelial growth factor (VEGF), type I and II collagen]. An SOC was visible for the first time on the last embryonic day (E20). Cartilage canals were an extension of the vascularized perichondrium and its mesenchymal stem cell layers into the hyaline cartilage. The canals formed a complex network within the epiphysis and some of them penetrated into the SOC were they ended blind. The growth of the canals into the SOC was promoted by VEGF. As the development progressed the SOC increased in size and adjacent canals were incorporated into it. The canals contained chondroclasts, which opened the lacunae of hypertrophic chondrocytes, and this was followed by invasion of mesenchymal cells into the empty lacunae and formation of an osteoid layer. In older stages this layer mineralized and increased in thickness by addition of further cells. Outside the SOC cartilage canals are surrounded by osteoid, which is formed by the process of perichondral bone formation. We conclude that cartilage canals contribute to both perichondral and endochondral bone formation and that osteoblasts have the same origin in both processes.     

Beitrag zur Technik der Registrierung bioelektrischer Potentiale mit der Braunschen Röhre

Zusammenfassung Unter besonderer Berücksichtigung ihrer Eignung für die Bedürfnisse der elektrobiologischen Forschung werden die Wechselstrom-(RC-) und die Gleichstrom-(R-)Verstärkerschaltungen verglichen. RC-Verstärker sind den R-Verstärkern in praktischer Beziehung weit überlegen, in ihren elektrischen Leistungen in wenigen, im Spezialfalle allerdings entscheidenden Punkten, unterlegen. Unter diesen Umständen war daher bisher die Verwendung R-gekoppelter Verstärker auf die Aktionsstromforschung beschränkt.Durch die Entwicklung geeigneter Spannungsregler und Verstärkerschaltungen gelingt es, dem R-Verstärker die Gebrauchseigenschaften eines einfachen Meßinstruments zu geben und ihn damit gleichzeitig praktisch vielseitiger zu machen. Ein derartiger Regler und Verstärker werden nach eingehender Erprobung beschrieben.     

Zur Casuistik der Heterotaxien

Ohne Zusammenfassung Das betreffende Pr?parat wurde am 9. Juli d. J. in der Berliner medicinischen Gesellschaft demonstrirt.     

Warum ist die Ansicht vom amerikanischen Ursprung der Syphilis jetzt die vorherrschende?

Ohne ZusammenfassungNach einem in der Abteilung für Geschichte der Medizin der 81. Versammlung deutscher Naturforscher und Ärzte in Salzburg am 22. Sept. 1909 gehaltenen Vortrag.     

Ein Beitrag zur Kenntnis der Entstehung der Arzneiausschläge

Ohne Zusammenfassung