The accuracy of intramedullary femoral alignment in total knee replacement in the prescence of ipsilateral hip replacement

Objectives: During total knee replacement (TKR) surgery, the most commonly used method for aligning the distal femur appropriately is via an intramedullary (IM) distal femoral alignment rod. The alignment of the rod itself is reliant on the isthmus which is used to most accurately place the rod in the correct anatomical axis. In the instance of something preventing the rod from entering the isthmus correctly, such as a hip replacement, then the degree of accuracy could be assumed to be even less. Mechanical-anatomical malalignment has been shown to decrease the implant (TKR) survival and so methods of increasing accuracy of alignment relative to the mechanical axis have been developed. At present the most accurate method intraoperatively is computer navigation and several studies have demonstrated improved alignment. An increasing number of patients year on year are having both knee and hip replacements and as the population ages the likelihood of having both a knee and hip replacement will also increase. We propose that the presence of a hip replacement within the isthmus of the femur may further decrease the accuracy of the IM alignment of the femur leading to incorrect implant positioning. Methods: The study was conducted on 10 cadaveric specimens (20 femurs). Computational navigation instrumentation was attached in turn to each femur and the ideal alignment data recorded in a standard fashion by a single operator (principal investigator). A standard entry port was then be made in the femur for the introduction of the IM rod. An IM rod was then inserted with the distal femoral cutting block in the accepted position recorded blindly on the computer navigation (both in terms of varus/valgus alignment to the mechanical axis and the degree of flexion). The process was then repeated at 3 levels to represent primary and revision hip lengths from the greater trochanter (replicating the changes that would occur in the presence of a hip replacement) The process was recorded three times at each level. Results: The resection angles between the cutting surface and the mechanical axis were measured and collected by means of computer navigation system. The results show that the IM alignment had mean Valgus of 0 degrees +/- 0.8 but with a hip replacement in situ this increased to 0.46 degrees +/- 1.49 (range 2.5 varus to 4.5 valgus), with a revision stem 0.825 +/- 1.68 (range 2.5 varus to 4.5 valgus)and long stemmed revision 1.325 +/- 2.09 (range 5 varus to 6.5 valgus). In terms of Flexion IM alignment had a mean flexion of 0.92 +/- 1.7 (range 3 extension to 4 flexion) but with a hip replacement in situ this increased to 1.88 degrees +/- 2.03 (range 2.5 extension to 8.5 flexion), with a revision stem 2.35 +/- 2.2 (range 2.5 extension to 8 flexion) and long stemmed revision 2.75 +/- 2.16(range 3.5 extension to 7 flexion). Conclusion: This Study concludes that the prescence of a hip replacement, in particular long stemmed prosthesis, further reduces the accuracy of IM alignment in the Femur for Total Knee Replacement. Consideration of an alternative method, such as navigation, should be considered insuch situations

Ultrafast dynamics in light-driven molecular rotary motors probed by femtosecond stimulated raman spectroscopy

Photochemical isomerization in sterically crowded chiral alkenes is the driving force for molecular rotary motors in nanoscale machines. Here the excited state dynamics and structural evolution of the prototypical light driven rotary motor are followed on the ultrafast timescale by femtosecond stimulated Raman spectroscopy (FSRS) and transient absorption (TA). TA reveals a sub 100 fs blue shift and decay of the Franck-Condon bright state arising from relaxation along the reactive potential energy surface. The decay is accompanied by coherently excited vibrational dynamics which survive the excited state structural evolution. The ultrafast Franck-Condon bright state relaxation is to a dark excited state, which FSRS reveals to have a rich spectrum compared to the electronic ground state, with the most intense Raman active modes shifted to significantly lower wavenumber. This is discussed in terms of a reduced bond order of the central bridging bond and overall weakening of bonds in the dark state, which is supported by electronic structure calculations. The observed evolution in the FSRS spectrum is assigned to vibrational cooling accompanied by partitioning of the dark state between the product isomer and the original ground state. Formation of the product isomer is observed in real time by FSRS. It is formed vibrationally hot and cools over several picoseconds, completing the characterization of the light driven half of the photocycle

PRACTICE OF CAD AND CAE DESIGN IN THE FIELD OF PLASMA TECHNOLOGIES

The effectiveness of automated plasma torch design methods can be improved by integrating design and engineering analysis technologies. The features of CAD and CAE technologies for designing plasma torches are considered. Shows examples of the design of plasma torches for cutting metals and waste treatment with the use of digital technologies.Эффективность автоматизированных методов проектирования плазмотронов можно повысить за счет интеграции технологий проектирования и инженерного анализа. Рассмотрены особенности CAD и CAE технологий проектирования плазмотронов. Показаны примеры проектирования плазмотронов для резки металлов и обезвреживания отходов с применением цифровых технологий

