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a: Measurements with the Matlab Method. Cement distribution 1 mm underneath the tibial tray over the 4 quadrants. AL = Antero-Lateral quadrant, AM = Antero-Medial quadrant, PL = Postero-Lateral quadrant, PM = Postero-Medial quadrant. b: Measurements with the Matlab Method. Cement distribution 3 mm underneath the tibial tray over the 4 quadrants. AL = Antero-Lateral quadrant, AM = Antero-Medial quadrant, PL = PosteroLateral quadrant, PM = Postero-Medial quadrant. c: Measurements with the Matlab Method. Cement distribution 5 mm underneath the tibial tray over the 4 quadrants. AL = Antero-Lateral quadrant, AM = Antero-Medial quadrant, PL = Postero-Lateral quadrant, PM = Postero-Medial quadrant
Source publication
Abstract Background To evaluate the reliability of two different techniques for measuring penetration and distribution of the cement mantle in the proximal tibia after total knee arthroplasty (TKA) with Computer Tomography (CT) in vivo. Methods Standardized CT scans of the proximal tibia were taken 1 to 2 years after total knee arthroplasties impla...
Context in source publication
Citations
... Failure of tibial implants is more frequent at the interface between the implant and cement [28,29]. The volume of cement below the tibial tray decreases with increasing distance from the implant, and the distribution differs by tibia quadrant [30]. The volume of applied cement decreases with increasing application times for both cements, with significantly higher volume observed for Simplex P at 3 minutes. ...
Background
Application time and viscosity are factors that can significantly affect the properties of bone cement and implant fixation. The aim of this study was to investigate the influence of different application times of 2 different cements on mechanical parameters, cement interdigitation, and cement distribution.
Methods
P.F.C. Sigma tibial trays were cemented with high-viscous Palacos R and medium- to low-viscous Simplex P in an open-cell model. The application was performed at different times within the manufacturer’s specifications. Cement interdigitation and micromotion were measured with computed tomography scan using a novel method.
Results
Significant differences of insertion forces were found at all times of cement application. Cement penetration decreased with increasing pressure and viscosity. No significant differences were shown for micromotion between Palacos R and Simplex P except for an increase for Simplex P from 3 to 7 minutes at the bone-cement interface. Simplex P appeared to trap air at the implant-cement interface at 3 minutes and increased at 7 minutes.
Conclusions
Cement distribution and intrusion of Palacos R and Simplex P decreased with time. Simplex P trapped air at the implant-cement interface, decreasing the amount of contact at the implant-cement interface, which is worrisome for long-term implant fixation. Given the significant changes in cement properties after mixing, it is necessary for surgeons to understand the viscosity and timing of cement application to achieve optimal cement penetration and surface contact area to potentially decrease implant loosening. High-viscous Palacos R should be applicated immediately with doughing time and medium-viscous Simplex P for about 4 minutes considering a threshold of minimum pressure.
... In most previous reports, the evaluations of cement penetration were based on radiographs. Only one study was based on computed tomography (CT) measurements: Verburg et al. [6] investigated cement penetration under the tibial baseplate by using CT scans obtained after TKA. However, their method involved measuring the area of penetration on a postoperative horizontal CT slice. ...
... Therefore, increasing the depth of penetration can improve the survival rate of TKA. The CT-based Fig. 1 was used to evaluate the mean and maximum cement penetration evaluation method of Verburg et al. [6] does not measure the vertical distance of cement penetration, whereas our method uses slices of coronal to evaluate the vertical distance. In addition, by using bone morphometric techniques, we measured not only the maximum depths of penetration but also the mean depths of penetration anteriorly, centrally, and posteriorly, which is a more reliable method of measurement. ...
Purpose
This study aimed to investigate the differences in cement penetration between cementing techniques in total knee arthroplasty (TKA).
Materials and methods
We retrospectively evaluated knee undergone TKA at our hospital for both preoperative and postoperative computed tomographic (CT) evaluations. Cementing was performed with hand mixing and hand packing (HM group) and with vacuum mixing and cement gun use (VM group). We measured the area under the tibial baseplate (sclerotic and nonsclerotic sides) and compared the mean and maximum depths of cement penetration at each area.
Results
Of the 44 knees evaluated, 20 and 24 knees were in the HM and VM groups, respectively. At the center of the sclerotic side, the mean penetration depths (2.0 ± 0.7 and 2.5 ± 0.7 mm, p = 0.02) and the maximum penetration depths (4.0 ± 0.9 and 5.0 ± 1.6 mm, p = 0.02) were significantly deeper in the VM group than in the HM group. The correlation between preoperative Hounsfield unit values and mean penetration were r = –0.617 ( p < 0.01) and –0.373 ( p = 0.01) in the HM and VM groups, respectively.
Conclusion
The cementing technique of vacuum mixing and using a cement gun allowed for deeper cement penetration compared with the hand mixing and hand packing technique, even in bone sclerotic sites.
Test-retest reliability of fMRI is often assessed using the intraclass correlation coefficient (ICC), a numerical representation of reliability. Reports of low reliability at the individual level may be attributed to analytical approaches and inherent bias/error in the measures used to calculate ICC. It is unclear whether low reliability at the individual level is related to methodological decisions or if fMRI is inherently unreliable. The purpose of this study was to investigate methodological considerations when calculating ICC to improve understanding of fMRI reliability. fMRI data were collected from adolescent females (N = 23) at pre- and post-cognitive behavioral therapy. Participants completed an emotion processing task during fMRI. We calculated ICC values using contrasts and β coefficients separately from voxelwise and network (ICA) analyses of the task-based fMRI data. For both voxelwise analysis and ICA, ICC values were higher when calculated using β coefficients. This work provides support for the use of β coefficients over contrasts when assessing reliability of fMRI, and the use of contrasts may underlie low reliability estimates reported in the existing literature. Continued research in this area is warranted to establish fMRI as a reliable measure to draw conclusions and utilize fMRI in clinical settings.
Background
Aseptic loosening is one of the most common reasons for revision in knee arthroplasty. Its pathogenesis is multifactorial, and early diagnosis is necessary to initiate appropriate therapy and to avoid serious complications, such as substantial bone loss or even periprosthetic fractures.Objectives
This paper describes the current standard in the diagnosis of aseptic loosening in total knee arthroplasty. Sensitivity and specificity of the individual diagnostic procedures are presented, and other causes for differential diagnoses of painful total knee arthroplasty (TKA) are discussed.ResultsIn the case of suspected loosening in TKA, infection diagnostics should be performed to rule out periprosthetic infection, as this is crucial in terms of surgical strategy. The gold standard in diagnosing aseptic loosening is conventional radiography. Radiolucent lines at the cement-bone or metal-cement interface of more than 2 mm or increasing in translucency, migration of components, and cement fractures are obvious signs of loosening. Artifact-reduced computed tomography can bring additional information regarding periprosthetic osteolysis. A single bone scan is not reliable in diagnosing aseptic loosening, especially in the first 2 years after surgery. Single photon emission computed tomography (SPECT-CT) could be a useful extension in loosening diagnosis in the future.Conclusions
The diagnosis of aseptic loosening poses a great challenge to the treating physician and requires a structured diagnostic algorithm. After exclusion of infection, conventional radiography is the basic examination, which should be supplemented by computed tomography and nuclear medicine examinations according to the clinical symptoms and the time course.
