Introducion: The malimplantation of the total knee arthroplasty (TKA) components is one of the main reasons for revision surgery. For determining the correct intraoperative femoral rotation several anatomic rotational axes were described in order to achieve a parallel, balanced flexion gap. In this cadaveric study prevalent used rotational femoral axes and a navigated functional rotational axis were compared to the flexion-extension axis defined as the gold standard in rotation for femoral TKA component rotation.
Materials And Methods: Thirteen body donors with knee osteoarthritis (mean age: 78.85 ± 6.09; eight females and five males) were examined. Rotational computer tomography was performed on their lower extremities pre- and postoperatively. Knee joint arthroplasties were implanted and CT diagnostics were used to compare the preoperatively determined flexion-extension axis (FEA). The FEA is the axis determined by our surgical technique and serves as an internal reference. It was compared to other axes such as (i) the anatomical transepicondylar axis (aTEA), (ii) the surgical transepicondylar axis (sTEA), (iii) the posterior condylar axis (PCA) and (iv) the functional rotation axis (fRA).
Results: Examination of 26 knee joint arthroplasties revealed a significant angular deviation (p < 0.0001) for all axes when the individual axes and FEA were compared. aTEA show mean angular deviation of 5.2° (± 4.5), sTEA was 2.7° (± 2.2), PCA 2.9° (± 2.3) and the deviation of fRA was 4.3° (± 2.7). A tendency towards external rotation was observed for the relative and maximum axis deviations of the aTEA to the FEA, for the sTEA and the fRA. However, the rotation of the posterior condylar axis was towards inwards.
Conclusions: All axes showed a significant angular deviation from the FEA. We conclude that the presented technique achieves comparable results in terms of FEA reconstruction when compared with the use of the known surrogate axes, with certain deviations in terms of outliers in the internal or external rotation.
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http://dx.doi.org/10.1007/s00402-024-05394-3 | DOI Listing |
Spine Deform
January 2025
Department of Orthopedic Surgery, Children's Mercy Kansas City, Kansas City, Missouri, USA.
Purpose: Scoliosis is a complex multi-dimensional deformity of the spine that is common in children and adults. Of the various treatments for scoliosis, one is posterior spinal fusion with instrumentation. The rods typically used are composed of titanium or cobalt-chrome.
View Article and Find Full Text PDFJ Craniomaxillofac Surg
January 2025
Digital Technology Center, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China. Electronic address:
Objectives: This study aimed to evaluate the anthropometric accuracy of 3D face reconstruction based on neural networks (3DFRBN) using 2D images, including the assessment of global errors and landmarks, as well as linear and angular measurements.
Methods: Thirty healthy volunteers were recruited in this study. For each volunteer, five standard photos were taken, capturing anterior, 45° to left and right, and 90° to left and right views.
Waveguide coupling design is one of the most challenging topics in augmented reality (AR) near-eye displays (NED). The primary challenge stems from the necessity to simultaneously address two competing factors: the overall volume of the AR system and the occurrence of chromatic aberration. To address this issue, what we believe to be a novel tandem trilayer achromatic metasurface is specifically designed for waveguide coupling in AR NEDs, capable of achieving an achromatic effect in a nanometer-thin layer.
View Article and Find Full Text PDFSpatial anti-bunching, in contrast to the well-known bunching behavior observed in classical light sources, describes a situation where photons tend to avoid each other in space, resulting in a reduced probability of detecting two or more photons in proximity. This anti-bunching effect, a hallmark of nonclassical light, signifies a deviation from classical intensity fluctuations and has been observed not only in free electrons and entangled photon pairs but also in chaotic-thermal light. This work investigates the generation mechanism of spatial anti-bunching correlation in random light fields, leveraging the wandering of light centers to induce a second-order coherence degree below unity.
View Article and Find Full Text PDFJ Dent
January 2025
Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University; Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Disease, College of Stomatology, Xi'an Jiaotong University; Department of Implant Dentistry, College of Stomatology, Xi'an Jiaotong University. Electronic address:
Objective: The study aimed to evaluate the accuracy and safety of the semi-active robotic system for implant placement in atrophic posterior maxilla.
Methods: Patients underwent robot-assisted implant placement in atrophic posterior maxilla were identified and included. Cone-beam computed tomography (CBCT) was performed before surgery.
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