PURPOSE OF THE STUDY: The purpose of this report was to study the repercussions of rotator cuff condition on unconstrained shoulder arthroplasty results. METHODS: Between 1986 and 1993, 40 unconstrained shoulder prostheses were performed (24 total and 16 hemiarthroplasties). At the time of the operation, rotator cuff condition was reported to be normal in 15 shoulders, atrophic in 10, scarred in 3, torn in 12. Clinical and radiographical results were analyzed and supplemented with a rotator cuff echography. Postoperative follow-up averaged 42.25 months (12 to 97 months). RESULTS: When the rotator cuff was intact at the time of operation, clinical results were the best at the time of review. Constant score, overall mobility, forward elevation, external rotation with the elbow along the side were better for intact than for atrophic, scarred or torn rotator cuffs (p < 0.01). Ruptures repaired by local tissue transfer or trapezo deltoidal flap substitution (3 cases) gave satisfactory results, whereas two dacron cuff prostheses failed. In the non repaired ruptures (7 cases), arthroplasty resulted in 3/4 fair or poor results. At the time of review, the total incidence of postoperative rotator cuff tears was high (12 cases), functional repercussions were variable. Among the 15 rotator cuff tears observed at the time of the review, the long head of the biceps was present and in place in 9 cases and ruptured in 6 cases. In these latter cases, Constant score (p < 0.01), the forward elevation (p < 0.01), external rotation with elbow along side (p < 0.05) and overall mobility (p < 0.05) were worse; moreover, humeral head superior migration was greater (p < 0.01). DISCUSSION: Our study confirms the superiority of clinical results when the cuff was intact at the time of the operation. The repair of rotator cuff tears seems to be justified. When the rupture has not been repaired, clinical results were fair or poor in 5 cases out of 7, the initial rupture spread to the other tendons in 3 cases out of 7. Secondary ruptures were frequent (12 cases). No predictive factor was identified, but an overlapping of the greater tuberosity appears to be detrimental. Among rotator cuff tears present at the time of review, long head of the biceps rupture jeopardized clinical results and was associated with a proximal migration of the humeral head which was significantly more severe than with an intact non displaced long head of the biceps. CONCLUSION: During unconstrained shoulder prosthesis implantation, it is therefore recommend to systematically repair any associated rotator cuff rupture, in order to avoid any greater tuberosity overlap relative to the prosthetic head and to preserve the long head of the biceps tendon which limits upward migration of the humeral head and improves prosthetic kinetics. 相似文献
This paper presents an efficient method which provides the optimal generation mix and the optimal generation construction process. The approximation method in which the dynamic programming technique and gradient method are combined is applied to determine the optimal generation mix with hydropower generation technologies. The successive approximations dynamic programming (SADP) technique, which is very suitable for high-dimensional multistage decision process problems, is used for obtaining the optimal generation construction process. The effectiveness and feasibility of the developed technique are demonstrated on a practical power system model which has five types of generation technologies including a hydropower generation technology. 相似文献
The electrode characteristics of perovskite-type oxides, La0.6Sr0.4CoO3 and La0.6Sr0.4MnO3, on ceria-based oxide and stabilized zirconia were analysed by the a.c. impedance method. The ionic conductivities of the electrolyte and electrode conductivities from the a.c. impedance analysis agreed with those obtained from the current interruption and d.c. four-probe methods. Two semicircles from the charge transfer and diffusion processes appeared as the electrode resistance. The relative contribution of these two processes to the overall electrode resistance strongly depended on the microstructure of the electrode. The electrode microstructure could be controlled by the dispersion medium used for the electrode slurry. The La0.6Sr0.4MnO3 electrode coated with n-butyl acetate slurry exhibited the smallest electrode resistance. 相似文献
Using regression analyses between the properties of coals and the strengths of their cokes several significant correlations are derived, which are useful to evaluate coals in the making of metallurgical coke. Slight but significant modification was necessary for their application to coal blends. For example, plasticities of the coal blends required a different equation from that derived for the single coals. The region of high coke-strength in the diagram of volatile matter vs. total dilatation was expanded considerably towards coals of lower caking properties by blending of coals, suggesting that the blending may serve to increase the coking properties of component coals. The coke strength, especially after the gasification was found to increase with the increasing inert maceral content in the parent coals up to 30 wt %. The high level of strength was maintained even above 35 wt % of inert content. 相似文献
In this paper, we propose a new video conferencing system that presents correct gaze directions of a remote user by switching among images obtained from multiple cameras embedded in a screen according to a local user’s position. Our proposed method reproduces a situation like that in which the remote user is in the same space as the local user. The position of the remote user to be displayed on the screen is determined so that the positional relationship between the users is reproduced. The system selects one of the embedded cameras whose viewing direction towards the remote user is the closest to the local user’s viewing direction to the remote user’s image on the screen. As a result of quantitative evaluation, we confirmed that, in comparison with the case using a single camera, the accuracy of gaze estimation was improved by switching among the cameras according to the position of the local user.
The importance of grain size refinement in enabling superplasticity is reviewed, and the current understanding of grain boundary
characteristics is summarized. The application of orientation-imaging microscopy (OIM) methods to the processing response
and the deformation and failure modes in superplastic aluminum alloys are illustrated through microtexture analysis and determination
of grain boundary characteristics in selected commercial materials. Continuous and discontinuous recrystallization reactions
exhibit distinct microtextures and grain boundary characteristics. The application of OIM and microtexture analysis to the
evaluation of both deformation and failure mechanisms during superplastic forming is illustrated.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
This paper deals with the fracture toughness and R-curve behavior of ceramic-metal functionally graded materials (FGMs). A possibility of stable crack growth in a three-point-bending specimen is examined based on the driving force and resistance for crack growth in FGMs, and the distribution of fracture toughness or R-curve behavior is evaluated on FGMs fabricated by powder metallurgy using partially stabilized zirconia (PSZ) and stainless steel (SUS 304). The materials have a functionally graded surface layer (FGM layer) with a thickness of 1 mm or 2 mm on a SUS 304 substrate. Three-point-bending tests are carried out on a rectangular specimen with a very short crack in the ceramics surface. On the three-point-bending test, a crack is initiated from a short pre-crack in unstable manner, and then it propagates in stable manner through the FGM layer with an increase in the applied load. From the relationship between applied load and crack length during the stable crack growth in the FGM layer, the fracture toughness is evaluated. The fracture toughness increases with an increase in a volume fraction of SUS 304 phase. 相似文献