L-shaped caliper for limb length measurement during total hip arthroplasty
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Abstract:
The existing methods of assessing limb lengthening during total hip arthroplasty (THA) are prone to error because the measurements are not parallel to the limb lengthening axis. In order to address this, we designed a caliper to estimate limb lengthening during THA and evaluated its accuracy compared with our previous device, the straight caliper. Limb lengths were measured in 100 patients. The L-shaped caliper was used in 50 cases and the straight caliper in 50. The correlation between intra-operative and post-operative radiographic measurements was significantly improved using the L-shaped device (p < 0.0001, r = 0.934). This method was extremely accurate in predicting changes in limb length due to surgery.Keywords:
Calipers
The linkage arm and single caliper log tools have some disadvantages in higher inclined and horizontal well logging, such as loose contact between arm-pads and borewall, untrue caliper curves, etc. Based on the analyzes of the circuit in 3-arm caliper log tool, proposed is a design scheme of new caliper, namely, an unlinkage 4-arm caliper with 4 independent arms and providing 4 caliper curves that present the true borehole sizes. Data communication adopts PCM mode; the caliper can acquire 4 caliper curves or X-Y curves.
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The JJG30-2002 Verification Regulation of General Calipers,which was put out by state,replaces five traditional verificafion regulations for vernier caliper,dial caliper,digital display caliper and vernier depth gauge.Comparing with the traditional regulations ,it has five provisions changed greatly.This paper discusses the five provisions from their charcterization,reasons for improving and related consequence.
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The modified logging tool with 3arm caliper responds to changes of hole inner diameter by serial potentiometers.On the basis of a mathematics model of this system,simulated are changes of downhole and the varying decentrations by computer programs.Analyses show that caliper measured is less than or equal to the actual value of the well.This measuring method causes negative system(error),which is interrelated with the decentration of 4209XA.Based on analysed result,proposed is a method for reducing the error.The proposed method is able to acquire three caliper signals simulta-(neously.)
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Value (mathematics)
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Caliper logging is mainly used to determine the change of inside diameters of casings , perforating depth and the depth of collars. A new type of multi-arm caliper tool can not only log the maximal inner diameter and the minimal inner diameter of a casing, but also log the minimal inner diameter of casing in different directions, determine more exactly the change of wall thickness, bend, rupture, and cauterization of casing. Based on an 40 arm caliper tool, a qualitative analysis and direct picture processing methods of the multi-arm caliper tool are presented. Compared with other conventional caliper meters, data recorded by the new multi-arm caliper tool are more comprehensive and the imaging effects are also more visible.
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Abstract Craniometric measuremnts from a three‐dimensional (3‐D) digitizing system were compared with those from sliding and spreading calipers. The 3‐D system consisted of a 3‐Space Digitizer, Macintosh Plus computer, and Unigraphics CAD/CAM system. Twenty‐nine standard measurements were made and repeated on two normal and three deformed skulls. The percentage of difference was calculated for original versus repeat measures and caliper versus 3‐D measures. For objective anatomic structures and fiducial points, there was less than 2 mm (maximum) of difference between 1) the original digitizer versus repeat 3‐D measures and 2) caliper versus 3‐D measures. This represented 2% or less measurement incongruence. There were no significant differences for these comparisons (p > 0.1), and all regressions were highly significant (P < 0.001), with r 2 > 0.999. 3‐D measurements were made more easily and quickly than were caliper measurements, with no loss in precision. It is concluded that 3‐D measurements are equivalent in quality to caliper measurements for craniometric studies, but are easier to obtain.
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Fiducial marker
Mean difference
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Caliper inspection for long-distance pipeline is influenced by many factors. Sometimes there is actually no abnormal deformation of pipeline, but the caliper plate has deformation and goffer and it indicates disqualified results. The factors affecting caliper inspection accuracy are analyzed. It was tried that after the hydraulic test finished and in first water scavenging, another caliper inspection was carried out. Thus the caliper plate damage caused by impact owing to pig leather cup abrasion and pig overquick moving could be avoided furthest. The accuracy of caliper inspection for long-distance could be increased and ensured.
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Abrasion (mechanical)
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Purpose The study aimed to determine the precision of different ophthalmic calipers used in our tertiary eye care center. Methods All Castroviejo calipers available in the operating room, minor treatment room, and intravitreal injection clinic were included in the study. All calipers were evaluated at four screening points (1, 5, 10, and 15 mm) on a standard ruler and compared to their expected corresponding readings on the caliper scale. If any caliper showed a discrepancy of ≥0.5 mm at any of the screening points, the caliper underwent further analysis on 10 measurement points. Results Forty-one calipers were evaluated, of which 16 (39%) showed at least one point of ≥0.5 mm discrepancy on the caliper reading scale. Six calipers had errors >0.5 mm and two calipers had measurement errors of 1 mm in at least one point between 1-15-mm ruler measurement points. The majority of calipers (15/16) overestimated lengths. Conclusion Calipers are prone to damage with prolonged use that may affect their precision. Thus, calipers should be calibrated against a standard ruler prior to use even if they look grossly intact. Regular screening of calipers is recommended to identify any discrepancy and prevent avoidable complications.
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Ruler
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Abstract There are several types of sliding calipers, but most are expensive and not capable of measuring large body dimensions such as arm length or knee height in older children and adults. A new sliding caliper from Medi‐form can accurately measure lengths from 0.0 to 80.0 cm. This caliper is slightly more accurate than a Holtain sliding caliper, and its cost is low.
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To investigate the appropriate inclined angles, spacing between caliper and square steel satisfying the requirement of caliper switching mechanism and the appropriate tooth parameters, the relation of inclined angles of caliper and meshing force is analyzed. And the hardness parameters of caliper and square steel are also analyzed. The appropriate tooth parameters are determined based on hardness parameters of caliper and square steel and tooth parameters of caliper.
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Square (algebra)
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