Total Adduction Research Articles

Luxatio erecta bilateral: um relato de caso

O deslocamento inferior do ombro (luxatio erecta) é uma lesão rara, acometendo aproximadamente 0,5% dos deslocamentos dessa articulação. A grande maioria desses casos ocorre unilateralmente. Em setembro de 2004, um homem de 43 anos chegou ao pronto-socorro do Hospital Universitário de Santa Maria (HUSM) com queixa de dor bilateral no ombro e incapacidade de abaixar os braços, em consequência de uma queda com os braços abduzidos, enquanto desempenhava sua atividade laboral. Após o exame físico e radiológico constatou- se que o indivíduo apresentava uma luxação inferior bilateral dos ombros. O paciente foi então encaminhado ao bloco cirúrgico onde foi realizada redução incruenta das luxações sob anestesia através da técnica de tração e contra-tração. No dia seguinte recebeu alta com imobilização tipo Velpeau mantendo os ombros totalmente aduzidos e rotados internamente, com orientação de manter a imobilização por três semanas. Foi orientado também a realizar fisioterapia.

The Effect of Valgus Bracing and Lateral Wedge Orthotics on Intra-articular Knee Loads During Gait

PURPOSE: Tibiofemoral load in the medial compartment of the knee is determined mainly by the ground reaction force and the resulting external adduction moment. Applying an abduction moment about the knee with valgus bracing may shift tibiofemoral load from the medial compartment to the lateral compartment by reducing varus malalignment and/or by applying an abduction moment to resist the external adduction moment. Alternatively, shifting the COP laterally under the foot with lateral wedge orthotics may reduce the resultant GRF moment arm about the knee, and thereby reduce the external adduction moment. Most in vivo studies show a positive correlation between these conservative approaches to medial compartment OA, pain relief, and a reduced adductor moment. METHODS: A computer model of the knee and the lower limb was used to calculate the reduction of medial tibiofemoral joint load that might be achieved by using a valgus moment knee brace. The analysis was performed for the instant of opposite toe off, when peak medial compartment load occurs during normal gait. Medial compartment load was calculated as the abduction moment applied by a simulated valgus brace was increased in 1 Nm increments, starting from the value for normal walking. To evaluate the affects of lateral wedges, a separate analysis was performed in which the COP under the foot was shifted laterally in increments of 1 mm. RESULTS: A 3 Nm brace abduction moment at the knee reduced the total adduction moment at the knee by 8% and the peak medial compartment load by 3%. Medial compartment load decreased as a linear function of the abduction moment applied by the brace. Valgus angle decreased by less than 1o when a 3 Nm abduction moment was applied to the knee. Medial compartment load was reduced mainly by the decrease in the external adduction moment, and not by a change in the varus alignment of the leg. A 3 mm lateral shift in COP reduced the total knee adduction moment by 5% and the peak medial compartment load by 2%. Medial compartment load decreased linearly with lateral displacement of the COP. CONCLUSIONS: Our results help to explain the reduction in knee pain obtained with valgus bracing and foot orthoses, and provide quantitative estimates of the reduction in medial compartment load during gait, estimates that cannot be obtained from an inverse dynamics analysis alone.

Anatomic study of femoral vein occlusion during simulated hip arthroplasty

An anatomic study was undertaken to establish whether positioning of the leg and surgical approaches for total hip replacement (THR) cause changes in the femoral v. which may contribute to the development of deep vein thrombosis (DVT). The patency of 32 femoral vv. of 18 cadavers was inspected at different levels during simulated THR. Before and after removal of the femoral head through a transgluteal or posterior approach, a wide-angle endoscope was inserted into the femoral v. via the external iliac v. Blood flow was simulated by proximal irrigation with saline through the popliteal v. After removal of the femoral head distinct changes were observed in both approaches. In the transgluteal approach the changes were dependent on the degree of adduction and the body build of the cadaver. Initially, an oval form was seen in a constricted lumen with an increasingly oblique oval deformation and a final facet-like closure, usually at about 5 to 7.5 cm below the inguinal ligament. In total adduction this stenosis occurred regardless of build. Using a posterior approach, the necessary internal rotation caused a closure of the vein in 50% of cases. In combination with flexion and adduction there was stenosis in all cadavers regardless of body build. Our results indicate that the duration of the adducted position of the thigh during THR via a transgluteal approach should be minimised, as there is a reduction in blood flow with even minor degrees of adduction. In the posterior approach the stenosis occurs earlier, and is independent of the build of the cadaver.

Nucleosome structure modulates benzo[a]pyrenediol epoxide adduct formation.

