Mid-term survivorship and clinical outcomes of revision knee arthroplasty using a mobile bearing tibial tray: A single-center registry review

BACKGROUND

Revision total knee arthroplasty can successfully restore function and relieve pain for patients with failed knee replacements. Mobile-bearing implants were designed to provide greater congruency between the implant and the polyethylene insert. The goal of this study was to review the clinical outcomes and survivorship for a revision mobile-bearing tibial design.

METHODS

A retrospective outcomes review was conducted to assess survivorship and clinical outcomes for a mobile bearing tibial tray, used with metaphyseal sleeves, in revision total knee arthroplasty.

RESULTS

At time of furthest follow-up, KM estimates (95% CI; n with further follow-up) for all-cause revision were 82.5% (75.8%; 87.5%; 42) at 7 years for the clinical assumption (CA), and 88.5% (84.4%,91.6%; 53) at 13 years for the registry assumption (RA). For revision of the tray as the endpoint, survivorship estimates were 93.4% (87.0%,96.7%; 42) at 7 years for CA, and 96.2% (93.2%,97.9%; 53) at 13 years for RA.

CONCLUSION

In this single-center registry evaluation, we found excellent mid-term survivorship and clinical outcomes for a mobile-bearing tibial tray used with metaphyseal sleeves in revision total knee arthroplasty.

Corrigendum to 'Long-Term Results of Delta Ceramic-On-Ceramic Total Hip Arthroplasty' [Arthroplasty Today Volume 13, February 2022, Pages 130-135]

[This corrects the article DOI: 10.1016/j.artd.2021.11.006.].

Intermediate-Term Survivorship of Total Hip Arthroplasty With a Proximally Coated Tapered-Wedge Femoral Stem: A Retrospective, Multi-Center Registry Review

BACKGROUND

Short tapered-wedge stems have been used frequently over the past decade, but long-term follow-up data are not readily available in the literature.

METHODS

A retrospective outcomes review was conducted to assess survivorship and clinical outcomes for the TRI-LOCK® Bone Preservation Stem (TRI-LOCK BPS; DePuy Synthes, Warsaw, IN, USA), a proximally coated, tapered-wedge femoral stem.

RESULTS

In a cohort of 2,040 hips, Kaplan-Meier survivorship estimates (95% CI {confidence interval}; N with further follow-up, where N is the number of hips remaining at each post-operative interval), with survivorship defined as no revision of any component for any reason were 96.6% (92.8%,98.4%; 45) at eight years under the clinical assumption and 98.6% (97.9%,99.1%; 90) at 14 years under the registry assumption. With survivorship defined as stem revision for any reason, estimates were 97.7% (93.7%,99.2%; 45) at eight years under the clinical assumption and 99.2% (98.6%,99.5%; 90) under the registry assumption. Mean Harris Hip Scores and WOMAC scores were 90.08 and 21.98, respectively, at 10 years postoperatively.

CONCLUSION

Our evaluation demonstrates excellent construct and stem survivorship and clinical outcomes at intermediate-term postoperative follow-up.

Atomic force microscopy: a tool for studying biophysical surface properties underpinning fungal interactions with plants and substrates

One of the primary roles of the cell surface is to provide an effective barrier to various external environmental factors. Specifically, the surface properties of organisms serve as a critical obstacle to pathogen attack. Since its inception, Atomic Force Microscopy (AFM) has enabled nanoscale imaging of cell surfaces in their native state. However AFM has yet to be systematically applied toward resolving surface features and the forces underpinning plant-fungal interactions. In an effort to understand the physical forces involved at the plant-microbe interface, we describe a method for the attachment of fungal spores to AFM tips and the subsequent measurement of unbinding forces between spores with a range of substrates and plant surfaces under physiologically relevant conditions. Investigations of binding events using AFM offer an unexplored, sensitive, and quantitative method for analyzing host-pathogen/microbe-surface interactions.

Selection of optimal reference genes for normalization in quantitative RT-PCR

Background

Normalization in real-time qRT-PCR is necessary to compensate for experimental variation. A popular normalization strategy employs reference gene(s), which may introduce additional variability into normalized expression levels due to innate variation (between tissues, individuals, etc). To minimize this innate variability, multiple reference genes are used. Current methods of selecting reference genes make an assumption of independence in their innate variation. This assumption is not always justified, which may lead to selecting a suboptimal set of reference genes.

Results

We propose a robust approach for selecting optimal subset(s) of reference genes with the smallest variance of the corresponding normalizing factors. The normalizing factor variance estimates are based on the estimated unstructured covariance matrix of all available candidate reference genes, adjusting for all possible correlations. Robustness is achieved through bootstrapping all candidate reference gene data and obtaining the bootstrap upper confidence limits for the variances of the log-transformed normalizing factors. The selection of the reference gene subset is optimized with respect to one of the following criteria: (A) to minimize the variability of the normalizing factor; (B) to minimize the number of reference genes with acceptable upper limit on variability of the normalizing factor, (C) to minimize the average rank of the variance of the normalizing factor. The proposed approach evaluates all gene subsets of various sizes rather than ranking individual reference genes by their stability, as in the previous work. In two publicly available data sets and one new data set, our approach identified subset(s) of reference genes with smaller empirical variance of the normalizing factor than in subsets identified using previously published methods. A small simulation study indicated an advantage of the proposed approach in terms of sensitivity to identify the true optimal reference subset in the presence of even modest, especially negative correlation among the candidate reference genes.

Conclusions

The proposed approach performs comprehensive and robust evaluation of the variability of normalizing factors based on all possible subsets of candidate reference genes. The results of this evaluation provide flexibility to choose from important criteria for selecting the optimal subset(s) of reference genes, unless one subset meets all the criteria. This approach identifies gene subset(s) with smaller variability of normalizing factors than current standard approaches, particularly if there is some nontrivial innate correlation among the candidate genes.

Chunking mechanisms in human learning

Pioneering work in the 1940s and 1950s suggested that the concept of 'chunking' might be important in many processes of perception, learning and cognition in humans and animals. We summarize here the major sources of evidence for chunking mechanisms, and consider how such mechanisms have been implemented in computational models of the learning process. We distinguish two forms of chunking: the first deliberate, under strategic control, and goal-oriented; the second automatic, continuous, and linked to perceptual processes. Recent work with discrimination-network computational models of long- and short-term memory (EPAM/CHREST) has produced a diverse range of applications of perceptual chunking. We focus on recent successes in verbal learning, expert memory, language acquisition and learning multiple representations, to illustrate the implementation and use of chunking mechanisms within contemporary models of human learning.