Objectives
Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty for patients who require treatment of single-compartment osteoarthritis, especially for young patients. To satisfy this requirement, new patient-specific prosthetic designs have been introduced. The patient-specific UKA is designed on the basis of data from preoperative medical images. In general, knee implant design with increased conformity has been developed to provide lower contact stress and reduced wear on the tibial insert compared with flat knee designs. The different tibiofemoral conformity may provide designers the opportunity to address both wear and kinematic design goals simultaneously. The aim of this study was to evaluate wear prediction with respect to tibiofemoral conformity design in patient-specific UKA under gait loading conditions by using a previously validated computational wear method.
Methods
Three designs with different conformities were developed with the same femoral component: a flat design normally used in fixed-bearing UKA, a tibia plateau anatomy mimetic (AM) design, and an increased conforming design. We investigated the kinematics, contact stress, contact area, wear rate, and volumetric wear of the three different tibial insert designs.
Results
Conforming increased design showed a lower contact stress and increased contact area. In addition, increased conformity resulted in a reduction of the wear rate and volumetric wear. However, the increased conformity design showed limited kinematics.
Conclusion
Our results indicated that increased conformity provided improvements in wear but resulted in limited kinematics. Therefore, increased conformity should be avoided in fixed-bearing patient-specific UKA design. We recommend a flat or plateau AM tibial insert design in patient-specific UKA.
Cite this article
: Y-G. Koh, K-M. Park, H-Y. Lee, K-T. Kang. Influence of tibiofemoral congruency design on the wear of patient-specific unicompartmental knee arthroplasty using finite element analysis.
Bone Joint Res
2019;8:156–164. DOI: 10.1302/2046-3758.83.BJR-2018-0193.R1.
Angelica keiskei (AK) is a leafy green vegetable rich in phytochemicals such as carotenoids (C) and flavonoids (F). To determine the absorption kinetics of polyphenols in AK and the alteration of antioxidant performance in vivo, older adults (>60 y) with metabolic syndrome (MetS, n=5) and healthy controls (HC, n=5) consumed 5 g dry AK powder encapsulated in gelatin capsules with a low C & F liquid diet. Plasma samples were collected at baseline, 30 min, 1, 2, 3, 4, 5, 6, 7, and 8 h and analyzed for C and F using HPLC with UV and EC detection, respectively, for Total Antioxidant Performance (TAP) by fluorometry, and for DNA damage using single cell gel electrophoresis (Comet assay). After ingesting AK, increases in plasma quercetin were observed at 1–3 and 6–8 h in the HC and at all time points in the MetS groups compared to baseline (p<0.05). Plasma lutein was elevated in the HC group at all time points and at 6–8 h in the MetS group compared to baseline (p<0.05). Increase in TAP were observed at 1, 3, 6, and 7 h in the HC group and at 1 and 5h in the MetS group compared to baseline (p<0.05). Baseline DNA damage was more than 10% higher in the MetS compared to the HC group (p<0.05). Thus, phytochemicals in AK are bioavailable and can increase antioxidant performance in both HC and MetS subjects. [Supported by USDA ARS #1950‐51000‐065‐08S, USA and BioGreen 21 #20070301034009 RDA, Korea]
An integrated and fully automated high resolution mass spectrometric and bioinformatic approach was set‐up for the rapid and unequivocal identification of flavonoids and other phenol compounds in plant extract. The approach consists of the following steps: 1) direct infusion of the extract into an Orbitrap mass analyzer (resolution 100,000; negative ion‐mode, ESI source); 2) automated identification of the monoisotopic masses and of the corresponding isotopic patterns by a Boolean logic algorithm; 3) searching the experimental monoisotopic masses (tolerance 5 ppm) in a database of flavonoids (http://www.phenol-explorer.eu/compounds; http://www.metabolome.jp/download/flavonoid/) implemented with phenol compounds (i.e. chalcons). Final identification is achieved by matching the isotopic pattern and by MS/MS fragmentation studies. In particular, experimental MS/MS fragments are matched with those retrieved by the data base http://www.massbank.jp and by the predicted ions obtained by the software ACD/MS‐fragmenter. The method was firstly validated by mixtures of standard polyphenols and was then applied for the identification of phenols and flavonoids contained in an EtOH extract of Angelica keiskei. The method can also be used for semiquantitative analysis using Trolox as internal standard. [Supported by USDA ARS #58‐1950‐7‐707, USA and BioGreen 21 #20070301034009 RDA, Korea]
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