21 research outputs found

    Functional results of hemi- and total shoulder arthroplasty according to diagnosis and patient age at surgery

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    <p>Background and purpose — There is a lack of information on any associations between the functional outcome and age and diagnosis in patients who have undergone shoulder arthroplasty. We therefore evaluated the functional outcome in “young” and “old” patients treated with either hemiarthroplasty (HA) or total shoulder arthroplasty (TSA) with diverse diagnoses.</p> <p>Patients and methods — The functional results of 496 primary shoulder arthroplasties were analyzed using the Constant score (age- and sex-adjusted) and subjective satisfaction. Patients ≤55 years of age at surgery were defined as “young. Diagnoses were primary osteoarthritis (n = 339), posttraumatic osteoarthritis (n = 78), cuff tear arthropathy (n = 36), avascular necrosis (n = 30), and rheumatoid arthritis (n = 13). Mean length of follow-up was 4 (2–14) years.</p> <p>Results — 70% of the TSA patients were very satisfied with the postoperative result, as compared to 39% after HA. The Constant score and patient satisfaction were similar in the “young” and “old” groups. Pain relief was better in the “old” group. The mean improvement in the Constant score after cuff tear arthropathy (22 points) was inferior to that for primary osteoarthritis (36 points), avascular necrosis (34 points), and rheumatoid arthritis (37 points). Inferior mean Constant scores were also seen for posttraumatic osteoarthritis (29 points) compared to primary osteoarthritis (36 points). 63% of patients with primary osteoarthritis were very satisfied, as compared to only 36% of the patients with posttraumatic osteoarthritis.</p> <p>Interpretation — Shoulder arthroplasty is successful in the medium term for different glenohumeral diseases, irrespective of patient age at surgery. However, the appropriate treatment method for cuff tear and posttraumatic conditions of the shoulder remains to be found, particularly in young patients.</p

    Tuning of the ‘Constant in gain Lead in phase’ Element for Mass-like Systems

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    The development of the high-tech industry has pushed the requirements of motion applications to extremes regarding precision, speed and robustness. A clear example is given by the wafer and reticle stages that require rigorous demands like robust nanometer precision and high-speed motion profiles to ensure product quality and production efficiency. Industrial workhorse Proportional Integral Derivative (PID) has been widely used for its simple implementation and good performance. However, PID is insufficient to meet the ever-increasing demands in the high-tech industry due to its inherent constraints of linear controllers such as the waterbed effect. To overcome these fundamental limitations, researchers have turned to nonlinear controllers. Nevertheless, most of the nonlinear controllers are difficult to design and implement and thus are not widely accepted in the industry. Reset control is anonlinear controller that is easy to implement and design since it maintains compatibility with the PID loop shaping technique using a pseudo-linear analysis tool named describing function method. However, the reset control as a nonlinear controller also introduces high order harmonics to the system that can negatively affect system performance by causing unwanted dynamics. Hence, describing function analysis as a linear approximation approach that only considers first harmonics is not accurate enough. Recently, a theory to analyze high order harmonics of nonlinear system in frequency domain termed higher order sinusoidal describing function has been developed, which enables the possibility to perform more precise analysis on reset systems. The majority of research on reset control has focused on the phase lag reduction but a novel reset element proposed in literature termed ”Constant in gain, Lead in phase” (CgLp) is used to provide broadband phase compensation and has been shown to improve system performance. However, there is no systematic designing and tuning approach in literature such that the full advantage of CgLp elements is extracted. This work focuses on the tuning of the CgLp elements in order to obtain optimal performance. High order harmonics are also considered in the tuning analysis since they are critical to system performance due to the effect of unwanted dynamics. When a group of CgLp elements are designed to provide pre-determined phase compensation at the crossover frequency, it is seen that the optimal tracking precision performance is always obtained with the case that has the highest frequency of third order harmonic peak and has almost the smallest magnitude of high order harmonics at low frequencies. Moreover,the second order CgLp controllers are observed to outperform the first order CgLp controller regarding tracking precision. On the other hand, configurations that have the lowest magnitude of third order harmonic at high frequency are found to have the best noise attenuation performance.Mechanical Engineering | Mechatronic System Design (MSD

    Assessment of renal function in routine care of people living with HIV on ART in a resource-limited setting in urban Zambia

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    <div><p>Introduction</p><p>Data on renal impairment in sub-Saharan Africa (SSA) remains scarce, determination of renal function is not part of routine assessments. We evaluated renal function and blood pressure in a cohort of people living with HIV (PLWH) on antiretroviral treatment (ART) in the Renal Care Zambia project (ReCaZa).</p><p>Methods</p><p>Using routine data from an HIV outpatient clinic from 2011–2013, we retrospectively estimated the glomerular filtration rate (eGFR, CKD-Epi formula) of PLWH on ART in Lusaka, Zambia. Data were included if adults had had at least one serum creatinine recorded and had been on ART for a minimum of three months. We investigated the differences in eGFR between ART subgroups with and without tenofovir disproxil fumarate (TDF), and applied multivariable linear models to associate ART and eGFR, adjusted for eGFR before ART initiation.</p><p>Results and discussion</p><p>Among 1118 PLWH (63,3% female, mean age 41.8 years, 83% ever on TDF; median duration 1461 [range 98 to 4342] days) on ART, 28.3% had an eGFR <90 ml/min, and 5.5% <60 ml/min at their last measurement. Information on other conditions associated with renal impairment was not systematically documented. Fourteen per cent of the PLWH who later switched to TDF-free ART had an initial eGFR lower 60ml/min. Nineteen percent had first-time hypertensive readings at their last visit. The multivariable models suggest that physicians acted according to guidelines and replaced TDF-containing ART if patients developed moderate/severe renal impairment.</p><p>Conclusions</p><p>Assessment of renal function in SSA remains a challenge. The vast majority of PLWH benefit from long-term ART, including improved renal function. However, approximately 5% of PLWH on ART may have clinically relevant decreased eGFR, and 27% hypertension. While a routine renal assessment might not be feasible, strategies to identify patients at risk are warranted. Targeted monitoring prior and during ART is recommended, however, should not delay ART access.</p></div
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