Medium to long-term results of a recessed glenoid for glenoid resurfacing in total shoulder arthroplasty

Background: Recessed mini-glenoid components provide an alternative to total shoulder replacement that may avoid some of the known shortcomings and complications associated with shoulder hemiarthroplasty or standard glenoid components in difficult cases. This study reports survivorship, radiological and clinical outcomes of a recessed mini-glenoid implant in a consecutive cohort. Methods: Retrospective cohort study reporting outcomes of 28 consecutive shoulders (27 patients) following total shoulder replacement using a recessed, cemented mini-glenoid implant at two sites. Results: The most frequent diagnosis was primary osteoarthritis (79%); glenoid morphology was Walch Type A (67%), B1 15%, B2 10% and C 10%. At final follow-up, pain was 16.3 (SD = 23.1), American Shoulder and Elbow Score was 64.5 (SD = 31.9) and (normalized) Constant score was 83.0 (SD = 20.7). Implant survivorship at average final follow-up of seven years (3–13) was 96.4%. Seven mini-glenoids showed small peripheral radiolucent lines at one-year X-ray follow-up but were non-progressive on subsequent imaging. Discussion: Recessed polyethylene mini-glenoid is an attractive alternative for shoulder arthroplasty and provides an intermediate solution between standard glenoid components and hemiarthroplasty. Our medium to long-term results demonstrate reliable clinical outcomes, absence of glenoid erosion, low complication rate and satisfactory implant survivorship

Ultrafast isomerization dynamics of a unidirectional molecular rotor revealed by femtosecond stimulated raman spectroscopy (FSRS)

Unidirectional molecular rotors based on chiral overcrowded alkenes operate via sequential photochemical- and thermal-activated steps. Over the last decade the rotation rate limiting thermal step has been optimized through modification of the molecular structure. In recent years we have shown the photochemical step proceeds on an ultrafast timescale via a barrierless isomerization reaction. Here we reveal for the first time the excited state vibrational structure and associated ultrafast dynamics for a unidirectional molecular rotor, providing insight into the structural and electronic evolution involved in the rotary motion

PD1 blockade potentiates the therapeutic efficacy of photothermally-activated and MRI-guided low temperature-sensitive magnetoliposomes

This study investigates the effect of PD1 blockade on the therapeutic efficacy of novel doxorubicin-loaded temperature-sensitive liposomes. Herein, we report photothermally-activated, low temperature-sensitive magnetoliposomes (mLTSL) for efficient drug delivery and magnetic resonance imaging (MRI). The mLTSL were prepared by embedding small nitrodopamine palmitate (NDPM)-coated iron oxide nanoparticles (IO NPs) in the lipid bilayer of low temperature-sensitive liposomes (LTSL), using lipid film hydration and extrusion. Doxorubicin (DOX)-loaded mLTSL were characterized using dynamic light scattering, differential scanning calorimetry, electron microscopy, spectrofluorimetry, and atomic absorption spectroscopy. Photothermal experiments using 808 nm laser irradiation were conducted. In vitro photothermal DOX release studies and cytotoxicity was assessed using flow cytometry and resazurin viability assay, respectively. In vivo DOX release and tumor accumulation of mLTSL(DOX) were assessed using fluorescence and MR imaging, respectively. Finally, the therapeutic efficacy of PD1 blockade in combination with photothermally-activated mLTSL(DOX) in CT26-tumor model was evaluated by monitoring tumor growth, cytokine release and immune cell infiltration in the tumor tissue. Interestingly, efficient photothermal heating was obtained by varying the IO NPs content and the laser power, where on-demand burst DOX release was achievable in vitro and in vivo. Moreover, our mLTSL exhibited promising MR imaging properties with high transverse r 2 relaxivity (333 mM −1 s −1), resulting in superior MR imaging in vivo. Furthermore, mLTSL(DOX) therapeutic efficacy was potentiated in combination with anti-PD1 mAb, resulting in a significant reduction in CT26 tumor growth via immune cell activation. Our study highlights the potential of combining PD1 blockade with mLTSL(DOX), where the latter could facilitate chemo/photothermal therapy and MRI-guided drug delivery