We have studied the binding of a chemical carcinogen to DNA reconstituted with histone octamers to determine the effect that nucleosome structure has on covalent adduct formation. Reconstitution of a plasmid containing the somatic 5S rRNA gene from Xenopus borealis resulted in characteristic nucleosome structure, as determined by micrococcal nuclease digestion, shifted migration in agarose gels, and hydroxyl radical footprinting. Formation of covalent adducts by benzo[a]pyrenediol epoxide (BPDE) occurred initially at a slower rate in reconstituted DNA than in naked plasmid, but after 2 h the total adduction levels (adducts/plasmid) were equal in both samples. Analysis of adduction at the sequence level by primer extension indicated that, after a 2-h BPDE reaction, the degree of adduction within the 5S rRNA nucleosome was suppressed by approximately 50% compared to naked DNA. The rotational setting of the guanines on the helix did not explain the level of adduction observed, since guanines in close proximity to the histone core were equally susceptible to adduction as guanines on the outer nucleosome surface. At early reaction times with BPDE, however, sequences near the 5S nucleosome dyad, where known modulations in the minor groove width occur, were the least susceptible to adduction. These results indicate that the structural features of DNA assembled into nucleosomes contribute to the susceptibility of the DNA to modification by BPDE.

32P-postlabeling analysis of DNA adduction in mice by synthetic metabolites of the environmental carcinogen, 7H-dibenzo[c,g]carbazole: chromatographic evidence for 3-hydroxy-7H-dibenzo[c,g]carbazole being a proximate genotoxicant in liver but not skin.

The DNA adduction by the environmental carcinogen 7H-dibenzo[c,g]carbazole (DBC) and chemically synthesized 2-OH, 3-OH, and 4-OH metabolites of DBC was investigated in liver and skin of female CD-1 mice. After topical application to the skin of 37 mumol/kg of DBC or the phenolic metabolites, DNA adducts were measured by a 32P-post-labeling assay employing carrier-free [gamma-32P]ATP and ATP-deficient conditions. In liver, DBC produced four major and several minor chromatographically distinct adducts of as yet undetermined chemical structure. The adduct pattern elicited by 3-OH-DBC was qualitatively similar to the DBC adduct pattern, while this was not the case for 2-OH-DBC and 4-OH-DBC. On the basis of co-chromatography experiments under various conditions, the DBC and 3-OH-DBC adducts appeared identical, and the total of adduction elicited by these compounds in liver was substantial. Similar results were observed when DBC or 3-OH-DBC were administered i.p. As a major difference between the two compounds, one 3-OH-DBC adduct (no. 3) was 4.4- and 7.0-fold lower than the corresponding DBC adduct after i.p. and topical dosing, respectively. In skin, DBC produced two major adduct fractions after topical application, one of which could be chromatographically resolved into three subcomponents. Prominent adducts produced in skin DNA by each of the three metabolites were different from those elicited by DBC, and the level of adduction by the metabolites was significantly lower than that by DBC. Comparison of the skin and liver DBC-DNA adduct patterns after topical application of DBC showed that only one of the four major chromatographically resolved skin adducts corresponded to a major liver adduct (no. 3), and that total adduction in liver was 13.5-fold higher than in skin. These results suggested that activation of DBC to DNA-binding compounds in liver occurs through at least two pathways with 3-OH-DBC being a proximate carcinogen involved in the formation of most of the adducts; 3-OH-DBC and the other two phenolic metabolites investigated play a minor role, if any, in the formation of DBC-DNA adducts in skin; metabolic activation of DBC to DNA-binding compounds in liver and skin appears to follow pathways that are different in terms of both the chemical nature and the amount of the adducts formed; and DBC and 3-OH-DBC exhibit a strong preference for liver versus skin DNA.

N-methylation reduces the DNA-binding activity of 7H-dibenzo[c,g]carbazole approximately 300-fold in mouse liver but only approximately 2-fold in skin: possible correlation with carcinogenic activity.

N-methyl-dibenzo[c,g]carbazole (MeDBC) lacks the potent hepatocarcinogenic activity in mice characteristic for 7H-dibenzo[c,g]carbazole (DBC), while both compounds are local carcinogens, leading to papilloma and carcinoma formation in skin after topical application. Because DNA binding is considered an essential step in the initiation of chemical carcinogenesis, the DNA adduction by MeDBC was compared with that by DBC in mouse liver and skin via a 32P-postlabeling technique. Both compounds elicited chromatographically similar adducts in liver; however, the extent of total DNA binding of DBC was 343- and 265-fold greater than that of MeDBC 24 h after topical and i.p. administration, respectively, of a 37 mumol/kg dose. In skin, the adduct pattern elicited by either compound after topical application was different from that seen in liver, and three of four adducts derived from MeDBC were chromatographically distinct from those produced by DBC. Quantitative analysis revealed that total adduction in skin by DBC was 2.3-fold higher than by MeDBC. When the adduct levels were compared between liver and skin, topically applied MeDBC bound preferentially to skin versus liver DNA by a factor of 10, while the opposite was true for DBC. These data are in agreement with the carcinogenicity reported for DBC and MeDBC and support the hypothesis that the extent of covalent DNA modification by these compounds is associated with their biological activity. We conclude that an unsubstituted nitrogen is essential for the genotoxic activity of DBC in liver but not skin. The results also demonstrate the potential of the 32P-postlabeling assay in predicting the organotropism of closely related carcinogens.