3D Printing-Assisted Supramalleolar Osteotomy for Ankle Osteoarthritis

Ankle osteoarthritis (OA) is an important factor that causes pain and dysfunction after ankle joint movement. In early and mid-term ankle OA, supramalleolar osteotomy can delay the progression of disease and maximize the preservation of ankle joint function. Three-dimensional printing (3DP) technology has brought us new hope, which can improve the accuracy of osteotomy, reduce the number of fluoroscopy, reduce the amount of blood loss, and achieve personalized and accurate treatment. The data of 16 patients with ankle OA in our center from January 2003 to July 2020 were retrospectively analyzed and divided into the 3DP group and the traditional group according to different treatment methods. Seven patients in the 3DP group used the 3DP personalized osteotomy guide; nine patients were treated by traditional osteotomy. All patients were followed up for 13.9 ± 3.1 months after the operation. The operation time in the 3DP group was 126.4 ± 11.1 min, its intraoperative blood loss was 85.7 ± 24.1 mL, and its intraoperative fluoroscopy time was 2.4 ± 0.2, which were all significantly less than 167.3 ± 12.2 min, 158.3 ± 22.8 mL, and 5.8 ± 0.2 times in the traditional group (P < 0.05), respectively. In the 3DP group, its postoperative tibial anterior surface (TAS) angle was 90.6 ± 0.3° and the talar tilt (TT) angle was 2.2 ± 0.6°, which were all significantly different compared with its preoperative data of 83.4 ± 1.7 and 8.0 ± 1.5°, respectively (P < 0.05). Compared with traditional osteotomy, 3DP-assisted supramalleolar osteotomy for varus and valgus ankle OA can significantly shorten the operation time and reduce intraoperative bleeding and the frequency of intraoperative fluoroscopy; personalized 3DP osteotomy guides and models can assist in the accurate correction of varus deformity during operation, restore the lower limb alignment, and improve the biomechanical status of the lower limbs. In addition, the 3DP of porous tantalum has good histocompatibility, and its interface structure and porosity are more conducive to bone ingrowth. For complex bone defects and revision prostheses, matching implants can be printed individually, which could realize the personalized precise treatment

The discipline information given by PNAS.

<p>The panels (a,b) respectively come from <a href="http://www.pnas.org/content/110/18.toc" target="_blank">http://www.pnas.org/content/110/18.toc</a>, <a href="http://www.pnas.org/content/110/18.toc#PhysicalSciences" target="_blank">http://www.pnas.org/content/110/18.toc#PhysicalSciences</a>.</p

Quantitative Analysis of the Interdisciplinarity of Applied Mathematics

<div><p>The increasing use of mathematical techniques in scientific research leads to the interdisciplinarity of applied mathematics. This viewpoint is validated quantitatively here by statistical and network analysis on the corpus PNAS 1999–2013. A network describing the interdisciplinary relationships between disciplines in a panoramic view is built based on the corpus. Specific network indicators show the hub role of applied mathematics in interdisciplinary research. The statistical analysis on the corpus content finds that algorithms, a primary topic of applied mathematics, positively correlates, increasingly co-occurs, and has an equilibrium relationship in the long-run with certain typical research paradigms and methodologies. The finding can be understood as an intrinsic cause of the interdisciplinarity of applied mathematics.</p></div

The correlation coefficients of certain time series pairs.

<p>In each table cell, the first value is the Spearman’s rank correlation coefficient, and the second value is the Pearson product-moment correlation coefficient.</p><p>The correlation coefficients of certain time series pairs.</p

The slopes of the linear fitting of certain time series.

<p>The time series are the annual proportion of papers containing “algorithm” and a certain topic word (the column heading) amongst papers containing that word (the first row), and amongst all of the papers (the second row).</p><p>The slopes of the linear fitting of certain time series.</p

The quarterly proportions of the papers containing a certain topic word.

<p>The topic words respectively represent four research paradigms, viz. model, experiment, simulation, and data-driven, and three transdisciplinary topics, viz. system, network, and control.</p

The discipline network.

<p>It contains 42 nodes and 354 edges. Two disciplines are connected if there is a paper in PNAS 1999-2013 belonging to them simultaneously.</p

The quarterly proportions of the papers containing “algorithm” and a certain topic word amongst the papers containing that word (Panels (a,b)), and amongst all of the papers (Panels (c,d)).

<p>The quarterly proportions of the papers containing “algorithm” and a certain topic word amongst the papers containing that word (Panels (a,b)), and amongst all of the papers (Panels (c,d)).</p

Certain quantitative indicators for the interdisciplinarity of disciplines.

<p>The degree, PageRank and betweenness centrality of the nodes in the unweighted (weighted) discipline network are denoted by <i>K</i> (<i>K</i>_<i>W</i>), <i>P</i> (<i>P</i>_<i>W</i>), and <i>B</i> respectively. The interdisciplinary strength is <i>S</i> = <i>M</i>/<i>N</i> and the cross indicator is <i>C</i> = <i>SK</i>, where <i>N</i> is the number of the papers and <i>M</i> is the number of the interdisciplinary papers of a certain discipline in PNAS 1999–2013.</p><p>Certain quantitative indicators for the interdisciplinarity of disciplines.</p

The boolean decisions of the Johansen test on certain time series pairs.

<p>When doing the test, we let the scalars of nominal significance levels be 0.05, choose the lagged difference in {1, …, 3} by AIC, and assume that there are intercepts and linear trends in the cointegrating relations and there are quadratic trends in the data. The values equal to 1 indicate cointegration, and 0 indicate not.</p><p>The boolean decisions of the Johansen test on certain time series pairs.</p